article_text
stringlengths 294
32.8k
⌀ | topic
stringlengths 3
42
|
|---|---|
Asteroids: The Building Blocks of the Solar System
Asteroids are rocky objects that orbit the Sun, mostly between Mars and Jupiter in the main asteroid belt. Some called Trojans, share the orbit of Jupiter and travel ahead or behind it. Asteroids are remnants of the early solar system when planets were forming from a disk of gas and dust around the young Sun. By studying them, we can learn more about the origin and evolution of our solar system and the planets within it.
Key takeaways:
- They are leftovers from the formation of the solar system 4.6 billion years ago
- It could be that they have different compositions depending on where they formed and how they moved
- Asteroids may have brought water and organic materials to Earth, possibly contributing to the emergence of life
- NASA’s James Webb Space Telescope will observe several asteroids in near- and mid-infrared light to reveal their properties and history
Table of Contents
What are asteroids made of?
They are made of different materials depending on where they form in the solar system. Some asteroids are rich in carbon, while others are mostly silicate (rocky) or metallic. Some may also contain water ice, organic molecules, or minerals that form in the presence of water. These variations reflect the different temperatures and pressures that existed in different regions of the solar system when it was forming.
Some may not have formed where they currently orbit. The gravitational influence of the giant planets, especially Jupiter, may have scattered some from their original locations to new ones. For example, some that formed closer to the Sun may have been flung to the outer solar system, while some that formed farther away may have migrated inward. This process may have mixed up different types of asteroids and changed their compositions over time.
Why are asteroids important?
One reason they are important is because they are fossils of the solar system. They preserve information about the conditions and processes that shaped our planetary neighborhood 4.6 billion years ago. By studying them, we can learn more about how the planets formed and evolved, and how they interacted with each other and with smaller bodies.
Another reason is that they may have played a role in the origin of life on Earth. Some may have even brought water and organic materials to our planet when they collided with it in the past. These materials are essential for life as we know it, and may have provided the building blocks for the first living cells. Some scientists even think that life may have originated on asteroids or comets, and then transferred to Earth via impacts.
How do we study asteroids?
We study asteroids using various methods, such as telescopes, spacecraft, and sample return missions. Telescopes can observe from Earth or from orbit, measuring their brightness, color, shape, size, rotation, and orbit. Telescopes can also analyze the light reflected or emitted by asteroids to determine their surface temperature, composition, and structure.
Spacecraft can visit asteroids and fly by them or orbit them for extended periods of time. Spacecraft can carry cameras, spectrometers, radars, magnetometers, and other instruments to study asteroids in more detail than telescopes can. Spacecraft can also land on or touch them briefly to collect samples or deploy rovers or probes.
Sample return missions can bring back material from asteroids to Earth for laboratory analysis. This allows scientists to examine the physical and chemical properties at high resolution and accuracy, using techniques that are not possible in space. Sample return missions can also preserve some of the original characteristics of asteroids that may be altered by exposure to space radiation or heating during entry into Earth’s atmosphere.
What will NASA’s James Webb Space Telescope do?
NASA’s James Webb Space Telescope (Webb) is a new observatory that will launch in 2021 and operate in space for at least five years. Webb will observe the universe in near- and mid-infrared light, which is invisible to human eyes but can reveal hidden features of celestial objects. Webb will study a wide range of topics, from planets and stars to galaxies and cosmology.
Webb will also study several asteroids in our solar system, both in the main asteroid belt and among Jupiter’s Trojans. Webb will use its Near Infrared Camera (NIRCam) and Mid-Infrared Instrument (MIRI) to measure the spectra of these asteroids, which will show their chemical composition and thermal properties. Webb will also use its Near Infrared Imager and Slitless Spectrograph (NIRISS) to measure how they vary in brightness as they rotate, which will reveal their shape and size.
Webb’s observations of asteroids will complement and extend the data collected by other NASA missions, such as Dawn, OSIRIS-REx, Lucy, and Psyche. Webb will also test new techniques for studying them in infrared light, which may help future missions to explore these fascinating worlds.
Check out NASA’s Website on Astroids here
Check out this article on potential Life on the moon.
Vincent Humphreys has loved space since he was a kid. The twinkling stars, boundless skies, and the allure of the unknown captivated his young imagination, setting the foundation for a lifelong fascination with the cosmos.
|
Cosmology & The Universe
|
The annular eclipse that passed over the Americas on Saturday, Oct.14, was also seen from space by earth-observation satellites.
The eclipse, during which the moon blocked out the center of the sun, causing it to appear as a glowing ring of fire in the sky over Earth, was seen by the National Oceanic and Atmospheric Administration (NOAA) satellites GOES-East and GOES-West.
Rather than the annular eclipse appearing as a fiery golden ring, the NOAA satellites saw a darker and arguably more ominous impression of the event, witnessing a dark shadow sweep over the surface of Earth. The shadow was caused by the moon passing in front of the sun as it traveled along the path of the annular eclipse.
Here is a complete satellite loop of today's eclipse from our GOES-16 satellite! #gawx pic.twitter.com/kXtr7d5ivMOctober 14, 2023
On Saturday, the annular eclipse kicked off over Oregon at around 09:13 PDT (12:13 p.m. EDT, 1613 GMT) before moving across the states of Nevada, Utah, New Mexico, and Texas. From there, the eclipse passed across the Gulf of Mexico to Mexico, then Guatemala, Belize, Honduras, Nicaragua, Costa Rica, Panama, Colombia, and Brazil before the ring of fire disappeared from the skies over the Atlantic Ocean at sunset.
The individual views provided by GOES-16 were posted to X by the National Weather Service (NWS) Atlanta. During the time-lapse footage showing the entirety of the eclipse, the moon's shadow can be seen passing diagonally across the Earth from top left to bottom right.
The GOES-West position is covered by GOES-18, which took over from GOES-17 in January 2023. It also had a view of the annular eclipse as it passed over Earth, albeit from a different angle than GOES-16. The Cooperative Institute for Research in the Atmosphere (CIRA) at Colorado State University posted GOES-West's view of the event's shadow on its X account, showing the shadow of the moon moving from the Western U.S. to South America and around the limb of Earth.
GOES-West caught the annular eclipse as it moved from the western US down to South America. pic.twitter.com/WR2J6E48jFOctober 15, 2023
An eclipse occurs when the moon passes between Earth and the sun when the three are aligned. If the moon is close to Earth, then the lunar disk will completely block the sun in an event called a total eclipse. A partial solar eclipse happens when only part of the lunar disk encroaches on the sun, making the solar disk appear like a "bite" has been taken out of it.
An annular eclipse like the one of Saturday over the Americas occurs when the moon is further from the Earth, something that happens because the moon's orbit is an ellipse rather than a perfect circle, meaning that there are times it is closer to the planet and times it is further away. Because of its distance from the planet, the moon is smaller and thus can't cover the entire disk of the sun and a famous "ring of fire" is created.
This annular was, for many skywatchers, a warm-up for the total solar eclipse that will be visible from the U.S. on April 8, 2024. During this event, which is the first total solar eclipse seen in the U.S. since 2017 and the last until 2044, the moon will completely obscure the sun.
During this total eclipse, rather than sweeping from Oregon to Mexico, the path of the eclipse will run from Mexico through Texas and up to the Northeast of the U.S. and up to Canada.
Originally posted on Space.com.
Live Science newsletter
Stay up to date on the latest science news by signing up for our Essentials newsletter.
Robert Lea is a science journalist in the U.K. who specializes in science, space, physics, astronomy, astrophysics, cosmology, quantum mechanics and technology. Rob's articles have been published in Physics World, New Scientist, Astronomy Magazine, All About Space and ZME Science. He also writes about science communication for Elsevier and the European Journal of Physics. Rob holds a bachelor of science degree in physics and astronomy from the U.K.’s Open University
|
Cosmology & The Universe
|
Cambridge, MA – Astronomers agree that planets are born in protoplanetary disks — rings of dust and gas that surround young, newborn stars. While hundreds of these disks have been spotted throughout the universe, observations of actual planetary birth and formation have proved difficult within these environments. Now, astronomers at the Center for Astrophysics | Harvard & Smithsonian have developed a new way to detect these elusive newborn planets — and with it, "smoking gun" evidence of a small Neptune or Saturn-like planet lurking in a disk. The results are described today in The Astrophysical Journal Letters. "Directly detecting young planets is very challenging and has so far only been successful in one or two cases," says Feng Long, a postdoctoral fellow at the Center for Astrophysics who led the new study. "The planets are always too faint for us to see because they’re embedded in thick layers of gas and dust." Scientists instead must hunt for clues to infer a planet is developing beneath the dust. "In the past few years, we've seen many structures pop up on disks that we think are caused by a planet's presence, but it could be caused by something else, too" Long says. "We need new techniques to look at and support that a planet is there." For her study, Long decided to re-examine a protoplanetary disk known as LkCa 15. Located 518 light years away, the disk sits in the Taurus constellation on the sky. Scientists previously reported evidence for planet formation in the disk using observations with the ALMA Observatory. Long dove into new high-resolution ALMA data on LkCa 15, obtained primarily in 2019, and discovered two faint features that had not previously been detected. About 42 astronomical units out from the star — or 42 times the distance Earth is from the Sun — Long discovered a dusty ring with two separate and bright bunches of material orbiting within it. The material took the shape of a small clump and a larger arc, and were separated by 120 degrees. Long examined the scenario with computer models to figure out what was causing the buildup of material and learned that their size and locations matched the model for the presence of a planet. "This arc and clump are separated by about 120 degrees," she says. "That degree of separation doesn’t just happen — it’s important mathematically." Long points to positions in space known as Lagrange points, where two bodies in motion — such as a star and orbiting planet — produce enhanced regions of attraction around them where matter may accumulate. "We're seeing that this material is not just floating around freely, it's stable and has a preference where it wants to be located based on physics and the objects involved," Long explains. In this case, the arc and clump of material Long detected are located at the L4 and L5 Lagrange points. Hidden 60 degrees between them is a small planet causing the accumulation of dust at points L4 and L5. The results show the planet is roughly the size of Neptune or Saturn, and around one to three million years old. (That's relatively young when it comes to planets.) Directly imaging the small, newborn planet may not be possible any time soon due to technology constraints, but Long believes further ALMA observations of LkCa 15 can provide additional evidence supporting her planetary discovery. She also hopes her new approach for detecting planets — with material preferentially accumulating at Lagrange points — will be utilized in the future by astronomers. "I do hope this method can be widely adopted in the future," she says. "The only caveat is that this requires very deep data as the signal is weak." Long recently completed her postdoctoral fellowship at the Center for Astrophysics and will join the University of Arizona as a NASA Hubble Fellow this September. Co-authors on the study are Sean Andrews, Chunhua Qi, David Wilner and Karin Oberg of the CfA; Shangjia Zhang and Zhaohuan Zhu of the University of Nevada; Myriam Benisty of the University of Grenoble; Stefano Facchini of the University of Milan; Andrea Isella of Rice University; Jaehan Bae of the University of Florida; Jane Huang of the University of Michigan and Ryan Loomis of the National Radio Astronomy Observatory. This study involved high resolution ALMA observations taken with Band 6 (1.3mm) and Band 7 (0.88mm) receivers. # # # About the Center for Astrophysics | Harvard & Smithsonian The Center for Astrophysics | Harvard & Smithsonian is a collaboration between Harvard and the Smithsonian designed to ask—and ultimately answer—humanity's greatest unresolved questions about the nature of the universe. The Center for Astrophysics is headquartered in Cambridge, MA, with research facilities across the U.S. and around the world. Media Contact: Nadia Whitehead
Public Affairs Officer
Center for Astrophysics | Harvard & Smithsoniannadia.whitehead@cfa.harvard.edu
617-721-7371
|
Cosmology & The Universe
|
By Matt WilliamsIn February of 2017, the world was astounded to learn that astronomers – using data from the TRAPPIST telescope in Chile and the Spitzer Space Telescope – had identified a system of seven rocky exoplanets in the TRAPPIST-1 system. As if this wasn’t encouraging enough for exoplanet-enthusiasts, it was also indicated that three of the seven planets orbited within the stars’ circumstellar habitable zone (aka. “Goldilocks Zone”). Artist's impression of rocky exoplanets orbiting Gliese 832, a red dwarf star just 16 light-years from Earth. - Image Credit: ESO/M. Kornmesser/N. Risinger Since that time, this system has been the focus of considerable research and follow-up surveys to determine whether or not any of its planets could be habitable. Intrinsic to these studies has been the question whether or not the planets have liquid water on their surfaces. But according to a new study by a team of American astronomers, the TRAPPIST planets may actually have too much water to support life.The study, titled “Inward Migration of the TRAPPIST-1 Planets as Inferred From Their Water-Rich Compositions“, recently appeared in the journal Nature Astronomy. The study was led by Cayman T. Unterborn, a geologist with the School of Earth and Space Exploration (SESE), and included Steven J. Desch, Alejandro Lorenzo (also from the SESE) and Natalie R. Hinkel – an astrophysicists from Vanderbilt University, Nashville. For the sake of their study, the team used data from prior surveys that attempted to place constraints on the mass and diameter of the TRAPPIST-1 planets in order to calculate their densities. Much of this came from a dataset called the Hypatia Catalog (developed by contributing author Hinkel), which merges data from over 150 literary sources to determine the stellar abundances of stars near to our Sun.Using this data, the team constructed mass-radius-composition models to determine the volatile contents of each of the TRAPPIST-1 planets. What they noticed is that the TRAPPIST planets are traditionally light for rocky bodies, indicating a high content of volatile elements (such as water). On similarly low-density worlds, the volatile component is usually thought to take the form of atmospheric gases.But as Unterborn explained in a recent SESE news article, the TRAPPIST-1 planets are a different matter:“[T]he TRAPPIST-1 planets are too small in mass to hold onto enough gas to make up the density deficit. Even if they were able to hold onto the gas, the amount needed to make up the density deficit would make the planet much puffier than we see.” Artist’s impression of some of the planets orbiting the ultra-cool red dwarf star TRAPPIST-1 - Image Credit: ESO Because of this, Unterborn and his colleagues determined that the low-density component in this planetary system had to be water. To determine just how much water was there, the team used a unique software package developed known as ExoPlex. This software uses state-of-the-art mineral physics calculators that allowed the team to combine all of the available information about the TRAPPIST-1 system – not just the mass and radius of individual planets.What they found was that the inner planets (b and c) were “drier” – having less than 15% water by mass – while the outer planets (f and g) had more than 50% water by mass. By comparison, Earth has only 0.02% water by mass, which means that these worlds have the equivalent of hundreds of Earth-sized oceans in their volume. Basically, this means that the TRAPPIST-1 planets may have too much water to support life. As Hinkel explained:“We typically think having liquid water on a planet as a way to start life, since life, as we know it on Earth, is composed mostly of water and requires it to live. However, a planet that is a water world, or one that doesn’t have any surface above the water, does not have the important geochemical or elemental cycles that are absolutely necessary for life.”These findings do not bode well for those who believe that M-type stars are the most likely place to have habitable planets in our galaxy. Not only are red dwarfs the most common type of star in the Universe, accounting for 75% of stars in the Milky Way Galaxy alone, several that are relatively close to our Solar System have been found to have one or more rocky planets orbiting them. Artist’s impression of a sunset seen from the surface of an Earth-like exoplanet. - Image Credit: ESO/L. Calçada Aside from TRAPPIST-1, these include the super-Earths discovered around LHS 1140 and GJ 625, the three rocky planets discovered around Gliese 667, and Proxima b – the closest exoplanet to our Solar System. In addition, a survey conducted using the HARPS spectrograph at the ESO’s La Silla Observatory in 2012 indicated that there could be billions of rocky planets orbiting within the habitable zones of red dwarf stars in the Milky Way.Unfortunately, these latest findings indicate that the planets of the TRAPPIST-1 system are not favorable for life. What’s more, there would probably not be enough life on them to produce biosignatures that would be observable in their atmospheres. In addition, the team also concluded that the TRAPPIST-1 planets must have formed father away from their star and migrated inward over time. This was based on the fact that the ice-rich TRAPPIST-1 planets were far closer to their star’s respective “ice line” than the drier ones. In any solar system, planets that lie within this line will be rockier since their water will vaporize, or condense to form oceans on their surfaces (if a sufficient atmosphere is present). Beyond this line, water will take the form of ice and can be accreted to form planets.From their analyses, the team determined that the TRAPPIST-1 planets must have formed beyond the ice line and migrated towards their host star to assume their current orbits. However, since M-type (red dwarf) stars are known to be brightest after the first form and dim over time, the ice line would have also moved inward. As co-author Steven Desch explained, how far the planets migrated would therefore depend on when they had formed.“The earlier the planets formed, the farther away from the star they needed to have formed to have so much ice,” he said. Based on how long it takes for rocky planets to form, the team estimated that the planets must have originally been twice as far from their star as they are now. While there are other indications that the planets in this system migrated over time, this study is the first to quantify the migration and use composition data to show it.This study is not the first to indicate that planets orbiting red dwarf stars may in fact be “water worlds“, which would mean that rocky planets with continents on their surfaces are a relatively rare thing. At the same time, other studies have been conducted that indicate that such planets are likely to have a hard time holding onto their atmospheres, indicating that they would not remain water worlds for very long.However, until we can get a better look at these planets – which will be possible with the deployment of next-generation instruments (like the James Webb Space Telescope) – we will be forced to theorize about what we don’t know based what we do. By slowly learning more about these and other exoplanets, our ability to determine where we should be looking for life beyond our Solar System will be refined.Source: Universe Today - Further Reading: SESE, Nature Astronomy If you enjoy our selection of content please consider following Universal-Sci on social media:
|
Cosmology & The Universe
|
Astronomers have found that renegade objects from alien star systems could be captured by Earth's gravity and linger in orbit around our planet for potentially millions of years. However, most of these objects would likely be too small to detect with current telescopes, according to a new study published May 17 on the preprint server arXiv.
"Objects entering the solar system from the interstellar space outside of it can be trapped into bound orbits around the sun as a result of a close passage to Jupiter," co-author Avi Loeb, a professor of physics at Harvard University, told Live Science in an email. "We investigate the possibility that some of them are captured and become Near-Earth Objects (NEOs)."
Related: Are aliens real?
These "interstellar interlopers," as the team calls them, would take the form of icy rocks jettisoned from their home star systems before taking up residence in ours. However, Loeb and his colleagues do not rule out the possibility that objects crafted by intelligent aliens could end up in our solar system as well.
Intruders in our solar system
Interstellar visitors have been of great interest to astronomers since 2017, when the first "intruder" space rock — a cigar-shaped object called 'Oumuamua — was discovered in our cosmic backyard.
'Oumuamua's 1,300-foot-long (400 meters), highly elongated shape makes it around 10 times as long as it is wide, setting it apart from any known asteroids or comets native to our solar system. After observing the javelin-like space rock further, scientists concluded that it had been wandering our galaxy, unassociated with any star system, for hundreds of millions of years before its chance encounter with the solar system.
A renewed search for interstellar objects soon turned up a second object, the rogue comet Borisov — an Eiffel Tower-size ball of ice and dust from outside the solar system discovered in 2019.
Neither 'Oumuamua nor Borisov is bound to the sun, meaning both objects will eventually exit the solar system as capriciously as they entered it, with the cigar-shaped object already fleeing beyond the orbit of Neptune. In their new paper, the study authors investigated whether other interstellar bodies could be caught by the gravity of the sun, or even the planets, and thus be forced to remain in the solar system.
Previous attempts to study this idea have focused on capture by the sun and Jupiter system. For the new study, the researchers set about investigating if Earth could also capture interstellar visitors and hold on to them as NEOs.
Using numerical simulations, the team found that it is possible for Earth to periodically capture interstellar objects in its orbit. However, the effect is small compared with that of Jupiter, which is roughly a thousand times more efficient at catching interstellar objects than Earth is.
Additionally, the researchers found that any objects caught by Earth’s gravity would be unstable and would survive around our planet for a shorter time than currently known NEOs do. Eventually, these objects would be disturbed by interactions with the other planets or the sun and would be hurled from the solar system just as they were once tossed from their planetary system of origin.
Loeb explained that while the team doesn't theorize that there are currently interstellar objects orbiting Earth, astronomers should continue to check for this possibility. And the forthcoming Vera C. Rubin Observatory, set to open its eye to the universe in August 2024, should help in this quest.
"Using computer simulations, we find that a few captured objects [roughly] the size of a football field would be detectable by the Rubin Observatory that will survey the Southern sky every four days with a 3.2 billion pixel camera," Loeb said.
Studying interstellar objects around Earth could reveal new insights about the formation of distant star systems. However, Loeb added, there may be a small possibility that this interloper investigation could reveal something even more extraordinary.
"Interstellar objects originate from outside the solar system and could potentially be technological in origin, similar to the five interstellar probes that humanity has launched, Voyager 1 and 2, Pioneer 10 and 11, and New Horizons," Loeb said. (Of these five, only Voyager 1 and 2 have already left the solar system.) "If [the objects] are artificial in origin … they can tell us about extraterrestrial technological civilizations."
Live Science newsletter
Stay up to date on the latest science news by signing up for our Essentials newsletter.
Robert Lea is a science journalist in the U.K. who specializes in science, space, physics, astronomy, astrophysics, cosmology, quantum mechanics and technology. Rob's articles have been published in Physics World, New Scientist, Astronomy Magazine, All About Space and ZME Science. He also writes about science communication for Elsevier and the European Journal of Physics. Rob holds a bachelor of science degree in physics and astronomy from the U.K.’s Open University
|
Cosmology & The Universe
|
The U.S. space agency NASA released the set of the first full-color images from the James Webb Space Telescope Tuesday, a day after sharing a full-color picture of stars and galaxies deeper into the cosmos than ever seen before. Watch here: U.S. President Joe Biden said the telescope offered "a new window into the history of our universe." Tuesday’s images took weeks to render using data from the telescope. They show areas of the universe where researchers will focus future scientific inquiries. The $10 billion telescope, the largest and most powerful ever launched into space, peers farther into the cosmos than any before it.
A peek into the past
Scientists describe the telescope as looking back in time. That is because it can see galaxies that are so far away that it takes light from those galaxies billions of years to reach the telescope. "Light travels at 186,000 miles per second (299,000 meters). And that light that you are seeing on one of those little specs (in the picture) has been traveling for over 13 billion years," said NASA Administrator Bill Nelson, who attended Monday's news briefing along with Biden and Vice President Kamala Harris. The Webb telescope can see light that was created just after the Big Bang, the furthest humanity has peered into the past. A successor to the Hubble Space Telescope, Webb is about 100 times more sensitive than its 30-year-old predecessor. It is also able to use the infrared spectrum, while the Hubble used mainly optical and ultraviolet wavelengths. This image provided by NASA on July 11, 2022, shows galaxy cluster SMACS 0723, captured by the James Webb Space Telescope. The telescope is designed to peer back so far that scientists can get a glimpse of the dawn of the universe about 13.7 billion years ago. The telescope is so precise, Nelson said, that scientists will be able to see the chemical composition of planets deep in space and determine if they are habitable or not. "We are going to be able to answer questions that we don't even know what the questions are yet," he said. Harris said the telescope would "enhance what we know about the origins of our universe, our solar system and possibly life itself."
Into the cosmos
The telescope was launched December 25 from French Guiana in South America and traveled 1.6 million kilometers from Earth before beginning to capture images. Biden said the telescope took a "journey 1 million miles (1.6 million kilometers) into the cosmos … along the way unfolding itself, deploying a mirror 21 feet wide (6.4 meters), a sunshield the size of a tennis court, and 250,000 tiny shutters, each one smaller than a grain of sand." Nelson said future images would peer even further back into the origin of the cosmos, looking about 13.5 billion years into the past. Scientists will use the Webb telescope to study stars, galaxies and planets as far as the edges of the cosmos, as well as look at objects closer to us with a sharper view, including our own solar system.
Some information in this report came from The Associated Press and Reuters.
|
Cosmology & The Universe
|
James Webb Telescope is getting closer to finding what ionized the universe
Astronomers have determined that so-called "leaky" galaxies may have responsible for triggering the last great transformational epoch in our universe, one which ionized the neutral interstellar gas.
Billions of years ago our universe was a lot smaller and a lot hotter than it is today. At very early times it was so small and hot that it was in the state of a plasma, where electrons were separated from atomic nuclei. But when the universe was roughly 380,000 years old, it cooled to the point that electrons could recombine onto their nuclei, forming a soup of neutral atoms.
However, observations of the present-day universe reveal that almost all the matter in the universe is not neutral at all. Instead it's ionized, once again in the state of a plasma. Something had to happen in the intervening billions of years to transform the neutral gas of the cosmos into an ionized plasma. Astronomers call this event the Epoch of Reionization and suspect that it happened within the first few hundred million years after the Big Bang. But they are not sure how this transformational event proceeded.
One of the great debates in modern cosmology is the source of reionization. One hypothesis is that quasars are responsible. Quasars are the ultra bright cores surrounding supermassive black holes which pump out enormous amounts of high energy radiation. This radiation could easily flood the universe and transform it from neutral to ionized. But the problem with this hypothesis is that quasars are relatively rare, and so they have difficulty covering the volume of the universe.
Another hypothesis is that young galaxies rich with star formation are responsible. In this scenario the process of ionizing the neutral gas is more spread out throughout the universe. Each individual galaxy is only capable of ionizing the gas in its nearby vicinity, but since there are so many galaxies it's possible to reionization the entire universe. But the only way to do this is if enough high energy radiation leaks out of galaxies and into the surrounding medium.
One team of astronomers have used the James Webb Space Telescope to investigate this hypothesis. They can't study the radiation coming out of the galaxies directly, because that radiation gets absorbed by the billions of light-years worth of matter between us and those galaxies. So instead they had to look for other clues. Using the James Webb's ability to study distant galaxies, they were able to measure how compact the galaxies were, and how rich in star formation they were. They were then able to compare these galaxies to similar galaxies found i- the present day universe to create an estimate of the amount of radiation leaking from them.
They estimate that on average the galaxies in the early universe leaked roughly 12% of their available high energy photons. This is just enough to potentially reionization the entire cosmos in a relatively short amount of time. The findings are published in the journal Astronomy & Astrophysics.
The results are not conclusive, however, because of the number of assumptions that the astronomers had to make. But it does point in an intriguing direction in solving this long-standing cosmic riddle.
More information: S. Mascia et al, Closing in on the sources of cosmic reionization: first results from the GLASS-JWST program, Astronomy & Astrophysics (2023). DOI: 10.1051/0004-6361/202345866
Journal information: Astronomy & Astrophysics
Provided by Universe Today
|
Cosmology & The Universe
|
FILE – In this April 13, 2017 photo provided by NASA, technicians lift the mirror of the James Webb Space Telescope using a crane at the Goddard Space Flight Center in Greenbelt, Md. The telescope is designed to peer back so far that scientists will get a glimpse of the dawn of the universe about 13.7 billion years ago and zoom in on closer cosmic objects, even our own solar system, with sharper focus. (Laura Betz/NASA via AP, File)
This image provided by NASA on Monday, July 11, 2022, shows galaxy cluster SMACS 0723, captured by the James Webb Space Telescope. The telescope is designed to peer back so far that scientists can get a glimpse of the dawn of the universe about 13.7 billion years ago and zoom in on closer cosmic objects, even our own solar system, with sharper focus. (NASA/ESA/CSA via AP)
A James Webb Space Telescope photo provided by NASA shows the Carina Nebula, showing the earliest stages of star formation. (NASA via The New York Times) Ñ EDITORIAL USE ONLY Ñ
A James Webb Space Telescope photo provided by NASA shows StephanÕs Quintet, showing five galaxies, four of which interact, colliding into each other and pulling and stretching each othersÕ gravity. (NASA via The New York Times) Ñ EDITORIAL USE ONLY Ñ
A James Webb Space Telescope photo provided by NASA shows the Southern Ring Nebula, a dying star, expelling a colorful gas cloud that will eventually expand and fade away into the space between stars. (NASA via The New York Times) Ñ EDITORIAL USE ONLY Ñ
A still image from video provided by NASA shows a graph based on data from the James Webb Space Telescope. The telescope spotted the unambiguous signature of water, indications of haze and evidence of clouds in the exoplanet WASP-96b, the most detailed exoplanet spectrum to date. (NASA via The New York Times) Ñ EDITORIAL USE ONLY Ñ
An image provided by NASA shows a detail of damage to one of the James Webb Space TelescopeÕs mirrors, which was hit by a micrometeoroid. (NASA via The New York Times) Ñ EDITORIAL USE ONLY Ñ
A photo provided by NASA shows NASA Administrator James Webb circa 1962-1963. Astronomers have pushed NASA to take the name of Webb off the agencyÕs space telescope, saying he was involved in homophobic incidents. (NASA via The New York Times) Ñ EDITORIAL USE ONLY Ñ
IN SPACE – JULY 12: In this handout photo provided by NASA, the dimmer star at the center of this scene has been sending out rings of gas and dust for thousands of years in all directions, and NASA’s James Webb Space Telescope has revealed for the first time that this star is cloaked in dust on July 12, 2022 in space. Two cameras aboard Webb captured the latest image of this planetary nebula, cataloged as NGC 3132, and known informally as the Southern Ring Nebula. It is approximately 2,500 light-years away. (Photo by NASA, ESA, CSA, and STScI via Getty Images)
This image provided by NASA on Monday, July 11, 2022, shows galaxy cluster SMACS 0723, captured by the James Webb Space Telescope. The telescope is designed to peer back so far that scientists can get a glimpse of the dawn of the universe about 13.7 billion years ago and zoom in on closer cosmic objects, even our own solar system, with sharper focus. (NASA/ESA/CSA via AP)
A James Webb Space Telescope photo provided by NASA (NASA via The New York Times) Ñ EDITORIAL USE ONLY Ñ By Munina Lam
JET PROPULSION LABORATORY — It is a slide show like no other.
NASA on Tuesday, July 12, began releasing the full set of full-colored “deep field” images and data of distant galaxies captured by the James Webb Space Telescope, the successor of the Hubble telescope.
But this isn’t your everyday scroll through instagram. No no.. This is the epitome of “A long time ago, in a galaxy far, far away…” — as in what are now snapshots of a corner of the universe, capturing light from more than 13 billion years ago, from swirly white specs, faint galaxies, starlight against the darkness. These images are showing the farthest humanity has ever peered outward into the stretches of the universe. And on Tuesday, one by one at the Jet Propulsion Laboratory in La Cañada Flintridge, four galactic shots from the telescope’s initial outward gazes were set to mesmerize even the veteran scientists at JPL who contributed to the mission that would bring those images back to Earth.
The “deep field” images — images that were taken with a long exposure time to capture faint objects — were being released simultaneously across several platforms – NASA Television, Youtube, Twitter, Facebook and more.
Among them, a stunning planetary nebula, now known as the Southern Ring Nebula. The Southern Ring, or “Eight-Burst” nebula, is an expanding cloud of gas, surrounding a dying star. It is about approximately 2,000 light years away from Earth. Some stars go out with a bang. In these images of the Southern Ring planetary nebula, @NASAWebb shows a dying star cloaked by dust and layers of light. Explore this star's final performance at https://t.co/63zxpNDi4I #UnfoldTheUniverse. pic.twitter.com/dfzrpvrewQ
— NASA (@NASA) July 12, 2022 Then there was a “dance,” of sorts. As NASA described it, the telescope peered through the thick dust of Stephan’s Quintet, a galaxy cluster showing huge shockwaves and tidal tails.
“This is a front-row seat to galactic evolution,” wrote NASA on Twitter.
Stephan’s Quintet, a galaxy cluster showing huge shockwaves and tidal tails.
They include a view of a giant gaseous planet outside our solar system, more images of a nebula where stars are born and die in spectacular beauty and an update of a classic image of five tightly clustered galaxies that dance around each other.
The deepest infrared image of the universe ever taken—the first full-color image from NASA’s Webb Telescope. Cosmic cliffs & a sea of stars. @NASAWebb reveals baby stars in the Carina Nebula, where ultraviolet radiation and stellar winds shape colossal walls of dust and gas. https://t.co/63zxpNDi4I #UnfoldTheUniverse pic.twitter.com/dXCokBAYGQ
— NASA (@NASA) July 12, 2022 File photo of the James Webb Space Telescope as it was about to begin final assembly at Northrop, (Credit Northrop Grumman Corporation)
Named after NASA’s second administrator James E. Webb, Webb is an international collaborative project between NASA, the European Space Agency and Canadian Space Agency. The $10 billion telescope – the world’s biggest and most powerful – is 21 feet wide and has a sunshield that is a size of a tennis court.
The telescope was rocketed to space last December from French Guiana in South America. It reached its lookout point 1 million miles (1.6 million kilometers) from Earth in January. Then the lengthy process began to align the mirrors, get the infrared detectors cold enough to operate and calibrate the science instruments, all protected by a sunshade the size of a tennis court that keeps the telescope cool.
The plan is to use the telescope to peer back so far that scientists will get a glimpse of the early days of the universe about 13.7 billion years ago and zoom in on closer cosmic objects, even our own solar system, with sharper focus.
Webb will be used to study stars and galaxies that were formed over 13.5 billion years ago with help from its instruments: Near-Infrared Camera (NIRCam), Near-Infrared Spectrograph (NIRSpec), Mid-Infrared Instrument (MIRI), and Near-Infrared Imager and Slitless Spectrograph (NIRISS) with the Fine Guidance Sensor (FGS).
In other words, this is how galaxies looked more than 13 billion years ago.
Researchers can then study how galaxies evolve throughout the years.
The world got a preview on Monday when President Joe Biden unveiled the image of galaxy cluster called SMACS 0723 during a White House event.
Biden marveled at the image that he said showed “the oldest documented light in the history of the universe from over 13 billion — let me say that again — 13 billion years ago. It’s hard to fathom.
NASA administrator Bill Nelson described the image — filled with white, yellow, orange and red swirls, streaks and spirals — as “one little speck of the universe”, according to the Associated Press.
The deep field of SMACS 0723, composited from several different images, took Webb 12.5 hours to produce. In comparison, the same process would have taken its predecessor, Hubble, weeks to achieve.
Vice President Kamala Harris, who is also the chair of the National Space Council, lauded Webb as “one of humanity’s great engineering achievements” at the event, saying, “It will enhance what we know about the origins of our universe, our solar system and, possibly, life itself.”
Biden said that the telescope shows how America can lead by example by participating in an international collaborative effort in discovering more about the planet and climate, symbolizing American ingenuity.
“That’s why the federal government must invest in science and technology more than we have in the past,” he said.
The release of these images marks the start of Webb’s general science operations, where teams of scientists will use the telescope to do research and observations. The teams’ proposals were selected via a rigorous process over the course of the COVID-19 pandemic.
Out of over 1000s proposals, only 286 proposals were selected. Munina Lam is a freelancer for the Southern California News Group. The Associated Press contributed to this story.
|
Cosmology & The Universe
|
By Victoria GillScience correspondent, BBC NewsImage source, NASA/ESA/CSA/STScIImage caption, SMACS 0723: Red arcs in the image trace light from galaxies in the very early UniverseThere were 10 times more galaxies just like our own Milky Way in the early Universe than previously thought. This cosmic insight comes form one of the first studies of images captured by Nasa's new James Webb Space Telescope. One of its authors, Prof Christopher Conselice from the University of Manchester, UK, said that Webb could "zoom in on the early Universe". This yielded insights about objects in space that "we knew existed but didn't understand how and when they formed". Disc galaxies dominate the "galaxy population" today," the researcher explained. "Our own galaxy is a disc, Andromeda (our nearest neighbour, which is 2.5 million light-years from Earth) is a disc."Three-quarters of nearby galaxies are discs, but it was thought that they formed late in the evolution of the Universe," he told BBC News. That was before the James Webb Space Telescope gave astronomers a view so far back in time. The study, which has been published on a preprint server, meaning it has yet to be peer reviewed by other scientists in the field, used the first image released from the telescope. This image shows a foreground cluster of galaxies called SMACS 0723. The gravity of this great mass of objects has magnified the light of galaxies in the background, in distant Universe, making them visible for the first time. Some of these galaxies existed a mere 600 million years after the Big Bang.Image source, NASA/ESA/CSA/STScIImage caption, Webb is taking some incredible pictures: "This might the most important telescope ever"Webb, with its 6.5m-wide golden mirror and super-sensitive infrared instruments, is able to resolve their shapes and count them."We knew we would see things Hubble didn't see. But in this case we're seeing things differently," said Prof Conselice, who will be presenting some of his discoveries on Saturday 23 July at the Bluedot Festival at Jodrell Bank in Cheshire. The Universe is about 13.8 billion years old, so the images that the JWST is capturing are glimpses of the processes that formed stars and planets long before our own came into existence. "These are the processes we need to understand if we want to understand our origins," said Prof Conselice. "This might be the most important telescope ever," he added. "At least since Galileo's." James Webb is a joint effort between the American, European and Canadian space agencies, with Nasa in the lead. Follow Victoria on Twitter
|
Cosmology & The Universe
|
A mission to find the missing 95 per cent of the universe is due to launch on Saturday in a journey which could shed light on mysterious dark forces which helped shape Earth.
The European Space Agency (ESA) is sending up a massive telescope to look for dark energy and dark matter, two of the most mysterious and important forces in the cosmos, which are responsible for dragging galaxies further apart and binding them together.
Just five per cent of the universe is visible. The rest is made up of strange unknowns whose presence can only be inferred by their influence on the universe.
Without dark energy the universe would not continue to accelerate as it expands, while galaxies rely on the gravitational heft of dark matter to keep them together. Both have been notoriously difficult to pin down.
“It’s very difficult to find a black cat in a dark room, especially if there is no cat,” said Prof Henk Hoekstra, cosmology coordinator of the Euclid Consortium.
“We lack a good theory. So far nobody has come up with a good explanation.”
The £1.2 billion Euclid space telescope, which includes a camera developed by University College London, will peer 10 billion years into the past to find out how dark energy and matter shaped the early universe and how it has changed over time.
The telescope’s enormous field of vision is 250 times larger than the Hubble Space Telescope and once functioning will create more data in one day than Hubble has ever produced/ It will create the largest, most accurate 3-D map of space and time ever achieved.
The two instruments on board, one in the visible light spectrum and the other in the infra-red, will capture their impact on 1.5 billion galaxies – more than one third of the visible sky, and probe 70 per cent of cosmic time.
The project is 20 years in the making and has involved more than 2,500 scientists and engineers, many from Britain.
Dr Paul McNamara, the astronomy and astrophysics coordinator for Euclid at ESA, originally from Glasgow, said: “If we think about the universe, only five per cent is stuff we are made of, about 25 per cent is dark matter and the rest is dark energy.
“Dark matter doesn’t interact with normal matter. So there could be dark matter in this room we just never know about it. It doesn’t interact with us.”
Seeded the formation of galaxies
Scientists believe that after the Big Bang dark matter and visible matter began to form little clumps which seeded the formation of galaxies.
Although dark energy existed at the time, the universe was so small that dark matter was the overriding force. But about five billion years ago the universe had expanded to such an extent that dark energy became the driving force, speeding up expansion.
The change might have had a large impact on the universe and consequently Earth.
“It could well be that if we didn’t have that expansion we wouldn’t have the physics that we do,” said Dr McNamara.
The idea that the universe is being kept in static equilibrium by an invisible pervading energy was first proposed by Albert Einstein in 1917, who dubbed it the “cosmological constant”.
The telescope could prove Einstein was correct, or usher in an entirely new era of cosmology.
It has the potential to determine whether dark energy is vacuum energy – where particles pop in and out existence in empty space – a finding that would force scientists to revise theories of particle physics.
Prof Tom Kitching, of UCL Mullard Space Science Laboratory, who is one of four science coordinators for Euclid, said: “The puzzles we hope to address are fundamental.
“What is dark energy? Is it vacuum energy? Is it a new particle field that we didn’t expect?
“Or it may be Einstein’s theory of gravity that is wrong. Whatever the answer, a revolution in physics is almost guaranteed.”
A parking spot in space
The mission is due for lift-off from SpaceX, Cape Canaveral in Florida, at 4:12 pm BST on Saturday July1 2023, on a Falcon 9 rocket.
It was originally scheduled to launch on a Russian Soyuz rocket, but the war with Ukraine has caused a rift between the Russian and European space agencies.
Once in space, Euclid will travel more than one million miles away from the Sun to a point called Lagrange 2, where gravitational forces cancel out, essentially creating a parking spot in space.
Unlike normal matter, dark matter does not reflect or emit light. To map it, the Euclid mission will use a technique called weak gravitational lensing which works by measuring how much light is bent on its way through space, a good indicator of where dark matter is lurking.
|
Cosmology & The Universe
|
Lunar Telescope Will Search for Ancient Radio Waves
DOE and NASA are collaborating to land a radio telescope on the far side of the moon and probe an unexplored era of the early universe
March 8, 2023
Earth always sees the same side of the moon. The side that can't be seen, the lunar far side, is an inhospitable place where there's enough radio silence for the Dark Ages Signal to be detected.
UPTON, NY—Scientists at the U.S. Department of Energy’s (DOE) Brookhaven National Laboratory are leading a new effort to land a radio telescope on the moon. If successful, the project will mark the first step towards exploring the Dark Ages of the universe.
The Dark Ages are an early era of cosmological history starting about 380,000 years after the Big Bang. There were no stars or planets in the Dark Ages. It’s a point in time that scientists have never been able to observe. Though radio waves from the Dark Ages still linger in space, the abundance of radio interference on Earth has masked these signals from scientists seeking to study them.
If cosmologists could detect radio waves from the Dark Ages—what is known as the “Dark Ages Signal”—they could help uncover answers to some of the universe’s biggest mysteries, such as the nature of dark energy or the formation of the universe itself.
Paul O'Connor, Anže Slosar, and Sven Herrmann (pictured left to right) are shown in the instrumentation lab at Brookhaven where the team is developing LuSEE-Night's spectrometer, the heart of the instrument.
“Modeling the universe is easier before stars have formed. We can calculate almost everything exactly,” said Brookhaven physicist Anže Slosar. “So far, we can only make predictions about earlier stages of the universe using a benchmark called the cosmic microwave background. The Dark Ages Signal would provide a new benchmark. And if predictions based on each benchmark don’t match, that means we’ve discovered new physics.”
Now, a new project called the Lunar Surface Electromagnetics Experiment-Night (LuSEE-Night) aims to access the Dark Ages Signal for the first time. LuSEE-Night is a remarkable concept for a radio telescope that will be developed in collaboration between NASA and DOE, with Brookhaven Lab leading DOE’s role in the project and DOE’s Lawrence Berkeley National Lab providing key technical support.
LuSEE-Night is set to make history for its ability to reach—and survive in—an inhospitable place where there’s enough radio silence for the Dark Ages Signal to be detected: the lunar far side.
Surviving the Dark Side of the Moon
Some may know it as the “dark side of the moon,” but what is scientifically known as “the lunar far side” isn’t eternally dark. The lunar far side is named for its inability to be seen from Earth, but it experiences its own day and night cycle.
“The moon and Earth are tidally locked, which means that the moon rotates around its own axis with the same velocity as it does around the Earth,” said Slosar, who is leading DOE’s contributions to LuSEE-Night’s science program and operations and is also the LuSEE-Night collaboration spokesperson. “This is why we always see the same side of the moon. But the side we can’t see, the lunar far side, is shielded from many sources of radio interference at night by the moon’s own mass.”
Cosmologists around the world have been interested in observing the universe from the lunar far side for decades and they have attempted to reach it before. But in exchange for the radio silence the lunar far side provides, it presents a treacherous environment with little chance for scientific equipment to survive—let alone transmit data back to Earth.
The LuSEE-Night landing site is located on the lunar far side at 23°48'50"S 176°49'47"E, on a local topographical high point. The southern location gives scientists improved coverage by the relay communication satellite.
The lunar far side is in total darkness for 14 Earth days followed by 14 days of brutal sunlight. That causes temperatures to fluctuate between 250 and -280 degrees Fahrenheit—and a dramatic change can happen in a matter of hours.
“The moon is easier to reach than Mars, but everything else is more challenging,” said Paul O’Connor, a senior scientist in Brookhaven’s Instrumentation Division and LuSEE-Night Project Instrument Scientist. “There's a reason only one robotic rover has landed on the Moon in the last 50 years, while six went to Mars, which is 100 times farther away. It’s a vacuum environment, which makes removing heat difficult, and there’s a bunch of radiation.”
LuSEE-Night must reject heat in a vacuum environment during the day and keep itself from freezing at night—all while powering itself through 14 days of continuous darkness and conducting first-of-its-kind science.
“The power has to come from a battery, which can only be so efficient based on its size,” O’Connor said. “More powerful batteries are heavier, and a flight mission to the moon has a strict mass limit. We have to be very parsimonious with the power that we allocate, and it puts us in a familiar domain where we must make trade-offs between power and sensitivity.”
Brookhaven’s Expertise Leads the Way
Building world-leading scientific instrumentation under strict design requirements is a longstanding area of expertise for Brookhaven Lab’s Instrumentation Division.
“We have a long history of building detector instrumentation that reaches the ultimate limits of sensitivity, whether that be for detecting subatomic particles in high energy physics experiments or ultrabright x-rays at the National Synchrotron Light Source II,” O’Connor said. “Over the last 15 years we’ve moved toward more astrophysics applications. Most notably, Brookhaven developed the 3.2 gigapixel sensor array for the Rubin Observatory. It is the biggest charge-coupled device (CCD) array that has ever been built.”
Brookhaven’s leadership role in the LuSEE-Night project also brings expertise in radio cosmology. In particular, the Lab has previously demonstrated the ability to design, construct, and operate a prototype radio telescope. Physicists, engineers, and technicians from the Lab’s Instrumentation Division and Physics Department collaborated to create the prototype and observe large swaths of the distant cosmos with high sensitivity.
The Lab’s scientific and technical expertise is a critical combination for achieving LuSEE-Night’s ambitious science goals and design requirements—particularly for developing highly sensitive radio telescopes.
“LuSEE-Night is not a standard radio telescope,” Slosar said. “It’s more of a radio receiver. It will work like an FM radio, picking up radio signals in a similar frequency band. The spectrometer is at the heart of it. Like a radio tuner, it can separate out radiofrequencies, and it turns signals into spectra. That’s where our expertise gives us a starting point. Even though nobody has built an instrument like this before, we know how to build the most crucial component—a very sensitive spectrometer.”
Anže Slosar, Sven Herrmann, and Paul O'Connor (pictured left to right) stand in front of BMX, the prototype radio telescope that was developed at Brookhaven in collaboration between the Physics Department and the Instrumentation Division.
In addition to building the all-important spectrometer, Brookhaven is leading the DOE effort to construct the whole telescope.
“We will build out LuSEE-Night’s electronics, procure the batteries, solar panels, and communications equipment, and ensure all components of the instrument are cohesive and suited for spaceflight,” said Brookhaven scientist Sven Herrmann, the LuSEE-Night Construction Project Manager for DOE’s part of the mission and a researcher at the Kavli Institute for Particle Astrophysics and Cosmology. “We will handle the inner equipment assembly, then ship the pieces to UC Berkeley’s Space Sciences Laboratory for end integration. NASA will coordinate the launch through its Commercial Lunar Payload Services program, which leverages private companies to provide the transport to the moon .”
After touching down on the lunar far side, LuSEE-Night’s lander will turn off permanently so it does not produce any interference. The telescope will then deploy four three-meter-long antennas, developed by Berkeley Lab, on a turntable for data collection. Then, LuSEE-Night must face its greatest challenge: surviving its first night on the lunar far side.
At home on Earth, scientists must patiently wait 40 days for LuSEE-Night to collect and transmit its first dataset to a relay satellite that talks to Earth. Until then, they won’t know if LuSEE-Night survived.
If LuSEE-Night does survive, the collaboration will achieve its main goal: to prove that the long-sought lunar far side is accessible for radio cosmology experiments. Scientists will then have a proof-of-concept for developing a more elaborate telescope in the future that is better equipped to detect the distant Dark Ages Signal—if it’s needed.
While LuSEE-Night is primarily considered a pathfinder, it is designed to collect data for two years and magnificent discoveries are possible. LuSEE-Night could exceed its main goal and detect the Dark Ages Signal on its own, or even uncover new and unexpected mysteries hidden deep in the cosmos along the way.
Brookhaven National Laboratory is supported by the Office of Science of the U.S. Department of Energy. The Office of Science is the single largest supporter of basic research in the physical sciences in the United States and is working to address some of the most pressing challenges of our time. For more information, visit science.energy.gov.
2023-19559 | INT/EXT | Newsroom
|
Cosmology & The Universe
|
The most accurate observation to date of distant stars that periodically change in brightness may spark a rethink of the rate at which the universe expands — perhaps by settling a longstanding problem in cosmology, or deepening it.
The observation confirms a disparity that exists between the two major methods of measuring how fast the universe is expanding, conforming with one but not the other, a new study reports.
Researchers with the Stellar Standard Candles and Distances group used data collected by Europe's Gaia spacecraft to study Cepheid variable stars, which pulsate in a regular manner, providing a way of accurately measuring cosmic distances. The Cepheid star measurement technique expands on other methods, such as one that relies on observations of Type 1a supernovas.
The light output of supernovas, mammoth explosions that occur at the end of big stars' lives, is so uniform they are referred to as "standard candles" and form an important part of what astronomers call the "cosmic distance ladder." The Cepheid star distance measurement method adds another "rung" to that metaphorical ladder, and this new research has strengthened that rung.
"We developed a method that searched for Cepheids belonging to star clusters made up of several hundreds of stars by testing whether stars are moving together through the Milky Way," study co-author Richard Anderson, a physicist at the École Polytechnique Fédérale de Lausanne (EPFL) in Switzerland, said in a statement (opens in new tab).
"Thanks to this trick, we could take advantage of the best knowledge of Gaia's parallax measurements while benefiting from the gain in precision provided by the many cluster member stars," Anderson said. "This has allowed us to push the accuracy of Gaia parallaxes to their limit and provides the firmest basis on which the distance ladder can be rested."
The cosmic distance ladder is also used to measure the expansion rate of the universe, known as the Hubble constant. This new recalibration of the Cepheid "rung" deepens a problem with the rate at which the universe expands, which has come to be known as the "Hubble tension."
What is the Hubble tension?
In the early 20th century, shockwaves rippled through physics and astronomy when Edwin Hubble uncovered evidence that the universe is not static, as was believed at the time, but is actually expanding. This rate of expansion therefore became known as the Hubble constant.
This concept underwent a major shakeup in the late 1990s, when astronomers discovered via the observation of distant supernovas that, not only is the universe expanding, but it is doing so at an accelerating rate. Since then, measuring the Hubble constant has become a thorny issue for astronomers and cosmologists, because there are two major ways of determining this value — and they don't agree.
One method uses galaxies' velocities as a function of distance to deliver a Hubble constant value of about 73 ± 1 kilometers per second per megaparsec (km/s/Mpc), with 1 Megaparsec representing around 3.26 million light-years. This is known as the "late time" solution, because it comes from measurements of the universe in recent times.
The other method of measuring the Hubble constant looks at the light from an event shortly after the Big Bang called "the last scattering," in which electrons combined with protons to form the first atoms. As free electrons had previously scattered photons (particles of light) dramatically, preventing them from traveling very far, this event meant that light was suddenly allowed to travel through the cosmos freely.
This "first light" is now seen as the cosmic microwave background (CMB), and it almost uniformly fills the cosmos, barring tiny variations. When astronomers measure these tiny variations in this fossil radiation, it predicts a modern-day value for the Hubble constant of around 67.5 ± 0.5 km/s/Mpc.
The differences between the two estimations of the Hubble constant have strangely only grown as measuring techniques for both have been refined and have become more precise. This 5.6 km/s/Mpc difference, and the general trouble surrounding it, is referred to as the "Hubble tension." It's a serious issue for cosmologists, as it suggests there is something wrong with our understanding of the basic physical laws that govern the universe.
Cepheid variables pick a side
Anderson explained why a difference of just a few km/s/Mpc in the Hubble constant matters, even given the vast scale of the universe. (The width of the observable cosmos alone is estimated to be around 29,000 MPC.)
"This discrepancy has a huge significance," Anderson said. "Suppose you wanted to build a tunnel by digging into two opposite sides of a mountain. If you've understood the type of rock correctly and if your calculations are correct, then the two holes you're digging will meet in the center. But if they don't, that means you've made a mistake — either your calculations are wrong or you're wrong about the type of rock."
Anderson said that is analogous to the Hubble tension and what's going on with the Hubble constant.
"The more confirmation we get that our calculations are accurate, the more we can conclude that the discrepancy means our understanding of the universe is mistaken, that the universe isn't quite as we thought," he added.
The improved calibration of the Cepheid variable measurement tool means that this technique finally "takes a side" in the Hubble tension debate, providing agreement with the "late time" solution.
"Our study confirms the 73 km/s/Mpc expansion rate, but more importantly, it also provides the most precise, reliable calibrations of Cepheids as tools to measure distances to date," Anderson said. "It means we have to rethink the basic concepts that form the foundation of our overall understanding of physics."
The team's results have other implications as well. For example, the more accurate Cepheid calibration also helps to better reveal the shape of our galaxy, study team members said.
"Because our measurements are so precise, they give us insight into the geometry of the Milky Way," study lead author Mauricio Cruz Reyes, a Ph.D. student in Anderson's research group, said in the same statement. "The highly accurate calibration (opens in new tab) we developed will let us better determine the Milky Way's size and shape as a flat-disk galaxy and its distance from other galaxies, for example."
The new study was published last week in the journal Astronomy & Astrophysics (opens in new tab).
|
Cosmology & The Universe
|
(The Conversation is an independent and nonprofit source of news, analysis and commentary from academic experts.) (THE CONVERSATION) Astronomers now routinely discover planets orbiting stars outside of the solar system – they’re called exoplanets. But in summer 2022, teams working on NASA’s Transiting Exoplanet Survey Satellite found a few particularly interesting planets orbiting in the habitable zones of their parent stars. One planet is 30% larger than Earth and orbits its star in less than three days. The other is 70% larger than the Earth and might host a deep ocean. These two exoplanets are super-Earths – more massive than the Earth but smaller than ice giants like Uranus and Neptune. I’m a professor of astronomy who studies galactic cores, distant galaxies, astrobiology and exoplanets. I closely follow the search for planets that might host life. Earth is still the only place in the universe scientists know to be home to life. It would seem logical to focus the search for life on Earth clones – planets with properties close to Earth’s. But research has shown that the best chance astronomers have of finding life on another planet is likely to be on a super-Earth similar to the ones found recently. Common and easy to find Most super-Earths orbit cool dwarf stars, which are lower in mass and live much longer than the Sun. There are hundreds of cool dwarf stars for every star like the Sun, and scientists have found super-Earths orbiting 40% of cool dwarfs they have looked at. Using that number, astronomers estimate that there are tens of billions of super-Earths in habitable zones where liquid water can exist in the Milky Way alone. Since all life on Earth uses water, water is thought to be critical for habitability. Based on current projections, about a third of all exoplanets are super-Earths, making them the most common type of exoplanet in the Milky Way. The nearest is only six light-years away from Earth. You might even say that our solar system is unusual since it does not have a planet with a mass between that of Earth and Neptune. Another reason super-Earths are ideal targets in the search for life is that they’re much easier to detect and study than Earth-sized planets. There are two methods astronomers use to detect exoplanets. One looks for the gravitational effect of a planet on its parent star and the other looks for brief dimming of a star’s light as the planet passes in front of it. Both of these detection methods are easier with a bigger planet. Super-Earths are super habitable Over 300 years ago, German philosopher Gottfried Wilhelm Leibniz argued that Earth was the “best of all possible worlds.” Leibniz’s argument was meant to address the question of why evil exists, but modern astrobiologists have explored a similar question by asking what makes a planet hospitable to life. It turns out that Earth is not the best of all possible worlds. Due to Earth’s tectonic activity and changes in the brightness of the Sun, the climate has veered over time from ocean-boiling hot to planetwide, deep-freeze cold. Earth has been uninhabitable for humans and other larger creatures for most of its 4.5-billion-year history. Simulations suggest the long-term habitability of Earth was not inevitable, but was a matter of chance. Humans are literally lucky to be alive. Researchers have come up with a list of the attributes that make a planet very conducive to life. Larger planets are more likely to be geologically active, a feature that scientists think would promote biological evolution. So the most habitable planet would have roughly twice the mass of the Earth and be between 20% and 30% larger by volume. It would also have oceans that are shallow enough for light to stimulate life all the way to the seafloor and an average temperature of 77 degrees Fahrenheit (25 degrees Celsius). It would have an atmosphere thicker than the Earth’s that would act as an insulating blanket. Finally, such a planet would orbit a star older than the Sun to give life longer to develop, and it would have a strong magnetic field that protects against cosmic radiation. Scientists think that these attributes combined will make a planet super habitable. By definition, super-Earths have many of the attributes of a super habitable planet. To date, astronomers have discovered two dozen super-Earth exoplanets that are, if not the best of all possible worlds, theoretically more habitable than Earth. Recently, there’s been an exciting addition to the inventory of habitable planets. Astronomers have started discovering exoplanets that have been ejected from their star systems, and there could be billions of them roaming the Milky Way. If a super-Earth is ejected from its star system and has a dense atmosphere and watery surface, it could sustain life for tens of billions of years, far longer than life on Earth could persist before the Sun dies. Detecting life on super-Earths To detect life on distant exoplanets, astronomers will look for biosignatures, byproducts of biology that are detectable in a planet’s atmosphere. NASA’s James Webb Space Telescope was designed before astronomers had discovered exoplanets, so the telescope is not optimized for exoplanet research. But it is able to do some of this science and is scheduled to target two potentially habitable super-Earths in its first year of operations. Another set of super-Earths with massive oceans discovered in the past few years, as well as the planets discovered this summer, are also compelling targets for James Webb. But the best chances for finding signs of life in exoplanet atmospheres will come with the next generation of giant, ground-based telescopes: the 39-meter Extremely Large Telescope, the Thirty Meter Telescope and the 24.5-meter Giant Magellan Telescope. These telescopes are all under construction and set to start collecting data by the end of the decade. Astronomers know that the ingredients for life are out there, but habitable does not mean inhabited. Until researchers find evidence of life elsewhere, it’s possible that life on Earth was a unique accident. While there are many reasons why a habitable world would not have signs of life, if, over the coming years, astronomers look at these super habitable super-Earths and find nothing, humanity may be forced to conclude that the universe is a lonely place. This article is republished from The Conversation under a Creative Commons license. Read the original article here: https://theconversation.com/super-earths-are-bigger-more-common-and-more-habitable-than-earth-itself-and-astronomers-are-discovering-more-of-the-billions-they-think-are-out-there-190496.
|
Cosmology & The Universe
|
Cosmologist Laura Mersini-Houghton says our universe is one of many – and she argues that we have already seen signs of those other universes in the cosmic microwave background, the light left over from the big bang Physics 31 October 2022 Nabil Nezzar
HOW did our universe begin? This is among the most profound questions of all, and you would be forgiven for thinking it is impossible to answer. But Laura Mersini-Houghton says she has cracked it. A cosmologist at the University of North Carolina at Chapel Hill, she was born and raised under communist dictatorship in Albania, where her father was considered ideologically opposed to the regime and exiled. She later won a Fulbright scholarship to study in the US, forging a career in cosmology in which she has tackled the origins of the universe – and made an extraordinary proposal.
Mersini-Houghton’s big idea is that the universe in its earliest moments can be understood as a quantum wave function – a mathematical description of a haze of possibilities – that gave rise to many diverse universes as well as our own. She has also made predictions about how other universes would leave an imprint upon our own. Those ideas have been controversial, with some physicists arguing that her predictions are invalid. But Mersini-Houghton argues that they have been confirmed by observations of the radiation left over from the big bang, known as the cosmic microwave background.
Here, she tells New Scientist about her ideas and her life, which she has described in her new book Before the Big Bang: The origins of our universe in the multiverse.
Rowan Hooper: Let’s start with your own story of growing up in Albania. To what extent has that shaped your thinking?
Laura Mersini-Houghton: It’s contributed a lot. I was lucky because I had the kind of parents who spotted early on that I was interested in …
|
Cosmology & The Universe
|
Is there intelligent life elsewhere in the universe? It’s a question that has been debated for centuries, if not millenia. But it is only recently that we’ve had an actual chance of finding out, with initiatives such as SETI (Search for Extraterrestrial Intelligence) using radio telescopes to actively listen for radio messages from alien civilizations.
What should we expect to detect if these searches succeed? My suspicion is that it is very unlikely to be little green men – something I speculated about at a talk at a Breakthrough Listen (a SETI project) conference.
Suppose there are other planets where life began and that it followed something like a Darwinian evolution (which needn’t be the case). Even then, it’s highly unlikely that the progression of intelligence and technology would happen at exactly the same pace as on Earth. If it lagged significantly behind, then that planet would plainly reveal no evidence of extraterrestrial life to our radio telescopes. But around a star older than the Sun, life could have had a head start of a billion years or more.
Human technological civilization only dates back millennia (at most) – and it may be only one or two more centuries before humans, made up of organic materials such as carbon, are overtaken or transcended by inorganic intelligence, such as AI. Computer processing power is already increasing exponentially, meaning AI in the future may be able to use vastly more data than it does today. It seems to follow that it could then get exponentially smarter, surpassing human general intelligence.
Perhaps a starting point would be to enhance ourselves with genetic modification in combination with technology – creating cyborgs with partly organic and partly inorganic parts. This could be a transition to fully artificial intelligences.
AI may even be able to evolve, creating better and better versions of itself on a faster-than-Darwinian timescale for billions of years. Organic human-level intelligence would then be just a brief interlude in our “human history” before the machines take over. So if alien intelligence had evolved similarly, we’d be most unlikely to “catch” it in the brief sliver of time when it was still embodied in biological form. If we were to detect extraterrestrial life, it would be far more likely to be electronic than flesh and blood – and it may not even reside on planets.
We must therefore reinterpret the Drake equation, which was established in 1960 to estimate the number of civilizations in the Milky Way with which we could potentially communicate. The equation includes various assumptions, such as how many planets there are, but also how long a civilization is able to release signals into space, estimated to be between 1,000 and 100 million years.
But the lifetime of an organic civilization may be millennia at most, while its electronic diaspora could continue for billions of years. If we include this in the equation, it seems there may be more civilizations out there than we thought, but that the majority of them would be artificial.
We may even want to rethink the term “alien civilizations”. A “civilization” connotes a society of individuals. In contrast, extraterrestrials might be a single integrated intelligence.
Decoding messages
If SETI succeeded, it would therefore be unlikely to record decodable messages. Instead, it may spot a byproduct (or even a malfunction) of some super complex machine far beyond our comprehension.
SETI focuses on the radio part of the electromagnetic spectrum. But as we have no idea of what’s out there, we should clearly explore all wavebands, including the optical and X-ray parts. Rather than just listening for radio transmission, we should also be alert to other evidence of non-natural phenomena or activity. These include artificial structures built around stars to absorb their energy (Dyson spheres) or artificially created molecules, such as chlorofluorocarbons – nontoxic, nonflammable chemicals containing carbon, chlorine, and fluorine – in planet atmospheres. These chemicals are greenhouse gasses that can’t be created by natural processes, meaning they could be a sign of “terraforming” (changing a planet to make it more habitable) or industrial pollution.
|
Cosmology & The Universe
|
Einstein's theory of gravity — general relativity — has been very successful for more than a century. However, it has theoretical shortcomings. This is not surprising: the theory predicts its own failure at spacetime singularities inside black holes — and the Big Bang itself.
Unlike physical theories describing the other three fundamental forces in physics — the electromagnetic and the strong and weak nuclear interactions — the general theory of relativity has only been tested in weak gravity.
Deviations of gravity from general relativity are by no means excluded nor tested everywhere in the universe. And, according to theoretical physicists, deviation must happen.
Deviations and quantum mechanics
According to Einstein, our universe originated in a Big Bang. Other singularities hide inside black holes: Space and time cease to have meaning there, while quantities such as energy density and pressure become infinite. These signal that Einstein's theory is failing there and must be replaced with a more fundamental one.
Naively, spacetime singularities should be resolved by quantum mechanics, which apply at very small scales.
Quantum physics relies on two simple ideas: point particles make no sense; and the Heisenberg uncertainty principle, which states that one can never know the value of certain pairs of quantities with absolute precision — for example, the position and velocity of a particle. This is because particles should not be thought of as points but as waves; at small scales they behave as waves of matter.
This is enough to understand that a theory that embraces both general relativity and quantum physics should be free of such pathologies. However, all attempts to blend general relativity and quantum physics necessarily introduce deviations from Einstein's theory.
Therefore, Einstein's gravity cannot be the ultimate theory of gravity. Indeed, it was not long after the introduction of general relativity by Einstein in 1915 that Arthur Eddington, best known for verifying this theory in the 1919 solar eclipse, started searching for alternatives just to see how things could be different.
Einstein's theory has survived all tests to date, accurately predicting various results from the precession of Mercury's orbit to the existence of gravitational waves. So, where are these deviations from general relativity hiding?
A century of research has given us the standard model of cosmology known as the Λ-Cold Dark Matter (ΛCDM) model. Here, Λ stands for either Einstein’s famous cosmological constant or a mysterious dark energy with similar properties.
Dark energy was introduced ad hoc by astronomers to explain the acceleration of the cosmic expansion. Despite fitting cosmological data extremely well until recently, the ΛCDM model is spectacularly incomplete and unsatisfactory from the theoretical point of view.
In the past five years, it has also faced severe observational tensions. The Hubble constant, which determines the age and the distance scale in the universe, can be measured in the early universe using the cosmic microwave background and in the late universe using supernovae as standard candles.
These two measurements give incompatible results. Even more important, the nature of the main ingredients of the ΛCDM model — dark energy, dark matter and the field driving early universe inflation (a very brief period of extremely fast expansion originating the seeds for galaxies and galaxy clusters) — remains a mystery.
From the observational point of view, the most compelling motivation for modified gravity is the acceleration of the universe discovered in 1998 with Type Ia supernovae, whose luminosity is dimmed by this acceleration. The ΛCDM model based on general relativity postulates an extremely exotic dark energy with negative pressure permeating the universe.
Problem is, this dark energy has no physical justification. Its nature is completely unknown, although a plethora of models has been proposed. The proposed alternative to dark energy is a cosmological constant Λ which, according to quantum-mechanical back-of-the-envelope (but questionable) calculations, should be huge.
However, Λ must instead be incredibly fine-tuned to a tiny value to fit the cosmological observations. If dark energy exists, our ignorance of its nature is deeply troubling.
Alternatives to Einstein's theory
Could it be that troubles arise, instead, from wrongly trying to fit the cosmological observations into general relativity, like fitting a person into a pair of trousers that are too small? That we are observing the first deviations from general relativity while the mysterious dark energy simply does not exist?
This idea, first proposed by researchers at the University of Naples, has gained tremendous popularity while the contending dark energy camp remains vigorous.
There is now a large literature on theories of gravity alternative to general relativity, going back to Eddington's 1923 early investigations. A very popular class of alternatives is the so-called scalar-tensor gravity. It is conceptually very simple since it only introduces one additional ingredient (a scalar field corresponding to the simplest, spinless, particle) to Einstein's geometric description of gravity.
The consequences of this program, however, are far from trivial. A striking phenomenon is the "chameleon effect," consisting of the fact that these theories can disguise themselves as general relativity in high-density environments (such as in stars or in the solar system) while deviating strongly from it in the low-density environment of cosmology.
As a result, the extra (gravitational) field is effectively absent in the first type of systems, disguising itself as a chameleon does, and is felt only at the largest (cosmological) scales.
The current situation
Nowadays the spectrum of alternatives to Einstein gravity has widened dramatically. Even adding a single massive scalar excitation (namely, a spin-zero particle) to Einstein gravity — and keeping the resulting equations "simple" to avoid some known fatal instabilities — has resulted in the much wider class of Horndeski theories, and subsequent generalizations.
Theorists have spent the last decade extracting physical consequences from these theories. The recent detections of gravitational waves have provided a way to constrain the physical class of modifications of Einstein gravity allowed.
However, much work still needs to be done, with the hope that future advances in multi-messenger astronomy lead to discovering modifications of general relativity where gravity is extremely strong.
Live Science newsletter
Stay up to date on the latest science news by signing up for our Essentials newsletter.
PhD in Astrophysics, supervisor George F.R. Ellis, worked in relativity, cosmology, and alternative theories of gravity for 30 years, been at Bishop's University for 16 years, currently full professor in the Physics & Astronomy Department. Author of 210 refereed journal articles and 7 books, funded by NSERC and volunteered extensively for NSERC, the Canadian Association of Physicists, and occasionally for other organizations worldwide.
|
Cosmology & The Universe
|
By Seth Borenstein | Associated Press
Our view of the universe just expanded: The first image from NASA’s new space telescope unveiled Monday is brimming with galaxies and offers the deepest look of the cosmos ever captured.
The first image from the $10 billion James Webb Space Telescope is the farthest humanity has ever seen in both time and distance, closer to the dawn of time and the edge of the universe. That image will be followed Tuesday by the release of four more galactic beauty shots from the telescope’s initial outward gazes.
The “deep field” image released at a White House event is filled with lots of stars, with massive galaxies in the foreground and faint and extremely distant galaxies peeking through here and there. Part of the image is light from not too long after the Big Bang, which was 13.8 billion years ago. “We’re going to give humanity a new view of the cosmos,” NASA Administrator Bill Nelson told reporters last month in a briefing. “And it’s a view that we’ve never seen before.”
The images on tap for Tuesday include a view of a giant gaseous planet outside our solar system, two images of a nebula where stars are born and die in spectacular beauty and an update of a classic image of five tightly clustered galaxies that dance around each other.
The world’s biggest and most powerful space telescope rocketed away last December from French Guiana in South America. It reached its lookout point 1 million miles (1.6 million kilometers) from Earth in January. Then the lengthy process began to align the mirrors, get the infrared detectors cold enough to operate and calibrate the science instruments, all protected by a sunshade the size of a tennis court that keeps the telescope cool.
The plan is to use the telescope to peer back so far that scientists will get a glimpse of the early days of the universe about 13.7 billion years ago and zoom in on closer cosmic objects, even our own solar system, with sharper focus.
Webb is considered the successor to the highly successful, but aging Hubble Space Telescope. Hubble has stared as far back as 13.4 billion years. It found the light wave signature of an extremely bright galaxy in 2016. Astronomers measure how far back they look in light-years with one light-year being 5.8 trillion miles (9.3 trillion kilometers). “Webb can see backwards in time to just after the Big Bang by looking for galaxies that are so far away that the light has taken many billions of years to get from those galaxies to our telescopes,” said Jonathan Gardner, Webb’s deputy project scientist said during the media briefing.
How far back did that first image look? Over the next few days, astronomers will do intricate calculations to figure out just how old those galaxies are, project scientist Klaus Pontoppidan said last month.
The deepest view of the cosmos “is not a record that will stand for very long,” Pontoppidan said, since scientists are expected to use the telescope to go even deeper.
Thomas Zurbuchen, NASA’s science mission chief said when he saw the images he got emotional and so did his colleagues: “It’s really hard to not look at the universe in new light and not just have a moment that is deeply personal.”
At 21 feet (6.4 meters), Webb’s gold-plated, flower-shaped mirror is the biggest and most sensitive ever sent into space. It’s comprised of 18 segments, one of which was smacked by a bigger than anticipated micrometeoroid in May. Four previous micrometeoroid strikes to the mirror were smaller. Despite the impacts, the telescope has continued to exceed mission requirements, with barely any data loss, according to NASA.
NASA is collaborating on Webb with the European and Canadian space agencies.
“I’m now really excited as this dramatic progress augurs well for reaching the ultimate prize for many astronomers like myself: pinpointing “Cosmic Dawn” — the moment when the universe was first bathed in starlight,” Richard Ellis, professor of astrophysics at University College London, said via email.
AP Aerospace Writer Marcia Dunn contributed.
|
Cosmology & The Universe
|
An international team of researchers has created an extraordinary virtual representation of our universe. It is the largest and most accurate virtual simulation of its kind to date. The team used supercomputer simulations to recreate the entire evolution of the cosmos, from the Big Bang to the present day.Simulating our own universeOver the past two decades, cosmologists have developed a "standard model" of cosmology, the so-called cold dark matter model (CDM). This model is used to explain a wealth of observed astronomical data, from the properties of leftover heat from the Big Bang to the number of galaxies we observe around us today, as well as their spatial distribution. When simulating a virtual cold dark matter universe, most cosmologists track a "typical" or arbitrary patch of sky, similar to our own observed universe, but only in a statistical sense. The simulations performed in this study are different: they are tuned to reproduce our particular existing patch of the universe using advanced generative algorithms, thus containing existing structures near our own galaxy that astronomers have observed for decades.This means that well-known structures in the nearby universe, such as the Virgo, Coma, and Perseus clusters, the Great Wall, and the Local Void - our cosmic habitat - are precisely reproduced in the simulation. Software and hardwareThe simulation software developed at the Leiden Institute of Physics (the Netherlands) is the technological key to this effort. By deploying a giant supercomputer for over a month, the team was able to bring to life a virtual counterpart of our own universe. The unique geometry and properties of the simulation, combined with its raw size, made the simulation a challenge that could only be accomplished by virtue of the many years of experience of the local simulation group built on past efforts, such as the Leiden-led EAGLE project, which recently received the Group Award from the British Royal Astronomical Society.Comparing the virtual universe to the real universeThe research closely compares the output of the virtual universe with a series of observations in the real world, finding the right locations and properties for the virtual counterparts of known structures. The first findings show that our nearby universe could be unusual: the simulation predicts a lower average number of galaxies due to a local large-scale 'underdensity' of matter. While the authors believe that the level of this underdensity poses no threat to the Standard Model of cosmology, it may have implications for how astronomers interpret information from surveys of observed galaxiesCo-author Matthieu Schaller from the Leiden Observatory stated that the project is a milestone in the search for ways to test the current established model of the evolution of our universe. According to Schaller, these simulations show that the Standard Model of Cold Dark Matter is capable of producing all the galaxies we see in our environment. The simulation has been a critical test for the model.
|
Cosmology & The Universe
|
eso2316 — Science Release
Furthest ever detection of a galaxy’s magnetic field
6 September 2023
Using the Atacama Large Millimeter/submillimeter Array (ALMA), astronomers have detected the magnetic field of a galaxy so far away that its light has taken more than 11 billion years to reach us: we see it as it was when the Universe was just 2.5 billion years old. The result provides astronomers with vital clues about how the magnetic fields of galaxies like our own Milky Way came to be.
Lots of astronomical bodies in the Universe have magnetic fields, whether it be planets, stars or galaxies. “Many people might not be aware that our entire galaxy and other galaxies are laced with magnetic fields, spanning tens of thousands of light-years,” says James Geach, a professor of astrophysics at the University of Hertfordshire, UK, and lead author of the study published today in Nature.
“We actually know very little about how these fields form, despite their being quite fundamental to how galaxies evolve,” adds Enrique Lopez Rodriguez, a researcher at Stanford University, USA, who also participated in the study. It is not clear how early in the lifetime of the Universe, and how quickly, magnetic fields in galaxies form because so far astronomers have only mapped magnetic fields in galaxies close to us.
Now, using ALMA, in which the European Southern Observatory (ESO) is a partner, Geach and his team have discovered a fully formed magnetic field in a distant galaxy, similar in structure to what is observed in nearby galaxies. The field is about 1000 times weaker than the Earth’s magnetic field, but extends over more than 16 000 light-years.
“This discovery gives us new clues as to how galactic-scale magnetic fields are formed,” explains Geach. Observing a fully developed magnetic field this early in the history of the Universe indicates that magnetic fields spanning entire galaxies can form rapidly while young galaxies are still growing.
The team believes that intense star formation in the early Universe could have played a role in accelerating the development of the fields. Moreover, these fields can in turn influence how later generations of stars will form. Co-author and ESO astronomer Rob Ivison says that the discovery opens up “a new window onto the inner workings of galaxies, because the magnetic fields are linked to the material that is forming new stars.”
To make this detection, the team searched for light emitted by dust grains in a distant galaxy, 9io9 [1]. Galaxies are packed full of dust grains and when a magnetic field is present, the grains tend to align and the light they emit becomes polarised. This means that the light waves oscillate along a preferred direction rather than randomly. When ALMA detected and mapped a polarised signal coming from 9io9, the presence of a magnetic field in a very distant galaxy was confirmed for the first time.
“No other telescope could have achieved this,” says Geach. The hope is that with this and future observations of distant magnetic fields the mystery of how these fundamental galactic features form will begin to unravel.
Notes
[1] 9io9 was discovered in the course of a citizen science project. The discovery was helped by viewers of the British BBC television programme Stargazing Live, when over three nights in 2014 the audience was asked to examine millions of images in the hunt for distant galaxies.
More information
This research was presented in a paper to appear in Nature.
The team is composed of J. E. Geach (Centre for Astrophysics Research, School of Physics, Engineering and Computer Science, University of Hertfordshire, UK [Hertfordshire]), E. Lopez-Rodriguez (Kavli Institute for Particle Astrophysics and Cosmology, Stanford University, USA), M. J. Doherty (Hertfordshire), Jianhang Chen (European Southern Observatory, Garching, Germany [ESO]), R. J. Ivison (ESO), G. J. Bendo (UK ALMA Regional Centre Node, Jodrell Bank Centre for Astrophysics, Department of Physics and Astronomy, The University of Manchester, UK), S. Dye (School of Physics and Astronomy, University of Nottingham, UK) and K. E. K. Coppin (Hertfordshire).
The European Southern Observatory (ESO) enables scientists worldwide to discover the secrets of the Universe for the benefit of all. We design, build and operate world-class observatories on the ground — which astronomers use to tackle exciting questions and spread the fascination of astronomy — and promote international collaboration for astronomy. Established as an intergovernmental organisation in 1962, today ESO is supported by 16 Member States (Austria, Belgium, the Czech Republic, Denmark, France, Finland, Germany, Ireland, Italy, the Netherlands, Poland, Portugal, Spain, Sweden, Switzerland and the United Kingdom), along with the host state of Chile and with Australia as a Strategic Partner. ESO’s headquarters and its visitor centre and planetarium, the ESO Supernova, are located close to Munich in Germany, while the Chilean Atacama Desert, a marvellous place with unique conditions to observe the sky, hosts our telescopes. ESO operates three observing sites: La Silla, Paranal and Chajnantor. At Paranal, ESO operates the Very Large Telescope and its Very Large Telescope Interferometer, as well as survey telescopes such as VISTA. Also at Paranal ESO will host and operate the Cherenkov Telescope Array South, the world’s largest and most sensitive gamma-ray observatory. Together with international partners, ESO operates ALMA on Chajnantor, a facility that observes the skies in the millimetre and submillimetre range. At Cerro Armazones, near Paranal, we are building “the world’s biggest eye on the sky” — ESO’s Extremely Large Telescope. From our offices in Santiago, Chile we support our operations in the country and engage with Chilean partners and society.
The Atacama Large Millimeter/submillimeter Array (ALMA), an international astronomy facility, is a partnership of ESO, the U.S. National Science Foundation (NSF) and the National Institutes of Natural Sciences (NINS) of Japan in cooperation with the Republic of Chile. ALMA is funded by ESO on behalf of its Member States, by NSF in cooperation with the National Research Council of Canada (NRC) and the National Science and Technology Council (NSTC) in Taiwan and by NINS in cooperation with the Academia Sinica (AS) in Taiwan and the Korea Astronomy and Space Science Institute (KASI). ALMA construction and operations are led by ESO on behalf of its Member States; by the National Radio Astronomy Observatory (NRAO), managed by Associated Universities, Inc. (AUI), on behalf of North America; and by the National Astronomical Observatory of Japan (NAOJ) on behalf of East Asia. The Joint ALMA Observatory (JAO) provides the unified leadership and management of the construction, commissioning and operation of ALMA.
About the University of Hertfordshire: Defined by the spirit of innovation and enterprise, the University of Hertfordshire has been an innovative, vocation-first educational force for more than 70 years. From our start as a leading educator within Britain’s aeronautical industry to our extensive offering today, we have always specialised in providing the environment and expertise needed to power every kind of potential. For our thriving community of more than 30,000 students from over 140 countries, that means high-quality teaching from experts engaged in groundbreaking research with real-world impact. Access to over 550 career-focused degree options and a chance to study at more than 170 universities worldwide, using outstanding, true to life facilities. And industry connections that offer professional networking opportunities which take talents even further. We are Herts. Herts. Beats Faster. Discover a place where ideas move at a different pace. Visit herts.ac.uk.
Links
- Research paper
- Photos of ALMA
- For journalists: subscribe to receive our releases under embargo in your language
- For scientists: got a story? Pitch your research
Contacts
James Geach
Centre for Astrophysics Research, University of Hertfordshire
Hatfield, UK
Email: j.geach@herts.ac.uk
Enrique Lopez Rodriguez
Kavli Institute for Particle Astrophysics and Cosmology, Stanford University
Stanford, California, USA
Email: elopezrodriguez@stanford.edu
Rob Ivison
European Southern Observatory (ESO), Germany; Macquarie University, Australia; Dublin Institute for Advanced Studies, Ireland; University of Edinburgh, Scotland; ARC Centre of Excellence for All Sky Astrophysics in 3 Dimensions, Australia
Email: Rob.Ivison@eso.org
Bárbara Ferreira
ESO Media Manager
Garching bei München, Germany
Tel: +49 89 3200 6670
Cell: +49 151 241 664 00
Email: press@eso.org
Press Office
University of Hertfordshire
Hatfield, UK
Tel: +441707 285770
Email: news@herts.ac.uk
About the Release
|Release No.:||eso2316|
|Name:||9io9|
|Type:||Early Universe : Galaxy|
|Facility:||Atacama Large Millimeter/submillimeter Array|
|
Cosmology & The Universe
|
The pictures from the James Webb telescope – described by Nasa as a “time machine” because the light has taken billions of years to reach us – raise the question: will it be possible to someday see the big bang itself? I asked Dr Matthew Bothwell, public astronomer at the University of Cambridge.Why is the James Webb telescope so good?First, it’s infrared. Firefighters wear infrared goggles because it helps them see through smoke and dust, and stars form behind a lot of smoke and dust. Also, and this is a bit technical, light that arrives from distant space is redshifted. That’s because, as the universe is growing and the light is travelling across it, the light gets stretched and becomes redder. Finally, the telescope is just really big.If the universe is stretching, why isn’t Earth? Why aren’t I stretching? Or am I? Oh God, I thought I felt odd today.We’re held together by electrostatic forces, which basically means that atoms – which we’re all made of – like sticking together. The expansion can only get a foothold where those forces or gravity are really weak. And that means the spaces between galaxies.Aw, big up the little atoms sticking together. So where is the universe expanding from? Would it be in the centre?There is no centre to the universe. It’s wrong to think of space and time as being a box that the universe sits inside. Space and time are properties inside the universe. The big bang created space. Every point in the universe was where the big bang happened.Could a telescope someday see it?Afraid not. From a cosmic perspective, light is quite slow. Light takes eight minutes to reach us from the sun, so when we look at the sun we’re looking at it eight minutes ago. If you look a million light years away, you’re getting messages from a million years in the past. At the time of the big bang, all the matter and stuff in the universe was squished into a small volume. It was so dense, it was opaque. It’s only as the universe grew that density dropped and light could travel through.So if space is a pair of tights, as it stretches you can see through it, but, before it’s stretched, it’s too opaque to see anything?Yes!Why is seeing the early universe important?When you try to solve difficult problems, you end up inventing stuff. A group in Cambridge uses millions of photographs to look for faint galaxies. It turns out the technique they developed is what you need for finding tumours you can’t see by eye. It’s improved cancer detection rates.Wow! Usually I don’t like talking about space; it makes me anxious seeing how insignificant and meaningless we all are.There’s a term for that – cosmological vertigo. I feel it, too, but it can be positive. It means anything bad in the world is also meaningless, cosmically.That makes it worse! All the pain we inflict on each other for nothing. But that cancer story was beautiful – how we mirror the universe in our bodies.Oh, 100%. When we look at very distant galaxies, we see the same components that we are made of. Carbon, hydrogen, iron. It’s like that Max Ehrmann poem: “You are a child of the universe no less than the trees and the stars.”
|
Cosmology & The Universe
|
October 06, 2022 02:11 PM Computer simulations created by scientists showcase alternate theories of how the moon was created through a giant impact, challenging the prevailing belief that the moon was formed from a disk of debris orbiting the Earth. The researchers from Durham University’s Institute for Computational Cosmology have released four different simulations showing that one object in space could have collided into another, creating the moon as we know it. The simulations showcase how most of the moon was formed immediately after the impact, meaning less of it became molten during its formation than in previous theories, according to EurekAlert. “This formation route could help explain the similarity in isotopic composition between the lunar rocks returned by the Apollo astronauts and Earth’s mantle," said Vincent Eke, one of the co-authors of the study. "There may also be observable consequences for the thickness of the lunar crust, which would allow us to pin down further the type of collision that took place.” WATCH: NASA SPACEX ROCKET TAKES ASTRONAUTS TO INTERNATIONAL SPACE STATION Computer simulations created by scientists showcase alternate theories of how the moon was created through a giant impact, challenging the prevailing belief that the moon was formed from a disk of debris orbiting the Earth. Jacob Kegerreis, Durham University/NASA Ames The moon is believed to have formed after a collision between the young Earth and a Mars-sized object called Theia, with most theories claiming that the moon was created by the gradual accumulation of debris from the impact. However, this theory has been challenged by measurements of lunar rocks showing their composition is similar to Earth’s mantle, while the impact produced debris that came mostly from Theia. The researchers also found that when a satellite passes in close proximity to the Earth, it can actually be pushed into a wider orbit rather than getting torn apart by the “tidal forces” from Earth’s gravity. "We went into this project not knowing exactly what the outcomes of these very high-resolution simulations would be," said lead researcher Jacob Kegerreis. "So, on top of the big eye-opener that standard resolutions can give you wrong answers, it was extra exciting that the new results could include a tantalizingly Moon-like satellite in orbit." CLICK HERE TO READ MORE FROM THE WASHINGTON EXAMINER The team of researchers who worked on these simulations included scientists at NASA Ames Research Centre and the University of Glasgow. Their simulation findings have been published in the Astrophysical Journal Letters.
|
Cosmology & The Universe
|
Astronomers might soon get their first peek into the dark universe.
On Saturday, July 1, the European Space Agency's (ESA) Euclid spacecraft will launch on a SpaceX rocket from Florida on a mission to peer into deep space and unveil the elusive dark universe — and NASA's James Webb Space Telescope will be an important partner in this cosmic quest.
After a month-long flight, Euclid will reach a vantage point about 1 million miles (1.5 million kilometers) from Earth, where it will share its cosmic accommodation with the James Webb Space Telescope (JWST), whose powerful infrared eye probes the universe as it was just 100 million years after the Big Bang.
JWST will complement a part of Euclid's mission that will investigate the nature of dark energy, the hypothetical "anti-gravity" force that scientists have proposed to explain why the universe is expanding at an accelerated rate. ESA will operate Euclid as it maps 36% of the observable sky over six years.
Euclid "is more than a space telescope; it is really a dark energy detector," René Laureijs, a project scientist for the Euclid mission, said during a news conference on June 23. "It would be beautiful if the two telescopes are online and James Webb could follow up the new findings of Euclid."
Euclid is designed to investigate dark energy, whose mysterious nature is ''the biggest embarrassment we currently have in cosmology,'' Guadalupe Cañas Herrera, a cosmologist at ESA, told reporters Friday.
When an immensely hot and dense universe birthed with the Big Bang about 13.7 billion years ago, space itself ballooned faster than the speed of light, and the universe doubled in size at least 90 times. That inflation eased into a steady growth as matter that manifested in the universe tugged at itself due to gravity. However, roughly 5 billion years ago, dark energy overtook gravity as the dominant force and began speeding up the universe's expansion.
To help scientists better understand the nature of dark energy, Euclid is expected to cover 15,000 square degrees of the sky, in which it will survey about 1.5 billion galaxies from the early universe by capturing light that is about 10 billion to 13 billion years old. Using these data, scientists hope to clock the universe's expansion across eons and pinpoint exactly when dark energy — which now makes up 68% to 72% of the universe's energy and matter — began accelerating the cosmos.
To gather the required data, Euclid will study light from early galaxies at near-infrared wavelengths, similar to what Webb does with its Near Infrared Camera (NIRCam). "Where Webb can observe extremely far back in time and zoom into the details, Euclid can go fast and wide," according to ESA.
Euclid is capable of viewing areas of the sky a 100 times wider than Webb's NIRCam. For example, Euclid will collect data from 40,000 fields of the sky, with each slice spanning two full moons and holding 10GB of data, Laureijs said. Webb would complement Euclid's goals by providing deeper follow-up observations of smaller slices of the sky than what Euclid is capable of, as well as by investigating outliers in the data.
The widely accepted cosmological model that represents our comprehension of the universe's history and evolution, known as the Lambda cold dark matter model, relies on a few assumptions. One is that general relativity stays put in cosmological scales. The model also assumes that the universe contains cold dark matter, which is a hypothetical type of dark matter that moves slower than the speed of light, doesn't interact with visible matter and makes itself known only gravitationally, and dark energy, which holds on to a constant density as the universe expands. The model lacks important information about the nature of dark matter and dark energy, and decades of direct and indirect searches to find dark matter particles continue to come up empty.
With Euclid, scientists plan to compare different cosmological models that attempt to explain the accelerated expansion and see which one best fits the telescope's data. Those results may prompt the design of a "modified gravity model or something more exotic," Cañas Herrera said.
Ultimately, scientists hope Euclid's findings will help explain if there is a "revolution" needed in our understanding of the laws of nature, said Yannick Mellier, an astronomer at the Paris Institute of Astrophysics who leads the Euclid consortium. "In principle, Euclid should provide a decisive response on the nature of dark energy."
|
Cosmology & The Universe
|
NASA's James Webb Space Telescope has captured its first direct images of a planet beyond our solar system.The planet, called HIP 65426 b, is a gas giant with no rocky surface, which means it likely cannot support alien life, according to astronomers who described the images in a NASA blog post published Thursday. The scientists are preparing a paper about the observations, but the findings have yet to be peer-reviewed.The observations are notable, however, because they hint at how the Webb telescope could be used to search for potentially habitable planets elsewhere in the universe."This is a transformative moment, not only for Webb but also for astronomy generally," Sasha Hinkley, an associate professor of physics and astronomy at the University of Exeter in the United Kingdom, said in a statement. Hinkley led the observations of HIP 65426 b with an international team. The exoplanet is located about 355 light-years away from Earth and was first discovered in 2017, according to NASA. The gas giant is up to 12 times the mass of Jupiter and its orbit is around 100 times farther from its host star than Earth is from the sun.NASA said the Webb telescope will be able to glean new details about HIP 65426 b, including a more precise measurement of its mass and age. Astronomers estimate that the exoplanet is about 15 million to 20 million years old, which means it’s a relatively young world compared to Earth, which is 4.5 billion years old.The Hubble Space Telescope has snapped direct images of exoplanets before, but it remains tricky to accomplish from space because stars typically outshine planets. In the case of HIP 65426 b, the exoplanet is more than 10,000 times fainter than its host star in near-infrared light, the astronomers said. "Obtaining this image felt like digging for space treasure," Aarynn Carter, a postdoctoral researcher at the University of California, Santa Cruz, who led the analysis of the images, said in a statement. "At first all I could see was light from the star, but with careful image processing I was able to remove that light and uncover the planet."The resulting image shows HIP 65426 b through four different light filters captured by Webb's Near-Infrared Camera and Mid-Infrared Instrument. The telescope's infrared "eyes" can see through dust and gas, making them able to pick up objects and features beyond the range of human sight. Both the Near-Infrared Camera and Mid-Infrared Instrument are also outfitted with so-called coronagraphs that help block out starlight.The $10 billion Webb telescope launched into space on Dec. 25, 2021. The first batch of images from the observatory was released in July, and early science operations have already yielded tantalizing discoveries."I think what's most exciting is that we've only just begun," Carter said in the statement. "There are many more images of exoplanets to come that will shape our overall understanding of their physics, chemistry, and formation. We may even discover previously unknown planets, too."Denise Chow is a reporter for NBC News Science focused on general science and climate change.
|
Cosmology & The Universe
|
The James Webb Space Telescope is set to launch after decades of work. Mission critical: Unravel the most enduring mysteries in space. By Denise Chow, JoElla Carman, Jiachuan Wu, Chad Yapyapan and Michael BasilicoDec. 21, 2021 Is there life on other planets? How did the first stars form? What happened in the turbulent early days of the universe? These are the tantalizing questions that the James Webb Space Telescope is meant to investigate. After more than three decades of development, the tennis court-sized observatory is set to launch into orbit around the sun this month. It will be able to see deeper into space and in greater detail than any space or ground-based telescope to date. The telescope’s mission is to unravel the most enduring mysteries in space, peering through more than 13 billion years of cosmic history with instruments sensitive enough to sniff out the atmospheres of exoplanets — including possibly faint biosignatures of alien life — and examine previously undetectable regions of space. NASA is calling this an “Apollo moment” — a giant leap forward that could revolutionize our understanding of the universe and humanity’s place in it. Some 40 million hours of work by thousands of scientists and engineers across three space agencies have gone into building the Webb telescope. And now, it is finally ready to come online. Telescopes essentially function as time machines because it takes time for light to travel through space. The Webb observatory will be able to see farther in the universe than ever before, and therefore farther back in time. This means that astronomers will have the chance to study primitive stars and galaxies from the earliest days of the universe. Webb’s long range ≈12.5 Present day ≈13 13.4 13.7 BIG BANG DARK AGE FIRST STARS FIRST GALAXIES MODERN UNIVERSE Hubble’s limit Webb’s limit Billions of years in the past ≈12.5 ≈13 13.4 13.7 Present day Hubble’s limit Webb’s limit Billions of years in the past MODERN UNIVERSE FIRST GALAXIES FIRST STARS DARK AGE BIG BANG Unlike Hubble, which sees primarily visible light, the Webb telescope will gaze at infrared light, which can pierce through thick veils of cosmic gas and dust that might otherwise obscure some celestial objects from view. It’s not just the instruments on board that set the Webb telescope apart. Part of what makes the mission so challenging — and potentially so rewarding — is its destination almost a million miles away from Earth. The telescope’s location in space is critical for its mission, but it’s also incredibly risky. At almost a million miles away, there’s no way to fix anything that could go wrong. And because of its size, the Webb telescope needs to be folded up for launch. Once in space, the observatory will undergo an intricate, monthlong unfurling process that NASA has nicknamed … “29 days on the edge.” Until then, nerves will be running high as NASA and its international partners face some of the highest stakes of the mission. If it fails, there will be no way to rescue the $10 billion project. And with the Hubble Space Telescope potentially nearing the end of its long life, the loss of a next-generation observatory would be a devastating setback for space science and astronomy. But if it’s successful, the Webb telescope will provide unparalleled views of the cosmos and could yield untold discoveries that help scientists piece together the origin and evolution of the universe. Art director: Ben Plimpton Senior projects editor: Anna Brand Denise Chow is a reporter for NBC News Science focused on general science and climate change. JoElla Carman JoElla Carman is the Data Graphics Interactive Visual Designer for NBC News. Jiachuan Wu is a national interactive journalist for NBC News. Chad Yapyapan Chad Yapyapan is a senior animator for NBC News. Michael Basilico Michael Basilico is a senior animator for NBC News. Ben Plimpton Ben Plimpton is an art director for NBC News. Anna Brand is a senior editor for news projects at NBC News Digital and oversees the Data Graphics team. Andrew Stern contributed. Francisco Dans contributed.
|
Cosmology & The Universe
|
This story was originally published in our July/August 2022 issue as "Waves of Discovery." Click here to subscribe to read more stories like this one.Gravitational-wave astronomy is growing up. These ripples in the fabric of space-time are created by accelerating masses, which then travel outward from their origin at the speed of light. While anything with mass can produce a gravitational wave (GW), only the biggest events are currently detectable: either from two black holes colliding, or two neutron stars smashing into each other, or a combination of the two.The first GWs were detected in 2015 by the Laser Interferometer Gravitational-wave Observatory (LIGO), when two black holes about 1.3 billion light-years away slammed into each other. LIGO consists of two interferometers — one in Louisiana, one in Washington state — which are L-shaped vacuum tunnels about 2.5 miles long on each side. A laser is shot from the crux of the L to mirrors at the end of each side, and if one of those laser beams arrives slightly late, the tardy beam is recorded by the detector. The detectors are sensitive enough to pick up nearby noises on Earth as well, such as passing trucks and falling trees. These events can maskor mimic gravitational-wave signals, so having two detectors far apart helps scientists distinguish real GW vibrations from false alarms.The actual detector that spotted the first gravitational wave is now in the Nobel Prize Museum in Stockholm, Sweden, as the 2017 Nobel Prize in physics was awarded for this discovery. But LIGO didn’t stop there: A few months later, in collaboration with the newly completed Virgo interferometer in Italy, LIGO detected another gravitational wave event — this time produced by colliding neutron stars. The discovery also corresponded with a short gamma-ray burst and subsequent discovery of the merger site with optical telescopes. Within days of that momentous discovery, however, LIGO went offline for scheduled upgrades. The detectors turned on again on April 1, 2019, for a new observing run, dubbed O3, which was highly anticipated by the astronomical community. New upgrades meant LIGO could spot GWs even further in space during its year-long run, and working in conjunction with Virgo meant even greater precision on where in space the detected merger happened. What would LIGO discover this time?LIGO team member Alena Ananyeva works on hardware upgrades in advance of LIGO’s third run. (Credit: LIGO/CalTech/MIT/Matt Heintze)Detecting Astronomical EventsData from the first half of O3 has been released, and it is clear that with O3, LIGO has entered a new phase. “We have moved from the discovery phase of GW events and are transitioning into routine,” explains Samaya Nissanke, an astrophysicist at the University of Amsterdam and member of the LIGO collaboration. The observing runs before O3 detected just 11 GW events; the O3 run detected several dozen. Almost overnight, the discovery of gigantic black holes smashing into each other millions of light-years away from us was rendered nearly routine.What’s more, for each new detection, LIGO sent out alerts in real time, as observatories routinely do for astronomical events that require rapid follow-up. These alerts were distributed automatically when the Virgo detector and both the Louisiana and Washington LIGO detectors saw what looked like a GW signal at the same time. The alert also included a sky map of where the signal might have come from, called a localization. Once issued, these messages were distributed through automatic alerts to astronomers, apps, and even the LIGO Twitter feed. Although the alerts were peppered at first with events subsequently attributed to local interference on Earth — “It was a bit of a rocky start,” admits Nissanke — once the kinks were smoothed out, astronomers could comb the sky almost instantaneously for any faint glow detected from a GW merger. Plans are in the works to apply automatic algorithms and machine-learning techniques to make the alerts more accurate in the future.As the verified O3 detections progressed, however, it was clear that LIGO was growing its sample of black holes at a fast rate. “We’ve seen a doubling in our number of black hole detections, and with that increase we’re getting a much better idea of the population out there,” explains Lionel London, an astrophysicist at MIT who specializes in modeling the GW signatures of black holes in LIGO. One notable example, called GW190814 (because it was detected on Aug. 14, 2019), was exciting because it was either the heaviest neutron star or the lightest black hole ever discovered.Previously, astronomers had noted that the heaviest-known neutron stars are about twice the mass of the sun, and the smallest-known black hole is three times the mass of the sun. This “mass gap,” as it’s called, puzzled scientists — was there a physical reason for it, or had we just not found anything to fill that gap yet? GW190814 is one of the first residents to fill it: One of the two components was around 2.6 times the mass of the sun. The jury is still out on what exactly the object was, but it’s clear it was something unusual, and that it met its end merging with a black hole 23 times the mass of our own sun. The two together formed a black hole nearly 26 times more massive than the sun — bigger than a black hole created by a dying star, for example — about 800 million light-years from Earth.This graphic shows the masses of all of LIGO’s announced gravitational wave detections, as well as black holes and neutron stars previously obtained through electromagnetic observations. (Credit: LIGO-Virgo-Kagra/Aaron Geller/Northwestern)Scientific discoveries have also come from the real-time detection alerts. Most notable has been the possible discovery of light from two colliding black holes reported by the Zwicky Transient Facility (ZTF) at Caltech, the first time such a detection has been claimed. Black holes are famously so dense that light cannot escape them, and the merger of two black holes is not expected to give off any light in normal circumstances either. In this case, however, a flash of light observed by ZTF is argued by the team to correspond with a GW event on May 21, 2019, when two black holes merged. The angular momentum from the merger itself, researchers argue, would have led to an interaction with surrounding gas. It is this interaction that could have, in turn, given off the sudden flash they observed.Beyond individual events, however, a catalog of black hole detections is invaluable for testing our understanding of physics itself. Each part of a GW detection is made of several components, including the inspiral of the two objects, the collision itself and the reverberating aftershock of the merger. The extreme physics during these moments provide a new hotbed for testing theories relating to gravity, ranging from general relativity to mysterious dark energy driving the expansion of the universe. “In terms of the theoretical interpretation, these are really early days,” explains London. “Some of the tests are really rudimentary.” Once the sample of events grows larger and the signatures are better understood, however, scientists can use statistics to probe physics in entirely new ways.Unfortunately, the O3 run was cut short in March 2020 by the coronavirus pandemic. GW scientists are confident, however, that the next run, O4, will be even more exciting when it begins in December 2022. Not only will they peer further into space than before, but in 2020, a new GW detector, the Kamioka Gravitational Wave Detector (KAGRA), came online in Japan. Working in tandem with the LIGO and Virgo instruments, KAGRA will allow for even more precise estimates for where the GWs originate from. Looking even further ahead, LIGO-India is currently in the works and slated to begin observations in 2026. When it does, the ability to pinpoint where a gravitational wave came from in the sky will be significantly better than where they are now. This will allow astronomers to identify the locations of cosmic collisions better than ever before.“We are opening the zoo of astrophysically formed black holes,” observes Nissanke, “and it’s exciting to see what’s out there.”
|
Cosmology & The Universe
|
NASA had a banner year in 2022, with many successful missions in what was one of the organization’s most active years in decades. I’m a professor of astronomy who has used NASA telescopes for decades to do research in observational cosmology. I also have a keen interest in the role science plays in humanity’s expansion into space. NASA’s missions over the past year have been remarkably far-ranging – from practicing how to protect the Earth to preparing for the first manned mission to Mars and learning about the earliest days in the universe. By working in the extremes, scientists are learning about and doing more in space than ever before. The DART mission successfully crashed a spacecraft into the asteroid Dimorphos and slightly nudged the orbit of the asteroid. NASA/Johns Hopkins APL, CC BY-NC Near and far Some NASA missions in 2022 focused on protecting or learning more about the Earth, while other missions were focused as far from Earth as possible. Close to home, NASA nudged an asteroid off its trajectory, successfully demonstrating technology that could save the Earth if an
asteroid or comet was on a collision course with Earth. The Double Asteroid Redirection Test, or DART, slammed the 1,340-pound (610-kilogram) DART spacecraft into an 11 billion-pound (5 billion-kilogram) asteroid called Dimorphos. Dimorphos is the smaller of a pair of asteroids that flew past Earth last year. The impact happened 6 million miles (11.7 million kilometers) from Earth and altered the asteroid’s orbit by a small but measurable amount. Dimorphos and its twin, Didymos, were never a threat to humanity, but NASA tracks potentially hazardous near-Earth objects for a reason, and DART showed that it would be possible to protect the Earth from an asteroid impact. NASA has also been studying water both near the Earth and in distant solar systems. On Dec. 16, 2022, a Space-X rocket carried NASA’s Surface Water and Ocean Topography satellite into orbit. This satellite will be looking down at Earth for three years in an attempt to survey nearly all the water on the Earth’s surface. The resulting data will be crucial in understanding how climate change is altering the world’s oceans. Looking out instead of down, NASA satellites also found two “water worlds” in a single star system 218 light years away. The planets are super-Earths, about 50% bigger than our planet, but they have thousands of times more water. On average, the Earth’s oceans are about 2.5 miles (4 kilometers) deep. These two newly discovered exoplanets are covered in oceans 1,250 miles (2,000 kilometers) deep. The data astronomers are collecting on these planets is offering some of the best clues to date about these common super-Earths that may be more hospitable to life than the Earth. Finally, the new James Webb Space Telescope has been looking for distant galaxies as far from Earth as possible. Distant light is old light, so the James Webb Space Telescope is capturing images of galaxies from the first few hundred million years of the universe, allowing astronomers to learn a lot about what the infant universe was like. The Artemis I mission launched the Orion capsule on a test trip around the Moon aboard the Space Launch System rocket and was the first of a series of launches for the Artemis program. NASA/Kim Shiflett via Flickr, CC BY-NC-SA Cheap and expensive The James Webb Space Telescope was originally budgeted at US$1 billion in the early 2000s. By the time Webb launched, that price tag had ballooned to an astonishing cost of $10 billion. But Webb was not the only expensive NASA mission from 2022. After numerous delays, the Artemis 1 mission had a successful flyby of the Moon before it splashed down on Dec. 11, 2022 – 50 years to the day after Apollo 17 was the last American spacecraft to land on the Moon. Artemis 1 is the first in a series of NASA missions that aim to return U.S. astronauts to the Moon by 2030 and eventually establish a Moon base. Each launch is estimated to cost around $4.1 billion, with the entire program – including four initial launches and associated research and development – expected to cost an eye-popping $93 billion. While many recent missions have been among the most ambitious and expensive in the history of space, in some ways 2022 was also the year space became cheap. NASA launched more than a dozen CubeSats, shoe-box-sized satellites that can do science experiments in orbit at a cost of only $50,000 each. CubeSats weigh just a few pounds, and thanks to their small size and the ever-decreasing cost of rocket launches, even students can get an experiment into space. Almost 4,000 have been launched, a number that’s projected to double within six years. The streaks in this video from the Parker Solar Probe are structures called coronal streamers that are part of the surface of the Sun. Hot and cold 2022 also saw some of the hottest and coldest temperatures encountered by any spacecraft in history. Since its launch in August 2018, the Parker Solar Probe has been making closer and closer passes to the Sun, and on Dec. 11, 2022, it swooped past Earth’s star at just over 5 million miles (9 million kilometers) from the surface. The probe reaches incredible speeds as it passes the Sun and set the all-time speed record for a spacecraft at 364,000 mph (586,000 kph) in 2021. During each pass, the car-sized craft reaches a toasty 2,500 degrees Fahrenheit (1,371 Celsius) and is able to not only survive the heat but also measure the physical conditions in the outermost layers of the Sun. That data is helping astronomers better understand solar wind, the stream of high-energy particles that can interfere with electronics and telecommunications on Earth. Meanwhile, the Voyager 1 spacecraft continued its exploration of interstellar space. Since its launch in 1977, Voyager 1 and its twin, Voyager 2, have been traveling away from Earth. At a distance of 14.8 billion miles from Earth (22.5 billion kilometers) and counting, Voyager 1 is now the farthest human-made object from the Sun, and therefore also the coldest. The temperature beyond the edge of the Solar System where Voyager 1 now roams is a frigid 3 degrees above absolute zero, roughly minus-454 F (minus-270 C). The venerable spacecraft suffered a data glitch in May 2022, but despite the 22-hour travel time for a radio signal to travel between Voyager 1 and Earth, NASA engineers were able to restore full function to the craft. Volume and longevity NASA accomplished some incredible feats in 2022, but the organization’s pace is slow and steady compared to frenetic activity in the private sector. Last year set a record for the volume of space activity. There were 186 launches, all but six of which were successful. Space-X accounted for 61 orbital launches, doubling its total for 2021. Some of NASA’s achievements in 2022 were the result of persistence and durability. A U.S. citizen spent a record 355 days in orbit, setting the record for the longest single spaceflight. This year also marked the 22nd year of continuous human presence on the International Space Station, and the 25th year of continuous robotic exploration of Mars. The ancient Roman poet Virgil coined the phrase “ad astra per aspera,” or “to the stars through difficulties,” and this last year has shown that human efforts can overcome difficulties and reach for the stars.
|
Cosmology & The Universe
|
Heart-shape for the stars. My astronomy work. getty Astronomers have detected a radio signal from a far-off galaxy that flashes for up to three seconds on a regular basis. Over a billion light-years distant, the signal is called FRB 20191221A and it’s classed as a “fast radio burst”—a radio pulse. Around 1,000 times longer than most FRBs, FRB 20191221A is now the longest-lasting and most regular radio signal known in the entire night sky. It was detected using the CHIME radio telescope in British Columbia, Canada, which detected over 500 FRBs in its first year of operation. The results were published in Nature. Scientists think that the radio signal may be coming from a neutron star—what remains of the collapsed core of a giant star after it’s exploded as a supernova. Neutron stars spin rapidly. Though the origin of FRBs are mysterious it’s hoped that each one’s frequency, and how they differ in distance from us, could tell scientists about the exact rate at which the universe is expanding. The first FRB was discovered in 2007. FRB 20191221A was first detected on December 21, 2019. “It was unusual,” said Daniele Michilli, a postdoc in MIT’s Kavli Institute for Astrophysics and Space Research. “Not only was it very long, lasting about three seconds, but there were periodic peaks that were remarkably precise, emitting every fraction of a second — boom, boom, boom—like a heartbeat.” Artwork illustrating a fast-radio burst. Magnetars are types of neutron stars that have exceedingly ... [+] powerful magnetic fields, trillions of times stronger than Earth's own field and even more powerful than regular neutron stars. Recently, astronomers have suggested that asteroids might be orbiting some of these objects, leading to the emission of fast-radio bursts (FRBs). The idea is that asteroids orbiting within the magnetar's wind - a stream of fast particles emitted from its surface - carve a wake in the wind, leading to the generation of an electric current around the wake. When the magnetar's wind crosses the wake, a magnetic disturbance is created which generates an extremely intense, narrow beam of radio energy. In 2020, astronomers detected the first FRB from a magnetar - called SGR 1935+2154 - located within our own galaxy. The entire event was over in a fraction of a second. getty So what could be the source of FRB 20191221A? “There are not many things in the universe that emit strictly periodic signals,” said Michilli. “Examples that we know of in our own galaxy are radio pulsars and magnetars, which rotate and produce a beamed emission similar to a lighthouse. And we think this new signal could be a magnetar or pulsar on steroids.” Types of neutron stars, a pulsar is a neutron stars that emits beams of radio waves and appears to pulse as the star rotates while a magnetar has extreme magnetic fields. The FRB 20191221A signal is a million times brighter than pulsars and magnetars in the Milky Way. “From the properties of this new signal, we can say that around this source, there’s a cloud of plasma that must be extremely turbulent,” said Michilli. “Future telescopes promise to discover thousands of FRBs a month, and at that point we may find many more of these periodic signals.”
Wishing you clear skies and wide eyes.
Follow me on Twitter or LinkedIn. Check out my website or some of my other work here.
|
Cosmology & The Universe
|
In a series of papers, Professor Loeb and Michael Hippke indicate that conventional rockets would have a hard time escaping from certain kinds of extra-solar planets. - Image Credit: NASA/Tim Pyle Since the beginning of the Space Age, humans have relied on chemical rockets to get into space. While this method is certainly effective, it is also very expensive and requires a considerable amount of resources. As we look to more efficient means of getting out into space, one has to wonder if similarly-advanced species on other planets (where conditions would be different) would rely on similar methods.Harvard Professor Abraham Loeb and Michael Hippke, an independent researcher affiliated with the Sonneberg Observatory, both addressed this question in two recently–released papers. Whereas Prof. Loeb looks at the challenges extra-terrestrials would face launching rockets from Proxima b, Hippke considers whether aliens living on a Super-Earth would be able to get into space.The papers, tiled “Interstellar Escape from Proxima b is Barely Possible with Chemical Rockets” and “Spaceflight from Super-Earths is difficult” recently appeared online, and were authored by Prof. Loeb and Hippke, respectively. Whereas Loeb addresses the challenges of chemical rockets escaping Proxima b, Hippke considers whether or not the same rockets would able to achieve escape velocity at all. Artist’s impression of Proxima b, which was discovered using the Radial Velocity method. - Image Credit: ESO/M. Kornmesser For the sake of his study, Loeb considered how we humans are fortunate enough to live on a planet that is well-suited for space launches. Essentially, if a rocket is to escape from the Earth’s surface and reach space, it needs to achieve an escape velocity of 11.186 km/s (40,270 km/h; 25,020 mph). Similarly, the escape velocity needed to get away from the location of the Earth around the Sun is about 42 km/s (151,200 km/h; 93,951 mph).As Prof. Loeb told Universe Today via email:“Chemical propulsion requires a fuel mass that grows exponentially with terminal speed. By a fortunate coincidence the escape speed from the orbit of the Earth around the Sun is at the limit of attainable speed by chemical rockets. But the habitable zone around fainter stars is closer in, making it much more challenging for chemical rockets to escape from the deeper gravitational pit there.”As Loeb indicates in his essay, the escape speed scales as the square root of the stellar mass over the distance from the star, which implies that the escape speed from the habitable zone scales inversely with stellar mass to the power of one quarter. For planets like Earth, orbiting within the habitable zone of a G-type (yellow dwarf) star like our Sun, this works out quite while. This infographic compares the orbit of the planet around Proxima Centauri (Proxima b) with the same region of the Solar System. Proxima Centauri is smaller and cooler than the Sun and the planet orbits much closer to its star than Mercury. As a result it lies well within the habitable zone, where liquid water can exist on the planet’s surface. - Image Credit: ESO/M. Kornmesser/G. Coleman Unfortunately, this does not work well for terrestrial planets that orbit lower-mass M-type (red dwarf) stars. These stars are the most common type in the Universe, accounting for 75% of stars in the Milky Way Galaxy alone. In addition, recent exoplanet surveys have discovered a plethora of rocky planets orbiting red dwarf stars systems, with some scientists venturing that they are the most likely place to find potentially-habitable rocky planets.Using the nearest star to our own as an example (Proxima Centauri), Loeb explains how a rocket using chemical propellant would have a much harder time achieving escape velocity from a planet located within it’s habitable zone.“The nearest star to the Sun, Proxima Centauri, is an example for a faint star with only 12% of the mass of the Sun,” he said. “A couple of years ago, it was discovered that this star has an Earth-size planet, Proxima b, in its habitable zone, which is 20 times closer than the separation of the Earth from the Sun. At that location, the escape speed is 50% larger than from the orbit of the Earth around the Sun. A civilization on Proxima b will find it difficult to escape from their location to interstellar space with chemical rockets.”Hippke’s paper, on the other hand, begins by considering that Earth may in fact not be the most habitable type of planet in our Universe. For instance, planets that are more massive than Earth would have higher surface gravity, which means they would be able to hold onto a thicker atmosphere, which would provide greater shielding against harmful cosmic rays and solar radiation. Artists impression of a Super-Earth, a class of planet that has many times the mass of Earth, but less than a Uranus or Neptune-sized planet. - Image Credit: NASA/Ames/JPL-Caltech In addition, a planet with higher gravity would have a flatter topography, resulting in archipelagos instead of continents and shallower oceans – an ideal situation where biodiversity is concerned. However, when it comes to rocket launches, increased surface gravity would also mean a higher escape velocity. As Hippke indicated in his study:“Rockets suffer from the Tsiolkovsky (1903) equation : if a rocket carries its own fuel, the ratio of total rocket mass versus final velocity is an exponential function, making high speeds (or heavy payloads) increasingly expensive.”For comparison, Hippke uses Kepler-20 b, a Super-Earth located 950 light years away that is 1.6 times Earth’s radius and 9.7 times it mass. Whereas escape velocity from Earth is roughly 11 km/s, a rocket attempting to leave a Super-Earth similar to Kepler-20 b would need to achieve an escape velocity of ~27.1 km/s. As a result, a single-stage rocket on Kepler-20 b would have to burn 104 times as much fuel as a rocket on Earth to get into orbit. To put it into perspective, Hippke considers specific payloads being launched from Earth. “To lift a more useful payload of 6.2 t as required for the James Webb Space Telescope on Kepler-20 b, the fuel mass would increase to 55,000 t, about the mass of the largest ocean battleships,” he writes. “For a classical Apollo moon mission (45 t), the rocket would need to be considerably larger, ~400,000 t.”While Hippke’s analysis concludes that chemical rockets would still allow for escape velocities on Super-Earths up to 10 Earth masses, the amount of propellant needed makes this method impractical. As Hippke pointed out, this could have a serious effect on an alien civilization’s development.“I am surprised to see how close we as humans are to end up on a planet which is still reasonably lightweight to conduct space flight,” he said. “Other civilizations, if they exist, might not be as lucky. On more massive planets, space flight would be exponentially more expensive. Such civilizations would not have satellite TV, a moon mission, or a Hubble Space Telescope. This should alter their way of development in certain ways we can now analyze in more detail.”Both of these papers present some clear implications when it comes to the search for extra-terrestrial intelligence (SETI). For starters, it means that civilizations on planets that orbit red dwarf stars or Super-Earths are less likely to be space-faring, which would make detecting them more difficult. It also indicates that when it comes to the kinds of propulsion humanity is familiar with, we may be in the minority.“This above results imply that chemical propulsion has a limited utility, so it would make sense to search for signals associated with lightsails or nuclear engines, especially near dwarf stars,” said Loeb. “But there are also interesting implications for the future of our own civilization.” Artist’s concept of a bimodal nuclear rocket making the journey to the Moon, Mars, and other destinations in the Solar System. - Image Credit: NASA “One consequence of the paper is for space colonization and SETI,” added Hippke. “Civs from Super-Earths are much less likely to explore the stars. Instead, they would be (to some extent) “arrested” on their home planet, and e.g. make more use of lasers or radio telescopes for interstellar communication instead of sending probes or spaceships.”However, both Loeb and Hippke also note that extra-terrestrial civilizations could address these challenges by adopting other methods of propulsion. In the end, chemical propulsion may be something that few technologically-advanced species would adopt because it is simply not practical for them. As Loeb explained:“An advanced extraterrestrial civilization could use other propulsion methods, such as nuclear engines or lightsails which are not constrained by the same limitations as chemical propulsion and can reach speeds as high as a tenth of the speed of light. Our civilization is currently developing these alternative propulsion technologies but these efforts are still at their infancy.”One such example is Breakthrough Starshot, which is currently being developed by the Breakthrough Prize Foundation (of which Loeb is the chair of the Advisory Committee). This initiative aims to use a laser-driven lightsail to accelerate a nanocraft up to speeds of 20% the speed of light, which will allow it to travel to Proxima Centauri in just 20 years time.Hippke similarly considers nuclear rockets as a viable possibility, since increased surface gravity would also mean that space elevators would be impractical. Loeb also indicated that the limitations imposed by planets around low mass stars could have repercussions for when humans try to colonize the known Universe:“When the sun will heat up enough to boil all water off the face of the Earth, we could relocate to a new home by then. Some of the most desirable destinations would be systems of multiple planets around low mass stars, such as the nearby dwarf star TRAPPIST-1 which weighs 9% of a solar mass and hosts seven Earth-size planets. Once we get to the habitable zone of TRAPPIST-1, however, there would be no rush to escape. Such stars burn hydrogen so slowly that they could keep us warm for ten trillion years, about a thousand times longer than the lifetime of the sun.”But in the meantime, we can rest easy in the knowledge that we live on a habitable planet around a yellow dwarf star, which affords us not only life, but the ability to get out into space and explore. As always, when it comes to searching for signs of extra-terrestrial life in our Universe, we humans are forced to take the “low hanging fruit approach”. Basically, the only planet we know of that supports life is Earth, and the only means of space exploration we know how to look for are the ones we ourselves have tried and tested. As a result, we are somewhat limited when it comes to looking for biosignatures (i.e. planets with liquid water, oxygen and nitrogen atmospheres, etc.) or technosignatures (i.e. radio transmissions, chemical rockets, etc.).As our understanding of what conditions life can emerge under increases, and our own technology advances, we’ll have more to be on the lookout for. And hopefully, despite the additional challenges it may be facing, extra-terrestrial life will be looking for us!Professor Loeb’s essay was also recently published in Scientific American.Source: Universe Today - Further Reading: arXiv, arXiv (2), Scientific American If you enjoy our selection of content please consider following Universal-Sci on social media:
|
Cosmology & The Universe
|
China is readying a major project that not only augments the nation's astronomical research agenda but bolsters the use of the country's space station complex.
And there are bragging rights associated with China's star-studded venture.
The spacecraft is called Xuntian, known as the Chinese Survey Space Telescope or the Chinese Space Station Telescope (CSST). The name "Xuntian" can be literally translated as "surveying the sky" or "survey of the heavens."
Scheduled for launch next year, the bus-sized CSST houses a two-meter (6.6 foot) diameter primary mirror. This ultraviolet-optical space telescope is to co-orbit with the country's Tiangong space station. It has a nominal mission lifetime of 10 years, but the observatory's space duties could be extended.
Xuntian is designed to outdo NASA's Hubble Space Telescope. This large orbiting facility is to orbit near China's space station where it can be overhauled from time to time by Chinese spacewalkers.
Lin Xiqiang, deputy director of the China Manned Space Agency, has stated that the Xuntian in-orbit observatory is expected to make breakthroughs in cosmology, dark matter and dark energy, the Milky Way galaxy and other neighboring galaxies, star formation and evolution and exoplanets.
That's a tall order.
Lin said that the high-resolution telescope will take deep-field survey observations with an area of 17,500 square degrees, as well as make fine observations of different types of celestial bodies. Xuntian is endowed with a 2.5 billion pixel camera.
Field of view
Expected to be hurled into Earth orbit next year atop a Long March 5B rocket, Xuntian can obtain high-definition panoramic views of the universe having roughly the same spatial resolution as the Hubble Space Telescope. However, China's orbiting eye has a field of view more than 300 times larger than Hubble. The field of view is the area of the heavens a telescope can see at one time.
In an interview last year with China's state-run Xinhua news agency, Li Ran, project scientist of the CSST Scientific Data Reduction System, used the analogy of imaging a flock of sheep to point out CSST's capabilities.
"Hubble may see a sheep but the CSST sees thousands, all at the same resolution," Li said.
Moreover, this super-scope will stay in the same orbit as the space station for long-term independent flight and observations. It is designed to temporally dock with the space station for hands-on supply, maintenance and upgrading by Tiangong astronauts, Lin said.
High tech
In an interview with China Central Television (CCTV), Zhou Jianping, chief designer of the China manned space program, also heralded Xuntian's planned capabilities and contributions.
"The Xuntian telescope has been the most important scientific project since the launch of our country's space station program. It is a scientific facility that Chinese astronomical community has eagerly anticipated, and a scientific facility representing the state-level high tech in astronomy," Zhou said.
The telescope is also the most advanced in terms of its ability to produce images in the ultraviolet spectrum among all the ongoing telescope research projects in the world, added Zhou. "It's expected to greatly boost the development of astronomy, advance our country's astronomy research to an international leading level and help Chinese astronomers become a leading force in this field."
First-generation
According to Li Chengyuan of the School of Physics and Astronomy at China's Sun Yat-sen University, the China Space Station Telescope and NASA's Hubble Space Telescope are sensitive to a similar wavelength interval.
But Xuntian covers a field of view which is about 5 to 8 times wider than that of Hubble, Li emphasized last year in the journal Research in Astronomy and Astrophysics.
The "first-generation" Xuntian space telescope consists of five observation instruments, including the Xuntian module, the terahertz module, the multichannel imager, the integral field spectrograph and the extrasolar planetary imaging coronagraph.
The Xuntian module, a camera with a wide field of view, will take up major observation time.
Test and assembly
During its normal observations, the space telescope will fly independently in the same orbit as China's space station, but at a faraway distance.
"We are still developing the prototype sample. Currently, we've completed the development of all subsystems, components, and units, and we are preparing for the test after they are assembled," said Xu Shuyan, chief designer of the Xuntian optical facility and researcher from the National Astronomical Observatories of the Chinese Academy of Sciences.
"After this, we will start the development of the telescope sample, and start the research of the flying parts. Then we will conduct the joint test with the Xuntian platform and the test at the launch base, before it is launched," Xu told CCTV.
World-class center
In the big picture world of expanding the frontiers of space astronomy you need to look no further than the achievements of the Space Telescope Science Institute (STScI) in Baltimore, Maryland. STScI is a multi-mission science operations center for NASA's flagship observatories and a world-class astronomical research center.
STScI is home-base for wow-making science programs utilizing the James Webb Space Telescope, the Hubble Space Telescope and will be the science operations center for the Nancy Grace Roman Space Telescope launching in the mid-2020s.
The institute is located on the campus of Johns Hopkins University in Baltimore, Maryland, and is operated by the Association of Universities for Research in Astronomy for NASA.
Open questions
While Chinese space agency leaders are already boasting about the capabilities of Xuntian, some researchers have their doubts.
"For facilities open to the international scientific community, such as Hubble or Webb, we provide significant documentation and software so that researchers can plan outstanding science programs," said Tom Brown, an astronomer and head of the Hubble Mission Office at STScI.
"In contrast, not a lot is publicly known about the specific capabilities of the China Space Station Telescope, so it is difficult to judge how it will enable similar investigations," Brown told Space.com.
From the little that is known, Brown said it seems like China's Space Station Telescope will have a larger field of view than Hubble, but a smaller mirror, with less collecting area and spatial resolution.
The spectral resolution appears to be significantly lower than that available on Hubble, and CSST does not extend into the far-ultraviolet, that is, below 200 nanometers.
"There are a lot of open questions at this point," said Brown, including if the space-based telescope can be successfully launched, if it can be maintained in a space station environment, how observing time will be peer reviewed and awarded and how the data will be calibrated.
"Hubble continues to lead the field in all the ways one measures the worth of a world-class research facility, pursuing ground-breaking projects in all areas of astrophysics," Brown said. "I am curious to see how the China Space Station Telescope story unfolds."
|
Cosmology & The Universe
|
Webb identifies the earliest strands of the cosmic web
Galaxies are not scattered randomly across the universe. They gather together not only into clusters, but into vast interconnected filamentary structures with gigantic barren voids in between. This "cosmic web" started out tenuous and became more distinct over time as gravity drew matter together.
Astronomers using the James Webb Space Telescope have discovered a thread-like arrangement of 10 galaxies that existed just 830 million years after the Big Bang. The 3 million light-year-long structure is anchored by a luminous quasar—a galaxy with an active, supermassive black hole at its core. The team believes the filament will eventually evolve into a massive cluster of galaxies, much like the well-known Coma Cluster in the nearby universe.
"I was surprised by how long and how narrow this filament is," said team member Xiaohui Fan of the University of Arizona in Tucson. "I expected to find something, but I didn't expect such a long, distinctly thin structure."
"This is one of the earliest filamentary structures that people have ever found associated with a distant quasar," added Feige Wang of the University of Arizona in Tucson, the principal investigator of this program.
This discovery is from the ASPIRE project (A SPectroscopic survey of biased halos In the Reionization Era), whose main goal is to study the cosmic environments of the earliest black holes. In total, the program will observe 25 quasars that existed within the first billion years after the Big Bang, a time known as the Epoch of Reionization.
"The last two decades of cosmology research have given us a robust understanding of how the cosmic web forms and evolves. ASPIRE aims to understand how to incorporate the emergence of the earliest massive black holes into our current story of the formation of cosmic structure," explained team member Joseph Hennawi of the University of California, Santa Barbara.
Growing monsters
Another part of the study investigates the properties of eight quasars in the young universe. The team confirmed that their central black holes, which existed less than a billion years after the Big Bang, range in mass from 600 million to 2 billion times the mass of our sun. Astronomers continue seeking evidence to explain how these black holes could grow so large so fast.
"To form these supermassive black holes in such a short time, two criteria must be satisfied. First, you need to start growing from a massive 'seed' black hole. Second, even if this seed starts with a mass equivalent to a thousand Suns, it still needs to accrete a million times more matter at the maximum possible rate for its entire lifetime," explained Wang.
"These unprecedented observations are providing important clues about how black holes are assembled. We have learned that these black holes are situated in massive young galaxies that provide the reservoir of fuel for their growth," said Jinyi Yang of the University of Arizona, who is leading the study of black holes with ASPIRE.
Webb also provided the best evidence yet of how early supermassive black holes potentially regulate the formation of stars in their galaxies. While supermassive black holes accrete matter, they also can power tremendous outflows of material. These winds can extend far beyond the black hole itself, on a galactic scale, and can have a significant impact on the formation of stars.
"Strong winds from black holes can suppress the formation of stars in the host galaxy. Such winds have been observed in the nearby universe but have never been directly observed in the Epoch of Reionization," said Yang. "The scale of the wind is related to the structure of the quasar. In the Webb observations, we are seeing that such winds existed in the early universe."
These results were published in two papers in The Astrophysical Journal Letters on June 29.
More information: Feige Wang et al, A SPectroscopic Survey of Biased Halos in the Reionization Era (ASPIRE): JWST Reveals a Filamentary Structure around a z = 6.61 Quasar, The Astrophysical Journal Letters (2023). DOI: 10.3847/2041-8213/accd6f
Jinyi Yang et al, A SPectroscopic Survey of Biased Halos in the Reionization Era (ASPIRE): A First Look at the Rest-frame Optical Spectra of z > 6.5 Quasars Using JWST, The Astrophysical Journal Letters (2023). DOI: 10.3847/2041-8213/acc9c8
Journal information: Astrophysical Journal Letters
Provided by NASA
|
Cosmology & The Universe
|
There’s no two-ways about it, the Universe is an extremely big place! And thanks to the limitations placed upon us by Special Relativity, traveling to even the closest star systems could take millennia. As we addressed in a previous article, the estimated travel time to the nearest star system (Alpha Centauri) could take anywhere from 19,000 to 81,000 years using conventional methods.For this reason, many theorists have recommended that humanity rely on generation ships to spread the seed of humanity among the stars. Naturally, such a project presents many challenges, not the least of which is how large a spacecraft would need to be to sustain a multi-generational crew. In a new study, of international scientists addressed this very question and determined that a lot of interior space would be needed!The study, which recently appeared online, was led by Dr. Frederic Marin of the Astronomical Observatory of Strasbourg and Dr. Camille Beluffi, a particle physicist with the scientific start-up Casc4de. They were joined by Dr. Rhys Taylor of the Astronomical Institute of the Czech Academy of Science, and Dr. Loic Grau of the structural engineering firm Morphosense. Their study is the latest in a series conducted by Dr. Marin and Dr. Beluffi that address the challenges of sending a multi-generational spacecraft to another star system. In a previous study, they addressed how large a generation ship’s crew would need to be in order to make it to their destination in good health.They did this using custom-made numerical code software developed by Dr. Marin himself known as HERITAGE. In a previous interview with Dr. Marin, he described HERITAGE as “a stochastic Monte Carlo code that accounts for all possible outcomes of space simulations by testing every randomized scenario for procreation, life and death.”From their analysis, they determined that a minimum of 98 people would be needed to accomplish a multi-generational mission to another star system, without risks of genetic disorders and other negative effects associated with inter-marrying. For this study, the team addressed the equally important question of how to feed the crew.Given that dried food stocks would not be a viable option, since they would deteriorate and decay during the centuries that the ship was in transit, the ship and crew would have to be equipped to grow their own food. This raises the question, how much space would be needed to produce enough crops to keep a sizable crew fed?When it comes to space travel, the size of the spacecraft is a major issue. As Dr. Marin explained to Universe Today via email:“The heavier the satellite, the more expensive it is to launch it into space. Then, the larger/heavier the spaceship, the more complicated and resource-expensive will be the propulsion system. In fact, the size of the spaceship will constrain many parameters. In the case of a generation ship, the amount of food we can produce is directly related to the surface area inside the ship. This area is, in turn, related with the size of the population aboard. Size, food production and population are in fact intrinsically connected.”To address this important question – “how big does the ship need to be?” – the team relied on an updated version of the HERITAGE software. As they state in their study, this version “accounts for age-dependent biological characteristics such as height and weight, and features related to the varying number of colonists, such as infertility, pregnancy and miscarriage rates.”Beyond this, the team also took into account the caloric needs of the crew in order to calculate how much food would need to be produced per year. To accomplish this, the team included anthropomorphic data in their simulations to determine how much calories would be consumed based on a passenger’s age, weight, height, activity levels, and other medical data.“Using the Harris-Benedict equation to estimate an individual’s basal metabolic rate, we evaluated how many kilo-calories must be eaten per day per person in order to maintain ideal body weight. We took care to include weight and height variations to account for a realistic population, including heavy/light corpulence and tall/small people. Once the caloric requirement was estimated, we computed how much food geoponics, hydroponics and aeroponics farming techniques could produce per year per kilometer square.”By comparing these numbers with conventional and modern farming techniques, they we are able to predict the amount of artificial land that would have to be allocated to farming inside the vessel. They then based their overall calculations on a relatively large screw (500 people) and derived an overall figure. As Dr. Marin explained:“We found that, for an heterogeneous crew of, e.g., 500 people living on an omnivorous, balanced diet, 0.45 km² [0.17 mi²]of artificial land would suffice in order to grow all the necessary food using a combination of aeroponics (for fruits, vegetables, starch, sugar, and oil) and conventional farming (for meat, fish, dairy, and honey).”These values also provide some architectural constraints for the minimum size of the generation ship itself. Assuming the ship were designed to generate artificial gravity by centripetal force (i.e. a rotating cylinder) the would need be a minimum of about 224 meters (735 feet) in radius and 320 meters (1050 feet) in length.“Of course, other facilities besides farming are necessary – human habitation, control rooms, power generation, reaction mass and engines, which make the spaceship at least twice larger,” Dr. Marin added. “Interestingly, even if we double the length of the spaceship, we find a structure that is still smaller than the tallest building in the world – Burj Khalifa (828 m; 2716.5 ft).”For aficionados of interstellar space exploration, and mission planners, this latest study (and others in the series) are highly significant, in that they are providing an increasingly clear picture of what the mission architecture of a generation ship would look like. Beyond merely theoretical propositions of what would be involved, these studies provide actual numbers that scientists may be able work with someday.And as Dr. Marin explained, it also makes such a grandiose project (which seems daunting on its face) appear that much more feasible:“This work gives us an insight on the real possibility to create generation ships. We are already capable to build such large structures on Earth. We have now quantified with precision how large should be the surface dedicated to farming in generation ships so that the population can feed during centuries-long trips.” According to Marin, the only remaining issue that needs to be explored is water. Any mission involving a large crew spending upwards of a few centuries in interstellar space is going to need plenty of water for drinking, irrigation, and sanitation. And it is not enough to simply rely on recycling methods to ensure a steady supply.This, Marin indicates, will be the subject of their next study. “In deep-space (far away from planets, moons or large asteroids), water might be very difficult to collect,” he said. “Then the resources on-board might suffer from the lack of water. We must dedicate our future investigations to solve this issue.”As with most things pertaining to deep space exploration or the colonization of other worlds, the answer to the invariable question (“can it be done?”) is almost always the same – “How much are you willing to spend?” There is no doubt that an interstellar mission, regardless of what form it might take, would require a massive commitment in terms of time, energy, and resources. It would also require that people be willing to risk their lives, so only adventurous people would apply. But perhaps most of all, it would need the will to see it through. Barring urgency or extreme necessity (i.e. planet Earth is doomed), it’s hard to imagine all of these factors coming together.However, knowing exactly how much it will cost us in terms of money, resources and time to mount such a project is a very good first step. Only then can humanity decide if they are willing to make the commitment.Source: Universe Today - Further Reading: arXiv If you enjoy our selection of content please consider following Universal-Sci on social media:
|
Cosmology & The Universe
|
Astronomers using NASA's James Webb Space Telescope (JWST) and Chandra X-ray Observatory have discovered the oldest and most distant X-ray-spitting quasar in the known universe, and it seems to be powered by the "seed" of an ancient supermassive black hole.
Quasars are the bright hearts of active galaxies, which are fueled by active supermassive black holes that cause infalling matter to emit intense thermal radiation as they feed. Quasars can be so bright across the entire electromagnetic spectrum that they often outshine the combined light from every star in the galaxy surrounding them.
This primordial quasar, designated UHZ1, was spotted in high-energy X-ray light emitted when the cosmos was no more than 450 million years old and has thus been traveling through the universe for around 13.7 billion years to reach us. As such, this quasar could be an example of a black hole "seed" in the early universe that helps reveal how supermassive black holes reached tremendous masses of millions, or even billions, of times that of the sun.
"It's thrilling to be able to reveal the presence of a supermassive black hole, in place at the center of a galaxy a mere 450 million years after the Big Bang," study co-author Priyamvada Natarajan, a professor of astronomy and physics at Yale University, said in a statement. "NASA's Chandra space telescope detected X-rays from this distant quasar, which harbors an outsized black hole in its center."
The discovery of UHZ1 is detailed in a paper published in the journal Nature Astronomy.
Understanding how supermassive black holes got so huge
Scientists theorize that supermassive black holes grew to such tremendous sizes by starting off as black hole seeds in the early universe and growing steadily by gorging on matter and merging with other black holes.
The question is, how big were these seeds to begin with? One variation of this theory suggests the early universe was packed with "light seeds" — black holes created when massive stars ran out of fuel for nuclear fusion and exploded in supernova blasts, collapsing under their own gravity.
However, this explanation doesn't give supermassive black holes enough time to reach masses equivalent to millions, let alone billions, of suns at the early times astronomers observe these behemoths in the infant universe.
One idea that would give supermassive black holes a "head start" on this process is if they started growing from "heavy seeds." Between 2006 and 2007, Natarajan developed a model suggesting that heavy black hole seeds could form in galaxies where star formation is suppressed.
These would be satellite galaxies located near the galaxies in the early universe that birthed the first stars. This model suggests that large disks of gas and dust in these satellite galaxies could collapse directly into black-hole-heavy seeds, instead of first birthing stars that eventually collapsed into black holes millions or billions of years later. These heavy-seed black hole satellite galaxies would then merge with the main star-forming galaxies nearby.
In 2017, Natarajan and her colleagues suggested that heavy black hole seed galaxies should be observable in the early universe thanks to their unique properties. In particular, the central black hole in a heavy-black-hole-seed galaxy would outweigh that galaxy's stars. This should be visible as X-ray quasars to the Chandra X-ray Observatory, as well as to the yet-to-be-launched JWST, Natarajan proposed in 2017.
Finding a heavy black hole seed
Now, six years later, the team's prediction bears fruit with the discovery of this distant X-ray quasar. UHZ1 was identified by a team led by Akos Bogdan, an astrophysicist at the Harvard and Smithsonian Center for Astrophysics, and Andy Goulding, an astrophysicist at Princeton, who combined recent data from the Chandra X-ray Observatory and JWST to peer behind galaxy Abell 2744.
"UHZ1 is the first candidate that matches all our predicted properties for this transient class of over-massive black hole galaxies," Natarajan said. "And now we're seeing compelling first evidence. This is an exciting intersection of topics, a culmination of all the things I have been working on."
Goulding thinks there are many more heavy-seed galaxies out there just waiting to be uncovered.
"UHZ1 may only be the tip of the iceberg," he said. "The JWST has opened a new window on the early universe. It will no doubt help us find more UHZ1s and ultimately understand if over-massive black holes were commonplace."
Live Science newsletter
Stay up to date on the latest science news by signing up for our Essentials newsletter.
Robert Lea is a science journalist in the U.K. who specializes in science, space, physics, astronomy, astrophysics, cosmology, quantum mechanics and technology. Rob's articles have been published in Physics World, New Scientist, Astronomy Magazine, All About Space and ZME Science. He also writes about science communication for Elsevier and the European Journal of Physics. Rob holds a bachelor of science degree in physics and astronomy from the U.K.’s Open University
|
Cosmology & The Universe
|
By Matt WilliamsDirection is something we humans are pretty accustomed to. Living in our friendly terrestrial environment, we are used to seeing things in term of up and down, left and right, forwards or backwards. And to us, our frame of reference is fixed and doesn’t change, unless we move or are in the process of moving. But when it comes to cosmology, things get a little more complicated. Is there an up out there? New research says no. Out there in the universe, one direction is much like another. - image Credit: NASA; ESA; Z. Levay and R. van der Marel, STScI; T. Hallas; and A. Mellinger For a long time now, cosmologists have held the belief that the universe is homogeneous and isotropic – i.e. fundamentally the same in all directions. In this sense, there is no such thing as “up” or “down” when it comes to space, only points of reference that are entirely relative. And thanks to a new study by researchers from the University College London, that view has been shown to be correct.For the sake of their study, titled “How isotropic is the Universe?“, the research team used survey data of the Cosmic Microwave Background(CMB) – the thermal radiation left over from the Big Bang. This data was obtained by the ESA’s Planck spacecraft between 2009 and 2013.The team then analyzed it using a supercomputer to determine if there were any polarization patterns that would indicate if space has a “preferred direction” of expansion. The purpose of this test was to see if one of the basic assumptions that underlies the most widely-accepted cosmological model is in fact correct. The cosmic microwave background radiation, enhanced to show the anomalies. Credit: ESA and the Planck Collaboration The first of these assumptions is that the Universe was created by the Big Bang, which is based on the discovery that the Universe is in a state of expansion, and the discovery of the Cosmic Microwave Background. The second assumption is that space is homogenous and istropic, meaning that there are no major differences in the distribution of matter over large scales.This belief, which is also known as the Cosmological Principle, is based partly on the Copernican Principle (which states that Earth has no special place in the Universe) and Einstein’s Theory of Relativity – which demonstrated that the measurement of inertia in any system is relative to the observer.This theory has always had its limitations, as matter is clearly not evenly distributed at smaller scales (i.e. star systems, galaxies, galaxy clusters, etc.). However, cosmologists have argued around this by saying that fluctuation on the small scale are due to quantum fluctuations that occurred in the early Universe, and that the large-scale structure is one of homogeneity. Timeline of the Big Bang and the expansion of the Universe. - Image Credit: NASA By looking for fluctuations in the oldest light in the Universe, scientists have been attempting to determine if this is in fact correct. In the past thirty years, these kinds of measurements have been performed by multiple missions, such as the Cosmic Background Explorer (COBE) mission, the Wilkinson Microwave Anisotropy Probe (WMAP), and the Planck spacecraft.For the sake of their study, the UCL research team – led by Daniela Saadeh and Stephen Feeney – looked at things a little differently. Instead of searching for imbalances in the microwave background, they looked for signs that space could have a preferred direction of expansion, and how these might imprint themselves on the CMB.As Daniela Saadeh – a PhD student at UCL and the lead author on the paper – told Universe Today via email:“We analyzed the temperature and polarization of the cosmic microwave background (CMB), a relic radiation from the Big Bang, using data from the Planck mission. We compared the real CMB against our predictions for what it would look like in an anisotropic universe. After this search, we concluded that there is no evidence for these patterns and that the assumption that the Universe is isotropic on large scales is a good one.”Basically, their results showed that there is only a 1 in 121 000 chance that the Universe is anisotropic. In other words, the evidence indicates that the Universe has been expanding in all directions uniformly, thus removing any doubts about their being any actual sense of direction on the large-scale. A “now and then” all-sky image captured by the Planck spacecraft, simultaneously showing our galaxy and its structures seen as in recent history; and ‘then’ – the red afterglow of the Big Bang seen as it was just 380,000 years later. – Image Credit: ESA And in a way, this is a bit disappointing, since a Universe that is not homogenous and the same in all directions would lead to a set of solutions to Einstein’s field equations. By themselves, these equations do not impose any symmetries on space time, but the Standard Model (of which they are part) does accept homogeneity as a sort of given.These solutions are known as the Bianchi models, which were proposed by Italian mathematician Luigi Bianchi in the late 19th century. These algebraic theories, which can be applied to three-dimensional spacetime, are obtained by being less restrictive, and thus allow for a Universe that is anisotropic.On the other hand, the study performed by Saadeh, Feeney, and their colleagues has shown that one of the main assumptions that our current cosmological models rest on is indeed correct. In so doing, they have also provided a much-needed sense of closer to a long-term debate.“In the last ten years there has been considerable discussion around whether there were signs of large-scale anisotropy lurking in the CMB,” said Saadeh. “If the Universe were anisotropic, we would need to revise many of our calculations about its history and content. Planck high-quality data came with a golden opportunity to perform this health check on the standard model of cosmology and the good news is that it is safe.”So the next time you find yourself looking up at the night sky, remember… that’s a luxury you have only while you’re standing on Earth. Out there, its a whole ‘nother ballgame! So enjoy this thing we call “direction” when and whereyou can.Source: Universe Today - Further Reading: arXiv, Science
|
Cosmology & The Universe
|
LEAD, S.D. -- In a former gold mine a mile underground, inside a titanium tank filled with a rare liquified gas, scientists have begun the search for what so far has been unfindable: dark matter. Scientists are pretty sure the invisible stuff makes up most of the universe’s mass and say we wouldn't be here without it — but they don't know what it is. The race to solve this enormous mystery has brought one team to the depths under Lead, South Dakota. The question for scientists is basic, says Kevin Lesko, a physicist at Lawrence Berkeley National Laboratory. “What is this great place I live in? Right now, 95% of it is a mystery.”The idea is that a mile of dirt and rock, a giant tank, a second tank and the purest titanium in the world will block nearly all the cosmic rays and particles that zip around — and through — all of us every day. But dark matter particles, scientists think, can avoid all those obstacles. They hope one will fly into the vat of liquid xenon in the inner tank and smash into a xenon nucleus like two balls in a game of pool, revealing its existence in a flash of light seen by a device called “the time projection chamber.”Scientists announced Thursday that the five-year, $60 million search finally got underway two months ago after a delay caused by the COVID-19 pandemic. So far the device has found ... nothing. At least no dark matter. That’s OK, they say. The equipment appears to be working to filter out most of the background radiation they hoped to block. “To search for this very rare type of interaction, job number one is to first get rid of all of the ordinary sources of radiation, which would overwhelm the experiment,” said University of Maryland physicist Carter Hall.And if all their calculations and theories are right, they figure they’ll see only a couple fleeting signs of dark matter a year. The team of 250 scientists estimates they’ll get 20 times more data over the next couple of years.By the time the experiment finishes, the chance of finding dark matter with this device is “probably less than 50% but more than 10%,” said Hugh Lippincott, a physicist and spokesman for the experiment in a Thursday news conference. While that's far from a sure thing, “you need a little enthusiasm," Lawrence Berkeley's Lesko said. “You don’t go into rare search physics without some hope of finding something.” Two hulking Depression-era hoists run an elevator that brings scientists to what's called the LUX-ZEPLIN experiment in the Sanford Underground Research Facility. A 10-minute descent ends in a tunnel with cool-to-the-touch walls lined with netting. But the old, musty mine soon leads to a high-tech lab where dirt and contamination is the enemy. Helmets are exchanged for new cleaner ones and a double layer of baby blue booties go over steel-toed safety boots.The heart of the experiment is the giant tank called the cryostat, lead engineer Jeff Cherwinka said in a December 2019 tour before the device was closed and filled. He described it as “like a thermos” made of “perhaps the purest titanium in the world” designed to keep the liquid xenon cold and keep background radiation at a minimum.Xenon is special, explained experiment physics coordinator Aaron Manalaysay, because it allows researchers to see if a collision is with one of its electrons or with its nucleus. If something hits the nucleus, it is more likely to be the dark matter that everyone is looking for, he said. These scientists tried a similar, smaller experiment here years ago. After coming up empty, they figured they had to go much bigger. Another large-scale experiment is underway in Italy run by a rival team, but no results have been announced so far.The scientists are trying to understand why the universe is not what it seems. One part of the mystery is dark matter, which has by far most of the mass in the cosmos. Astronomers know it's there because when they measure the stars and other regular matter in galaxies, they find that there is not nearly enough gravity to hold these clusters together. If nothing else was out there, galaxies would be “quickly flying apart,” Manalaysay said.“It is essentially impossible to understand our observation of history, of the evolutionary cosmos without dark matter,” Manalaysay said. Lippincott, a University of California, Santa Barbara, physicist, said “we would not be here without dark matter.”So while there's little doubt that dark matter exists, there's lots of doubt about what it is. The leading theory is that it involves things called WIMPs — weakly interacting massive particles. If that's the case, LUX-ZEPLIN could be able to detect them. We want to find “where the wimps can be hiding,” Lippincott said. ———Follow Seth Borenstein on Twitter at @borenbears. ———The Associated Press Health and Science Department receives support from the Howard Hughes Medical Institute’s Department of Science Education. The AP is solely responsible for all content.
|
Cosmology & The Universe
|
Cosmologists have spent decades striving to understand why our universe is so stunningly vanilla. Not only is it smooth and flat as far as we can see, but it’s also expanding at an ever-so-slowly increasing pace, when naive calculations suggest that—coming out of the Big Bang—space should have become crumpled up by gravity and blasted apart by repulsive dark energy.To explain the cosmos’s flatness, physicists have added a dramatic opening chapter to cosmic history: They propose that space rapidly inflated like a balloon at the start of the Big Bang, ironing out any curvature. And to explain the gentle growth of space following that initial spell of inflation, some have argued that our universe is just one among many less hospitable universes in a giant multiverse.But now two physicists have turned the conventional thinking about our vanilla universe on its head. Following a line of research started by Stephen Hawking and Gary Gibbons in 1977, the duo has published a new calculation suggesting that the plainness of the cosmos is expected, rather than rare. Our universe is the way it is, according to Neil Turok of the University of Edinburgh and Latham Boyle of the Perimeter Institute for Theoretical Physics in Waterloo, Canada, for the same reason that air spreads evenly throughout a room: Weirder options are conceivable but exceedingly improbable.The universe “may seem extremely fine-tuned, extremely unlikely, but [they’re] saying, ‘Wait a minute, it’s the favored one,’” said Thomas Hertog, a cosmologist at the Catholic University of Leuven in Belgium.“It’s a novel contribution that uses different methods compared to what most people have been doing,” said Steffen Gielen, a cosmologist at the University of Sheffield in the United Kingdom.The provocative conclusion rests on a mathematical trick involving switching to a clock that ticks with imaginary numbers. Using the imaginary clock, as Hawking did in the ’70s, Turok and Boyle could calculate a quantity, known as entropy, that appears to correspond to our universe. But the imaginary time trick is a roundabout way of calculating entropy, and without a more rigorous method, the meaning of the quantity remains hotly debated. While physicists puzzle over the correct interpretation of the entropy calculation, many view it as a new guidepost on the road to the fundamental, quantum nature of space and time.“Somehow,” Gielen said, “it’s giving us a window into perhaps seeing the microstructure of space-time.”Imaginary PathsTurok and Boyle, frequent collaborators, are renowned for devising creative and unorthodox ideas about cosmology. Last year, to study how likely our universe may be, they turned to a technique developed in the ’40s by the physicist Richard Feynman.Aiming to capture the probabilistic behavior of particles, Feynman imagined that a particle explores all possible routes linking start to finish: a straight line, a curve, a loop, ad infinitum. He devised a way to give each path a number related to its likelihood and add all the numbers up. This “path integral” technique became a powerful framework for predicting how any quantum system would most likely behave.As soon as Feynman started publicizing the path integral, physicists spotted a curious connection with thermodynamics, the venerable science of temperature and energy. It was this bridge between quantum theory and thermodynamics that enabled Turok and Boyle’s calculation.The South African physicist and cosmologist Neil Turok is a professor at the University of Edinburgh.Photograph: Gabriela Secara/Perimeter InstituteThermodynamics leverages the power of statistics so that you can use just a few numbers to describe a system of many parts, such as the gajillion air molecules rattling around in a room. Temperature, for instance—essentially the average speed of air molecules—gives a rough sense of the room’s energy. Overall properties like temperature and pressure describe a “macrostate” of the room.But a macrostate is a crude account; air molecules can be arranged in a tremendous number of ways that all correspond to the same macrostate. Nudge one oxygen atom a bit to the left, and the temperature won’t budge. Each unique microscopic configuration is known as a microstate, and the number of microstates corresponding to a given macrostate determines its entropy.Entropy gives physicists a sharp way of comparing the odds of different outcomes: The higher the entropy of a macrostate, the more likely it is. There are vastly more ways for air molecules to arrange themselves throughout the whole room than if they’re bunched up in a corner, for instance. As a result, one expects air molecules to spread out (and stay spread out). The self-evident truth that probable outcomes are probable, couched in the language of physics, becomes the famous second law of thermodynamics: that the total entropy of a system tends to grow.The resemblance to the path integral was unmistakable: In thermodynamics, you add up all possible configurations of a system. And with the path integral, you add up all possible paths a system can take. There’s just one rather glaring distinction: Thermodynamics deals in probabilities, which are positive numbers that straightforwardly add together. But in the path integral, the number assigned to each path is complex, meaning that it involves the imaginary number i, the square root of −1. Complex numbers can grow or shrink when added together—allowing them to capture the wavelike nature of quantum particles, which can combine or cancel out.Yet physicists found that a simple transformation can take you from one realm to the other. Make time imaginary (a move known as a Wick rotation after the Italian physicist Gian Carlo Wick), and a second i enters the path integral that snuffs out the first one, turning imaginary numbers into real probabilities. Replace the time variable with the inverse of temperature, and you get a well-known thermodynamic equation.This Wick trick led to a blockbuster finding by Hawking and Gibbons in 1977, at the end of a whirlwind series of theoretical discoveries about space and time.The Entropy of Space-TimeDecades earlier, Einstein’s general theory of relativity had revealed that space and time together form a unified fabric of reality—space-time—and that the force of gravity is really the tendency for objects to follow the folds in space-time. In extreme circumstances, space-time can curve steeply enough to create an inescapable Alcatraz known as a black hole.In 1973, Jacob Bekenstein advanced the heresy that black holes are imperfect cosmic prisons. He reasoned that the abysses should absorb the entropy of their meals, rather than deleting that entropy from the universe and violating the second law of thermodynamics. But if black holes have entropy, they must also have temperatures and must radiate heat.A skeptical Stephen Hawking tried to prove Bekenstein wrong, embarking on an intricate calculation of how quantum particles behave in the curved space-time of a black hole. To his surprise, in 1974 he found that black holes do indeed radiate. Another calculation confirmed Bekenstein’s guess: A black hole has entropy equal to one-quarter the area of its event horizon—the point of no return for an infalling object.In the years that followed, the British physicists Malcolm Perry and Gibbons, and later Gibbons and Hawking, arrived at the same result from another direction. They set up a path integral, in principle adding up all the different ways space-time might bend to make a black hole. Next, they Wick-rotated the black hole, marking the flow of time with imaginary numbers, and scrutinized its shape. They discovered that in the imaginary time direction the black hole periodically returned to its initial state. This Groundhog Day-like repetition in imaginary time gave the black hole a sort of stasis that allowed them to calculate its temperature and entropy.They might not have trusted the results if the answers had not precisely matched those calculated earlier by Bekenstein and Hawking. By the end of the decade, their collective work had yielded a startling notion: The entropy of black holes implied that space-time itself is made of tiny, rearrangeable pieces, much as air is made of molecules. And miraculously, even without knowing what these “gravitational atoms” were, physicists could count their arrangements by looking at a black hole in imaginary time.“It’s that result which left a deep, deep impression on Hawking,” said Hertog, Hawking’s former graduate student and longtime collaborator. Hawking immediately wondered if the Wick rotation would work for more than just black holes. “If that geometry captures a quantum property of a black hole,” Hertog said, “then it’s irresistible to do the same with the cosmological properties of the whole universe.”Counting All Possible UniversesRight away, Hawking and Gibbons Wick-rotated one of the simplest imaginable universes—one containing nothing but the dark energy built into space itself. This empty, expanding universe, called a “de Sitter” space-time, has a horizon, beyond which space expands so quickly that no signal from there will ever reach an observer in the center of the space. In 1977, Gibbons and Hawking calculated that, like a black hole, a de Sitter universe also has an entropy equal to one-fourth its horizon’s area. Again, space-time seemed to have a countable number of microstates.But the entropy of the actual universe remained an open question. Our universe is not empty; it brims with radiating light and streams of galaxies and dark matter. Light drove a brisk expansion of space during the universe’s youth, then the gravitational attraction of matter slowed things to a crawl during cosmic adolescence. Now dark energy appears have taken over, driving a runaway expansion. “That expansion history is a bumpy ride,” Hertog said. “To get an explicit solution is not so easy.”Over the past year or so, Boyle and Turok have built just such an explicit solution. First, in January, while playing with toy cosmologies, they noticed that adding radiation to de Sitter space-time didn’t spoil the simplicity required to Wick-rotate the universe.Then over the summer they discovered that the technique would withstand even the messy inclusion of matter. The mathematical curve describing the more complicated expansion history still fell into a particular group of easy-to-handle functions, and the world of thermodynamics remained accessible. “This Wick rotation is murky business when you move away from very symmetric space-time,” said Guilherme Leite Pimentel, a cosmologist at the Scuola Normale Superiore in Pisa, Italy. “But they managed to find it.”By Wick-rotating the roller-coaster expansion history of a more realistic class of universes, they got a more versatile equation for cosmic entropy. For a wide range of cosmic macrostates defined by radiation, matter, curvature, and a dark energy density (much as a range of temperatures and pressures define different possible environments of a room), the formula spits out the number of corresponding microstates. Turok and Boyle posted their results online in early October.Latham Boyle, a physicist and cosmologist at the Perimeter Institute for Theoretical Physics, coauthored a new calculation about the relative likelihoods of different universes.Photograph: Gabriela Secara/Perimeter InstituteExperts have praised the explicit, quantitative result. But from their entropy equation, Boyle and Turok have drawn an unconventional conclusion about the nature of our universe. “That’s where it becomes a little more interesting, and a little more controversial,” Hertog said.Boyle and Turok believe the equation conducts a census of all conceivable cosmic histories. Just as a room’s entropy counts all the ways of arranging the air molecules for a given temperature, they suspect their entropy counts all the ways one might jumble up the atoms of space-time and still end up with a universe with a given overall history, curvature, and dark energy density.Boyle likens the process to surveying a gigantic sack of marbles, each a different universe. Those with negative curvature might be green. Those with tons of dark energy might be cat’s-eyes, and so on. Their census reveals that the overwhelming majority of the marbles have just one color—blue, say—corresponding to one type of universe: one broadly like our own, with no appreciable curvature and just a touch of dark energy. Weirder types of cosmos are vanishingly rare. In other words, the strangely vanilla features of our universe that have motivated decades of theorizing about cosmic inflation and the multiverse may not be strange at all.“It’s a very intriguing result,” Hertog said. But “it raises more questions than it answers.”Counting ConfusionBoyle and Turok have calculated an equation that counts universes. And they’ve made the striking observation that universes like ours seem to account for the lion’s share of the conceivable cosmic options. But that’s where the certainty ends.The duo make no attempt to explain what quantum theory of gravity and cosmology might make certain universes common or rare. Nor do they explain how our universe, with its particular configuration of microscopic parts, came into being. Ultimately, they view their calculation as more of a clue to which sorts of universes are preferred than anything close to a full theory of cosmology. “What we’ve used is a cheap trick to get the answer without knowing what the theory is,” Turok said.Their work also revitalizes a question that has gone unanswered since Gibbons and Hawking first kicked off the whole business of space-time entropy: What exactly are the microstates that the cheap trick is counting?“The key thing here is to say that we don’t know what that entropy means,” said Henry Maxfield, a physicist at Stanford University who studies quantum theories of gravity.At its heart, entropy encapsulates ignorance. For a gas made of molecules, for instance, physicists know the temperature—the average speed of particles—but not what every particle is doing; the gas’s entropy reflects the number of options.After decades of theoretical work, physicists are converging on a similar picture for black holes. Many theorists now believe that the area of the horizon describes their ignorance of the stuff that’s fallen in—all the ways of internally arranging the building blocks of the black hole to match its outward appearance. (Researchers still don’t know what the microstates actually are; ideas include configurations of the particles called gravitons or the strings of string theory.)A recent calculation by Ted Jacobson, top, and Batoul Banihashemi of the University of Maryland offers a possible interpretation of the entropy of de Sitter space.Courtesy of Ted Jacobson; Courtesy of Batoul BanihashemiBut when it comes to the entropy of the universe, physicists feel less certain about where their ignorance even lies.In April, two theorists attempted to put cosmological entropy on a firmer mathematical footing. Ted Jacobson, a physicist at the University of Maryland renowned for deriving Einstein’s theory of gravity from black hole thermodynamics, and his graduate student Batoul Banihashemi explicitly defined the entropy of a (vacant, expanding) de Sitter universe. They adopted the perspective of an observer at the center. Their technique, which involved adding a fictitious surface between the central observer and the horizon, then shrinking the surface until it reached the central observer and disappeared, recovered the Gibbons and Hawking answer that entropy equals one-quarter of the horizon area. They concluded that the de Sitter entropy counts all possible microstates inside the horizon.Turok and Boyle calculate the same entropy as Jacobson and Banihashemi for an empty universe. But in their new calculation pertaining to a realistic universe filled with matter and radiation, they get a much larger number of microstates—proportional to volume and not area. Faced with this apparent clash, they speculate that the different entropies answer different questions: The smaller de Sitter entropy counts microstates of pure space-time bounded by a horizon, while they suspect their larger entropy counts all the microstates of a space-time filled with matter and energy, both inside and outside the horizon. “It’s the whole shebang,” Turok said.Ultimately, settling the question of what Boyle and Turok are counting will require a more explicit mathematical definition of the ensemble of microstates, analogous to what Jacobson and Banihashemi have done for de Sitter space. Banihashemi said she views Boyle and Turok’s entropy calculation “as an answer to a question that is yet to be fully understood.”As for more established answers to the question “Why this universe?” cosmologists say inflation and the multiverse are far from dead. Modern inflation theory, in particular, has come to solve more than just the universe’s smoothness and flatness. Observations of the sky match many of its other predictions. Turok and Boyle’s entropic argument has passed a notable first test, Pimentel said, but it will have to nail other, more detailed data to more seriously rival inflation.As befits a quantity that measures ignorance, mysteries rooted in entropy have served as harbingers of unknown physics before. In the late 1800s, a precise understanding of entropy in terms of microscopic arrangements helped confirm the existence of atoms. Today, the hope is that if the researchers calculating cosmological entropy in different ways can work out exactly what questions they’re answering, those numbers will guide them toward a similar understanding of how Lego bricks of time and space pile up to create the universe that surrounds us.“What our calculation does is provide huge extra motivation for people who are trying to build microscopic theories of quantum gravity,” Turok said. “Because the prospect is that that theory will ultimately explain the large-scale geometry of the universe.”Original story reprinted with permission from Quanta Magazine, an editorially independent publication of the Simons Foundation whose mission is to enhance public understanding of science by covering research developments and trends in mathematics and the physical and life sciences.
|
Cosmology & The Universe
|
We see countless stars and galaxies sparkling in the universe today, but how much matter is actually there? The question is simple enough — its answer, however, is turning out to be quite a head-scratcher.
This dilemma exists largely because current cosmological observations simply disagree on how matter is distributed in the present-day universe.
Of some help could be a new computer simulation that traces how all elements of the universe — ordinary matter, dark matter and dark energy — evolve according to the laws of physics. The breathtaking visuals virtually show galaxies, and clusters of galaxies, manifesting in the universe, fed by the so-called cosmic web. This web is the largest structure in the universe, built with filaments made up of both normal matter, or baryonic matter, and dark matter.
Unlike previous simulations that only considered dark matter, the new work, carried out by a project called FLAMINGO (short for Full-hydro Large-scale structure simulations with All-sky Mapping for the Interpretation of Next Generation Observations), tracks ordinary matter too.
"Although the dark matter dominates gravity, the contribution of ordinary matter can no longer be neglected," Joop Schaye, a professor at Leiden University in the Netherlands and a co-author of the three new studies on the FLAMINGO project, said in a statement.
As for how much matter the universe really contains, astronomers say computer simulations like this one are not just great cosmic eye candy but also important probes to help pin down the cause of a major discrepancy in cosmology called the "S8 tension." That's the debate over how matter in the cosmos is distributed.
What is the S8 tension?
When investigating the universe, astronomers sometimes work with what's known as the S8 parameter. This parameter basically characterizes how "lumpy," or strongly clustered, all the matter in our universe is, and can be measured precisely with what are known as low-redshift observations. Astronomers use redshift to measure how far an object is from Earth, and low-redshift studies like "weak gravitational lensing surveys" can illuminate processes unfolding in the distant, and therefore older, universe.
But S8's value can also be predicted using the standard model of cosmology; scientists can essentially tune the model to match known properties of the cosmic microwave background (CMB), which is the radiation leftover from the Big Bang, and calculate the lumpiness of matter from there.
So, here's the thing.
Those CMB experiments find a higher S8 value than the weak gravitational lensing surveys. And cosmologists don't know why — they call this discrepancy the S8 tension.
In fact, S8 tension is a brewing crisis in cosmology slightly different from its famous cousin: Hubble tension, which refers to the inconsistencies scientists face in pinning down the rate of expansion of the universe.
The reason it's a big deal that the team's new simulation doesn't offer an answer to S8 tension is, unlike previous simulations that only considered the effects of dark matter on an evolving universe, the latest work takes into account the effects of ordinary matter too. In contrast to dark matter, ordinary matter is governed by gravity as well as pressure from gas across the universe. For example, galactic winds driven by supernova explosions and actively accreting supermassive black holes are crucial processes that redistribute ordinary matter by blowing its particles out into intergalactic space.
However, even the new work's consideration of ordinary matter as well as some of the most extreme galactic wind was not sufficient to explain the weak clumping of matter that is observed in the present-day universe.
"Here I am at a loss," Schaye told Space.com.. "An exciting possibility is that the tension is pointing to shortcomings in the standard model of cosmology, or even the standard model of physics."
Exotic physics or a flawed model?
So, where did this S8 tension originate?
"We don't know, which is what makes this so exciting," Ian McCarthy, a theoretical astrophysicist at Liverpool John Moores University in the U.K. and the co-author of three new studies, told Space.com.
Computer simulations, however, like those carried out by FLAMINGO could be bringing us a step closer. They may help reveal the cause of S8 tension because a grand, virtual map of the cosmos might assist with identifying possible errors in our current measurements. For example, astronomers are slowly ruling out more mundane explanations for the issue, such as the fact it could be due to general uncertainties in observations of large-scale structures or related to a problem with the CMB itself.
In reality, the team speculates, perhaps the effects of normal matter are a lot stronger than in current simulations. That too seems unlikely though, as simulations agree very well with observed properties of galaxies and galaxy clusters.
"All of these possibilities are extremely exciting and have important implications for fundamental physics and cosmology," said McCarthy. The most exciting possibility, however, "is the Standard Model is incorrect in some way."
For example, dark matter could have exotic self-interacting properties not considered in the standard model — the S8 tension may be signaling a breakdown of our theory of gravity on the largest scales, McCarthy said.
Nonetheless, while the latest simulations track effects of normal matter and subatomic particles known as neutrinos — both of which are found to be important to make accurate predictions of how galaxies evolve across eons — they did not resolve the S8 tension.
Here's the ultimate head-scratcher: At low-redshifts, the universe is significantly less lumpy than predicted by the standard model. But measurements that probe structures of the universe between the CMB and low-redshift measurements are "fully consistent with standard model predictions," McCarthy said. "It seems the universe behaved as expected for a significant fraction of cosmic history, but that something changed later on in cosmic history."
Maybe the key to resolving the S8 tension lies in the answer to what, exactly, drove that change.
|
Cosmology & The Universe
|
One of the new high-resolution simulations of the dark matter enveloping the Milky Way and its neighbor, the Andromeda galaxy. The new study shows that earlier, failed attempts to find counterparts of the plane of satellites which surrounds the Milky Way in dark matter simulations was due to a lack of resolution. Credit: Till Sawala/Sibelius collaboration Astronomers say they have solved an outstanding problem that challenged our understanding of how the universe evolved—the spatial distribution of faint satellite galaxies orbiting the Milky Way. These satellite galaxies exhibit a bizarre alignment—they seem to lie on an enormous thin rotating plane—called the "plane of satellites."
This seemingly unlikely arrangement had puzzled astronomers for over 50 years, leading many to question the validity of the standard cosmological model that seeks to explain how the universe came to look as it does today.
Now, new research jointly led by the Universities of Durham, U.K., and Helsinki, Finland, has found that the plane of satellites is a cosmological quirk which will dissolve over time in the same way that star constellations also change.
Their research removes the challenge posed by the plane of satellites to the standard model of cosmology.
This model explains the formation of the universe and how the galaxies we see now formed gradually within clumps of cold dark matter—a mysterious substance that makes up about 27% of the universe.
The findings are published in the journal Nature Astronomy.
The Milky Way's satellites seem to be arranged in an implausibly thin plane piercing through the galaxy and, oddly, they are also circling in a coherent and long-lived disk.
There is no known physical mechanism that would make satellites planes. Instead, it was thought that satellite galaxies should be arranged in a roughly round configuration tracing the dark matter.
Since the plane of satellites was discovered in the 1970s, astronomers have tried without success to find similar structures in realistic supercomputer simulations that track the evolution of the universe from the Big Bang to the present day.
The fact that the arrangement of satellites could not be explained led researchers to think that the cold dark matter theory of galaxy formation might be wrong.
However, this latest research saw astronomers use new data from the European Space Agency's Gaia space observatory. Gaia is charting a six-dimensional map of the Milky Way, providing precise positions and motion measurements for about one billion stars in our galaxy (about 1% of the total), and its companion systems. Positions and orbits of the 11 classical satellite galaxies of the Milky Way, projected “face-on” (top) and “edge-on” (bottom), integrated for 1 billion years into the past and future. The right panels are a zoom-in of the left panels. The black dot marks the center of the Milky Way, arrows mark the observed positions and the directions of travel of the satellites. While they currently line up in a plane (indicated by the gray horizontal line), that plane quickly dissolves as the satellites move along their orbits. Credit: Till Sawala / Sibelius collaboration These data allowed scientists to project the orbits of the satellite galaxies into the past and future and see the plane form and dissolve in a few hundred million years—a mere blink of an eye in cosmic time. The researchers also searched new, tailor-made cosmological simulations for evidence of planes of satellites.
They realized that previous studies based on simulations had been misled by failing to consider the distances of satellites from the center of the Galaxy, which made the virtual satellite systems appear much rounder than the real one.
Taking this into account, they found several virtual Milky Ways which boast a plane of satellite galaxies very similar to the one seen through telescopes.
The researchers say this removes one of the main objections to the validity of the standard model of cosmology and means that the concept of dark matter remains the cornerstone of our understanding of the universe.
Study co-author Professor Carlos Frenk, Ogden Professor of Fundamental Physics in the Institute for Computational Cosmology, at Durham University, U.K., said, "The strange alignment of the Milky Way's satellite galaxies in the sky had perplexed astronomers for decades, so much so that it was deemed to pose a profound challenge to cosmological orthodoxy.
"But thanks to the amazing data from the Gaia satellite and the laws of physics, we now know that the plane is just a chance alignment, a matter of being in the right place at the right time, just as the constellations of stars in the sky.
"Come back in a billion years, and the plane will have disintegrated, as will today's constellations.
"We have been able to remove one of the main outstanding challenges to the cold dark matter theory. It continues to provide a remarkably faithful description of the evolution of our universe."
Study lead author Dr. Till Sawala, of the University of Helsinki, said, "The plane of satellites was truly mind boggling.
"It is perhaps unsurprising that a puzzle which has endured for almost fifty years required a combination of methods to solve it—and an international team to come together." More information: Till Sawala, The Milky Way's plane of satellites is consistent with ΛCDM, Nature Astronomy (2022). DOI: 10.1038/s41550-022-01856-z. www.nature.com/articles/s41550-022-01856-z Citation: Cosmological enigma of Milky Way's satellite galaxies solved (2022, December 19) retrieved 19 December 2022 from https://phys.org/news/2022-12-cosmological-enigma-milky-satellite-galaxies.html This document is subject to copyright. Apart from any fair dealing for the purpose of private study or research, no part may be reproduced without the written permission. The content is provided for information purposes only.
|
Cosmology & The Universe
|
A rare, warped supernova that appears three times in a single image could help researchers finally solve a long-standing inconsistency about the universe that has threatened to unravel our understanding of the cosmos, one expert claims.
The type 1a supernova, named SN H0pe, was first discovered lurking in photographs captured by NASA's James Webb Space Telescope (JWST) in March. In these images, the exploding star can be seen as an arc of orange light with three bright points that surround part of the galaxy cluster PLCK G165.7+67.0 (G165), which is around 4.5 billion light-years from Earth.
The light arc is the result of gravitational lensing — an effect caused when light from a distant object, such as a supernova, passes through space-time that has been warped by the gravity of a massive foreground object, like a large galaxy, that is positioned directly between the distant object and the observer. This also magnifies the distant object, making it easier for researchers to analyze.
The three bright spots in the arc around G165 make it seem like there are three separate light sources being visually manipulated, or lensed by the foreground galaxy. But in reality, the supernova, which is located around 16 billion light-years from us, has been duplicated twice by the lensing effect.
In a new article published on BigThink.com on Sept. 20, astrophysicist and science communicator Ethan Siegel, who was not involved in the study, wrote that SN H0pe could help solve a longstanding inconsistency about the expansion of the universe — the "Hubble tension."
The Hubble tension is based on a discrepancy between the two main ways of estimating the rate of the universe's expansion, known as the Hubble constant. The first method, which involves measuring expansion using the cosmic microwave background (CMB) — leftover radiation from the Big Bang that was first detected in 1964 — comes out with one value for the Hubble constant. But the second method, which involves measuring how far specific objects, such as galaxies and supernovas, are moving away from us, consistently comes out with a slightly higher value.
This problem has confused scientists for decades because there is no clear reason why one method should produce a different result from the other, Siegel wrote. The conundrum has even caused some researchers to declare it a crisis in cosmology.
SN H0pe could help solve the Hubble tension because it is a type 1a supernova, which astronomers refer to as a "standard candle" — an incredibly reliable reference point from which we can measure the universe's expansion, Siegel wrote.
Type 1a supernovas involve a white dwarf star stealing matter from a binary partner star, before reaching critical mass and exploding. These bright explosions all have near-equal initial luminosity and dim over time at the same rate. By comparing these standard candles at various distances from Earth, scientists can work out exactly how fast they are moving away from us and can then deduce the expansion rate of the universe.
SN H0pe is a particularly important standard candle because it is the second most distant type 1a supernova ever detected, Siegel wrote. The strong gravitational lensing and duplication in the new images also give researchers more information to work with than normal, he added.
The idea of using duplicated supernovae to tackle the problem of Hubble tension is not new. In May, scientists used data from a reappearing, quadruple-lensed supernova named Refsdal to calculate a new value for the Hubble constant. Although this still differed from the value calculated using the CMB, the difference between the two was reduced, suggesting that they could one day match up.
It is currently unclear whether SN H0pe can be used to calculate an even more reliable value for the Hubble constant. But researchers are confident that if JWST's keen eye can continue to pick out more distant standard candles, the problem of Hubble tension may finally be solved.
Live Science newsletter
Stay up to date on the latest science news by signing up for our Essentials newsletter.
Harry is a U.K.-based staff writer at Live Science. He studied Marine Biology at the University of Exeter (Penryn campus) and after graduating started his own blog site "Marine Madness," which he continues to run with other ocean enthusiasts. He is also interested in evolution, climate change, robots, space exploration, environmental conservation and anything that's been fossilized. When not at work he can be found watching sci-fi films, playing old Pokemon games or running (probably slower than he'd like).
|
Cosmology & The Universe
|
By Steve Gorman and Joey Roulette(Reuters) -Drawing back the curtain to a photo gallery unlike any other, NASA will soon present the first full-color images from its James Webb Space Telescope, a revolutionary apparatus designed to peer through the cosmos to the dawn of the universe.The highly anticipated unveiling this week of pictures and spectroscopic data from the newly operational observatory follows a six-month process of remotely unfurling various components, aligning its mirrors and calibrating instruments.With Webb now finely tuned and fully focused, astronomers will embark on a competitively selected list of science projects exploring the evolution of galaxies, the life cycles of stars, the atmospheres of distant exoplanets and the moons of our outer solar system.The first batch of photos, which have taken weeks to process from raw telescope data, are expected to offer a compelling glimpse at what Webb will capture on the science missions that lie ahead.NASA on Friday posted a list of the five celestial subjects chosen for its showcase debut of Webb, built for the U.S. space agency by aerospace giant Northrop Grumman Corp.Among them are two nebulae - enormous clouds of gas and dust blasted into space by stellar explosions that form nurseries for new stars - and two sets of galaxy clusters.One of those, according to NASA, features objects in the foreground so massive that they act as "gravitational lenses," a visual distortion of space that greatly magnifies the light coming from behind them to expose even fainter objects farther away and further back in time. How far back and what showed up on camera remains to be seen.NASA will also present Webb's first spectrographic analysis of an exoplanet - one roughly half the mass of Jupiter that lies more than 1,100 light years away - revealing the molecular signatures of filtered light passing through its atmosphere.'MOVED ME AS A SCIENTIST ... AS A HUMAN BEING'All five of the Webb's introductory targets were previously known to scientists. One of them, the galaxy group 290 million light-years from Earth known as Stephan's Quintet, was first discovered in 1877.But NASA officials promise Webbs imagery captures its subjects in an entirely new light, literally."What I have seen moved me as a scientist, as an engineer and as a human being," NASA deputy administrator Pam Melroy, who has reviewed the images, told reporters during a June 29 news briefing.One unspecified image from the collection will be unveiled on Monday evening by U.S. President Joe Biden at a White House briefing with NASA chief Bill Nelson, the space agency said on Sunday.The rest will be released as previously scheduled in a live broadcast and webcast on Tuesday from NASA's Goddard Space Flight Center in Greenbelt, Maryland, by NASA and its European and Canadian space agency collaborators.The $9 billion infrared telescope, the largest and most complex astronomical observatory ever sent to space, was launched on Christmas Day from French Guiana, on the northeastern coast of South America.A month later, the 14,000-pound (6,350-kg) instrument reached its gravitational parking spot in solar orbit, circling the sun in tandem with Earth nearly 1 million miles from home.Webb, which views its subjects chiefly in the infrared spectrum, is about 100 times more sensitive than its 30-year-old predecessor, the Hubble Space Telescope, which orbits Earth from 340 miles (547 km) away and operates mainly at optical and ultraviolet wavelengths.The larger light-collecting surface of Webb's primary mirror - an array of 18 hexagonal segments of gold-coated beryllium metal - enables it to observe objects at greater distances, thus further back in time, than Hubble or any other telescope.Its infrared sensitivity allows it to detect light sources that would otherwise be hidden in the visible spectrum by dust and gas.Taken together, these features are expected to transform astronomy, providing the first glimpse of infant galaxies dating to just 100 million years after the Big Bang, the theoretical flashpoint that set the expansion of the known universe in motion an estimated 13.8 billion years ago.Webb's instruments also make it ideal to search for signs of potentially life-supporting atmospheres around scores of newly documented plants orbiting distant stars and to observe worlds much closer to home, such as Mars and Saturn's icy moon Titan.Besides a host of studies already lined up for Webb, the telescope's most revolutionary findings may prove to be those that have yet to be anticipated.Such was the case in Hubble's surprising discovery, through observations of distant supernovas, that the expansion of the universe is accelerating, rather than slowing down, opening a new field of astrophysics devoted to a mysterious phenomenon scientists call dark energy.(Reporting and writing by Steve Gorman; Additional reporting by Joey Roulette; Editing by Lisa Shumaker)
|
Cosmology & The Universe
|
Scientists have discovered new evidence that the universe was briefly governed by different physical laws than it is today, producing a violation to which we owe our very existence, reports a new study.
The results open a window into the mysterious epoch of inflation, an ultrashort period when the universe expanded exponentially fractions of a second after the Big Bang.
By studying more than a million galaxies observed in sky surveys, researchers were able to show that the universe more often molded galactic groups in a certain cluster shape, as opposed to its mirror image. This finding violates what’s known as parity symmetry, an idea embedded in our current physical models that the universe is essentially symmetrical and does not prefer any shape over its reversed image.
Scientists have long suspected that a so-called “parity violation” occurred in the early universe, in part because matter—the stuff we’re all made of—somehow became far more abundant than antimatter, matter’s oppositely charged counterpart. Our current physical laws suggest that matter and antimatter should have canceled each other out after the Big Bang, but clearly that didn’t happen because, well, we exist, and we’re made of matter, and so is a lot of other stuff, like stars, planets, and galaxies. Antimatter, by comparison, is very rare in the universe today, an unexplained outcome that is considered one of the biggest mysteries in science.
Now, researchers led by Jiamin Hou, a postdoctoral fellow and cosmologist at the University of Florida, have used a supercomputer to analyze an immense dataset that of galaxies organized into trillions of different “quadruplets,” or groups of four galaxies in close proximity that take on a tetrahedral shape.
The results revealed a clear preference for one tetrahedron over its mirror image, offering the first evidence that parity violation in the epoch of inflation influenced the clustering of galaxies later in cosmic history. The new discovery “opens a new avenue for probing new forces during the epoch of inflation with 3D large-scale structure,” according to a study published on Monday in the Monthly Notices of the Royal Astronomical Society.
“What is the beginning of the universe? What are the rules under which it evolves? Why is there something rather than nothing?” said Zachary Slepian, a UF astronomy professor and co-author of the study, in a statement. “This work addresses those big questions.”
The discovery of the weird clustering in galactic quadruplets is a signal that the laws of the universe may have changed in some way during the epoch of inflation. This type of event cannot be explained by the Standard Model of cosmology, a well-corroborated framework that explains a lot of phenomena in our universe. Though the Standard Model is robust, there are many potential challenges to it, including curious evidence that the laws of physics may not apply everywhere in the universe even to this day.
Previous studies have also uncovered hints of parity violations in the early universe, but much of this research examines interactions on tiny subatomic scales, whereas Hou’s team examined the effect on huge cosmic scales. The researchers detailed their novel approach in another new study, which was published this week in Physical Review Letters.
“The detection of a parity-violating signal in [Large Scale Structure of the universe] would illuminate early Universe physics and perhaps even reveal physical processes beyond the Standard Model,” the team said in that study.
While Hou and her colleagues have uncovered strong evidence for parity violation, there are still uncertainties in the measurements that will need to be cross-checked in the coming years. Fortunately, a number of next-generation astronomical surveys are in the works, including the Vera Rubin Observatory in Chile and the European Space Agency’s Euclid telescope, which is due for launch in July. These projects will provide extremely high-quality spectrographic observations that will be useful for studying parity violations on large scales, among many other topics.
We haven’t yet solved the riddle of why the universe contains something, namely matter, instead of nothing, which is how it should have turned out according to our current understanding of physics. But the weirdly clustered galaxies reported by Hou’s team offer new clues about this strange imbalance that ultimately led to our modern reality complete with stars, planets, and people on planets who are trying to figure all of this out.
|
Cosmology & The Universe
|
President Joe Biden on Monday will reveal the first image from NASA’s new space telescope — the deepest view of the cosmos ever captured.
The unveiling of the first image is expected to begin at 5:00 p.m. EDT. Watch live our the player above.
The first image from the $10 billion James Webb Space Telescope is going to show the farthest humanity has ever seen in both time and distance, closer to the dawn of the universe and the edge of the cosmos. That image will be followed Tuesday by the release of four more galactic beauty shots from the telescope’s initial outward gazes.
NASA said Biden will show a “deep field” image. That shot is likely to be be filled with lots of stars, with massive galaxies in the foreground distorting the light of the objects behind, telescoping them and making faint and extremely distant galaxies visible. Part of the image will be of light from not too long after the Big Bang.
READ MORE: NASA’s new space telescope sees 1st starlight, takes selfie
The images to be released Tuesday include a view of a giant gaseous planet outside our solar system, two images of a nebula where stars are born and die in spectacular beauty and an update of a classic image of five tightly clustered galaxies that dance around each other.
The world’s biggest and most powerful space telescope rocketed away last December from French Guiana in South America. It reached its lookout point 1 million miles (1.6 million kilometers) from Earth in January. Then the lengthy process began to align the mirrors, get the infrared detectors cold enough to operate and calibrate the science instruments, all protected by a sunshade the size of a tennis court that keeps the telescope cool.
The plan is to use the telescope to peer back so far that scientists will get a glimpse of the dawn of the universe about 13.7 billion years ago and zoom in on closer cosmic objects, even our own solar system, with sharper focus.
Webb is considered the successor to the highly successful, but aging Hubble Space Telescope. Hubble has stared as far back as 13.4 billion years. It found the light wave signature of an extremely bright galaxy in 2016.
Thomas Zurbuchen, NASA’s science mission chief said, with the new telescope, the cosmos is “giving up secrets that had been there for many, many decades, centuries, millennia.”
READ MORE: Bigger and more powerful than the Hubble, NASA’s new telescope will see the “awe-inspiring”
“It’s not an image. It’s a new world view that you’re going to see,” he said during a recent media briefing.
Zurbuchen said when he saw the images he got emotional and so did his colleagues: “It’s really hard to not look at the universe in new light and not just have a moment that is deeply personal.”
NASA is collaborating on Webb with the European and Canadian space agencies.
|
Cosmology & The Universe
|
The secret to directly detecting dark matter might be blowin’ in the wind. The mysterious substance continues to elude scientists even though it outweighs visible matter in the universe by about 8 to 1. All laboratory attempts to directly detect dark matter — seen only indirectly by the effect its gravity has on the motions of stars and galaxies — have gone unfulfilled. Those attempts have relied on the hope that dark matter has at least some other interaction with ordinary matter in addition to gravity (SN: 10/25/16). But a proposed experiment called Windchime, though decades from being realized, will try something new: It will search for dark matter using the only force it is guaranteed to feel — gravity. Sign Up For the Latest from Science News Headlines and summaries of the latest Science News articles, delivered to your inbox “The core idea is extremely simple,” says theoretical physicist Daniel Carney, who described the scheme in May at a meeting of the American Physical Society’s Division of Atomic Molecular and Optical Physics in Orlando, Fla. Like a wind chime on a porch rattling in a breeze, the Windchime detector would try to sense a dark matter “wind” blowing past Earth as the solar system whips around the galaxy. If the Milky Way is mostly a cloud of dark matter, as astronomical measurements suggest, then we should be sailing through it at about 200 kilometers per second. This creates a dark matter wind, for the same reason you feel a wind when you stick your hand out the window of a moving car. The Windchime detector is based on the notion that a collection of pendulums will swing in a breeze. In the case of backyard wind chimes, it might be metal rods or dangling bells that jingle in moving air. For the dark matter detector, the pendulums are arrays of minute, ultrasensitive detectors that will be jostled by the gravitational forces they feel from passing bits of dark matter. Instead of air molecules bouncing off metal chimes, the gravitational attraction of the particles that make up the dark matter wind would cause distinctive ripples as it blows through a billion or so sensors in a box measuring about a meter per side. Within the Windchime detector (illustrated as an array of small pendulums), a passing dark matter particle (red dot) would gravitationally tug on sensors (blue squares) and cause a detectable ripple, much like wind blowing through a backyard wind chime.D. Carney et al/Physical Review D 2020 While it may seem logical to search for dark matter using gravity, no one has tried it in the nearly 40 years that scientists have been pursuing dark matter in the lab. That’s because gravity is, comparatively, a very weak force and difficult to isolate in experiments. “You’re looking for dark matter to [cause] a gravitational signal in the sensor,” says Carney, of Lawrence Berkeley National Laboratory in California. “And you just ask . . . could I possibly see this gravitational signal? When you first make the estimate, the answer is no. It’s actually going to be infeasibly difficult.” That didn’t stop Carney and a small group of colleagues from exploring the idea anyway in 2020. “Thirty years ago, this would have been totally nuts to propose,” he says. “It’s still kind of nuts, but it’s like borderline insanity.” The Windchime Project collaboration has since grown to include 20 physicists. They have a prototype Windchime built of commercial accelerometers and are using it to develop the software and analysis that will lead to the final version of the detector, but it’s a far cry from the ultimate design. Carney estimates that it could take another few decades to develop sensors good enough to measure gravity even from heavy dark matter. Carney bases the timeline on the development of the Laser Interferometer Gravitational-Wave Interferometer, or LIGO, which was designed to look for gravitational ripples coming from black holes colliding (SN: 2/11/16). When LIGO was first conceived, he says, it was clear that the technology would need to be improved by a hundred million times. Decades of development resulted in an observatory that views the sky in gravitational waves. With Windchime, “we’re in the exact same boat,” he says. Even in its final form, Windchime will be sensitive only to dark matter bits that are roughly the mass of a fine speck of dust. That’s enormous on the spectrum of known particles — more than a million trillion times the mass of a proton. “There is a variety of very interesting dark matter candidates at [that scale] that are definitely worth looking for … including primordial black holes from the early universe,” says Katherine Freese, a physicist at the University of Michigan in Ann Arbor who is not part of the Windchime collaboration. Black holes slowly evaporate, leaking mass back into space, she notes, which could leave many relics formed shortly after the Big Bang at the mass Windchime could detect. But if it never detects anything at all, the experiment still stands out from other dark matter detection schemes, says Dan Hooper, a physicist at Fermilab in Batavia, Ill., also not affiliated with the project. That’s because it would be the first experiment that could entirely rule out some types of dark matter. Even if the experiment turns up nothing, Hooper says, “the amazing thing about [Windchime] … is that, independent of anything else you know about dark matter particles, they aren’t in this mass range.” With existing experiments, a failure to detect anything could instead be due to flawed guesses about the forces that affect dark matter (SN: 7/7/22). Windchime will be the only experiment yet imagined where seeing nothing would definitively tell researchers what dark matter isn’t. With a little luck, though, it could uncover a wind of tiny black holes, or even more exotic dark matter bits, blowing past as we careen around the Milky Way.
|
Cosmology & The Universe
|
A supernova that exploded close to our newly forming sun could have destroyed what became our solar system — if it weren't for a shield of molecular gas.
Scientists reached this conclusion by studying isotopes of elements discovered in meteorites. These space rocks are pieces of asteroids, which formed from material that was around when the sun and then the planets of the solar system formed. As such, meteorites are fossils of a sort, allowing scientists to reconstruct the evolution of the solar system.
The research team found varying concentrations of a radioactive isotope of aluminum in meteorite samples. This information revealed that, around 4.6 billion years ago, an additional amount of the radioactive aluminum entered our planetary backyard. The best explanation for such an injection of radioactive material is a nearby supernova blast, study team members said.
Our infant solar system therefore probably survived a supernova blastwave, according to the researchers, led by National Astronomical Observatory of Japan astrophysicist Doris Arzoumanian. The birth cocoon of the solar system likely acted as a buffer to this shockwave, they added.
Supernova explosions occur when dying massive stars run out of the fuel for nuclear fusion, and their cores can no longer support themselves against gravitational collapse. As the core collapses, a supernova is triggered that spreads the heavy elements the star has forged throughout its life into space.
This material becomes the building blocks of the next generation of stars — but the blast wave that carries it outward can be strong enough to rip apart any newborn planetary systems that happen to be nearby.
Stars are born in giant clouds of molecular gas that are composed of dense tendrils or filaments. Smaller stellar bodies, like the sun, form along these filaments, while larger stars, like the one that would have exploded in this supernova, tend to form at points where these filaments cross each other.
Considering this, Arzoumanian and the team estimated that it would take around 300,000 years for the supernova shockwave to break up the dense filament shielding the infant solar system.
Meteorites that are rich in radioactive isotopes broke apart from larger bodies like asteroids that were born in the first 100,000 of the solar system, while it was still in this dense filament. The cocoon would have acted to protect the forming solar system from harsh radiation emitted from hot and massive stars called OB stars, something that could have negatively impacted the formation of planets like Earth.
The new results suggest that, as well as acting like a shield, the filament could have caught and channeled radioactive isotopes, bringing them into the region around the infant sun.
The researchers believe that their findings could be crucial in understanding the formation and evolution of stars and their planetary systems.
"This scenario may have multiple important implications in our understanding of the formation, evolution and properties of stellar systems," the team wrote in the study which was published in April in the Astrophysical Journal Letters.
"For example, the host filament may play an important role in shielding the young solar system from the far-ultraviolet radiation from OB stars that would photo-evaporate the protostellar disk affecting its final size, which would have a direct impact on planet formation within the disk," they added.
Originally posted on Space.com.
Live Science newsletter
Stay up to date on the latest science news by signing up for our Essentials newsletter.
Robert Lea is a science journalist in the U.K. who specializes in science, space, physics, astronomy, astrophysics, cosmology, quantum mechanics and technology. Rob's articles have been published in Physics World, New Scientist, Astronomy Magazine, All About Space and ZME Science. He also writes about science communication for Elsevier and the European Journal of Physics. Rob holds a bachelor of science degree in physics and astronomy from the U.K.’s Open University
|
Cosmology & The Universe
|
Researchers used data from the Dark Energy Survey and the South Pole Telescope to re-calculate the total amount and distribution of matter in the universe. They found that there’s about six times as much dark matter in the universe as there is regular matter, a finding consistent with previous measurements.
But the team also found that the matter was less clumped together than previously thought, a finding detailed in a set of three papers, all published this week in Physical Review D.
The Dark Energy Survey observes photons of light at visible wavelengths; the South Pole Telescope looks at light at microwave wavelengths. That means the South Pole Telescope observes the cosmic microwave background—the oldest radiation we can see, which dates back to about 300,000 years after the Big Bang.
The team presented the datasets from the respective surveys in two maps of the sky; they then overlaid the two maps to understand the full picture of how matter is distributed in the universe.
“It seems like there are slightly less fluctuations in the current universe than we would predict, assuming our standard cosmological model anchored to the early universe,” said Eric Baxter, an astronomer at the University of Hawai’i and a co-author of the research, in a university release. “The high precision and robustness to sources of bias of the new results present a particularly compelling case that we may be starting to uncover holes in our standard cosmological model.”
Dark matter is something in the universe that we cannot observe directly. We know it’s there because of its gravitational effects, but otherwise we can’t see it. Dark matter makes up about 27% of the universe, according to CERN. (Ordinary matter is about 5% of the universe’s total content.) The remaining 68% is made up of dark energy, a hitherto uncertain category that is evenly distributed throughout the universe and responsible for the universe’s accelerating expansion.
The Dark Energy Survey still has three years of data to be analyzed, and a new look at the cosmic microwave background is currently being undertaken by the South Pole Telescope. Meanwhile, the Atacama Cosmology Telescope (high in the Chilean desert of the same name) is currently taking a high-sensitivity survey of the background. With newly precise data to probe, researchers may be able to put the standard cosmological model to a difficult test.
In 2021, the Atacama telescope helped scientists come up with a newly precise measurement for the age of the universe: 13.77 billion years. More querying of the cosmic microwave background could also help researchers deal with the Hubble tension, a disagreement between two of the best ways for measuring the expansion of the universe. (Depending on how it’s measured, researchers land on two different figures for the rate of that expansion.)
As means of observation get more precise, and more data is collected and analyzed, that information can be fed back into grand cosmological models to determine where we’ve been wrong in the past and lead us to new lines of investigation.
|
Cosmology & The Universe
|
Smoking-gun evidence for modified gravity at low acceleration from Gaia observations of wide binary stars
A new study reports conclusive evidence for the breakdown of standard gravity in the low acceleration limit from a verifiable analysis of the orbital motions of long-period, widely separated, binary stars, usually referred to as wide binaries in astronomy and astrophysics.
The study carried out by Kyu-Hyun Chae, professor of physics and astronomy at Sejong University in Seoul, used up to 26,500 wide binaries within 650 light years (LY) observed by European Space Agency's Gaia space telescope. The study was published in the 1 August 2023 issue of the Astrophysical Journal.
For a key improvement over other studies Chae's study focused on calculating gravitational accelerations experienced by binary stars as a function of their separation or, equivalently the orbital period, by a Monte Carlo deprojection of observed sky-projected motions to the three-dimensional space.
Chae explains, "From the start it seemed clear to me that gravity could be most directly and efficiently tested by calculating accelerations because gravitational field itself is an acceleration. My recent research experiences with galactic rotation curves led me to this idea. Galactic disks and wide binaries share some similarity in their orbits, though wide binaries follow highly elongated orbits while hydrogen gas particles in a galactic disk follow nearly circular orbits."
Also, unlike other studies Chae calibrated the occurrence rate of hidden nested inner binaries at a benchmark acceleration.
The study finds that when two stars orbit around with each other with accelerations lower than about one nanometer per second squared start to deviate from the prediction by Newton's universal law of gravitation and Einstein's general relativity.
For accelerations lower than about 0.1 nanometer per second squared, the observed acceleration is about 30 to 40% higher than the Newton-Einstein prediction. The significance is very high meeting the conventional criteria of 5 sigma for a scientific discovery. In a sample of 20,000 wide binaries within a distance limit of 650 LY two independent acceleration bins respectively show deviations of over 5 sigma significance in the same direction.
Because the observed accelerations stronger than about 10 nanometer per second squared agree well with the Newton-Einstein prediction from the same analysis, the observed boost of accelerations at lower accelerations is a mystery. What is intriguing is that this breakdown of the Newton-Einstein theory at accelerations weaker than about one nanometer per second squared was suggested 40 years ago by theoretical physicist Mordehai Milgrom at the Weizmann Institute in Israel in a new theoretical framework called modified Newtonian dynamics (MOND) or Milgromian dynamics in current usage.
Moreover, the boost factor of about 1.4 is correctly predicted by a MOND-type Lagrangian theory of gravity called AQUAL, proposed by Milgrom and the late physicist Jacob Bekenstein. What is remarkable is that the correct boost factor requires the external field effect from the Milky Way galaxy that is a unique prediction of MOND-type modified gravity. Thus, what the wide binary data show are not only the breakdown of Newtonian dynamics but also the manifestation of the external field effect of modified gravity.
On the results, Chae says, "It seems impossible that a conspiracy or unknown systematic can cause these acceleration-dependent breakdown of the standard gravity in agreement with AQUAL. I have examined all possible systematics as described in the rather long paper. The results are genuine. I foresee that the results will be confirmed and refined with better and larger data in the future. I have also released all my codes for the sake of transparency and to serve any interested researchers."
Unlike galactic rotation curves in which the observed boosted accelerations can, in principle, be attributed to dark matter in the Newton-Einstein standard gravity, wide binary dynamics cannot be affected by it even if it existed. The standard gravity simply breaks down in the weak acceleration limit in accordance with the MOND framework.
Implications of wide binary dynamics are profound in astrophysics, theoretical physics, and cosmology. Anomalies in Mercury's orbits observed in the nineteenth century eventually led to Einstein's general relativity.
Now anomalies in wide binaries require a new theory extending general relativity to the low acceleration MOND limit. Despite all the successes of Newton's gravity, general relativity is needed for relativistic gravitational phenomena such as black holes and gravitational waves. Likewise, despite all the successes of general relativity, a new theory is needed for MOND phenomena in the weak acceleration limit. The weak-acceleration catastrophe of gravity may have some similarity to the ultraviolet catastrophe of classical electrodynamics that led to quantum physics.
Wide binary anomalies are a disaster to the standard gravity and cosmology that rely on dark matter and dark energy concepts. Because gravity follows MOND, a large amount of dark matter in galaxies (and even in the universe) are no longer needed. This is also a big surprise to Chae who, like typical scientists, "believed in" dark matter until a few years ago.
A new revolution in physics seems now under way. Milgrom says, "Chae's finding is a result of a very involved analysis of cutting-edge data, which, as far as I can judge, he has performed very meticulously and carefully. But for such a far-reaching finding—and it is indeed very far reaching—we require confirmation by independent analyses, preferably with better future data."
"If this anomaly is confirmed as a breakdown of Newtonian dynamics, and especially if it indeed agrees with the most straightforward predictions of MOND, it will have enormous implications for astrophysics, cosmology, and for fundamental physics at large."
Xavier Hernandez, professor at UNAM in Mexico who first suggested wide binary tests of gravity a decade ago, says, "It is exciting that the departure from Newtonian gravity that my group has claimed for some time has now been independently confirmed, and impressive that this departure has for the first time been correctly identified as accurately corresponding to a detailed MOND model. The unprecedented accuracy of the Gaia satellite, the large and meticulously selected sample Chae uses and his detailed analysis, make his results sufficiently robust to qualify as a discovery."
Pavel Kroupa, professor at Bonn University and at Charles University in Prague, has come to the same conclusions concerning the law of gravitation. He says, "With this test on wide binaries as well as our tests on open star clusters nearby the sun, the data now compellingly imply that gravitation is Milgromian rather than Newtonian. The implications for all of astrophysics are immense."
More information: Kyu-Hyun Chae, Breakdown of the Newton–Einstein Standard Gravity at Low Acceleration in Internal Dynamics of Wide Binary Stars, The Astrophysical Journal (2023). DOI: 10.3847/1538-4357/ace101
Journal information: Astrophysical Journal
Provided by Sejong University
|
Cosmology & The Universe
|
The first full-color image from NASA's James Webb Space Telescope, a revolutionary apparatus designed to peer through the cosmos to the dawn of the universe, shows the galaxy cluster SMACS 0723, known as Webb’s First Deep Field, in a composite made from images at different wavelengths taken with a Near-Infrared Camera and released July 11, 2022. NASA, ESA, CSA, STScI, Webb ERO Production Team/Handout via REUTERS Register now for FREE unlimited access to Reuters.comJuly 12 (Reuters) - Following a presidential sneak peek of a galaxy-studded image from deep in the cosmos, NASA was due on Tuesday to unveil more of its initial showcase from the James Webb Space Telescope, the largest and most powerful orbital observatory ever launched.The first batch of full-color, high-resolution pictures, which took weeks to render from raw telescope data, were selected by NASA to provide compelling early images from Webb's major areas of inquiry and a preview of science missions ahead.The $9 billion infrared telescope, built for NASA by aerospace giant Northrop Grumman Corp , is expected to revolutionize astronomy by allowing scientists to peer farther than before and with greater clarity into the cosmos, to the dawn of the known universe.Register now for FREE unlimited access to Reuters.comA partnership between NASA, the European Space Agency and the Canadian Space Agency, the Webb was launched on Christmas Day, 2021, and reached its destination in solar orbit nearly 1 million miles from Earth a month later.Once there, the telescope underwent a months-long process to unfurl all of its components, including a sun shield the size of a tennis court, and to align its mirrors and calibrate its instruments.With Webb now finely tuned and fully focused, astronomers will embark on a competitively selected list of science projects exploring the evolution of galaxies, the life cycles of stars, the atmospheres of distant exoplanets and the moons of our outer solar system.The introductory assortment of pictures had been a closely guarded secret until Friday, when the space agency posted a list of five celestial subjects chosen for its big reveal on Tuesday at NASA's Goddard Space Flight Center in Greenbelt, Maryland.PRESIDENTIAL PEEKU.S. President Joe Biden got a jump on the unveiling with his own White House briefing on Monday to release the very first photo - an image of a galaxy cluster dubbed SMACS 0723 revealing the most detailed glimpse of the early universe recorded to date.Among the four other Webb "targets" getting their closeups on Tuesday are two enormous clouds of gas and dust blasted into space by stellar explosions to form incubators for new stars - the Carina Nebula and the Southern Ring Nebula, each thousands of light years away from Earth.The debut collection includes another galaxy cluster known as Stephan's Quintet, which was first discovered in 1877 and encompasses several galaxies described by NASA as "locked in a cosmic dance of repeated close encounters."NASA will also present Webb's first spectrographic analysis of an exoplanet - one roughly half the mass of Jupiter that lies more than 1,100 light years away - revealing the molecular signatures of filtered light passing through its atmosphere.Built to view its subjects chiefly in the infrared spectrum, Webb is about 100 times more sensitive than its 30-year-old predecessor, the Hubble Space Telescope, which operates mainly at optical and ultraviolet wavelengths.The much larger light-collecting surface of Webb's primary mirror - an array of 18 hexagonal segments of gold-coated beryllium metal - enables it to observe objects at greater distances, thus further back in time, than Hubble or any other telescope.All five of Webb's introductory targets were previously known to scientists, but NASA officials promise Webb's imagery captures its subjects in an entirely new light, literally.The SMACS 0723 image Biden released on Monday showed a 4.6 billion-year-old galaxy cluster whose combined mass acts as a "gravitational lens," distorting space to greatly magnify the light coming from more distant galaxies behind it.At least one of the faint, older specks of light appearing in the "background" of the photo - a composite of images of different wavelengths of light - dates back more than 13 billion years, NASA chief Bill Nelson said.That makes it just 800 million years younger than the Big Bang, the theoretical flashpoint that set the expansion of the known universe in motion some 13.8 billion years ago.The bejeweled-like composite photo, according to NASA, offers the "most detailed view of the early universe" as well as the "deepest and sharpest infrared image of the distant cosmos" yet taken.The thousands of galaxies appearing in the image were captured in a tiny patch of the sky roughly the size of a grain of sand held at arm's length by someone standing on Earth, Nelson said.Register now for FREE unlimited access to Reuters.comWriting and reporting by Steve Gorman in Los Angeles; Additional reporting by Joey Roulette; Editing by Raju GopalakrishnanOur Standards: The Thomson Reuters Trust Principles.
|
Cosmology & The Universe
|
Image: Marcos del Mazo/LightRocket via Getty ImagesThe search for intelligent life in the universe is getting a major boost from the Breakthrough Listen Initiative, which is the most comprehensive attempt ever to detect alien communications and technologies. Funded by billionaire Yuri Milner, the initiative is currently scanning one million stars within our galaxy, the Milky Way, for signs of alien civilizations.Now, a pair of scientists have demonstrated that this huge ongoing survey might serendipitously capture signs of aliens in even more remote locations, such as galaxies that appear in the background of images that are focused on stars in the Milky Way. These extragalactic objects are not the main targets of Breakthrough Listen, but they could help constrain “the prevalence of very powerful extraterrestrial transmitters,” according to a new study posted on the preprint server arxiv that is co-authored by Michael Garrett, who is the Sir Bernard Lovell chair of Astrophysics at the University of Manchester and the director of the Jodrell Bank Center for Astrophysics, and Andrew Siemion, the director of the Berkeley SETI Research Center and the principal investigator for Breakthrough Listen.“I think for a while we’ve realized that when we make a SETI observation with a radio telescope, we are sensitive to not only the target star in the center of the field but also a patch of sky about the size of the Moon—so that means we could potentially detect a signal from other objects in the field,” Garrett said in an email to Motherboard. "Other objects in the field include foreground stars and background stars in our own Milky Way,” he continued. “Until recently, we didn't know how to make use of this fact because we didn’t know the distance to these stars.” Fortunately, the European Space Agency launched a space telescope called Gaia in 2013 that has been rapidly filling in this critical information gap by measuring the positions, distances and motions of about one billion astronomical objects. Sign up for Motherboard’s daily newsletter for a regular dose of our original reporting, plus behind-the-scenes content about our biggest stories.The Gaia mission has permitted us to measure distances to a few billion stars in the Milky Way so when we look in these fields we know the distances to quite a few stars that are background and foreground to the target. Garrett and Siemion co-authored a previous study that explored Gaia’s capacity to aid the search for intelligent life, including technological signals that might originate many millions of light years beyond the stars directly studied by the initiative. These signals are akin to astronomical photobombs, or Easter eggs, that could get overlooked in the data because they are not the primary observational targets. To figure out the hidden potential of these distant skyscapes, Garrett and Siemion scoured surveys and built a “rudimentary census of extragalactic objects that were serendipitously observed” with the Robert C. Byrd Green Bank Telescope in West Virginia, according to the study. This approach yielded a whopping 143,024 objects, including radiant galactic cores, interacting galaxies, and at least one region where spacetime is warped into what’s known as a gravitational lens. “It turns out that wherever you point your telescope, the field of view is going to include some interesting cosmic object,” Garrett said. “I’ḿ not sure all SETI researchers had a feel for that, so we decided to look at 400 of the Breakthrough Listen target fields and just see what was in them—that was a lot of fun because the fields are very pretty and you can see some exciting things—like interacting galaxies.” This wealth of “astronomical exotica,” as the team calls it, could contain traces of alien technosignatures, which are detectable signs of advanced civilizations. These extragalactic transmitters would have to be very powerful to be visible at such enormous distances, but Garrett and Siemion suggest that some speculative technologies might do the trick. For instance, aliens in other galaxies could potentially be spotted if they used phased arrays with thousands of powerful transmitters, or microwave beamers for interstellar sails. “Our data points are quite useful because although we are only sensitive to really powerful radio signals, the galaxies in a field contain a lot of stars, hundreds of billions, so it might just be possible that because we're looking at so many stars we might get lucky and find a few of the very powerful signals that might be out there,” Garrett said. “It was fun to add those data points to the plot and then think about what they might mean,” he continued. “I think they suggest that we want more sensitive telescopes but also with a very wide field of view, so they can observe many stars, etc., simultaneously.” With that in mind, Garrett and Siemion recommend that scientists involved with SETI consider looking for alien transmissions beyond the objects that are targeted by Breakthrough Listen. After all, the quest to discover if we are alone in the universe amounts to a search for needles in a haystack, so we’ll need to use all the images at our disposal.“I think this is the first step in thinking about SETI on a very different scale,” Garrett concluded. “Very nearby galaxy groups and clusters are a good place to look for signals because you are pointing in a direction that contains many stars (and therefore hopefully planets, or spacecraft. or whatever else stars attract as good sources of energy for ET intelligence).” ORIGINAL REPORTING ON EVERYTHING THAT MATTERS IN YOUR INBOX.By signing up, you agree to the Terms of Use and Privacy Policy & to receive electronic communications from Vice Media Group, which may include marketing promotions, advertisements and sponsored content.
|
Cosmology & The Universe
|
In the early 1900s, Albert Einstein proposed the theory of general relativity, which challenged everything scientists believed they understood about the universe at the time. Over the years, scientists have questioned whether this theory was true. However, a newly created dark matter map finally gives undeniable proof.
We must first look at Einstein’s original theory to fully understand this new development. Before Einstein proposed the theory of general relativity, scientists believed space to be almost featureless and changeless. Further, they thought that time flowed at its own pace, oblivious to clocks that tried to measure it, as Isaac Newton had suggested two centuries earlier.
However, Einstein proposed that both space and time were one force, spacetime, and that matter within this ever-changing stage was controlled by the curving path that gravity dictated. But to create gravity, we needed mass, a force so strong it could literally curve spacetime around it. This is where dark matter comes into play.
Dark matter is an invisible force found throughout our universe in vast quantities. It, scientists believe, is the force creating the gravity pull that determines how the universe curves and moves. But we’ve never been able to map dark matter out, at least not until now.
Despite making up 85 percent of the universe’s matter, dark matter has always been hard to detect. We can see the effects it has, but creating a dark matter map and actually seeing where it exists was almost impossible.
But now, researchers using the Atacama Cosmology Telescope have done just that. The researchers used the light from the cosmic microwave background to detect all the matter between us and the light from the Big Bang. This allowed them to map the dark matter hiding within our universe.
The image showcases where the dark matter is; according to scientists, it’s precisely where previous theories have suggested. Now that we have a map of the dark matter found throughout our universe, we can finally prove once and for all that Albert Einstein’s theory was correct, a theory that others have only helped expand and clarify.
|
Cosmology & The Universe
|
JWST delves into nebulas, colliding galaxies, an active black hole, and even provides a breakthrough look at an alien world. Jackson Ryan Science Editor Jackson Ryan is CNET's science editor. In a previous life, he was a scientist but he wasn't very good. Now he has the best job in the world, telling stories about space, the planet, climate change and the people working at the frontiers of human knowledge. He also owns a lot of ugly Christmas sweaters. Don't ask. See full bio Monisha Ravisetti Science Writer Monisha Ravisetti covers all things science at CNET. On a separate note, she plays a ton of online chess and is a fan of overly complicated sci-fi movies. See full bio 8 min read It's not often that the sequel is as good as the original, but JWST's second image release certainly lived up to expectations set by the jaw-dropping deep field released on Monday evening. In fact, it surpassed it by leaps and bounds.The unveiling of that first image by President Joe Biden wasn't exactly impressive, but the image itself? Magnificent. Known as "Webb's First Deep Field," it gives astronomers a look at galaxy cluster "SMACS 0723." The image itself is a minuscule patch of the Southern Hemisphere sky -- equivalent to a grain of sand held up to the heavens -- yet replete with thousands of galaxies, from spirals and ellipticals to simple pinpricks of light only a few pixels wide. JWST's First Deep Field was revealed on July 11. NASA, ESA, CSA, and STScIAnd thanks to a phenomenon known as gravitational lensing, it provides us with the deepest -- and oldest -- view of the cosmos yet. That's a lot to live up to, right? Well, the suite of images released on Tuesday don't reach quite so far back in space and time. But they are undoubtedly profound and equal to the First Deep Field in beauty and exquisite detail. There are three major images in JWST's first full-color set. Two focus on nebulas, huge clouds of dust and gas within which stars are born, and the other analyzes a region known as Stephan's Quintet, a frightening corner of the cosmos where five galaxies are locked in an ultimately fatal dance. Then, there's the spectral data of WASP-96b, a really hot, gas giant exoplanet, which reveals the composition of its atmosphere in unprecedented detail. This one isn't an image like you'd expect, but arguably something better. Spectral data helps us understand not what a space-borne object aesthetically looks like but rather what it'd be like to stand on it. And, as they say, the book is often better than the film.Let's break down each one and explain why Webb's second batch of cosmic goodies is just as groundbreaking as its first.The NebulasIn short, nebulas are immense clouds of dust and gas that exist at either end of a star's life. Some are home to fledgling baby stars being born while others are created by their explosive deaths. But in both cases, nebulas are responsible for some of the most stunning visuals of our cosmos – through JWST's lens, the most powerful infrared imager we've ever had, their marvel is only enhanced.The dust and gas of a nebula would typically obscure our view of the features inside them – namely the stars that are just bursting to life. We also get a much better resolution than with a telescope such as Hubble, so Webb is able to see with exquisite clarity the structure of these nebulas.JWST has focused on two separate nebulas: The Carina Nebula, located about 8,500 light-years from Earth, and the Eight Burst Nebula and is much closer, at around 2,000 light-years away. Starting off strong, behold, the Southern Ring Nebula. It's also known as the Eight Burst Nebula. NASA"This is a planetary nebula," Karl Gordon, NASA astronomer said. "It's caused by a dying star that spilled a large fraction of its mass over in successive waves," said Karl Gordon. These waves can be clearly seen in the image. Plus, thanks to JWST's Mid-Infrared Instrument, the right picture shows a second star within the nebula that hadn't been seen before. It's brighter than the dying one, which appears redder, but according to NASA will probably eject its own planetary nebula in the future. Until then, though, that star is influencing this nebula's appearance. "As the pair continues to orbit one another," NASA says, "they 'stir the pot' of gas and dust, causing asymmetrical patterns."Also on the right-hand image, if you glance toward the top left, you'll see a blueish line that appears to have flung out from the nebula. "I made a bet that said 'It's part of the nebula,'" Gordon said. "I lost the bet, because then we looked more carefully at both Nircam and MIRI images, and it's very clearly an edge-on galaxy." Yep, there's an entire galaxy lurking in this pic.Next up is the Carina Nebula -- courtesy of JWST's Nircam and MIRI. NASA"Honestly, it took me a while to figure out what to call out in this image," Amber Straughn, NASA astrophysicist said. "There's just so much going on here. It's so beautiful." In this awesome image, which is technically the edge of a giant cavity within a nebula called NGC 3324, JWST captured the region's emerging stellar nurseries and individual stars. Previously, all those cosmic sparkles were completely obscured from our view due to the thick dust and gas surrounding them in the Carina Nebula located roughly 7,600 light-years away. JWST infrared cameras can literally pierce through that veil and locate the valuable stars within. Decoding this image could very well shed light on how stars are formed, what kind of star-making material goes into building stellar objects that anchor planets across the universe and even dissect what violent, starry winds do to the surrounding space. Curious about all those hills, valleys and spikes? So are NASA scientists. As Straughn puts it, "we see examples of structures that honestly we don't even know what they are."WASP-96bThe hot, gaseous, giant exoplanet, WASP-96b, is a scientific curiosity. Its parent star, WASP-96, lies about 1,120 light-years from Earth, making it the closest object in Webb's first batch of images. Here it is. NASAOK, though this image isn't what you'd normally think of when hoping for a sick space picture, it's actually incredibly groundbreaking for the field of astronomy. Simply, what you're looking at is direct spectral data of an exoplanet in a solar system beyond our own. And while we don't get a view of the planet hanging out in space by its star, this "spectra" clues us in to the ingredients that make up this foreign world. What astronomers detected is striking.JWST's spectral analysis of WASP-96b indicates a tell-tale signature of water vapor in the planet's atmosphere as well as evidence of clouds and hazes, which are tiny solid particles that sort of act like pseudo-clouds in the atmosphere. But before you get too excited about packing up to move to WASP-96b, a world decked-out in H2O, note that this exoplanet is closer to its star than mercury is to its sun. That means all its water is not liquid. Oh, and, it orbits that star every three and a half Earth days. This is probably (definitely) not habitable for us Earthlings. Regardless, this is an intriguing finding because while astronomers have, so far, located over 5,000 worlds outside of our solar system – and studied them with Hubble – WASP-96b has always stood out for its potentially unusual atmosphere."Most close-in exoplanets that have been studied with Hubble have flat, white spectra, which is taken as evidence that they are very cloudy," says Benjamin Pope, a planetary scientist at the University of Queensland in Australia. Clouds are a nuisance because they prevent astronomers from getting a good feel for the composition of an exoplanet's atmosphere. That's not a problem with WASP-96b."It has the clearest skies of any exoplanet we know of," says Coel Hellier, an astrophysicist at Keele University who was a member of the team that discovered the planet.In the grand scheme of things, this spectral data is proof of concept that JWST will be able to assess the composition of many planets' atmospheres. "It's nothing like our solar system planets," Knicole Colon, an astrophysicist at NASA said. "But that's okay – because what we're seeing is, again, the first exoplanet data from Webb. And this is just the beginning."While astronomers have long used Hubble, and other telescopes, to gather data about exoplanets and their atmospheres, there's just nothing like JWST. "JWST is just going to be so much better for this," notes Pope. WASP-96b is the first of many and it shows Webb works as we hoped. What comes next will likely change how we think of planets outside of our solar system.Moving on -- what can Webb teach us about galaxies? As it turns out, quite a bit. Say hello to your new galactic muses.Stephan's QuintetLast but absolutely not least for NASA's Tuesday JWST image release is the breathtaking glimpse we get of Stephan's Quintet.This dramatic grouping of galaxies was discovered in the 19th century, long before the first space telescopes -- well, even the first satellites -- made it to orbit. It's a bright region of space, made up of five galaxies and home to a huge shockwave courtesy of two galaxies colliding at extreme speed. We've been observing it from Earth for almost 150 years and Hubble has also captured striking images of the grouping.Of today's image releases, the Quintet is the farthest from Earth, with the galaxies located between 39 and 340 million light-years from Earth (one of the galaxies, NGC 7320, is much closer than the other four). NASAIn this gigantic image, JWST revealed the Quintet with so much detail that we can literally see individual stars speckling the galaxies. The one on the left, in particular, is a starry spectacle. But perhaps the most incredible aspect of this photo we're looking has to do with the top-most galaxy. It has an active galactic nucleus -- aka, a supermassive black hole 24 million times the mass of the sun. This void is pulling in materials and spitting out light energy equivalent to the burn of 40 billion suns. JWST's Nirspec and MIRI teamed up to dissect the features of this black hole, offering proof of matter swirling around the abyss. Further, if you zoom out and peruse the background of this image, you'll see lots of other galaxies speckling space. And that's just a happy accident that we might want to get used to. JWST is so powerful and precise that it's nearly impossible for it to take an image of what we'd consider "blank space." It can't help but capture the cosmic treasures every time. It's just...too good.It's also extremely efficient, which is why we can expect an unending influx of images and spectral data as incredible as JWST's first full set. "Hubble's extreme deep field was two weeks of continuous work," Bill Nelson, NASA administrator said. "Imaging with Webb, we took that image before breakfast. The amazing thing about Webb is the speed at which we can churn out discoveries"Though encapsulated in pomp and announced to the sound of champagne glasses clinking, everything we've seen from JWST, in this broadcast, took something like a week to put together. "We're going to be doing discoveries like this every week," Nelson said.
|
Cosmology & The Universe
|
Six massive ancient galaxies, which astronomers are calling "universe breakers" appear to have been discovered, which may upend existing theories of cosmology.
The galaxies, detected by the £8.3bn James Webb telescope, are believed to date back to within around 600 million years of the Big Bang.
While the year-old telescope has spotted older galaxies dating to within 300 million years of the beginning of the universe, the size and maturity of the mega-galaxies have stunned scientists.
Astronomers thought they had made a mistake when they spotted the "monsters".
Lead researcher Ivo Labbe, from Australia's Swinburne University of Technology, said: "While most galaxies in this era are still small and only gradually growing larger over time, there are a few monsters that fast-track to maturity. Why this is the case or how this would work is unknown."
"We were mind-blown, kind of incredulous," Mr Labbe said.
The six galaxies appear to weigh billions of times more than our sun, according to the scientists who published their results in the journal Nature.
But they are believed to be extremely compact, squeezing in as many stars as the Milky Way but in a relatively tiny slice of space.
Pennsylvania State University's Joel Leja, who took part in the study, said the discovery "upends what many of us had thought was settled science".
Read more:
NASA's James Webb Space Telescope finds signs of 'building blocks for life' in icy clouds
"It turns out we found something so unexpected it actually creates problems for science. It calls the whole picture of early galaxy formation into question."
Existing theories suggest that after a period of rapid expansion, the universe spent several hundred million years cooling down enough for gas to coalesce and collapse into the first stars and galaxies began to form. This period is known as the dark ages.
The observations of the new galaxies were among the data set that came from the Webb telescope.
NASA and the European Space Agency's Webb is considered the successor to the Hubble Space Telescope which was launched almost 33 years ago.
Unlike the Hubble, the bigger and more powerful Webb can see through clouds of dust with its infrared vision and find previously undiscovered galaxies.
Scientists hope to eventually observe the first galaxies and stars formed after the creation of the universe 13.8 billion years ago.
The research team is still waiting for official confirmation of the galaxies through sensitive spectroscopy. Mr Leja said it's possible that a few objects might not be galaxies, but obscured supermassive black holes.
While some may prove to be smaller, "odds are good at least some of them will turn out to be" galactic giants, Mr Labbe said. "The next year will tell us."
|
Cosmology & The Universe
|
A mysterious structure nearly 1 billion light-years across has been found in our cosmic neighborhood, and it could be a relic from the Big Bang.
The structure, consisting of a group of galaxies clustered around a gigantic spherical void just 820 million light years from the Milky Way, has been named Ho'oleilana, a name inspired by the Hawaiian creation chant, Kumulipo.
It is believed to be a baryon acoustic oscillation, a pressure wave frozen in time from the beginning of the cosmos and then stretched out to galactic scales by the universe’s expansion. The researchers who stumbled upon the weird relic published their findings Sept. 5 in The Astrophysical Journal.
"We were not looking for it. It is so huge that it spills to the edges of the sector of the sky that we were analyzing," Brent Tully, an astronomer at the University of Hawai'i at Manoa, said in a statement.
The sheer size of the bubble defies expectations and could imply the universe is expanding more rapidly than we thought, Tully said in the statement.
According to the standard model of cosmology, the universe began taking shape after the Big Bang, when the young cosmos was a roiling plasma broth of matter and antimatter particles that popped into existence only to annihilate each other upon contact. The force of gravity compressed these plasma pockets in on themselves, squeezing and heating the matter until sound waves traveling at half the speed of light — called baryon acoustic oscillations — rippled outward from the plasma clumps.
These ripples pushed away the matter that hadn't already been drawn into the center of a clump. This outward-flung matter then cooled as a halo around the clump. At that point, most of the universe's matter, slowly congealing into stars and then galaxies, was distributed as a series of thin films surrounding countless cosmic voids — like a foamy mass of soap bubbles in a sink.
The astronomers found the gigantic void by chance while compiling a catalog of 55,877 galaxies, which they mapped to reveal patterns in their spacing. From this map emerged a ring 1 billion light years wide, its circumference dotted with galaxies and connected to cosmic filaments, and its interior empty aside from a galaxy supercluster called the Boötes Supercluster in its center.
"I am the cartographer of the group, and mapping Hoʻoleilana in three dimensions helps us understand its content and relationship with its surroundings," Daniel Pomarede, a cosmographer at CEA Paris-Saclay University in France, said in the statement. "It was an amazing process to construct this map and see how the giant shell structure of Hoʻoleilana is composed of elements that were identified in the past as being themselves some of the largest structures of the universe."
Because Hoʻoleilana is bigger than most baryon acoustic oscillations, the researchers think it could be a sign the universe is expanding at a faster rate than first thought — at roughly 76.9 kilometers per second per megaparsec, as opposed to the standard range of 67 to 74.
To find out if this is true, they say that they will make even more detailed observations of the petrified cosmic bubble.
Live Science newsletter
Stay up to date on the latest science news by signing up for our Essentials newsletter.
Ben Turner is a U.K. based staff writer at Live Science. He covers physics and astronomy, among other topics like tech and climate change. He graduated from University College London with a degree in particle physics before training as a journalist. When he's not writing, Ben enjoys reading literature, playing the guitar and embarrassing himself with chess.
|
Cosmology & The Universe
|
Scientists may have solved a 60-year-old mystery by discovering that quasars — energetic objects that are powered by ravenous supermassive black holes and can outshine trillions of stars combined — form when galaxies collide and merge.
The findings indicate that the Milky Way could host a quasar of its own when it collides with the neighboring Andromeda galaxy several billion years from now.
Scientists have previously tracked quasars' bright, energetic emissions to regions at the hearts of galaxies that span roughly the width of the solar system — meaning quasars must come from incredibly compact objects. The leading theory suggests that quasars are supermassive black holes heating huge amounts of surrounding gas, thus releasing tremendous amounts of radiation before the material falls onto the black hole's surface.
Since their discovery six decades ago, quasars have puzzled scientists — mainly because it's unclear just how supermassive black holes can draw in enough raw material to fuel such powerful emissions. While supermassive black holes dwell at the centers of most galaxies, the gas needed to fuel quasars tends to orbit on the outskirts of galaxies. Thus, there must be some delivery service moving gas toward the hearts of galaxies.
Now, new research published in the journal Monthly Notices of the Royal Astronomical Society uses deep imaging observations from the Isaac Newton Telescope in Spain's Canary Islands to finally solve this puzzle.
"To understand how quasars are ignited we need to determine how gas can fall into the center of the host galaxies at sufficiently high rates," lead study author Clive Tadhunter, a professor in the Department of Physics and Astronomy at the University of Sheffield in the U.K., told Live Science via email. "One idea is that the necessary radial infall is caused by collisions between galaxies, whose associated gravitational forces can perturb the gas from its usual circular orbits."
When comparing 48 nearby galaxies hosting quasars to 100 non-quasar galaxies, the researchers discovered the presence of distorted structures at the edges of the quasar-hosting galaxies. These structures also indicate a past or ongoing collision and merger with another galaxy, Tadhunter said.
"We found a high rate of such structures in quasar-hosting galaxies, three times that measured for a carefully matched control sample of non-quasar galaxies that were imaged with the same techniques," Tadhunter said. "This provides strong evidence that quasars are indeed triggered in galaxy collisions."
The team's research isn't the first time galactic mergers have been linked to quasars. Tadhunter pointed out, however, that attempts to test this hypothesis by hunting for distorted structures at the outer parts of galaxies that are characteristic of such collisions had previously proved ambiguous.
"Some studies have found the expected structures but others have not," he continued. "We believe that much of the past ambiguity in this field is due to the fact that many of the previous imaging studies did not have sufficient depth to detect the sometimes faint distorted structures in the outer parts of the galaxies that host the quasars."
Quasars can have a large influence on the evolution of galaxies that host them; better understanding how quasars ignite could help scientists hone their models of galaxy evolution and the evolution of the universe as a whole.
"It's important to understand how, when, and where quasars are triggered, as once triggered, the enormous radiative power generated by a quasar can have a major, damaging effect on the surrounding host galaxy," Tadhunter said. "For example, the pressure of the radiation can expel the remaining gas in the remnant galaxy system. Since gas is required to form new stars, this will cut off any future star formation activity, effectively the death throes of the galaxy."
Tadhunter also pointed out that understanding the connection between galactic collisions and quasars is vital in determining the future of our own corner of the cosmos.
"The nearest large galaxy — the Andromeda Spiral — is coming directly towards us at a high velocity, and will collide and merge with the Milky Way in around 5 billion years," he said. "When this happens, it's likely that a quasar will be triggered as gas falls into the center of the remnant system."
The team intends to follow up on this research by examining other quasars that are at a wider range of distances and that have been detected using other methods, to see if they have the same features that connect them to galactic collisions.
Live Science newsletter
Stay up to date on the latest science news by signing up for our Essentials newsletter.
Robert Lea is a science journalist in the U.K. who specializes in science, space, physics, astronomy, astrophysics, cosmology, quantum mechanics and technology. Rob's articles have been published in Physics World, New Scientist, Astronomy Magazine, All About Space and ZME Science. He also writes about science communication for Elsevier and the European Journal of Physics. Rob holds a bachelor of science degree in physics and astronomy from the U.K.’s Open University
|
Cosmology & The Universe
|
Scientists have discovered a "strange and persistent" radio signal from a far-off galaxy that sounded like a heartbeat. Astronomers at the Massachusetts Institute of Technology and elsewhere detected the signal, which is classified as a fast radio burst, or FRB — but lasted much longer.A typical FRB, which is a strong burst of radio waves, lasts a few milliseconds. The new signal lasted up to three seconds – about 1,000 times longer than average, according to a news release. The astrophysical origins of FRBs are unknown.The signal repeated over .02 seconds in a clear pattern, almost like a heartbeat."It was unusual," said Daniele Michilli, a postdoc in MIT's Kavli Institute for Astrophysics and Space Research. "Not only was it very long, lasting about three seconds, but there were periodic peaks that were remarkably precise, emitting every fraction of a second — boom, boom, boom — like a heartbeat. This is the first time the signal itself is periodic."Astronomers detected a persistent radio signal from a far-off galaxy that appears to flash with surprising regularity. Named FRB 20191221A, this fast radio burst, or FRB, is currently the longest-lasting FRB, with the clearest periodic pattern, detected to date. Pictured is the large radio telescope CHIME that picked up the FRB. / Credit: Photo courtesy of CHIME, with background edited by MIT NewsThe signal came from a distant galaxy, several billion light-years from Earth. Researchers from MIT and McGill University in Canada, who published a study on the signal, have named it FRB 20191221A. It is currently the longest-lasting FRB with the clearest periodic pattern detected to date.The first FRB was discovered in 2007 and hundreds of similar radio flashes have been detected in space since.The Canadian Hydrogen Intensity Mapping Experiment, or CHIME, is an interferometric radio telescope that continuously observes the sky and is sensitive to fast radio bursts.Most FRBs are one-offs and last a few milliseconds before ending. But a signal that repeated every 16 days was recently discovered, although the signal was more random than periodic.But in December 2019, CHIME detected the periodic, heartbeat-like signal. Michilli was scanning the incoming data at the time. "There are not many things in the universe that emit strictly periodic signals," Michilli said.The source of the new FRB remains a mystery, but scientists think it could emanate from a radio pulsar or magnetar, which are neutron stars. These are dense, rapidly spinning collapsed cores of giant stars. "CHIME has now detected many FRBs with different properties," said Michilli. "We've seen some that live inside clouds that are very turbulent, while others look like they're in clean environments. From the properties of this new signal, we can say that around this source, there's a cloud of plasma that must be extremely turbulent."They hope to catch more bursts from FRB 20191221A. The detection could help them as they study the universe and neutron stars."This detection raises the question of what could cause this extreme signal that we've never seen before, and how can we use this signal to study the universe," said Michilli. "Future telescopes promise to discover thousands of FRBs a month, and at that point we may find many more of these periodic signals."More periodic signals from this source could be used as an astrophysical clock. "For instance, the frequency of the bursts, and how they change as the source moves away from Earth, could be used to measure the rate at which the universe is expanding," the press release reads.Man reunites with mom after two yearsSon dressed as a waiter surprises momFlower man dances down the aisle
|
Cosmology & The Universe
|
Discovery of massive early galaxies defies prior understanding of the universe
Six massive galaxies discovered in the early universe are upending what scientists previously understood about the origins of galaxies in the universe.
"These objects are way more massive than anyone expected," said Joel Leja, assistant professor of astronomy and astrophysics at Penn State, who modeled light from these galaxies. "We expected only to find tiny, young, baby galaxies at this point in time, but we've discovered galaxies as mature as our own in what was previously understood to be the dawn of the universe."
Using the first dataset released from NASA's James Webb Space Telescope, the international team of scientists discovered objects as mature as the Milky Way when the universe was only 3% of its current age, about 500-700 million years after the Big Bang. The telescope is equipped with infrared-sensing instruments capable of detecting light that was emitted by the most ancient stars and galaxies. Essentially, the telescope allows scientists to see back in time roughly 13.5 billion years, near the beginning of the universe as we know it, Leja explained.
"This is our first glimpse back this far, so it's important that we keep an open mind about what we are seeing," Leja said. "While the data indicates they are likely galaxies, I think there is a real possibility that a few of these objects turn out to be obscured supermassive black holes. Regardless, the amount of mass we discovered means that the known mass in stars at this period of our universe is up to 100 times greater than we had previously thought. Even if we cut the sample in half, this is still an astounding change."
In a paper published today (Feb. 22) in Nature, the researchers show evidence that the six galaxies are far more massive than anyone expected and call into question what scientists previously understood about galaxy formation at the very beginning of the universe.
"The revelation that massive galaxy formation began extremely early in the history of the universe upends what many of us had thought was settled science," said Leja. "We've been informally calling these objects 'universe breakers'—and they have been living up to their name so far."
Leja explained that the galaxies the team discovered are so massive that they are in tension with 99% percent of models for cosmology. Accounting for such a high amount of mass would require either altering the models for cosmology or revising the scientific understanding of galaxy formation in the early universe—that galaxies started as small clouds of stars and dust that gradually grew larger over time. Either scenario requires a fundamental shift in our understanding of how the universe came to be, he added.
"We looked into the very early universe for the first time and had no idea what we were going to find," Leja said. "It turns out we found something so unexpected it actually creates problems for science. It calls the whole picture of early galaxy formation into question."
On July 12, NASA released the first full-color images and spectroscopic data from the James Webb Space Telescope. The largest infrared telescope in space, Webb was designed to see the genesis of the cosmos, its high resolution allowing it to view objects too old, distant or faint for the Hubble Space Telescope.
"When we got the data, everyone just started diving in and these massive things popped out really fast," Leja said. "We started doing the modeling and tried to figure out what they were, because they were so big and bright. My first thought was we had made a mistake and we would just find it and move on with our lives. But we have yet to find that mistake, despite a lot of trying."
Leja explained that one way to confirm the team's finding and alleviate any remaining concerns would be to take a spectrum image of the massive galaxies. That would provide the team data on the true distances, and also the gasses and other elements that made up the galaxies. The team could then use the data to model a clearer of picture of what the galaxies looked like, and how massive they truly were.
"A spectrum will immediately tell us whether or not these things are real," Leja said. "It will show us how big they are, how far away they are. What's funny is we have all these things we hope to learn from James Webb and this was nowhere near the top of the list. We've found something we never thought to ask the universe—and it happened way faster than I thought, but here we are."
The other co-authors on the paper are Elijah Mathews and Bingjie Wang of Penn State, Ivo Labbe of the Swinburne University of Technology, Pieter van Dokkum of Yale University, Erica Nelson of the University of Colorado, Rachel Bezanson of the University of Pittsburgh, Katherine A. Suess of the University of California and Stanford University, Gabriel Brammer of the University of Copenhagen, Katherine Whitaker of the University of Massachusetts and the University of Copenhagen, and Mauro Stefanon of the Universitat de Valencia.
More information: Ivo Labbe, A population of red candidate massive galaxies ~600 Myr after the Big Bang, Nature (2023). DOI: 10.1038/s41586-023-05786-2. www.nature.com/articles/s41586-023-05786-2
|
Cosmology & The Universe
|
Researchers use supercomputer to investigate dark matter
A research team from the University of California, Santa Cruz, have used the Oak Ridge Leadership Computing Facility's Summit supercomputer to run one of the most complete cosmological models yet to probe the properties of dark matter—the hypothetical cosmic web of the universe that largely remains a mystery some 90 years after its existence was definitively theorized.
According to the Lambda-cold dark matter model of Big Bang cosmology—which is the working model of the universe that many astrophysicists agree provides the most reasonable explanations for why it is the way it is—85% of the total matter in the universe is dark matter. But what exactly is dark matter?
"We know that there's a lot of dark matter in the universe, but we have no idea what makes up that dark matter, what kind of particle it is. We just know it's there because of its gravitational influence," said Bruno Villasenor, a former doctoral student at UCSC and lead author of the team's paper, which was recently published in Physical Review D. "But if we can constrain the properties of the dark matter that we see, then we can discard some possible candidates."
By producing more than 1,000 high-resolution hydrodynamical simulations on the Summit supercomputer located at the Department of Energy's Oak Ridge National Laboratory, the team modeled the Lyman-Alpha Forest, which is a series of absorption features formed as the light from distant bright objects called quasars encounters material along its journey to Earth. These patches of diffuse cosmic gas are all moving at different speeds and have different masses and extents, forming a "forest" of absorption lines.
The researchers then simulated universes with different dark matter properties that affect the structure of the cosmic web, changing the fluctuations of the Lyman-Alpha Forest. The team compared the results from the simulations with fluctuations in the actual Lyman-Alpha Forest observed by telescopes at the W. M. Keck Observatory and the European Southern Observatory's Very Large Telescope and then eliminated dark matter contenders until they found their closest match.
Consequently, the team's results were contrary to the Lambda-CDM model's primary contention that the universe's dark matter is cold dark matter—hence the model's abbreviation, which references dark matter's slow thermal velocities rather than its temperature. Instead, the study's top prospect indicated the opposite supposition: We may indeed be living in a universe of warm dark matter, with faster thermal velocities.
"Lambda-CDM provides a successful view on a huge range of observations within astronomy and cosmology. But there are slight cracks in that foundation. And what we're really trying to do is push at those cracks and see whether there are issues with that fundamental foundation. Are we on solid ground?" said Brant Robertson, project leader and a professor at UCSC's Astronomy and Astrophysics Department.
Beyond possibly unsettling a few long-held assumptions about dark matter, and the universe itself, the UCSC project also stands out for its computational feat. The team accomplished an unprecedentedly comprehensive set of simulations produced with state-of-the-art simulation software that accounts for the physics that shape the structure of the cosmic web and leverages the computational power of the largest supercomputers in the world.
The UCSC team used a GPU-optimized hydrodynamics code called Cholla, or Computational Hydrodynamics On ParaLLel Architectures, as the starting point for its simulations on Summit. Developed by Evan Schneider, an assistant professor in the University of Pittsburgh's Department of Physics and Astronomy, Cholla was originally intended to help users better understand how the universe's gases evolve over time by acting as a fluid dynamics solver. However, the UCSC team required several more physics solvers to tackle its dark matter project, so Villasenor integrated them into Cholla over the course of three years for his doctoral dissertation at UCSC.
"Basically, I had to extend Cholla by adding some physics: the physics of gravity, the physics of dark matter, the physics of the expanding universe, the physics of the chemical properties of the gases and the chemical properties of hydrogen and helium," Villasenor said. "How is the gas going to be heated by radiation in the universe? How is that going to propagate the distribution of the gas? These physics are necessary to do these kinds of cosmological hydrodynamical simulations."
In the process, Villasenor has assembled one of the most complete simulation codes for modeling the universe. Previously, astrophysicists typically had to choose which parameters to include in their simulations. Now, combined with the computing power of Summit, they have many more physical parameters at their disposal.
"One of the things that Bruno accomplished is something that researchers have wanted to do for many years and was really only enabled by the supercomputer systems at OLCF: to actually vary the physics of the universe dramatically in many different ways," Robertson said. "That's a huge step forward—to be able to connect the physics simultaneously and do that in a way in which you can compare them directly with the observations.
"It just hasn't been possible before to do anything like this. It's orders of magnitude, in terms of computational challenge, beyond what had been done before."
Schneider, who advised Villasenor on his work to extend Cholla, said she thinks his additions will be "totally critical" as she prepares Cholla for her own simulations on the new exascale-class Frontier supercomputer, which is housed along with Summit at the OLCF, a DOE Office of Science user facility at ORNL. She is leading a project through the Frontier Center for Accelerated Application Readiness program to simulate the Milky Way galaxy and will be using some of the solvers added by Villasenor.
"Astrophysics software is very different than other kinds of software because I don't think there's ever any sort of ultimate version, and that certainly isn't the case for Cholla," Schneider said. "You can think of Cholla as being a multitool, so the more pieces we add to our multitool, the more kinds of problems we can solve. If I built the original tool as just a pocketknife, then it's like Bruno's added a screwdriver—there are a whole class of problems we can solve now that we couldn't address with the original code. As we keep adding more and more things, we'll be able to tackle more and more complicated problems."
More information: Bruno Villasenor et al, New constraints on warm dark matter from the Lyman- α forest power spectrum, Physical Review D (2023). DOI: 10.1103/PhysRevD.108.023502
Journal information: Physical Review D
Provided by Oak Ridge National Laboratory
|
Cosmology & The Universe
|
In 2019, a conference held at the Kavli Institute for Theoretical Physics in California concluded with a fraught statement: "We wouldn't call it a tension or a problem but rather a crisis."David Gross, a particle physicist and former director of the KITP was talking about the rate at which our universe is expanding. But Gross wasn't worried about the expansion itself. We've already known for decades that the cosmos is exponentially blasting apart, because celestial bodies surrounding our planet continuously drift farther away from us and from each other. No, Gross was worried about mathematics.To determine exactly how quickly this cosmic shift is happening, scientists must calculate an important value called the Hubble constant -- yet, even today, no one can agree on the answer. Thus, the astronomy community was permeated with a "crisis," but it was a dilemma that cradled innovation. Since that tense conference, experts everywhere have starkly adjusted the way they look at their Hubble constant equations as an attempt to restore peace among stargazers. And on Monday, one such team presented a very out-of-the box idea to settle the dispute, as outlined in a paper published Aug. 3 in the journal Physical Review Letters.Basically, astronomers from the University of Chicago believe when black holes lurking in deep space smash into one another – which they do sometimes – the gravitational leviathans reverberate ripples across the fabric of space and time that might leave traces of information crucial to decoding the Hubble constant. In the end, if scientists can figure out the true Hubble constant, they can also derive answers to some really big questions about our universe like: How did it evolve to the stunning realm we see today? What is it physically made out of? What might it look like billions of years from now, long after humanity ceases to exist and therefore can't cast an eye on it?Reading between the lines of spacetimeEvery so often, two enormous black holes collide. This means that a pair of the universe's most incomprehensibly massive objects combine into an even more incomprehensibly massive object. When this happens, the merger sends ripples across the fabric of space and time -- as coined by Albert Einstein's general relativity -- just like dropping a rock in a pond would send ripples across the water. Animation of gravitational waves produced by a fast binary orbit. NASA Just four years before Gross and fellow physicists hosted their stressful debate over the Hubble constant conundrum, two powerful observatories managed to capture those black hole-induced ripples from down here on Earth. They're called the US Laser Interferometer Gravitational-Wave Observatory and the Italian Virgo observatory. Over the past few years, both LIGO and Virgo have detected the ripples from almost 100 pairs of black hole collisions, and those readings might help us calculate the rate at which the universe is expanding, according to Daniel Holz, an astrophysicist at the University of Chicago and co-author of the new study. They might shed light on the Hubble constant. "If you took a black hole and put it earlier in the universe," Holz said in a press release, "the signal would change, and it would look like a bigger black hole than it really is." What this means is that if a black hole collision happened way (way) out in space, and the signal has been traveling for a long (long) time, the gravitational ripples emanating from the event would've been affected by the universe expanding since the incident. If you think about pond ripples again, for instance, dropping a rock in a pond usually creates righter ripples right at the point of contact. But if you keep watching those ripples extend outward, they get sort of wider and blunter.Therefore, if we can somehow measure the changes in black hole collision ripples, perhaps we can understand the rate at which some of those changes occur. That would help us understand the rate at which the universe's expansion might've affected them and finally, the rate at which the universe is legitimately expanding. "So we measure the masses of the nearby black holes and understand their features, and then we look further away and see how much those further ones appear to have shifted," Jose María Ezquiaga, a NASA Einstein Postdoctoral Fellow, Kavli Institute for Cosmological Physics Fellow and co-author of the new study, said in the release. "This gives you a measure of the expansion of the universe."Is there a catch?But there is a bit of a caveat -- this technique, which the researchers call the "standard siren" method, can't quite be implemented right now. In truth, LIGO and Virgo are going to have to really buckle down and get to work for us to even imagine a future where it becomes commonplace. "We need preferably thousands of these signals, which we should have in a few years, and even more in the next decade or two," Holz said. "At that point, it would be an incredibly powerful method to learn about the universe."Though a pretty promising aspect of the standard siren method is that it relies on Einstein's general relativity theory -- tried and tested rules that are considered unbreakable by many, and thus incredibly trustworthy. From left, an illustration of how relative amounts that the moon might warp spacetime, then the Earth, the sun, and a black hole all the way on the right. Zooey Liao/CNET By contrast, most other scientists tackling the Hubble constant crisis rely on stars and galaxies, the researchers said, which involves a lot of complex astrophysics and introduces an honest possibility of error. But, of note, there have been some other experts zeroing-in on gravitational waves as measurements of the Hubble constant. In 2019, for example, a separate crew of astronomers looked at ripples across space and time stemming from a neutron star merger, which was picked up by LIGO and Virgo in 2017. They were trying to understand how bright the collision was when it happened by reverse calculating from the gravitational waves and eventually arrive at a Hubble constant estimate. And in the same year, another team suggested that we need only about 25 neutron star collision readings to nail down the constant to within an accuracy of 3%.
|
Cosmology & The Universe
|
SpaceX launched the European Space Agency's $1.5 billion Euclid space telescope Saturday, an ambitious, first-of-a-kind attempt to pin down the nature of dark matter — an unknown material pervading the cosmos — and dark energy, the mysterious repulsive force that is speeding up the expansion of the universe.
"It's very difficult to find a black cat in a dark room, especially if there is no cat," said Henk Hoekstra, an astronomer at the University of Leiden and a Euclid science coordinator. "That's a little bit the situation we find ourselves in because we have these observations but we lack a good theory.
"So far, nobody has come up with a good explanation for dark matter, dark energy and other challenges also related to particle physics. ... The launch of Euclid really (carries) cosmology into the future. It's the first space mission designed to study dark energy."
In 1998, astronomers mapping the expansion of the universe expected to see it slowing down due to the gravity of all its constituents. They were astonished to discover the expansion of space and everything in it began speeding up 5 to 6 billion years ago. The unknown force powering that acceleration was dubbed dark energy.
Researchers have since concluded dark energy accounts for nearly three quarters of the mass-energy budget of the entire universe. Dark matter makes up about 24% of the universe, while the atoms and molecules making up normal matter — Earth, human beings, stars and galaxies — account for just 5%.
By studying subtle changes in the light from galaxies over the past 10 billion years, Euclid's cameras will help scientists find out if dark energy is consistent with an unchanging "cosmological constant" once predicted by Einstein's theory of general relativity or whether the current understanding of gravity needs revision.
Yannick Mellier, an astronomer at the Institut d'Astrophysique de Paris and a member of the Euclid science team, said it this way:
"The objective of the Euclid mission is to provide answers to the following questions: why is expansion of the universe accelerating, which translates into what is the nature of dark energy? Is it a cosmological constant? Is it a dynamical dark energy with properties that may vary with time? Or it is a deviation to general relativity on cosmological scales?"
At the same time, Euclid also will study the nature of dark matter, a sea of particles that do not emit or reflect light or any other electromagnetic radiation but whose gravitational effects are clearly seen. Dark matter keeps galaxies from flying apart and influences how galaxies have evolved and clustered over the 13.7 billion years since the big bang.
"Euclid will probe the distribution of dark matter and the distribution of galaxies to an unprecedented precision from space," Mellier said. "It will also reconstruct the cosmic history of the universe over the last 10 billion years."
It will do that by imaging more than 10 billion galaxies. Software on the ground will help identify 1.5 billion or more of the best candidates and analyze how their shapes have been distorted by clouds of unseen dark matter filling the space between Euclid and its targets.
The technique, known as weak gravitational lensing, is similar in concept to the way water slightly distorts the shapes of rocks strewn across a stream bed. It is an extremely subtle effect cosmologically, requiring complex software, powerful computers and more than 1,500 scientists at nine research centers to unravel.
But if all goes well, Euclid "will directly observe the distribution of dark matter using the gravitational lensing effect that modifies the shapes of galaxies, which are deflected by all the dark matter distribution along a given line of sight," Mellier said. "And that will provide the distribution of the unseen dark matter in a Euclid field."
Spectroscopic observations of tens of millions of galaxies will allow researchers to map out distances and velocities in three dimensions, shedding light on whether dark energy is, in fact, the force behind the acceleration of the cosmic expansion or whether some other explanation might be needed.
The mission began 11:12 a.m. EDT Saturday when a SpaceX Falcon 9 rocket roared to life at the Cape Canaveral Space Force Station. After a lightning-fast round of computer checks, the rocket was released to climb away atop 1.7 million pounds of thrust, putting on a spectacular weekend sky show for area residents and tourists.
Forty-one minutes later, after two firings of the rocket's second stage engine, Euclid was released to fly on its own. The Falcon 9's first stage, as usual for SpaceX, flew itself to landing on an off-shore droneship.
The European Space Agency, or ESA, had been gearing up to launch the Euclid space telescope last year on a Russian Soyuz rocket taking off from Kourou, French Guiana. But in the wake of Russia's invasion of Ukraine, those plans fell apart, leaving Euclid without a ride to space.
Last July, ESA approached SpaceX about possibly launching on the company's Falcon 9 rocket. By the end of the year, contracts were in place and the team was able to proceed to Saturday's launch.
"We owe ... huge thanks to SpaceX," said Mike Healy, head of science projects at ESA. "Without them, our satellite would be sitting on the ground for two years."
Euclid is bound for a region in space roughly a million miles from Earth -- Lagrange Point 2 -- where the gravity of sun and Earth combine to form a quiescent region where spacecraft can remain in place with minimal maneuvering and fuel usage. The James Webb Space Telescope also operates at the L2 point.
The 4,760-pound Euclid is equipped with a near-perfect 3-feet 11-inch-wide primary mirror and two instruments: a 600 megapixel visible light camera and a 64-megapixel infrared imaging spectrometer. The telescope's field of view is roughly twice the size of the full moon.
After a month-long checkout and calibration period, Euclid will begin mapping 15,000 square degrees of sky, which includes all the space outside the Milky Way galaxy, imaging galaxies and clusters of galaxies dating back 10 billion years.
That will capture the transition from the universe's initial gravity-driven deceleration to the era of accelerated expansion under the emerging dominance of dark energy.
"Euclid can, in one go, offer a field much larger than accessible by Hubble," said René Laureijs, ESA's Euclid project scientist. "During its entire lifetime, Hubble did not cover more than 100 square degrees, and this can be done by Euclid in 10 days. So in order to get our 15,000 square degrees, which is the size of our sky survey, we need these big images of the sky."
It will take Euclid six years to complete its map of the sky, generating on the order of 100 gigabytes of compressed data per day, or an estimated, difficult-to-imagine 70,000 terabytes over the course of the mission.
"Your iPhone has maybe 10 megapixels," said Jason Rhodes, a member of the Euclid Consortium of researchers. "So (the two Euclid) cameras together have close to 700 megapixels. We're going to take images with those cameras every few minutes for six years.
"But the amount of data we send down compared to the amount of data that's totally in the archive at the end of the process, that's another factor of a thousand."
Gaitee Hussain, head of the science division at ESA, said those images will include 8 billion galaxies, "from which the best one-and-a-half to 2 billion galaxies will be selected for the weak lensing experiment."
"We will be collecting millions, tens of millions of spectroscopic redshifts, as well as literally billions of photometric redshifts, in order to understand the distances of the galaxies that we're looking at," she added.
"This implies massive data rates, not only to get the data to the ground, but also in terms of delivering data ... This is what is required in order to answer what is arguably the most fundamental question in physics and cosmology today, which is, what is the universe actually made of?"
for more features.
|
Cosmology & The Universe
|
In a new study, an international team of astrophysicists has discovered several mysterious objects hiding in images from the James Webb Space Telescope: six potential galaxies that emerged so early in the universe’s history and are so massive they should not be possible under current cosmological theory.
Each of the candidate galaxies may have existed at the dawn of the universe roughly 500 to 700 million years after the Big Bang, or more than 13 billion years ago. They’re also gigantic, containing almost as many stars as the modern-day Milky Way Galaxy.
“It’s bananas,” said Erica Nelson, co-author of the new research and assistant professor of astrophysics at CU Boulder. “You just don’t expect the early universe to be able to organize itself that quickly. These galaxies should not have had time to form.”
Nelson and her colleagues, including first author Ivo Labbé of the Swinburne University of Technology in Australia, published their results Feb. 22 in the journal Nature.
The latest finds aren’t the earliest galaxies observed by James Webb, which launched in December 2021 and is the most powerful telescope ever sent into space. Last year, another team of scientists spotted several galaxies that likely coalesced from gas around 350 million years after the Big Bang. Those objects, however, were downright shrimpy compared to the new galaxies, containing many times less mass from stars.
The researchers still need more data to confirm that these galaxies are as large, and date as far back in time, as they appear. Their preliminary observations, however, offer a tantalizing taste of how James Webb could rewrite astronomy textbooks.
“Another possibility is that these things are a different kind of weird object, such as faint quasars, which would be just as interesting,” she said.
Fuzzy dots
There’s a lot of excitement going around: In 2022, Nelson and her colleagues, who hail from the United States, Australia, Denmark and Spain, formed an ad hoc team to investigate the data James Webb was sending back to Earth.
Their recent findings stem from the telescope’s Cosmic Evolution Early Release Science (CEERS) Survey. These images look deep into a patch of sky close to the Big Dipper—a relatively boring, at least at first glance, region of space that the Hubble Space Telescope first observed in the 1990s.
Nelson was peering at a postage stamp-sized section of one image when she spotted something strange: a few “fuzzy dots” of light that looked way too bright to be real.
“They were so red and so bright,” Nelson said. “We weren’t expecting to see them.”
She explained that in astronomy, red light usually equals old light. The universe, Nelson said, has been expanding since the dawn of time. As it expands, galaxies and other celestial objects move farther apart, and the light they emit stretches out—think of it like the cosmic equivalent of saltwater taffy. The more the light stretches, the redder it looks to human instruments. (Light from objects coming closer to Earth, in contrast, looks bluer).
The team ran calculations and discovered that their old galaxies were also huge, harboring tens to hundreds of billions of sun-sized stars worth of mass, on par with the Milky Way.
These primordial galaxies, however, probably didn’t have much in common with our own.
“The Milky Way forms about one to two new stars every year,” Nelson said. “Some of these galaxies would have to be forming hundreds of new stars a year for the entire history of the universe.”
Nelson and her colleagues want to use James Webb to collect a lot more information about these mysterious objects, but they’ve seen enough already to pique their curiosity. For a start, calculations suggest there shouldn’t have been enough normal matter—the kind that makes up planets and human bodies—at that time to form so many stars so quickly.
“If even one of these galaxies is real, it will push against the limits of our understanding of cosmology,” Nelson said.
Seeing back in time
For Nelson, the new findings are a culmination of a journey that began when she was in elementary school. When she was 10, she wrote a report about Hubble, a telescope that launched in 1990 and is still active today. Nelson was hooked.
“It takes time for light to go from a galaxy to us, which means that you're looking back in time when you're looking at these objects,” she said. “I found that concept so mind blowing that I decided at that instant that this was what I wanted to do with my life.”
The fast pace of discovery with James Webb is a lot like those early days of Hubble, Nelson said. At the time, many scientists believed that galaxies didn’t begin forming until billions of years after the Big Bang. But researchers soon discovered that the early universe was much more complex and exciting than they could have imagined.
“Even though we learned our lesson already from Hubble, we still didn’t expect James Webb to see such mature galaxies existing so far back in time,” Nelson said. “I’m so excited.”
Other co-authors on the new study include Pieter van Dokkum of Yale University; Rachel Bezanson of the University of Pittsburgh; Katherine Suess of the University of California, Santa Cruz; Joel Leja, Elijah Matthews and Bingjie Wang of the Pennsylvania State University; Gabriel Brammer and Katherine Whitaker of the University of Coppenhagen; and Mauro Stefanon of the University of Valencia.
|
Cosmology & The Universe
|
A brand new, detailed view of the universe that looks further back into space and time than ever before has been revealed in an extraordinary set of photos.NASA has released a full set of images from its James Webb Space Telescope, showing what is said to be the "deepest" and most detailed picture of the cosmos to date.
This new view of the universe is possible because the Webb is huge - with a mirror more than twice the size of the previously-used Hubble.It is the largest and most powerful telescope ever sent into space.NASA Administrator Bill Nelson said: "Every image is a new discovery and each will give humanity a view of the universe that we've never seen before.'' The first image: cluster of distant galaxies The image above shows a deep field cluster of distant galaxies, as they looked billions of years ago. More on Nasa James Webb Telescope live updates: NASA reveals images that tell secrets of universe The Hubble Space Telescope: What are its greatest hits? NASA reveals picture of distant universe taken by James Webb Space Telescope - but why is it a big deal? Jane Rigby, who worked on the project, says this shows them from about the time the sun and Earth formed.The image has a "sharpness and clarity" we've never had before, she says, and under a close-up, it is possible to see "individual clusters of stars forming, just popping up like popcorn".Although if it looks a bit familiar, it's because it was first revealed by NASA as a teaser yesterday.Sky's science and technology editor Tom Clarke says this is a long exposure photo of a tiny patch of the universe. Please use Chrome browser for a more accessible video player 'Jaws were on the floor' at NASA images "If you held out your arm outstretched with a grain of sand on your finger- that's the size of the patch of sky this image covers," he says.The second image: a giant planet This image is an analysis of the atmosphere of a giant planet called WASP-96 b, and is the first "spectrum analysis" of an exoplanet's atmosphere.Webb will take a number of "spectrum" photos in the coming months.This process involves spitting light into its component "colours" in order to show what a body is made of, how fast it is moving, or even what its temperature is.This analysis is of a giant gas planet located nearly 1,150 light-years from Earth, which orbits its star every 3.4 days.It has about half the mass of Jupiter, and its discovery was announced in 2014.NASA said: "Webb spotted the unambiguous signature of water, indications of haze & evidence for clouds (once thought not to exist there)!"The third image: a planetary nebula In this infrared image, we can see a planetary nebula caused by a dying star.It is nearly half a light-year in diameter and is located approximately 2,000 light-years away from Earth. A light-year is 5.8 trillion miles.The star can be seen expelling a large fraction of its mass.The Southern Ring Nebula, is sometimes also called "eight-burst". Today's images are anything but the final frontier Science and technology editor @aTomClarke Given the James Webb telescope’s extraordinary capability, we had expected these images to be phenomenal, in perhaps the truest sense of that word.
But wow, they really were. Not only did we see stars exploding, the cosmos “dancing” and 13 billion-year-old galaxies, but we also got to see all of that in the most brilliant of detail – better than ever before. The images themselves are an astonishing breakthrough, but the infrared technology used in some, is also hugely significant for astronomers as it reveals totally new insights into a process we only partly understand. In one picture, the telescope had been able to see water vapour in the atmosphere of a planet more than 1,000 light-years from Earth. That the JWST can see water in the atmosphere of a planet that far away is incredible and it shows it can survey the sky, looking for other "Earth-like" atmospheres: A major step toward seeing how common planets like ours might be. This was an amazing demonstration of Webb's power – and with the scope scheduled to be in operation for around 20 years, there’s so much more to come. The fourth image: Stephan's Quintet This image is of a group of five galaxies, two of which are in the process of merging.It's a combination of mid-infrared and near-infrared images that reveals stars being born.Although called a "quintet" only four of the galaxies are truly interacting in a cosmic dance - the one on the left is actually in the foreground.The fifth image: cosmic cliffs of the Carina Nebula This stunning image shows us - for the first time - hundreds of stars that were previously completely hidden from our view.The Carina Nebula is a nearby (in space terms) star-forming region within our own Milky Way galaxy.The "cosmic cliffs" were previously pictured by Hubble's telescope, but this new view gives us a rare glimpse of stars in their earliest, rapid stages of formation.The near-infrared shows hundreds of stars and background galaxies, while the mid-infrared shows dusty planet-forming disks (in red and pink) around young stars.Telescope's missionA partnership of scientists and engineers was formed between NASA, the European Space Agency and the Canadian Space Agency - and for 20 years they worked to complete the £8.4bn telescope. Image: US President Joe Biden got a sneak-peek of the images yesterday Read more: Analysis: Why are these pictures such a big deal?The deepest view of the universe ever captured: NASA releases first image from new space telescope On Christmas Day, 2021, the Webb was launched and it reached its destination in solar orbit nearly 1 million miles from Earth a month later.Once there, the telescope underwent a months-long process to unfurl all of its components, including a sun shield the size of a tennis court, and to align its mirrors and calibrate its instruments.The universe has been expanding for 13.8 billion years, meaning the light from the first stars and galaxies has been "stretched" from shorter visible wavelengths to longer infrared ones. This is what allows Webb to see the universe in unprecedented new detail.These pictures are the first of millions the new telescope will produce over its 20-year lifetime.Each full-colour, high-resolution picture that was unveiled on Tuesday took weeks to render from raw telescope data.Watch-parties for the picture release took place all over the world including in the US, Canada, Israel, UK and Europe.
|
Cosmology & The Universe
|
By Konstantinos Dimopoulos - Reader in Particle Cosmology, Lancaster UniversityThe dinosaur extinction 66m years ago was most likely caused by a comet or big asteroid hitting the Earth. But given that asteroids don’t actually hit our planet very often, could this really be the whole story? Many scientists are now asking whether some sort of cosmological event could have boosted the number of comets at the time, making such a collision more likely.In her book, American cosmologist Lisa Randall suggests that a huge disk of “dark matter” – a type of invisible matter that is five times more common than “normal” matter – could have been responsible. When sweeping past our solar system such a disk would cause a tiny perturbation in space, amounting to a flicker in the gravitational force that can knock comets out of the solar system’s Kuiper belt or the Oort cloud just outside and send them towards the Earth.But how credible is this theory? And are there other cosmological events that could explain the issue? A tricky questionMounting astrophysical and cosmological evidence suggests that there is a lot more dark matter in our galaxy than normal matter. Although it is invisible, we know it is there because of the gravitational pull it has on objects surrounding it.The fact that it is dark simply means that it does not emit or absorb light, which makes it difficult to spot. Most cosmologists believe this matter, which is after all part of our galaxies and galaxy clusters, moves slowly, and is “cold” (because fast-moving particles are hot).Randall suggests that there’s a whole disk of dark matter in our own galaxy. For it to have an effect on us it would need to be roughly aligned with the visible disk of the Milky Way so that the solar system oscillates around it as it travels around the galactic centre. But this is problematic because to be able to explain observations made so far, cosmologists believe dark matter would form large spherical halos around galaxies rather than disks. To get around this, we need to make dark matter weirder than it already is. Randall suggests that there is more than one type of dark matter in the form of a “contamination”, which she says could comprise 5-10% of the total dark matter. This kind of dark matter is different because it can interact with itself just like normal matter does. While the majority of dark matter can flow through itself without stopping, this special so-called “dissipative” dark matter can halt itself from moving and thereby form a galactic disk, like normal matter does. But, as Randall admits in her research papers, we do not know for sure that such dark matter would form a disk.Even if it did, there is no reason why this dark disk should be aligned with the visible disk of the Milky Way, which it would have to do for it to unleash a huge comet towards the Earth.Our nemesisRandall is a world-renowned cosmologist, so her proposal is certainly credible. Provided that the model doesn’t contradict future observations, Randall believes there is a small possibility in which her scenario would actually result in an increase in comets and asteroids.So is there any evidence of this in the geological or palaeontological record? While the issue is still under debate, there is no conclusive evidence that extinctions have happened periodically. Randall’s team claims the boost in comets may happen every 35m years or so, which some might argue could roughly correlate with mass extinctions.So, despite a number of unknowns, is a dark disk the best cosmological proposal to explain mass extinctions? One other proposal that has been put forward is that the sun has a companion star, called Nemesis. Nemesis is a hypothetical, faint red/brown dwarf star orbiting the sun at a distance of about 1.5 light years. Every 25m years or so, it makes a pass closer to the sun, which could result in enhanced comet activity, because of its gravitational pull. This is not an unreasonable hypothesis, since the majority of stars belong to systems with multiple stars. However, brown dwarfs are relatively uncommon and Nemesis has not been observed (yet).To me, Randall’s scenario is more of an interesting “what-if” speculation than a realistic proposal. While her theoretical model is very thorough and more concrete than it may sound at first, the fact that there is no real evidence of periodicity in mass extinctions and crater formation on Earth is a problem. In addition, according to Occam’s razor, which suggests the simplest solution is most likely the best, it is never a good idea to invent more types of dark matter than you actually need.However, the proposal is certainly not impossible and should be taken into account when making observations. What’s more, it serves to remind us that basic physics and cosmology are fundamental aspects of nature that may even influence the fate of life on Earth.Source: The ConversationMore interesting articles on the subject of Space & Exploration:Astronomers discovered a planet where it actually rains iron from the skyEuropean astronomers made an unexpected discovery in the early universeScientists are looking for the best strategy to avert incoming asteroids threatening EarthAstronomers may have caught an incredible, once in 200,000 years cosmic collisionFor the first time ever, astronomers have been able to measure wind speed on a brown dwarf
|
Cosmology & The Universe
|
In 1963, the mathematician Roy Kerr found a solution to Einstein’s equations that precisely described the spacetime outside what we now call a rotating black hole. (The term wouldn’t be coined for a few more years.) In the nearly six decades since his achievement, researchers have tried to show that these so-called Kerr black holes are stable. What that means, explained Jérémie Szeftel, a mathematician at Sorbonne University, “is that if I start with something that looks like a Kerr black hole and give it a little bump”—by throwing some gravitational waves at it, for instance—“what you expect, far into the future, is that everything will settle down, and it will once again look exactly like a Kerr solution.”The opposite situation—a mathematical instability—“would have posed a deep conundrum to theoretical physicists and would have suggested the need to modify, at some fundamental level, Einstein’s theory of gravitation,” said Thibault Damour, a physicist at the Institute of Advanced Scientific Studies in France.In a 912-page paper posted online on May 30, Szeftel, Elena Giorgi of Columbia University and Sergiu Klainerman of Princeton University have proved that slowly rotating Kerr black holes are indeed stable. The work is the product of a multiyear effort. The entire proof—consisting of the new work, an 800-page paper by Klainerman and Szeftel from 2021, plus three background papers that established various mathematical tools—totals roughly 2,100 pages in all.The new result “does indeed constitute a milestone in the mathematical development of general relativity,” said Demetrios Christodoulou, a mathematician at the Swiss Federal Institute of Technology Zurich.Shing-Tung Yau, an emeritus professor at Harvard University who recently moved to Tsinghua University, was similarly laudatory, calling the proof “the first major breakthrough” in this area of general relativity since the early 1990s. “It is a very tough problem,” he said. He did stress, however, that the new paper has not yet undergone peer review. But he called the 2021 paper, which has been approved for publication, both “complete and exciting.”One reason the question of stability has remained open for so long is that most explicit solutions to Einstein’s equations, such as the one found by Kerr, are stationary, Giorgi said. “These formulas apply to black holes that are just sitting there and never change; those aren’t the black holes we see in nature.” To assess stability, researchers need to subject black holes to minor disturbances and then see what happens to the solutions that describe these objects as time moves forward.For example, imagine sound waves hitting a wineglass. Almost always, the waves shake the glass a little bit, and then the system settles down. But if someone sings loudly enough and at a pitch that exactly matches the glass’s resonant frequency, the glass could shatter. Giorgi, Klainerman, and Szeftel wondered whether a similar resonance-type phenomenon could happen when a black hole is struck by gravitational waves.They considered several possible outcomes. A gravitational wave might, for instance, cross the event horizon of a Kerr black hole and enter the interior. The black hole’s mass and rotation could be slightly altered, but the object would still be a black hole characterized by Kerr’s equations. Or the gravitational waves could swirl around the black hole before dissipating in the same way that most sound waves dissipate after encountering a wineglass.Or they could combine to create havoc or, as Giorgi put it, “God knows what.” The gravitational waves might congregate outside a black hole’s event horizon and concentrate their energy to such an extent that a separate singularity would form. The spacetime outside the black hole would then be so severely distorted that the Kerr solution would no longer prevail. This would be a dramatic sign of instability.The three mathematicians relied on a strategy—called proof by contradiction—that had been previously employed in related work. The argument goes roughly like this: First, the researchers assume the opposite of what they’re trying to prove, namely that the solution does not exist forever—that there is, instead, a maximum time after which the Kerr solution breaks down. They then use some “mathematical trickery,” said Giorgi—an analysis of partial differential equations, which lie at the heart of general relativity—to extend the solution beyond the purported maximum time. In other words, they show that no matter what value is chosen for the maximum time, it can always be extended. Their initial assumption is thus contradicted, implying that the conjecture itself must be true.Klainerman emphasized that he and his colleagues have built on the work of others. “There have been four serious attempts,” he said, “and we happen to be the lucky ones.” He considers the latest paper a collective achievement, and he’d like the new contribution to be viewed as “a triumph for the whole field.”So far, stability has only been proved for slowly rotating black holes—where the ratio of the black hole’s angular momentum to its mass is much less than 1. It has not yet been demonstrated that rapidly rotating black holes are also stable. In addition, the researchers did not determine precisely how small the ratio of angular momentum to mass has to be in order to ensure stability.Given that only one step in their long proof rests on the assumption of low angular momentum, Klainerman said he would “not be surprised at all if, by the end of the decade, we will have a full resolution of the Kerr [stability] conjecture.”Giorgi is not quite so sanguine. “It is true that the assumption applies to just one case, but it is a very important case.” Getting past that restriction will require quite a bit of work, she said; she is not sure who will take it on or when they might succeed.Looming beyond this problem is a much bigger one called the final state conjecture, which basically holds that if we wait long enough, the universe will evolve into a finite number of Kerr black holes moving away from each other. The final state conjecture depends on Kerr stability and on other sub-conjectures that are extremely challenging in themselves. “We have absolutely no idea how to prove this,” Giorgi admitted. To some, that statement might sound pessimistic. Yet it also illustrates an essential truth about Kerr black holes: They are destined to command the attention of mathematicians for years, if not decades, to come.Original story reprinted with permission from Quanta Magazine, an editorially independent publication of the Simons Foundation whose mission is to enhance public understanding of science by covering research developments and trends in mathematics and the physical and life sciences.
|
Cosmology & The Universe
|
September 26, 2022 Full-sky map showing Cosmicflows-4’s 56,000 galaxies with distance measurements. Each dot represents a galaxy, and the color of the dot indicates distance from us.
How old is our universe, and what is its size? A team of researchers led by University of Hawaiʻi at Mānoa astronomers Brent Tully and Ehsan Kourkchi from the Institute for Astronomy have assembled the largest-ever compilation of high-precision galaxy distances, called Cosmicflows-4. Using eight different methods, they measured the distances to a whopping 56,000 galaxies. The study is being published in the Astrophysical Journal.
Four galaxies in roughly a vertical line lie at 270 million light years strongly interact. The galaxy to the left, NGC 7320, lies to the foreground, 54 million light years away. Knowledge of the properties of these stars yields a distance to the galaxy. (Credit: NASA)
Galaxies, such as the Milky Way, are the building blocks of the universe, each comprised of up to several hundred billion stars. Galaxies beyond our immediate neighborhood are rushing away, faster if they are more distant, which is a consequence of the expansion of the universe that began at the moment of the Big Bang. Measurements of the distances of galaxies, coupled with information about their velocities away from us, determine the scale of the universe and the time that has elapsed since its birth.
“Since galaxies were identified as separate from the Milky Way a hundred years ago, astronomers have been trying to measure their distances,” said Tully. “Now by combining our more accurate and abundant tools, we are able to measure distances of galaxies, and the related expansion rate of the universe and the time since the universe was born with a precision of a few percent.”
From the newly published measurements, the researchers derived the expansion rate of the universe, called the Hubble Constant, or H0. The team’s study gives a value of H0=75 kilometers per second per megaparsec or Mpc (1 megaparsec = 3.26 million light years), with very small statistical uncertainty of about 1.5%.
There are a number of ways to measure galaxy distances. Generally, individual researchers focus on an individual method. The Cosmicflows program spearheaded by Tully and Kourkchi includes their own original material from two methods, and additionally incorporates information from many previous studies. Because Cosmicflows-4 includes distances derived from a variety of independent, distinct distance estimators, intercomparisons should mitigate against a large systematic error. Related UH News story: Astronomers trace galaxy flows across 700 million light years, February 3, 2022 Cosmic dilemma
Astronomers have assembled a framework that shows the universe’s age to be a little more than 13 billion years old, however a dilemma of great significance has arisen in the details.
Physics of the evolution of the universe based on the standard model of cosmology predicts H0=67.5 km/s/Mpc, with an uncertainty of 1 km/s/Mpc. The difference between the measured and predicted values for the Hubble Constant is 7.5 km/s/Mpc—much more than can be expected given the statistical uncertainties. Either there is a fundamental problem with our understanding of the physics of the cosmos, or there is a hidden systematic error in the measurements of galaxy distances.
Additional studies
Cosmicflows-4 is also being used to study how galaxies move individually, in addition to flowing with the overall expansion of the universe. Deviations from this smooth expansion arise due to the gravitational influences of clumps of matter, on scales ranging from our Earth and Sun up to congregations of galaxies on scales of a half billion light years. The mysterious dark matter is the dominant component on larger scales. With knowledge of the motions of galaxies in response to the mass around them, we can recreate the orbits that galaxies have followed since they were formed, giving us a better understanding of how the universe’s vast, dark-matter dominated structures have formed over the eons of time.
|
Cosmology & The Universe
|
Review "At the Edge of Time clearly and cogently lays out our current understanding of the very early universe, and the prospects for future progress. In one particularly exciting section, Hooper describes the process of identifying and studying a candidate dark matter signal from the perspective of its discoverer. This is a fascinating first-hand account of an ongoing scientific debate."--Tracy Robyn Slatyer, Massachusetts Institute of Technology"At the Edge of Time is a gripping tale of the monumental discoveries and unsolved mysteries in cosmology. Well-written and exciting, Hooper's book leads us from the early days of Einstein to the puzzles of the modern era, as well as through the author's own adventures in the search for answers. He lays out these challenges in a way that will inspire a future generation of young scientists."--Katherine Freese, author of The Cosmic Cocktail: Three Parts Dark Matter"A clear and engaging tour of the mysterious birth of our universe, At the Edge of Time will keep you at the edge of your mental seat."--Daniel Whiteson, coauthor of We Have No Idea: A Guide to the Unknown Universe"This book convincingly guides readers through some of the hottest topics in modern physics and astronomy: Big Bang theory, dark matter, dark energy, and gravitational waves. Bringing a fresh perspective, Hooper effectively captures the feelings of the community of scientists working to solve the greatest mysteries and demonstrates that a scientific revolution might be around the corner."--Gianfranco Bertone, author of Behind the Scenes of the Universe: From the Higgs to Dark Matter "What a journey, from the very birth of the universe to its ultimate future. In accessible fashion, Hooper's book does a great job explaining the fundamental laws of physics and showing how they play out in cosmic evolution."--Sean Carroll, author of Something Deeply Hidden: Quantum Worlds and the Emergence of Spacetime"Where Weinberg's The First Three Minutes left off, Hooper's At the Edge of Time picks up. A riveting tour of modern cosmology told by one of its savviest guides, Hooper's book takes us on a journey from our universe's formerly inscrutable past to mesmerizing possible scenarios in its far future. A fascinating story that is to be savored."--Brian Keating, author of Losing the Nobel Prize: A Story of Cosmology, Ambition, and the Perils of Science's Highest Honor Review "Essential reading for any cosmology enthusiast."―Laura Nuttall, BBC Sky at Night"[An] informed introduction to 'the mysteries of our universe’s first seconds.'"―Andrew Robinson, Nature"Scientists know precious little about what happened when the universe got its start: many cosmologists think space and time underwent an extremely rapid expansion called inflation. . . . Hooper takes readers on a mind-bending expedition through these questions and shows how they all connect to the beginning."―Clara Moskowitz, Scientific American"If you're mystified and curious about the mysteries of the Universe . . . you won't want to miss this book."―Ethan Siegel, Forbes
|
Cosmology & The Universe
|
Science July 7, 2022 / 6:20 PM / AP In a former gold mine a mile underground, inside a titanium tank filled with a rare liquified gas, scientists have begun the search for what so far has been unfindable: dark matter.Scientists are pretty sure the invisible stuff makes up most of the universe's mass and say we wouldn't be here without it — but they don't know what it is. The race to solve this enormous mystery has brought one team to the depths under Lead, South Dakota.The question for scientists is basic, says Kevin Lesko, a physicist at Lawrence Berkeley National Laboratory. "What is this great place I live in? Right now, 95% of it is a mystery." This photo provided by Sanford Underground Research Facility shows members of the LZ team in the LZ water tank after the outer detector installation in Lead, South Dakota. Matthew Kapust/Sanford Underground Research Facility via AP The idea is that a mile of dirt and rock, a giant tank, a second tank and the purest titanium in the world will block nearly all the cosmic rays and particles that zip around — and through — all of us every day. But dark matter particles, scientists think, can avoid all those obstacles. They hope one will fly into the vat of liquid xenon in the inner tank and smash into a xenon nucleus like two balls in a game of pool, revealing its existence in a flash of light seen by a device called "the time projection chamber." Scientists announced Thursday that the five-year, $60 million search finally got underway two months ago after a delay caused by the COVID-19 pandemic. So far the device has found ... nothing. At least no dark matter.That's OK, they say. The equipment appears to be working to filter out most of the background radiation they hoped to block. "To search for this very rare type of interaction, job number one is to first get rid of all of the ordinary sources of radiation, which would overwhelm the experiment," said University of Maryland physicist Carter Hall. And if all their calculations and theories are right, they figure they'll see only a couple fleeting signs of dark matter a year. The team of 250 scientists estimates they'll get 20 times more data over the next couple of years.By the time the experiment finishes, the chance of finding dark matter with this device is "probably less than 50% but more than 10%," said Hugh Lippincott, a physicist and spokesman for the experiment in a Thursday news conference.While that's far from a sure thing, "you need a little enthusiasm," Lawrence Berkeley's Lesko said. "You don't go into rare search physics without some hope of finding something."Two hulking Depression-era hoists run an elevator that brings scientists to what's called the LUX-ZEPLIN experiment in the Sanford Underground Research Facility. A 10-minute descent ends in a tunnel with cool-to-the-touch walls lined with netting. But the old, musty mine soon leads to a high-tech lab where dirt and contamination is the enemy. Helmets are exchanged for new cleaner ones and a double layer of baby blue booties go over steel-toed safety boots. The heart of the experiment is the giant tank called the cryostat, lead engineer Jeff Cherwinka said in a December 2019 tour before the device was closed and filled. He described it as "like a thermos" made of "perhaps the purest titanium in the world" designed to keep the liquid xenon cold and keep background radiation at a minimum.Xenon is special, explained experiment physics coordinator Aaron Manalaysay, because it allows researchers to see if a collision is with one of its electrons or with its nucleus. If something hits the nucleus, it is more likely to be the dark matter that everyone is looking for, he said.These scientists tried a similar, smaller experiment here years ago. After coming up empty, they figured they had to go much bigger. Another large-scale experiment is underway in Italy run by a rival team, but no results have been announced so far.The scientists are trying to understand why the universe is not what it seems.One part of the mystery is dark matter, which has by far most of the mass in the cosmos. Astronomers know it's there because when they measure the stars and other regular matter in galaxies, they find that there is not nearly enough gravity to hold these clusters together. If nothing else was out there, galaxies would be "quickly flying apart," Manalaysay said."It is essentially impossible to understand our observation of history, of the evolutionary cosmos without dark matter," Manalaysay said.Lippincott, a University of California, Santa Barbara, physicist, said "we would not be here without dark matter." So while there's little doubt that dark matter exists, there's lots of doubt about what it is. The leading theory is that it involves things called WIMPs — weakly interacting massive particles.If that's the case, LUX-ZEPLIN could be able to detect them. We want to find "where the wimps can be hiding," Lippincott said. In: physics Thanks for reading CBS NEWS. Create your free account or log in for more features. Please enter email address to continue Please enter valid email address to continue
|
Cosmology & The Universe
|
Astronomy and cosmology can feel detached from everyday reality. But what if we could take a 23rd-century starship tour through the Milky Way and experience the cosmos like an Earth-bound tourist visiting exotic destinations? What would we see from our window?
Although physicists enjoy speculating about warp drives, or using wormholes to jump between locations, there is no way to travel faster than light at present. So we’re assuming a fictional ability to do this – but beyond that, everything we will encounter on our voyage is based on best current theories.
Passing other probes
As we exit the solar system and enter interstellar space, we will stop initially alongside Pioneer 11, one of the first probes to leave our planetary neighbourhood. There is no “you are leaving the solar system” sign – but the border is the limit of a solar phenomenon. The sun sprays out energetic particles that sweep away the gas and dust found between the stars. This no longer happens about 90 times the Earth’s distance from the sun.
Several probes have made it out of the solar system. To the sightseer they look similar: a large radio dish bolted to a collection of metal boxes. But their most interesting aspect lies in attempts to communicate with passing alien rubbish collectors. We could look at the gold discs on Voyagers 1 and 2, launched in 1977 to study the outer planets. Or we could unpack the interstellar version of a high-school time capsule on the 2006 New Horizons mission to Pluto and beyond… But we’ve arrived alongside Pioneer 11, which along with its twin, Pioneer 10, carries an enigmatic gold-plated plaque.
Parts of the image are straightforward: it shows two naked humans, with the probe to the same scale, and a solar system map. But what do you make of three small vertical lines over one horizontal line to the right of the female figure? Or a starburst effect filling half the plaque?
The concept behind this is to convey messages through a scientific symbolism that it was hoped could be understood by aliens. The collection of lines (representing binary) give the woman’s height, thanks to information deduced from the pair of linked circles (representing a process undergone by hydrogen atoms) at the top of the plaque.
And as for that starburst, it pinpoints Earth’s location. Each line represents the distance and direction to a series of pulsars – collapsed stars that flash out regular blasts of electromagnetic energy. The timing, shown by binary numbers on each line, indicates the pulsar’s frequency, based on timing implied by the hydrogen diagram. Some have worried that this map opens us up to alien invasion. Luckily, part of the pulsar data is slightly off. Even if it were precise, though, this is a message in a bottle on a galactic scale, and we are unlikely to be found.
Stellar nursery
Leaving Pioneer behind, we travel on to the Orion nebula. From Earth, this forms part of the familiar constellation of Orion, the hunter. We need to remember, though, that the apparent connection between a constellation’s stars is illusory: they are not actually linked. For example, Alnilam, the middle star of Orion’s belt, is about 1,342 light years from Earth, whereas Bellatrix, the top right of Orion’s main stars, is just 245 light years distant. A light year is the distance light travels in one year – around 5.9tn miles (9.5tn km).
From Earth, the nebula looks like a small fuzzy patch in Orion’s sword, about 1,500 light years away. This is where new stars are born out of the dust and gas, and it’s the closest-known nursery to us. It’s about 20 light years across and contains approximately 1,000 new stars forming. It’s a slow process, as the particles that make up the cloud – mostly hydrogen atoms – are slowly pulled together by gravity. As they squash ever closer, the atoms warm up, and with enough matter, the pressure and heat become so intense that nuclear fusion begins.
The young star begins to convert hydrogen into helium, releasing energy as it does. Stars need to be huge for this to happen. Our sun, for example, a middling star, contains 99.8% of the matter in the solar system and fuses about 600m tonnes of hydrogen every second.
Other worlds
Our next stop is a protoplanetary disc: a rotating disc of dense gas surrounding a young star. On the whole, matter in the universe spins around. Because the clouds of gas and dust giving rise to stars are not evenly distributed, the material starts to rotate as gravity pulls it inward. Just as a skater’s spin speeds up when they pull in their limbs, thanks to the conservation of angular momentum (the oomph with which something rotates), so the spin of the star accelerates as matter piles in.
The central star has so much gravitational attraction that it remains spherical, but matter further out from the centre flattens into a rotating disc, just as a ball of pizza dough does as it is spun. In both cases, there is attraction towards the centre, but not at 90 degrees to the direction of rotation, producing the flattening. Material in the disc eventually coalesces because of gravity, producing planets.
On our tour, we can now visit an extrasolar planet – more than 5,000 of these had been discovered by the 2020s. Trappist-1e is one of the most likely sites for life from the early 21st century discoveries. It’s rocky and similar to Earth in size. Though not certain in the 2020s, it appears to have liquid water and an Earth-like atmosphere. Admittedly, its relationship with its star is nothing like Earth: it completes its orbit in six days, being located about 15 times closer to its star than Mercury is to the sun. However, this is a very low-energy star, making Trappist-1e a viable potential home for life.
Supernova
The neighbourhood of our next destination will definitely not be habitable for long: Betelgeuse, the bright red star at the top left of Orion. In the 2020s, it was known that this red supergiant would go supernova during the following 100,000 years. We’re lucky – our fictional starship has arrived just as Betelgeuse undergoes this catastrophic change.
A supernova is a massive stellar explosion. From the Earth, this means some previously invisible stars flare into brightness – hence the term “nova”, from the Latin for “new”. Betelgeuse has always been visible – but it’s about to get much brighter. Its fusible material is running out. As heavier elements form, there comes a point when fusion takes more energy than the star can provide and it switches off. No atoms heavier than iron can be produced this way.
Up to now, the energy of nuclear reaction has fluffed up the star. Now, its inner parts collapse to form a neutron star – so dense that one teaspoon has a mass of around 100m tonnes. When that core collapses, it bounces back, blasting away the outer layers of the star, providing so much energy that heavier elements form. Over centuries, those outer layers will form a different type of nebula – a glowing remnant, such as the Crab nebula.
Milky Way
Our final stop before heading home enables us to see our galaxy, the Milky Way. This is partially visible from Earth, but is hard to see in built-up areas thanks to light pollution. In a dark sky it appears as an arch of fuzzy light. What we see from home is the view from within. But here, from the outside, we see it in all its glory.
Back in the 2020s we had never seen the Milky Way from the outside, but it was known to be a vast spiral about 100,000 light years across, with a central bar of densely packed stars. Despite being just one of approximately 200bn galaxies within the limits of the observable universe, the Milky Way is home to about 100bn stars.
Though we can’t see something as small as the sun from here, we can place it roughly near the edge of one of the outer spiral arms.
Back home
With a final jump, we return to Earth. It’s tiny in the perspective of the galaxy, let alone the universe. Yet this is a special place. Planets like ours, with so many things right for life, are rare. A whole host of features have come together.
Earth sits in the “Goldilocks zone” – not too hot nor too cold for liquid water, seemingly essential for life. Our unusually large moon stabilises the Earth’s orbit, and the Earth’s active surface, a result of the moon’s formation, helps keep our environment in balance. We have a stable star, plus a strong magnetic field and ozone layer protecting Earth from deadly solar radiation. Some say that Earth isn’t anything special. But it truly is, and we need to keep it that way.
|
Cosmology & The Universe
|
Astronomers have witnessed a young, sun-like star blasting out high-energy gamma radiation for the first time.
The observation represents the first evidence that this type of low-mass star, called a T. Tauri star and surrounded by a planet-forming disk of gas and dust, can emit gamma radiation. In a nutshell, this type of radiation represents the most energetic form of light. Down the line, these findings could have important implications for our understanding of stars and planetary systems during their formative years.
"This observational evidence is essential for understanding the origin of sources that have previously remained unknown for more than a decade, which is unquestionably a step forward in astronomy," Agostina Filócomo, discovery team leader and an astronomer at the Universidad Nacional de La Plata, said in a statement. "It is also critical to comprehend the processes that occur during the early phases of star formation: If a T Tauri star produces gamma-ray radiation, it will affect the gas conditions of the protoplanetary disk and, consequently, the evolution of planet formation."
The astronomers captured their observations of this intriguing star with the Fermi satellite telescope, which observes the universe in gamma rays. In other words, this telescope has the ability to collect high-energy radiation data that can be tough to gather from the surface of Earth. Fermi has been observing the sky since it launched in 2008, but about 30% of the gamma rays it has seen have yet to be attributed to a source. Thus, Filócomo and her team set about attempting to identify some of these mysterious sources.
Gamma rays could come from tantrum-throwing infant stars
The research team basically found that many gamma rays appear to originate from regions with actively forming stars. This is something that defied explanation and thus required deeper investigation, with the team honing in on the star-forming region NGC 2071.
In particular, Filócomo and colleagues looked for T.Tauri stars in NGC 2071, which lies in the northern part of the molecular cloud Orion B, located around 1,350 light years from Earth. T.Tauri stars are notable because they are often found near star-forming regions, still cocooned in the very gas and dust that created them. And because they are shrouded in these gaseous cradles, T. Tauri stars exhibit fluctuating levels of brightness — making them a type of variable star.
The team identified three different unidentified gamma-ray sources that seemed to be coming from the direction of NGC 2071, where at least 58 T. Tauri stars are known to be currently forming. There are no other objects in the region that could be sources of gamma-ray emissions, the researchers reasoned.
The team thinks T. Tauri stars could be emitting gamma rays sporadically during powerful flare events called "megaflares," which occur when magnetic energy stored in the atmospheres of young stars gets released in the form of powerful electromagnetic bursts.
This concept is similar to the way solar flares are launched by the sun, except they occur on a radically larger scale. Megaflares can stretch for distances equivalent to several times the radius of the stars that launch them in the first place and are so powerful that, if the sun were to blast out such an eruption, life on Earth would be threatened.
Yet despite this destructive potential, some scientists argue that megaflares in the early history of the solar system, when the sun was embedded in a disk of gas and dust, may have actually been beneficial to planet birth by driving gas and triggering the formation of pebbles and other small rocky materials.
As such, not only could the team's findings help account for previously unattributed gamma-ray detections, but could have implications for our understanding of the solar system — especially during the period when our planet was being created.
"The discovery of this phenomenon serves to understand how not only the sun but also our home planet, Earth, were formed and evolved," Filócomo concluded.
The team's research was published Aug. 23 in the journal Monthly Notices of the Royal Astronomical Society.
Live Science newsletter
Stay up to date on the latest science news by signing up for our Essentials newsletter.
Robert Lea is a science journalist in the U.K. who specializes in science, space, physics, astronomy, astrophysics, cosmology, quantum mechanics and technology. Rob's articles have been published in Physics World, New Scientist, Astronomy Magazine, All About Space and ZME Science. He also writes about science communication for Elsevier and the European Journal of Physics. Rob holds a bachelor of science degree in physics and astronomy from the U.K.’s Open University
|
Cosmology & The Universe
|
LIVE UPDATESIt's the highest resolution image of the universe ever taken.Last Updated: July 12, 2022, 11:14 AM ETThe first full-color image from NASA's James Webb Space Telescope has been released.The images, the full set of which will be released Tuesday morning, will be the deepest and highest resolution ever taken of the universe, according to NASA.The telescope will help scientists study the formation of the universe’s earliest galaxies, how they compare to today’s galaxies, how our solar system developed and if there is life on other planets.NASA has begun releasing the long-awaited new images from the James Webb Space Telescope.One of the first images revealed during a televised broadcast Tuesday from NASA's Goddard Space Flight Center in Greenbelt, Maryland, shows a graph of the atmospheric composition of WASP-96 b, the largest planet outside of our solar system.Officials explained that as the planet passes in front of star, the starlight filters through the atmosphere as it passed, which is broken down into wavelengths of light.The graph indicates the presence of water vapor, which is evidence that the planet had clouds, which were once thought not to exist there, NASA explained.The data also demonstrates, "Webb’s unprecedented ability to analyze atmospheres hundreds of light-years away," the space agency said.Ahead of the release Tuesday of the first images taken by the James Webb Space Telescope, NASA has revealed a list of the telescope's first targets.Among them is the Carina Nebula, which is one of the brightest nebulae in the sky -- according to the space agency -- and located about 7,600 light-years away.Other targets include WASP-96 b, the largest planet outside of our solar system, and the Southern Ring Nebula, which is a planetary nebula, or a cloud of gas that encircles a dying star.The telescope will also examine Stephan's Quintet, a group of five galaxies located 290 million light-years away and of which four are "locked in a cosmic dance of repeated close encounters," NASA said.The final target is the SMACS 0723, which is a cluster of galaxies that distorts the light of objects behind it and will allow scientists to look at planets, stars and other objects that would have been otherwise invisible to the human eye.President Joe Biden unveiled the first full-color image taken by the James Webb Space Telescope.The image, revealed during a press event held at the White House Monday and also attended by Vice President Kamala Harris, shows multiple galaxies.It is the highest-resolution image of the universe ever captured, officials said."Today is a historic day," said Biden. "It’s a new window into the history of our universe and today we’re going to get a first glimpse of the light to shine through that window."NASA Administrator Bill Nelson said the light seen on the image has been traveling for over 13 billion years.NASA announced Monday all four of the James Webb Space Telescope's scientific instruments are ready to start being used.The space agency said there are 17 modes, or ways, to operate the instruments. All have been examined and are "ready to begin full scientific operations."The last step was was checking the the telescope's NIRCam, which block starlight so scientists can detect other nearby structures, such as exoplanets.
|
Cosmology & The Universe
|
On Christmas Day last year, 30 years after its conception, the James Webb space telescope launched from French Guiana. On 28 December, it went past the moon. On 24 January, it fired its thrusters for five minutes and settled into its final orbit about 1.5m km from Earth. On 12 July, after months of painstaking setup, it produced its first image – showing us, for the first time, faraway galaxies as they were more than 13bn years ago.The Webb telescope has been adding to this miraculous beginning ever since. Now it’s brought us something a little closer to home, a mere 615m km away: the most extraordinarily detailed images of Jupiter we’ve ever seen.The James Webb space telescope is packed up for shipment to its launch site in Kourou, French Guiana. Photograph: Chris Gunn/Nasa/ReutersOxford University astrophysicist Dr Becky Smethurst, author of a forthcoming book, A Brief History of Black Holes, said that there were many reasons to be sceptical that it would ever get this far. “There were 344 single points of failure where if any tiny thing had gone wrong, the whole mission would have been scrapped. It was months of anxiety,” she said.One major source of uncertainty after the satellite launched was how closely it would hew to its intended trajectory – with any inaccuracy bringing with it the need to burn valuable fuel. “But it was perfect. We were promised five years of data, and instead we’re going to get 20. It’s just incredible.” Here are some of the images this impeccably directed telescope has produced – and what they show about how it operates, and the universe itself.Webb’s First Deep FieldWebb’s First Deep Field, which showcases a galaxy cluster called SMACS 0723 as it appeared 4.6bn years ago. Photograph: ESA/PAThe first of the Webb images to be revealed – by Joe Biden – shows a galaxy cluster known as SMACS 0723. The entire picture covers thousands of galaxies in an area of the sky equivalent to a single grain of rice held at arm’s length on the surface of the Earth. “We can see things in this tiny, tiny patch in way more detail than we’ve ever been able to with Hubble [the most powerful telescope until now],” Smethurst said. “It suggests there’s no blank sky any more – everywhere you look, you’re going to find something in the background.”Like all of the images produced by Webb, what you can see here is not visible light – but signals in the infrared spectrum captured by the satellite in monochrome, sent back to Earth as ones and zeros, and then reconstructed. The different colours don’t denote literal shades, but the wavelengths of the signals, which tell us how hot the source was. Colouring the images like this makes it easier for scientists to detect areas for further study (and generates more public excitement than a black-and-white picture ever could).In this image, the sharp, gleaming star at the centre is in our own galaxy. The fuzzy white dots below it are whole galaxies in the SMACS 0723 cluster, shown as they were 4.6bn years ago. Better still, this cluster in the centre acts as a kind of magnifying lens for other galaxies which are much further away – as much as 13bn light years, almost back to the dawn of the universe. Because they are distorted in the process, they show as the arcs streaking across the image: red objects are caked in cosmic dust – a crucial ingredient of star formation – while green ones are full of hydrocarbons. The Carina NebulaA comparison of the James Webb telescope’s views of the Carina Nebula with Hubble’s equivalent. Photograph: NasaThe comparison of this image of a nebula – a vast cloud of dust and gas studded with stars – to the equivalent area captured by Hubble is evidence of how much more powerful Webb is. “The Carina Nebula is in our own galaxy,” Smethurst said. “Although I think it looks a bit like the Lake District here. The value of this image is really in what is shows us about the benefit of looking at relatively nearby things in infrared.“It allows you to pierce through the dust – these little molecules of heavier elements like oxygen and carbon which scatter visible light so that you can’t see the stars that have formed. In this picture, we get through that dust to the three dimensional structure of the nebula.”Stephan’s QuintetThe first image from Nasa’s James Webb telescope of Stephan’s Quintet. Photograph: Nasa/PAThis image, constructed from more than 150m pixels sent by Webb, shows a group of galaxies in the Pegasus constellation, and provides scientists with the means to see how their interaction triggers the formation of stars. “This is my favourite, because it’s directly relevant to my work,” said Smethurst. “It shows four galaxies interacting, one of them with a growing black hole, and one which isn’t. What’s amazing is that if you zoom in you can see individual stars: until now we’ve barely been able to do that with our closest galaxy, Andromeda, and these are much more distant.”The galaxy to the left of the formation is closer than the others – 40m light years away as opposed to 290m. The topmost swirl in the image contains a black hole 24m times the mass of the sun. “It’s an incredibly bright source of light,” Smethurst said. “What this shows is the gas swirling around the black hole lit up in all its glory.”WASP-96b (spectrum)A transmission spectrum made from a single observation using Webb’s Near-Infrared Imager and Slitless Spectrograph (NIRISS) reveals atmospheric characteristics of the hot gas giant exoplanet WASP-96 b. Photograph: Nasa/UPI/Rex/ShutterstockThis is not an image, but “it’s still enormously exciting to astrophysicists”, Smethurst says. The set of data reveals clearly that this planet, 1,150 light years away, has the distinctive characteristics of water.Webb measured light coming from the WASP-96 system as the planet moved across the star – and the way the gas giant has “stolen away a little bit of the starlight” as it passes through its atmosphere reveals the unique signature of water, Smethurst said.The findings are also important because they show “what the telescope is capable of”, Smethurst said. “This is a big bright planet, very close to its star. It’s easier to observe the light passing through the atmosphere because it passes in front of the star often. Because it’s so easy here, it suggests that with the harder ones that are further away and pass in front of their star less often like Earth, you won’t be wasting your time. It’s this idea of finding ‘Earth’s twin’ – something that looks incredibly habitable for life as we know it.”JupiterA new Jupiter photo is depicted in space with enhanced colour that showcases the planet’s features in detail. Photograph: Nasa/Zuma Press Wire Service/Rex/ShutterstockIf the primary purpose of Webb is to tell us more about light sent by faraway stars billions of year ago, it turns out to also be able to produce stunning images of our own solar system unlike any we have seen before. “I was amazed when I saw the level of detail here – I thought it would be washed out because it’s so bright,” Smethurst said. “But it’s very clever how they’ve used different wavelengths to capture different things.”The red haze at the planet’s north and south poles are auroras – created by the interaction of particles from the sun with the planet’s magnetic field. The famous Great Red Spot, a storm so big it could swallow Earth, appears in white because it reflects so much sunlight. “And the darker areas reveal the areas where the light has pierced further into the atmosphere,” Smethurst said.Valuable though Webb’s observations will be for scientists, images like this also strike Smethurst as important for their sheer, universal beauty. “Everyone is curious about the world we live in,” she said.
|
Cosmology & The Universe
|
Astronomers looking at ancient light seen by the Webb Space Telescope have found three pinpricks that they think could be “dark stars,” theoretical objects powered by dark matter.
Dark matter makes up about 27% of the universe; its partner in ambiguity, dark energy, makes up about 68%. You can do the math: we know stunningly little of what makes up the universe and how it behaves. It’s in that zone of cosmic uncertainty that Webb’s latest targets pop up. The team’s research was published last week in Proceedings of the National Academy of Sciences.
The three targets are JADES-GS-z13-0, JADES-GS-z12-0, and JADES-GS-z11-0, and were identified as galaxies by Webb back in December 2022. The targets were imaged as part of the JWST Advanced Deep Extragalactic Survey (JADES), which takes deep field images of space, looking at extremely ancient light to help scientists understand the evolution of cosmic structures like galaxies.
The three objects date to when the universe was between 320 million and 400 million years old, making them quite young (in a cosmic sense). And while they could well be galaxies containing millions of stars, the recent research team posits that they are never-before-seen dark stars, which could be millions of times the mass of our Sun and would be powered by the collisions of dark matter particles, rather than nuclear fusion.
Dark matter is not literally dark, at least not necessarily. It is called dark matter because it is nearly impossible for humans to detect. We see dark matter in its gravitational effects; haloes of dark matter glom galaxies together, and astronomers see ancient light more clearly when dark matter bends and focuses the photons transiting its gravitational field.
While scientists don’t know what makes up dark matter, they have a few ideas. As Gizmodo reported earlier this year:
There are a couple leading candidates for dark matter (and it’s not a zero-sum game; multiple candidates could be contributing to the dark matter in the universe). Weakly Interacting Massive Particles (WIMPs) are theoretical things that have mass and behave like particles but only interact barely with ordinary matter—hence our inability to identify them.
The other major candidate is the axion, a theoretical particle (a boson, to be specific) named for a laundry detergent. The axion would be much smaller than a WIMP and has been theorized to behave more like a wave than a particle, like photons of light.
In April, a group of scientists studying Einstein rings (distant light that is strongly gravitationally lensed, creating a ring of light in space) found evidence that axionic dark matter is producing brightness anomalies in distant quasars.
But since dark matter candidates are not mutually exclusive, WIMPs could still well exist, and the recent research team suspects WIMPs are at the heart of theoretical dark stars. The idea is that WIMPs at the cores of dark stars collide, annihilating one another and releasing heat energy. That heat is released into hydrogen gas, making the objects shine brightly.
“Discovering a new type of star is pretty interesting all by itself, but discovering it’s dark matter that’s powering this—that would be huge,” said Katherine Freese, an astrophysicist at the University of Texas at Austin and the study’s co-author, in a university release. “If some of these objects that look like early galaxies are actually dark stars, the simulations of galaxy formation agree better with observations.”
Dark stars were first proposed in 2008, but only now is the Webb Space Telescope offering clear views of some of the most ancient light we can see. The theorized stars would be cool, puffy, and up to ten billion times the luminosity of the Sun, according to the research team.
Zany structures in space are described by astrophysicists from time to time, to provide mathematically described solutions for aspects of astrophysics that don’t completely make sense under the Standard Model of Cosmology. (The same could be said for different dark matter candidates, like axions, which were concocted to explain problems with the Standard Model of Particle Physics.)
Earlier this year, a team of physicists described a topological soliton, which would look like a black hole due to its gravitational effects but would still emit light. Boson stars and gravastars are examples of other objects that have been proposed mathematically but never observed.
In the same way, known objects are considered possible venues of dark matter production. In 2021, a team of astrophysicists suggested that axions may be produced at the cores of neutron stars, some of the universe’s densest objects. You can think of dark stars in the reverse: instead of their centers being factories for dark matter particles, they’re venues for their destruction.
The research team believes that dark stars could be misconstrued as large galaxies, and that the stars may seed the supermassive black holes seen even in the universe’s early days—which is to say, the first few hundred million years of its existence.
Some of those supermassive black holes may also be at play in the gravitational wave background, which astrophysicists saw the first signs of last month. As supermassive black holes orbit one another on the scale of hundreds of millions of years, they cause almost imperceptible ripples in spacetime that bounce through the cosmos.
More observations with Webb will give astrophysicists a better look at those ancient sources of light; be they galaxies or stars powered by dark matter, we hopefully won’t be kept in the dark much longer.
|
Cosmology & The Universe
|
The static speed of light assures that astronomers see faraway galaxies not as they are, but as they existed long ago. The same is true about the matter (regular or dark) that surrounds these ancient galaxies.Astronomers recently used this knowledge — as well as a cosmic signal sent out shortly after the Big Bang — to map how dark matter was distributed around galaxies some 12 billion years ago. In short, they found the dark matter was less 'clumpy' than expected, which, if confirmed, would suggest that many accepted models of cosmology are due for revisal.The new findings are presented in a study published Aug. 1 in Physical Review Letters.Back to the BeginningsThough it’s tricky to measure “invisible” matter, the typical approach involves two galaxies, one in the foreground and one in the background. According to Einstein, the immense gravity of the foreground galaxy actually warps the fabric of space-time near it. Thus, as light from the background galaxy travels past the foreground galaxy, it gets bent, as if by an optical lens. This results in the background galaxy being both heavily distorted and magnified, a phenomenon called gravitational lensing.Because the background galaxy (or “source galaxy") appears more heavily distorted when the foreground galaxy ("lens galaxy") has a lot of mass, astronomers can analyze the distortions to determine the distribution of matter — including dark matter — around the lens galaxy.Gravitational lensing occurs when light from a distant object is bent around intervening matter, such as a galaxy cluster. The result is a magnified, distorted image of the background object. (Credit: NASA/ESA)But this method only works when the source galaxy is bright enough to actually shed light on the lens galaxy. And because extremely distant galaxies are extremely faint, astronomers have so far been unable to assess dark matter in galaxies from before around 8 billion to 10 billion years ago. This has left them largely in the dark about the true structure of the early universe.Aiming to overcome this obstacle, a team of astronomers recently altered the approach. Instead of using two galaxies, they opted to use a more distant light source in place of a source galaxy: the cosmic microwave background (CMB), emitted when the universe was just 300,000 years old.“It was a crazy idea,” Masami Ouchi, a study author and astronomer at the University of Tokyo, says in a press release. “No one realized we could do this.”“Most researchers use source galaxies to measure dark matter distribution from the present to 8 billion years ago,” adds Yuichi Harikane, a study author and astronomer at the University of Tokyo. “However, we could look further back into the past because we used the more distant CMB to measure dark matter. For the first time, we were measuring dark matter from almost the earliest moments of the universe.”Illuminating Dark MatterTo employ their new approach, the astronomers selected 1.5 million galaxies — all seen as they were about 12 billion years ago — to collectively serve as the gravitational lens. And with the more distant CMB serving as the background source light, the team was able to measure how dark matter was dispersed around these lens galaxies.“I was happy that we opened a new window into that era,” says Hironao Miyatake, another study author and astronomer at Nagoya University, in a press release. "12 billion years ago, things were very different.”According to the team, their results could challenge prevalent theories of cosmology, including the idea that tiny variances in the CMB are what initially led to the earliest clumps of matter, which ultimately formed into stars and galaxies. As it turns out, the team says, the universe was much more homogeneous in its early years than previously thought.“Our finding is still uncertain,” Miyatake says in a press release. “But if it is true, it would suggest that the entire model is flawed as you go further back in time. This is exciting because if the result holds after the uncertainties are reduced, it could suggest an improvement of the model that may provide insight into the nature of dark matter itself.”Ultimately, the team says that their approach will provide astronomers with more accurate measurements of the amount and distribution of dark matter in ancient galaxies. It will also enable astronomers to explore other aspects of the early universe.“One of the strengths of looking at the universe using large-scale surveys, such as the ones used in this research, is that you can study everything that you see in the resulting images, from nearby asteroids in our solar system to the most distant galaxies from the early universe,” says Michael Strauss, a professor of astrophysical sciences at Princeton University who was not involved in the research, in a press release. "You can use the same data to explore a lot of new questions."
|
Cosmology & The Universe
|
NASA and its partners, the European and Canadian space agencies, will unveil the first full-color images from the Webb telescope in a much-anticipated event on July 12. Artist conception of the James Webb Space Telescope.Adriana Manrique Gutierrez / NASA GSFC/CIL fileJune 29, 2022, 7:10 PM UTCThe first images from NASA's next-generation James Webb Space Telescope are set to be released next month and will include the deepest view of the universe ever taken, agency officials confirmed Wednesday.NASA and its partners, the European Space Agency and the Canadian Space Agency, will unveil the initial batch of full-color images from the Webb telescope in a much-anticipated event on July 12. The $10 billion observatory is humanity's largest and most powerful space telescope, and experts have said it could revolutionize our understanding of the cosmos.Thomas Zurbuchen, associate administrator of NASA's Science Mission Directorate, said that seeing the first images from the Webb telescope will be an emotional milestone for humanity — a moment he described as witnessing nature "giving up secrets that have been there for many, many decades, centuries, millennia.""It's not an image. It's a new worldview," Zurbuchen said Wednesday in a news briefing.The release will be streamed live by NASA at 10:30am EDT. In addition to the deepest infrared view yet captured of the universe, NASA officials said they will release the Webb telescope's first spectrum of an exoplanet, showing light emitted at different wavelengths from a planet in another star system. These images could offer new insights into the atmospheres and chemical makeup of other exoplanets in the cosmos.Other images included in the inaugural release will be photos showing how galaxies interact and grow, and ones depicting the life cycle of stars, from the emergence of new ones to violent stellar deaths.The Webb telescope will continue to beam back data in the lead-up to the July 12 event, but NASA Deputy Administrator Pam Melroy described being impressed with what she has seen so far."I could not contain myself," Melroy said of the initial images. "What I have seen just moved me as a scientist, as an engineer and as a human being."The Webb telescope launched into space on Dec. 25, 2021. The tennis-court-sized observatory is able to peer deeper into the cosmos and in greater detail than any telescope that has come before it.NASA has spent the past six months configuring the observatory in orbit and testing its various scientific instruments. Agency officials said the telescope is performing better than expected and has enough fuel onboard to operate for 20 years.NASA Administrator Bill Nelson, who participated in Wednesday's briefing virtually because he tested positive for Covid-19, said scientists are only beginning to understand what the Webb telescope can and will do."It's going to explore objects in the solar system and atmospheres of exoplanets orbiting other stars, giving us clues as to whether potentially their atmospheres are similar to our own," he said. "It may answer some questions that we have: Where do we come from? What more is out there? Who are we? And, of course, it's going to answer some questions that we don't even know what the questions are. So in many ways, Webb's journey has only just begun."Denise Chow is a reporter for NBC News Science focused on general science and climate change.
|
Cosmology & The Universe
|
A new large survey of distant supernovae has made it possible to estimate the dark energy content of the universe and to calculate the rate of its expansion. However, these figures have not resolved, but only exacerbated, the old paradox of cosmology. They are even more inconsistent with similarly accurate results, but obtained from observations of the relic background.To estimate cosmic distances, standard candlesticks, distant objects with precisely known luminosity, are used. These include, for example, Type Ia supernovae, which are associated with thermonuclear explosions of white dwarfs that have pulled too much matter from a nearby nearby star. For a brief time, such explosions can shine brighter than an entire galaxy and become visible at distances of billions of light-years. Since explosions occur when they reach a strictly defined mass, their true brightness is almost the same, and their visible brightness depends on the distance. This allows them to be used as standard candles.In the late 1990s, it was type Ia supernovae that allowed us to observe the accelerating expansion of our Universe. Since then, new observations have emerged that clarify the speed of this process. Several years ago, as part of the Pantheon survey, astrophysicists analyzed the luminosities of about a thousand distant supernovae. And now they have supplemented and expanded that data: the new Pantheon+ survey already included more than 1,500 supernovae at distances as far as 10.7 billion light-years. It has made it possible to once again estimate the rate of expansion of the Universe, its dark matter and energy content. The report of the work is published in The Astrophysical Journal.According to these estimates, 33.8 percent of our world is made up of gravitational matter, ordinary and dark matter. The remaining 66.2 percent is dark energy, a mysterious entity that has been linked to the expansion of the universe. The rate of this expansion is described by the Hubble constant, which astronomers have determined to be 45.6 miles per second per megaparsec. In other words, the near Universe is expanding at a rate of nearly 161,500 miles per hour for every megaparsec, which in turn is about 3.26 light-years. This is slightly more than past estimates from supernovae observations.Unfortunately, these figures have not resolved the well-known cosmological crisis associated with the Hubble constant. The problem is that data from different observations give markedly different results. In particular, studies of the microwave background of the Universe indicate lower values of the constant, 41.5 miles per second per megaparsec. The Pantheon+ results only exacerbated the gap between these values and those obtained from supernovae observations. Moreover, the deviation has reached the proverbial value of five sigmas (σ) – meaning that it is statistically reliable, and the chances of an accident do not exceed one in a million. The problem remains, requiring new models to explain this difference.
|
Cosmology & The Universe
|
There are probably 200 billion stars in the Milky Way, stretched across space in a disk shaped like a ninja’s throwing star. It’s so big that, traveling at the speed of light, it’d still take you 100,000 years to traverse it. But if you could find the ideal point in space to stare at these stars around the clock for, say, eight years, tracking their movements and studying their brightness with highly accurate astronomy tools, you’d have created a pretty good moving, living map of the galaxy.Since 2013, the European Space Agency’s Gaia probe has been doing just that. The mission’s latest result, Data Release 3, which came out two weeks ago, maps 1.8 billion stars in and around our galaxy—covering about 1 or 2 percent of all stellar objects in the Milky Way. It’s the most comprehensive star map humankind has ever made, and scientists are already using it to unlock new secrets about our galactic neighborhood.“As a survey of stars in our galaxy, it blows all other surveys out of the water,” says Conny Aerts, a stellar astrophysicist at Katholieke Universiteit Leuven and member of the Gaia consortium.The Gaia mission launched in 2013, but its history runs much deeper. Its predecessor, the Hipparcos mission, was launched in 1989 to measure the positions, distances, and motions of stars with unprecedented precision—a field called “astrometry” that the mission pioneered in space. Precision astrometry of the entire sky is difficult on Earth; before Hipparcos launched, there were fewer than 9,000 accurate “parallax” measurements of stars. (Parallax means that as Earth moves, nearby stars appear to shift in the sky, just as a lamppost appears to shift relative to the background hills as you cross the street. The amount of shift indicates how far away objects are.) Hipparcos increased the number of those measurements to 120,000 by the end of the mission in 1993.“But we knew we could do better, even while Hipparcos was working,” says Anthony Brown, an astronomer at the University of Leiden and the lead of Gaia’s data processing team. Gaia, a nearly $1 billion mission, was approved in 2000 as an upgrade, with two much larger 1.5-meter telescopes and 106 charge-coupled devices, or CCDs, sensitive photon detectors. (This instrumentation is relatively similar to the Hubble Space Telescope’s in that regard.) But unlike Hubble, which carries a range of heavy instrumentation that was designed to train its gaze on tiny areas of space, Gaia’s mission is expansive: Survey the whole sky and collect massive amounts of data.“Our problem understanding the Milky Way Galaxy is that we are in it,” says Timo Prusti, a stellar astronomer for the ESA and project scientist on the Gaia mission. “Say you want to know what shape a forest has. If you’re dropped into that forest, you’ll see lots of trees, but no shape, because you are inside the forest itself.”In 2014, Gaia arrived at the second Lagrange point, an ideal, quiet perch from which to stare at the galaxy. Then the craft, which is shaped a bit like a top hat with a shiny brim, started looking.Every six hours, with its back pointing toward our sun, Gaia scans a great circle of the sky, spinning at a steady, slow rate and taking in tiny pinpricks of light from distant stars. That light is captured by its two telescopes, CCDs, photometers, and a spectrometer to measure each star’s position, motion, distance, radial velocity, brightness, and color—details that can reveal everything from a star’s mass to its makeup. Over its 10-year mission, the craft will collect data an average of 140 times from each star and other objects it spies.After some initial hurdles—a “wobble” that impaired the craft’s precision instruments was eventually repaired using data processing and calibration—the Gaia team dropped its first data in 2016, representing parallax and “proper motion” measurements for 2 million stars. (Proper motion is the apparent movement of a star in the sky.) “There are so many more stars than astrophysicists to analyze them, in this case,” says Aerts. “So we decided to share this with the community to get the maximum out of the data.”Gaia’s second release in 2018 jumped to 1.6 billion objects, with 1.3 billion measurements of parallax distance and proper motion. It also collected the accurate brightnesses and colors of these stars. This allowed scientists to better understand each star’s temperature, luminosity, and more. The mission also collected the radial velocity of stars—which combined with “proper motion” data shows where each one is going and how fast—for 7 million objects.In 2020, the Gaia team released some of its third data dump early, but this month’s official release offered the finest set of details yet about our more than 1.8 billion stellar neighbors. This data set also includes information about 1.1 million quasars, super-bright active nuclei of galaxies outside our own, each so far away they appear to not move, making them wonderful waypoints for navigation. Gaia also stared at 158,000 asteroids in our own solar system; and even gathered data on millions of other galaxies in our local universe.“This is a classical star map, to be used as star maps always have been, as a reference—for other missions and telescopes,” says Brown. But it’s also dynamic. “By repeatedly making this star map, we can see stars change over time. That information is the third dimension of the map—not just how far away is the star, but how fast is it moving? Where is it going? Over the course of time, we combine the snapshots of that star map that Gaia is taking and combine these into 3D pictures.”That data has been beamed down nearly constantly to the ESA’s three Earth-bound stations (and occasionally NASA’s Deep Space Network). Data Release 3 alone is 41 terabytes. In fact, there is so much data that its results cannot be fully parsed for correctness by the Gaia team, who instead use AI tools and algorithms to compare it to existing surveys of well-known objects, then share it with the science community. Scientists simply download the data online—and can select a subset, down to a single star.“My studies would not be possible without the Gaia mission,” says Madeline Lucey, a graduate research fellow at the University of Texas who is using Data Release 3 to scour for some of the oldest stars in the galaxy. Lucey studies “stellar DNA,” or the composition of stars, which hints at their age and ancestry. The stars she’s focusing on are called “carbon-enhanced” because they have unusually large amounts of carbon but small amounts of other elements that aren’t hydrogen and helium. This suggests that they are a newer generation of stars, which were enriched by the carbon and other elements that blew away when the universe’s very earliest stars went supernova. Their composition and location gives us more insight into how the universe went from having only hydrogen and helium in the period immediately after the Big Bang to the full array of elements known today.“I’ve used previous Gaia data in all of my past work for studying the location and movement of stars, but this is the first time they’ve released spectra,” Lucey says. Using that data and a special algorithm, Lucey and her team have increased the known number of carbon-enhanced stars to more than 2 million.The Gaia science team also released new information on “starquakes.” These stellar vibrations are caused by intrinsic physical phenomena inside active stars, and make the massive balls of gas move up and down in a complex, periodic way. Just like earthquakes help scientists understand the physical properties inside our planet, starquakes can be studied to better understand the interior of stars.Even our own sun experiences these “starquakes,” though they are too small to study with Gaia. Other stars in our galaxy, though, have experienced quakes so strong they have caused the stars to “blink” in Gaia’s repeated photometry surveys: Their stellar gas expands farther away from their inner regions, cooling, then contracts, making it hotter and brighter. The new Gaia data showed that “some stars have quite big starquakes—causing their radius to change by as much as 10 percent,” Aerts says. These “non-radial” starquakes, during which stars do not keep their spherical symmetry, can be thought of as massive, gaseous tsunamis.Jason Hunt, an astrophysics research fellow at the Flatiron Institute, calls Gaia’s observations “a truly revolutionary data set.” Hunt’s research builds on the discovery by astrophysicist Teresa Antoja that plotting the vertical position of stars near our sun against their vertical motion reveals a beautiful pattern called the “Gaia phase spiral.” These spiral shapes “are telling us that the galaxy is not in equilibrium, and has been perturbed by something, probably a satellite galaxy such as the Sagittarius dwarf galaxy, which is currently merging into the Milky Way,” Hunt wrote by email. His new findings show that the inner galaxy has a two-armed spiral, suggesting a different perturbation than the one that affects the outer galaxy—perhaps this one originates from the Milky Way’s central bar, or spiral arms.Kareem El-Badry, a Harvard astrophysicist, used Gaia’s new data release to study the occurrence of binary stars, which orbit around another star or some other object. For single stars, Gaia’s spectrograph data shows a steady velocity—those stars are moving toward us or away from us at a constant rate. But binary stars have different velocities every time Gaia looks at them, due to their orbits. Before Gaia, scientists had only studied around 10,000 binary stars. Now, they have data for 200,000 of them, and El-Badry’s research shows how some might have transferred much of their mass to their partners, turning them into what he calls “a helium core with a thin hydrogen envelope.”The Gaia data is vital not just for research, but for spacecraft navigation. “The more precise the star catalog, the more precise our understanding of the position of the stars, the better we can use them for understanding where our spacecraft is in the solar system,” says Coralie Adam, a deep-space optical navigation engineer at KinetX Aerospace. Adam and her team are using Gaia data to navigate NASA’s Lucy mission to several Jupiter Trojan asteroids over the next decade. Gaia’s data could also help improve autonomous navigation in deep space—a challenge that’s on the horizon for many missions.The astrometry technique may also help the search for life outside the solar system. “Using astrometry to measure the masses of potentially habitable exoplanets could provide important info to aid a biosignatures search with a future ‘super-Hubble’ space telescope,” says Aki Roberge, a NASA research astrophysicist. Roberge should know: She’s a study scientist for the proposed LUVOIR exoplanet-hunting mission, a front-runner in the Astro2020 Decadal Survey.Data Release 3 is only a few weeks old, and it will likely yield many more discoveries; the Gaia team plans fourth and fifth data releases in coming years. But that will be Gaia’s last hurrah. The space telescope has enough fuel to power its micro-movements until around 2025, at which point it will be retired to an orbit around the sun. Its final celestial act will be to become a tiny heavenly body in the massive galaxy it has so studiously mapped.
|
Cosmology & The Universe
|
image: Argonne Distinguished Fellow Esen Ercan Alp, right, and physicist and group leader Jiyong Zhao, left, at APS Beamline 3-ID-B, where scientists measured the composition of fragments of a near-Earth asteroid. view more Credit: (Image by Jason Creps/Argonne National Laboratory.) A year ago, scientists got their first look at material gathered from nearby asteroid 162173 Ryugu. Now the results of those studies have been revealed, and they shed light on the history of our solar system and the long trek of this cosmic wanderer. At its closest orbit, asteroid 162173 Ryugu is only about 60,000 miles from Earth. That’s only a quarter of the distance to the moon. But according to newly released results from an international team of scientists, this hunk of rock began its cosmic journey more than 4 billion years ago, and billions of miles away, in the outer part of our solar system. It traveled to us across space, taking in the history of this corner of the universe in the process. These revelations are only part of the results of a global effort to study samples from the surface of Ryugu. These specks of asteroid dust were carefully collected and transported back to Earth by Hayabusa 2, a mission operated by the Japanese space agency JAXA, and then sent to institutions around the world. Scientists put these tiny fragments through dozens of experiments to tease out their secrets, to determine what they are made of and how the asteroid they came from may have been formed. “For planetary scientists, this is first-degree information coming directly from the solar system, and hence it is invaluable.” — Esen Ercan Alp, Argonne Distinguished Fellow The resulting paper, recently published in Science, includes authors from more than 100 institutions in 11 countries. Numbered among them is the U.S. Department of Energy’s (DOE) Argonne National Laboratory, home to the Advanced Photon Source (APS), a DOE Office of Science user facility. The APS generates ultrabright X-ray beams that can be used to determine the chemical and structural makeup of samples atom by atom. Argonne Distinguished Fellow Esen Ercan Alp led the research team at Argonne, which includes physicist and group leader Jiyong Zhao and physicist Michael Hu, and beamline scientist Barbara Lavina of both Argonne and the University of Chicago. All are co-authors on the paper. Alp and his team worked for years to be included in this study. The key contribution of the APS, Alp said, is a particular X-ray technique he and his team specialize in. It’s called Mössbauer spectroscopy — named after German physicist Rudolf Mössbauer — and it is highly sensitive to tiny changes in the chemistry of samples. This technique allowed Alp and his team to determine the chemical composition of these fragments particle by particle. What they and their international colleagues found was surprising, Alp said. “There is enough evidence that Ryugu started in the outer solar system,” he said. “Asteroids found in the outer reaches of the solar system would have different characteristics than those found closer to the sun.” The APS, Alp said, found several pieces of evidence to support this hypothesis. For one, the grains that make up the asteroid are much finer than you would expect if it was formed at higher temperatures. For another, the structure of the fragments is porous, which means it once held water and ice. Lower temperatures and ice are much more common in the outer solar system, Alp said. The Ryugu fragments are very small — ranging from 400 microns, or the size of six human hairs, to 1 millimeter in diameter. But the X-ray beam used at beamline 3-ID-B can be focused down to 15 microns. The team was able to take several measurements on each of the fragments. They found the same porous, fine-grained structure across the samples. With the APS’s finely tuned spectroscopy capabilities, the team was able to measure the amount of oxidation that the samples had undergone. This was especially interesting since the fragments themselves had never been exposed to oxygen — they were delivered in vacuum-sealed containers, in pristine condition from their trip across space. While the APS team did find a chemical makeup similar to meteorites that have hit the Earth — specifically a group of them called CI chondrites, of which only nine are known to exist on the planet — they did discover something that set the Ryugu fragments apart. The spectroscopy measurements found a large amount of pyrrhotite, an iron sulfide that is nowhere to be found in the dozen meteorite samples the team also studied, courtesy of French collaborators Mathieu Roskoz (National Museum of Natural History) and Pierre Beck (Universite Grenoble Alpes). This result also helps scientists put a limit on the temperature and location of Ryugu’s parent asteroid at the time it was formed. “Our results and those from other teams show that these asteroid samples are different from meteorites, particularly because meteorites have been through fiery atmosphere entry, weatherization and in particular oxidation on Earth,” said Hu. “This is exciting because it’s a completely different kind of sample, from way out in the solar system.” With all of the data combined, the paper lays out the multi-billion-year history of 162173 Ryugu. It was once part of a much larger asteroid which formed about 2 million years after the solar system did — roughly 4.5 billion years ago. It was made of many different materials, including water and carbon dioxide ice, and over the next three million years, the ice melted. This led to an interior that was hydrated and surface that was dryer. About a billion years ago, another chunk of space rock collided with this asteroid, breaking it apart and sending debris flying, and some of those fragments coalesced into the Ryugu asteroid we know today. “For planetary scientists, this is first-degree information coming directly from the solar system, and hence it is invaluable,” Alp said. The Argonne team plans their own paper, going into detail about their X-ray techniques and results. But being part of such a large, multi national scientific effort was thrilling, they said, and they look forward to being part of future experiments of this type. “This was an exciting and challenging experience for us to participate in such a well-coordinated international research project.” Zhao said. “With an upgrade to the APS in the works that will deliver even brighter X-ray beams, we are anticipating studying more materials like this, from far-flung asteroids and planets.” This project was funded in part by a grant from France and Chicago Collaborating in the Sciences (FACCTS), administered by the University of Chicago. About the Advanced Photon Source The U. S. Department of Energy Office of Science’s Advanced Photon Source (APS) at Argonne National Laboratory is one of the world’s most productive X-ray light source facilities. The APS provides high-brightness X-ray beams to a diverse community of researchers in materials science, chemistry, condensed matter physics, the life and environmental sciences, and applied research. These X-rays are ideally suited for explorations of materials and biological structures; elemental distribution; chemical, magnetic, electronic states; and a wide range of technologically important engineering systems from batteries to fuel injector sprays, all of which are the foundations of our nation’s economic, technological, and physical well-being. Each year, more than 5,000 researchers use the APS to produce over 2,000 publications detailing impactful discoveries, and solve more vital biological protein structures than users of any other X-ray light source research facility. APS scientists and engineers innovate technology that is at the heart of advancing accelerator and light-source operations. This includes the insertion devices that produce extreme-brightness X-rays prized by researchers, lenses that focus the X-rays down to a few nanometers, instrumentation that maximizes the way the X-rays interact with samples being studied, and software that gathers and manages the massive quantity of data resulting from discovery research at the APS. This research used resources of the Advanced Photon Source, a U.S. DOE Office of Science User Facility operated for the DOE Office of Science by Argonne National Laboratory under Contract No. DE-AC02-06CH11357. Argonne National Laboratory seeks solutions to pressing national problems in science and technology. The nation’s first national laboratory, Argonne conducts leading-edge basic and applied scientific research in virtually every scientific discipline. Argonne researchers work closely with researchers from hundreds of companies, universities, and federal, state and municipal agencies to help them solve their specific problems, advance America’s scientific leadership and prepare the nation for a better future. With employees from more than 60 nations, Argonne is managed by UChicago Argonne, LLC for the U.S. Department of Energy’s Office of Science. The U.S. Department of Energy’s Office of Science is the single largest supporter of basic research in the physical sciences in the United States and is working to address some of the most pressing challenges of our time. For more information, visit https://energy.gov/science. Article Title Formation and evolution of carbonaceous asteroid Ryugu: Direct evidence from returned samples Article Publication Date 22-Sep-2022 Disclaimer: AAAS and EurekAlert! are not responsible for the accuracy of news releases posted to EurekAlert! by contributing institutions or for the use of any information through the EurekAlert system.
|
Cosmology & The Universe
|
How do you map the universe? Explorers once understood Earth by mapping what they saw. If I only included visible objects in my map of the universe, it would show a mere four percent of the cosmos. Equipped with Einstein’s theory of general relativity, I use gravity to see how invisible “dark matter” bends light from stars and galaxies. This provides a remarkably detailed picture of the structure of the universe. Is dark matter real? Scientists know a lot about how dark matter is distributed in the universe and the critical role it plays in the formation of galaxies. Dark matter is mysterious because it lacks much personality—it interacts very weakly with ordinary matter (like you), it moves sluggishly, and it accumulates in lumps. You are right to be skeptical—the history of science is replete with abandoned invisible explanations (ether, miasma, and phlogiston)—but there is much evidence that dark matter is real. Could a figure like Einstein exist today? No and yes. Many fields are so specialized that it is hard to imagine one person making an Einsteinian impact. That said, the Internet makes it much easier for an outsider to garner the attention of the scientific establishment. Of course she would still need transformative, innovative, and radical ideas. Where will we find the next radical scientific ideas? We now have copious data in cosmology, neuroscience, genetics, and material science. Finding and comprehending meaningful patterns in that data will allow us to mine for fundamental principles and new frontiers for exploration. This is how I think we are going to find the next radical idea that could upend everything! --This text refers to an alternate kindle_edition edition. [An] insightful overview of the hottest topics in astronomy today.-- "Marcia Bartusiak, author of Black Hole"A highly readable, insider's view of recent discoveries in astronomy.-- "Alan Lightman, New York Times bestselling author"An authoritative guide to the major cosmological breakthroughs of the past century.-- "Owen Gingerich, Harvard-Smithsonian Center for Astrophysics"Fascinating...shows that our current knowledge of our universe keeps on expanding month to month...A beautiful book.-- "Deepak Chopra, New York Times bestselling author"Listeners will be mesmerized by this audiobook as it unfolds its little-known cosmological booty. Using pacing, expression, and a confident tone, narrator Elisabeth Rodgers gives a flawless performance...It's a spellbinding listen with a super guide. Winner of AudioFile Earphones Award.-- "AudioFile"Natarajan bring a philosophical and well-informed historical depth to [her topic], consistently tying them in the theme of her passion for mapping...She deals with subjects that are extremely complex but makes them very clear, and the book is packed with well-researched facts.-- "BBC"Part history, part science, all illuminating. If you want to understand the greatest ideas that shaped our current cosmic cartography, read this book.-- "Adam G. Riess, Nobel Laureate in physics, 2011"The human view of the universe has changed radically over the last century, and this accessible work from Natarajan, professor of astronomy and physics at Yale, highlights those changes as well as the personalities-and the battles-behind them...By introducing the major players behind each discovery, Natarajan adds a lively human touch to her discussion, reinforcing the dynamism of a field that 'fans human curiosity and is driven by it as well.'-- "Publishers Weekly (starred review)"This excellent book describes the boisterous debates and hard slog whereby our current understanding of the cosmos has emerged. It's especially welcome as a faithful portrayal of how science is actually done.-- "Martin Rees, author of Just Six Numbers" --This text refers to the audioCD edition.
|
Cosmology & The Universe
|
Scientists using the H.E.S.S. observatory in Namibia have detected the highest energy gamma rays ever from a dead star called a pulsar. Phys.Org reports: The energy of these gamma rays clocked in at 20 tera-electronvolts, or about 10 trillion times the energy of visible light. This observation is hard to reconcile with the theory of the production of such pulsed gamma rays, as the international team reports in the journal Nature Astronomy. [...] The Vela pulsar, located in the Southern sky in the constellation Vela (sail of the ship), is the brightest pulsar in the radio band of the electromagnetic spectrum and the brightest persistent source of cosmic gamma rays in the giga-electronvolts (GeV) range. It rotates about eleven times per second. However, above a few GeV, its radiation ends abruptly, presumably because the electrons reach the end of the pulsar's magnetosphere and escape from it. But this is not the end of the story: using deep observations with H.E.S.S., a new radiation component at even higher energies has now been discovered, with energies of up to tens of tera-electronvolts (TeV).
"That is about 200 times more energetic than all radiation ever detected before from this object," says co-author Christo Venter from the North-West University in South Africa. This very high-energy component appears at the same phase intervals as the one observed in the GeV range. However, to attain these energies, the electrons might have to travel even farther than the magnetosphere, yet the rotational emission pattern needs to remain intact. "This result challenges our previous knowledge of pulsars and requires a rethinking of how these natural accelerators work," says Arache Djannati-Atai from the Astroparticle & Cosmology (APC) laboratory in France, who led the research. "The traditional scheme according to which particles are accelerated along magnetic field lines within or slightly outside the magnetosphere cannot sufficiently explain our observations. Perhaps we are witnessing the acceleration of particles through the so-called magnetic reconnection process beyond the light cylinder, which still somehow preserves the rotational pattern? But even this scenario faces difficulties to explain how such extreme radiation is produced."
Whatever the explanation, next to its other superlatives, the Vela pulsar now officially holds the record as the pulsar with the highest-energy gamma rays discovered to date. "This discovery opens a new observation window for detection of other pulsars in the tens of teraelectronvolt range with current and upcoming more sensitive gamma-ray telescopes, hence paving the way for a better understanding of the extreme acceleration processes in highly magnetized astrophysical objects," says Djannati-Atai.
"That is about 200 times more energetic than all radiation ever detected before from this object," says co-author Christo Venter from the North-West University in South Africa. This very high-energy component appears at the same phase intervals as the one observed in the GeV range. However, to attain these energies, the electrons might have to travel even farther than the magnetosphere, yet the rotational emission pattern needs to remain intact. "This result challenges our previous knowledge of pulsars and requires a rethinking of how these natural accelerators work," says Arache Djannati-Atai from the Astroparticle & Cosmology (APC) laboratory in France, who led the research. "The traditional scheme according to which particles are accelerated along magnetic field lines within or slightly outside the magnetosphere cannot sufficiently explain our observations. Perhaps we are witnessing the acceleration of particles through the so-called magnetic reconnection process beyond the light cylinder, which still somehow preserves the rotational pattern? But even this scenario faces difficulties to explain how such extreme radiation is produced."
Whatever the explanation, next to its other superlatives, the Vela pulsar now officially holds the record as the pulsar with the highest-energy gamma rays discovered to date. "This discovery opens a new observation window for detection of other pulsars in the tens of teraelectronvolt range with current and upcoming more sensitive gamma-ray telescopes, hence paving the way for a better understanding of the extreme acceleration processes in highly magnetized astrophysical objects," says Djannati-Atai.
|
Cosmology & The Universe
|
There’s something strange going on with the Milky Way. Recent measurements suggest that stars at the outskirts of our galaxy are misbehaving. They’re traveling far slower than similarly situated stars in other galaxies. One possible explanation for the Milky Way’s stellar slowpokes is that our galaxy is extraordinarily deficient in dark matter, the invisible substance thought to serve as gravitational scaffolding for cosmic structures. Another is that our core conceptions about dark matter—such as how much of it exists in the universe—are somehow deeply flawed.
This head-scratcher stems from the European Space Agency’s Gaia satellite, which provides unparalleled information on the speeds and positions of nearly two billion stars in the Milky Way. Last year the Gaia team released the space-based telescope’s most precise measurements yet, spurring astronomers to refresh their galaxy-spanning assessments of stellar behavior. Several independent groups have now reported the oddly sluggish orbits of stars along the Milky Way’s outer rim, the peripheral edge of our galaxy’s luminous whorl.
Stellar speeds offer a way to weigh a galaxy; the gravitational force each particular star feels depends on the galaxy’s total mass. A Gaia-derived study released on September 27 in the journal Astronomy & Astrophysics pegged the combined mass of our galaxy’s gas, dust, stars and dark matter at some 200 billion times that of our sun—hefty for you and me but on the order of five times less than that found in several other earlier assessments. Because the Milky Way’s visible material hasn’t disappeared, one easy—and especially thought-provoking—way to explain this result is that far less dark matter is floating around than previously believed.
Then again, weighing a galaxy is a notoriously tricky business, so it’s possible that errors lurk in Gaia’s data or the new analyses that create the illusion of the Milky Way as anomalously trim. But the fact that multiple teams have seen the same result gives more substance to the findings. If true, they could force a rethink of fundamental physics and prompt a reexamination of all other galaxies in the universe.
“Let me put it this way,” says Stacy McGaugh, an astronomer at Case Western Reserve University, who wasn’t involved in any of the recent studies. “If it worked out that way, it would be revolutionary.”
In the 1970s astronomer Vera Rubin and her colleagues began measuring stellar motions in other galaxies. Stars around a galaxy’s periphery were expected to orbit at a more leisurely pace than those closer in, much like how Neptune meanders around our sun every 165 years while Mercury zips about in 88 days. Yet, strangely, Rubin and her associates found that outlying stars were traveling at roughly the same rate as their more central siblings, suggesting that an enormous reservoir of hidden material in and around each galaxy was gravitationally tugging on the far-out stars to boost their speeds. This invisible stuff, already then called dark matter, was surmised to form immense halos surrounding galaxies, outweighing the visible material by a factor of 10 for large galaxies and as much as 100-fold for dwarf galaxies.
Measuring how everything in our galaxy moves while stuck inside of it is not the easiest task. So astronomers have tended to assume that stars in the Milky Way behave much like those seen in other galaxies. The sun, located roughly 26,000 light-years from the galactic center, orbits around it at about 500,000 miles per hour (800,000 kilometers per hour), and most observations of other stars within and beyond the Milky Way have supported the idea that stellar speeds farther out should be broadly consistent with that of our home star.
The Gaia satellite, which was launched in 2013, offers the best-yet test of this simple notion via the spacecraft’s extraordinarily precise measurements of the three-dimensional positions and motions of stars in the Milky Way. But this testing has been a gradual process because the precision of Gaia’s reckoning improves in lockstep with how long it observes its stellar sample. Using Gaia, theoretical physicist Francesco Sylos Labini of the Enrico Fermi Study and Research Center in Italy and his associates saw subtle hints of a decline in the Milky Way’s stellar speeds a few years ago. Those hints became much more obvious in Gaia’s most recent data release, from 2022, which pegs stellar motions with twice the precision of a previous offering from 2018. Such improvements allow astronomers to plot the paths of stars with greater accuracy and out to much farther distances than before.
This year alone, four different papers have revealed a precipitous decline in the speeds of stars out to 100,000 light-years from the Milky Way’s center. The recent Astronomy & Astrophysics study refers to this falloff as “Keplerian,” meaning it is like that seen in the planets in our solar system, whose motions were first accurately described by 17th-century German astronomer Johannes Kepler.
Such a finding flies in the face of all expectations. Minus a few minor deviations, plots of stellar orbits in other galaxies consistently show stars from center to rim all whirling with similar speed, as if held in dark matter’s gravitational grip. “But for the moment—and this is what is very interesting—we do not find any other galaxies showing this Keplerian decline,” says François Hammer of the Paris Observatory, a co-author of the recent Astronomy & Astrophysics study.
In a broad sense, the idea that the Milky Way is unique among all galaxies contradicts a basic tenet of cosmology, which holds that there’s nothing special about any particular place in the universe. The findings create more specific headaches because of the extrapolated lower mass estimate of 200 billion suns for our galaxy. Astronomers are quite confident in their measurements for the visible material in the Milky Way, which amount to a mass of circa 60 billion suns. If both figures are correct, this implies that the dark-to-ordinary matter ratio is just 2.3 to 1—far less than the 10:1 ratio found in galaxies of similar size.
Given that the perception of a downsized Milky Way emerges from several independent analyses, some researchers believe that while the decline may be genuine, it’s not representative of our galaxy as a whole. Stars even farther out and currently beyond the limits of Gaia’s high-precision scrutiny may well display a corresponding rise in speeds to offset the anomalous dip. “I’d be very surprised if it just keeps going because then there’ll be a lot of things that break all at once,” says astrophysicist Lina Necib of the Massachusetts Institute of Technology, a co-author of one of the other papers on the decline in stellar speeds, which was posted on the preprint server arXiv.org.
Her idea is backed by multiple lines of evidence. The Large Magellanic Cloud, which sits around 160,000 light-years from the galactic center, is a satellite galaxy that orbits our own at more than 650,000 mph (one million kilometers per hour)—a value consistent with standard dark matter models. Another line of evidence comes from stellar streams—remnants of small galaxies and star clusters that got too close to the Milky Way and were shredded by its gravity. These stellar streams arc out to great distances and provide estimates of our galaxy’s mass that line up with the weightier approximations.
There’s also the possibility that these different teams are inadvertently misinterpreting their data in some way. At the University of Pennsylvania, astronomer Robyn Sanderson makes simulated Milky Ways on a computer and then imagines what sorts of maps a virtual Gaia satellite would see if placed inside them. Any such plot requires certain assumptions that affect its results, she says, such as the overall shape of the galaxy’s distribution of dark matter. “My group has looked at how those overly simplistic assumptions—which everybody knows are overly simplistic—lead to a strange result where the model still describes the data but doesn’t necessarily correspond with the realities of the underlying system,” she says.
Sanderson, who wasn’t involved in any of the papers, is skeptical of drawing firm conclusions from them. She points out that while Gaia provides unrivaled 3-D information, the uncertainties on its stellar-speed measurements grow the farther out in the galaxy it looks.
Future data from facilities such as the Vera C. Rubin Observatory (originally called the Large Synoptic Survey Telescope and renamed in 2019) will hopefully be able to find stars in the outer parts of the Milky Way that can help settle the debate. Gaia’s next release, expected at the end of 2025, could also provide more accurate information. Hammer is eager to more closely examine other galaxies and see if their stellar speeds might also show declines similar to the Milky Way’s.
For McGaugh, the episode represents part of a normal, healthy churn expected from any mature research community. “It’s going to take a while to settle out, but I think we’ll learn things in the process,” he says. Necib agrees and says she finds the current debate more exciting than troubling. “Yeah, it’s weird,” she says, “which honestly makes for cool science. I love when things are weird.”
|
Cosmology & The Universe
|
Scientists may finally know what made the largest explosion in the universe ever seen by humankind so powerful.
Astronomers have discovered that the brightest gamma-ray burst (GRB) ever seen had a unique jet structure and was dragging an unusually large amount of stellar material along with it.
This might explain the extreme properties of the burst, believed to have been launched when a massive star located around 2.4 billion light-years from Earth in the direction of the constellation Sagitta underwent total gravitational collapse to birth a black hole, as well as why its afterglow persisted for so long.
The GRB officially designated GRB 221009A but nicknamed the BOAT, or the brightest of all time, was spotted on October 9, 2022, and stood out from other GRBs due to its extreme nature. It was seen as an immensely bright flash of high-energy gamma-rays, followed by a low-fading afterglow across many wavelengths of light.
"GRB 221009A represents a massive step forward in our understanding of gamma-ray bursts and demonstrates that the most extreme explosions do not obey the standard physics assumed for garden variety gamma-ray bursts," George Washington University researcher and study lead author Brendan O'Connor said in a statement. O'Connor led a team that continued to monitor the BOAT GRB with the Gemini South Telescope in Chile following its initial discovery in Oct 2023.
Northwestern University doctoral candidate Jillian Rastinejad, who was also part of a team that observed the BOAT on Oct. 14 after its initial discovery, told Live Science that GRB 221009A is thought to be brighter than other highly energetic GRBs by a factor of at least 10.
"Photons have been detected from this GRB that has more energy than the Large Hadron Collider (LHC) produces," she said.
Even before the BOAT was spotted, GRBs were already considered the most powerful, violent, and energetic explosions in the universe, capable of blasting out as much energy in a matter of seconds as the sun will produce over its entire around ten billion-year lifetime. There are two types of these blasts, long-duration, and short-duration, which might have different launch mechanisms, both resulting in the creation of a black hole.
Further examination of the powerful GRB has revealed that it is unique for its structure as well as its brightness. The GRB was surprisingly wide. So wide, in fact, that astronomers were initially unable to see its edges.
"Our work clearly shows that the GRB had a unique structure, with observations gradually revealing a narrow jet embedded within a wider gas outflow where an isolated jet would normally be expected," co-author and Department of Physics at the University of Bath scientist Hendrik Van Eerten said in a statement.
Thus, the jet of GRB 221009A appears to possess both wide and narrow "wings" that differentiate it from the jets of other GRBs. This could explain why the afterglow of the BOAT continued to be seen by astronomers in multiple wavelengths for months after its initial discovery.
Van Eerten and the team have a theory as to what gives the jet of the BOAT its unique structure.
"GRB jets need to go through the collapsing star in which they are formed," he said. "What we think made the difference in this case was the amount of mixing that happened between the stellar material and the jet, such that shock-heated gas kept appearing in our line of sight all the way up to the point that any characteristic jet signature would have been lost in the overall emission from the afterglow."
Van Eerten also points out the findings could help understand not just the BOAT but also other incredibly bright GRBs.
"GRB 221009A might be the equivalent of the Rosetta stone of long GRBs, forcing us to revise our standard theories of how relativistic outflows are formed in collapsing massive stars," O'Connor added.
The discovery will potentially lay the foundation for future research into GRBs as scientists attempt to unlock the mysteries still surrounding these powerful bursts of energy. The findings could also help physicists better model the structure of GRB jets.
"For a long time, we have thought about jets as being shaped like ice cream cones," study co-author and George Washington University associate professor of physics Alexander van der Horst said. "However, some gamma-ray bursts in recent years, and in particular the work presented here, show that we need more complex models and detailed computer simulations of gamma-ray burst jets."
The team's research is detailed in a paper published in the journal Science Advances.
Originally posted on Space.com.
Live Science newsletter
Stay up to date on the latest science news by signing up for our Essentials newsletter.
Robert Lea is a science journalist in the U.K. who specializes in science, space, physics, astronomy, astrophysics, cosmology, quantum mechanics and technology. Rob's articles have been published in Physics World, New Scientist, Astronomy Magazine, All About Space and ZME Science. He also writes about science communication for Elsevier and the European Journal of Physics. Rob holds a bachelor of science degree in physics and astronomy from the U.K.’s Open University
|
Cosmology & The Universe
|
Astronaut Mike Massimino Webb Telescope More Than Pretty Pics ... Might Show Birth of the Universe!!! 7/12/2022 2:56 PM PT TMZ.com NASA's very high hopes for the James Webb Telescope go way beyond those stunning, out-of-this-world images you've seen -- astronaut Mike Massimino says it could literally redefine the universe for us. Mike joined TMZ live Tuesday, shortly after NASA released even more impressive photos of galaxies and stars forming billions of light-years away from Earth. He says scientists hope the telescope will achieve 2 major goals. NASA The first is trying to look back into stellar history as far as possible -- about 13.8 billion years ago -- to see the very first light created at the moment of the Big Bang!!! Meaning, it would no longer just be theory. Mind-blowing, right??? Mike says the J-dub Telescope could also help us find other habitable planets. Now, he says there's no need to pack your bags -- we won't be able to hop on one of Elon Musk's rockets to get there, even IF we find such a planet. As we've told you, NASA released 4 new shockingly clear space images Tuesday, after unveiling an initial image on Monday ... which the space agency called "the deepest, sharpest infrared image of the universe ever." Waiting for your permission to load the Instagram Media. As for the whole Big Bang Theory (actual science, not a TV sitcom) ... we had to ask Mike how the telescope's findings might challenge some people's view of religion. Having been in space himself, he had a very interesting take on that huge question.
|
Cosmology & The Universe
|
- JWST spotted ten galaxies connected by an invisible cosmic filament.
- The filament, which is millions of light years long, is the earliest ever seen.
- Its discovery could shed light on how our universe formed and the invisible strings that hold it together.
NASA's James Webb Telescope has spotted a string of ancient galaxies connected by a cosmic filament dating back to the early days of the universe.
This is the earliest filament ever seen of the so-called "cosmic web," a mysterious network that connects the galaxies in our universe.
The filament is thought to be about three million light-years long. That is billions of times the distance from Earth to Mars.
Its discovery could shed light on how our universe formed and the invisible strings that hold it together.
"I was surprised by how long and how narrow this filament is," said Xiaohui Fan of the University of Arizona and a member of the ASPIRE consortium of researchers who made the discovery, in a press release about the finding.
"I expected to find something, but I didn't expect such a long, distinctly thin structure."
Galaxies are connected by a cosmic web
Looking at pictures of the universe, it could be tempting to think that galaxies appear randomly out of nothing.
But over the past 20 years, research has uncovered the universe is built on a sort of scaffolding, a series of filaments and clumps invisible to the naked eye.
In these clumps, dark matter and regular matter become very dense, creating the perfect conditions for the birth of stars and galaxies.
Between these clumps and filaments are "very low-density regions of the universe where there are very few galaxies and less matter," Niall Jeffrey, a cosmologist at University College London, previously told the Guardian.
Peering back into the early stages of the universe can give us a sense of how galaxies appeared within this mysterious network.
Earliest filament ever seen
The filament appeared about 830 million years after the Big Bang, very early on considering the universe is about 13 billion years old.
While the filament itself is invisible, it's possible to see how it brings galaxies together. It goes through ten galaxies that appear as tiny red dots on the picture, meaning their light comes from the earliest recesses of the universe.
A close-up of three of these galaxies is shown below.
A quasar, a luminous supermassive black hole, is thought to be anchoring the filament, researchers said. It is highlighted by the red arrow in the picture above.
The team believes that eventually the galaxies will be pulled together into a cluster, much like the nearby Coma galaxy cluster.
The ASPIRE team hopes the picture will shed more light on the cosmic web, but it is also very interested in how early quasars were formed in the universe's infancy.
"The last two decades of cosmology research have given us a robust understanding of how the cosmic web forms and evolves," said team member Joseph Hennawi of the University of California, Santa Barbara, in the press release.
"ASPIRE aims to understand how to embed the emergence of the earliest massive black holes into our current story of cosmic structure formation," he said.
|
Cosmology & The Universe
|
Where did the Moon come from? The widely-accepted view is that the Moon is a result of an ancient collision between the young Earth and a Mars-sized planet named Theia about 4.5 billion years ago. The impact melted Earth and Theia and sent molten material into orbit around Earth, where it formed a rotating torus of molten rock. That rock eventually coalesced into the Moon. It’s called the Giant Impact Hypothesis, and isotopic evidence from Apollo moon rocks illustrates the link between Earth and its Moon.
Case closed?
Not so fast. There’ve always been problems with this hypothesis. Can a new study answer them? In our quest to understand Nature, the Moon is a primary target for many of us. We look up at it when we’re children and wonder what it is. We wonder where it came from and why it’s there. A well-meaning relative might tell us that a God put it there. But if that’s where your curiosity ends, you’re probably not a Universe Today reader. Throughout history and even prehistory, people in different cultures have wondered about the Moon. Maoris thought it was the husband of all women since it controls their menstrual cycles. Siberians believed that a monster named Alklha explained the Moon. It eats a bit of it each night which makes it disappear. But the Moon disagrees with Alklha, and the monster vomits it up bit by bit, making it reappear. (If there’s an eclipse, throw rocks at the Moon to scare Alklha away.) Some indigenous people on the African continent thought the Moon goddess was a companion to the Sun god, and when they met and made love, there was an eclipse. Something to aspire to in our personal lives.
Humans have been trying to understand the Moon for a long time. New high-resolution simulations of the impact that created it are helping. Image Credit: NASA / GSFC / Arizona State University
But that was all before science got going. Science improved things a little, like when the British astronomer William Herschel said the Moon was inhabited, and he watched through his telescope as the Martians constructed things. He was wrong, but at least he was using a telescope. And after World War 2, some thought that Nazi astronauts had already landed on the Moon and were living in a top-secret base. Only slightly more plausible.
Lunar science took a giant step forward during NASA’s Apollo missions. Between 1969 and 1972, six Apollo missions brought back 382 kilograms (842 pounds) of lunar material. Scientists found no evidence of gods or supernatural beings. Nor of lovemaking so passionate that it caused an eclipse.
The image on the left shows some of the rocks returned to Earth by Apollo. On the right is a microscopic image of a zircon crystal used to date events billions of years ago. Image Credit: (L) NASA. (R) Apollo 17 / Nicholas E. Timms.
But they did find solid scientific evidence, and chief among the evidence was isotopes of oxygen. Scientists found that oxygen isotopes contained inside Moon rocks were uncannily similar to oxygen isotopes in Earth rocks. Could it be a coincidence?
Since then, generations of scientists have developed the Giant Impact Hypothesis. But they’ve also pointed out the holes in that hypothesis. One of the holes is in the initial finding that Earth and the Moon share isotope signatures. That means they had to come from the same source. But for that to happen, the impactor would’ve had to have the same isotope signature. That’s not likely because lighter elements were dispersed by the stellar wind in the early, still-forming Solar System. That’s why the inner planets are heavier rocky planets, while the outer planets are gas planets. The stellar wind couldn’t move the heavy elements so easily. So if Theia came from a region more distant from the Sun than Earth, it would have a different composition, and that should be reflected in the Moon. This is a simple illustration of the Giant Impact Hypothesis. Earth was going about its business 4.5 billion years ago when a protoplanet named Theia arrived from elsewhere in the Solar System, perhaps kicked out of its orbit by another calamity or by migrating gas giants. Theia impacts Earth and creates a torus of debris that coalesces into the Moon. Image Credit: By Citronade – Own work, CC BY-SA 4.0, https://commons.wikimedia.org/w/index.php?curid=72720188
There’s lots of evidence to support the current Giant Impact Hypothesis (GIH) and many unanswered questions. The Moon, the first target in our quest to understand the celestial, is still a hot topic of study.
That’s where this new study comes in. It still posits an impact as the source of Earth’s Moon, but thanks to improvements in supercomputer simulations, it arrives at a different type of impact.
The study is “Immediate Origin of the Moon as a Post-impact Satellite,” published in The Astrophysical Journal Letters. The lead author is Jacob Kegerreis from the Institute for Computational Cosmology in the Physics Department at Durham University. Kegerreis is also associated with NASA’s Ames Research Facility. The researchers used advances in computational power to run simulations of impacts with Earth at higher resolutions than ever before. These simulations show that the impact between Earth and Theia was much different than the Giant Impact Hypothesis. Instead of an impact casting a vast amount of molten material into space that condensed into the Moon over a longer timeframe, the simulation shows that the impact created the Moon by sending a single satellite immediately into orbit. If true, this is a massive shift in understanding, like finding out that Alklha isn’t real.
The researchers ran hundreds of simulations of impacts and varied impact angles, speeds, planet spins, masses and more. They found that previous lower-resolution simulations could miss essential aspects of massive collisions. A press release announcing the work said, “… qualitatively new behaviours emerge in a way that wasn’t possible in previous studies.”
The simulations showed that the material was sent into space when the impact occurred, just like in the GIH. But the material never formed a torus of rotating molten rock. Instead, the proto-satellite that would become the Moon separated from the remnant of the impactor. The remnant from the impactor also forms two bodies: an inner remnant and an outer remnant. The inner remnant transfers its angular momentum to the outer remnant and the ejected Earth and Theia material forming the proto-Moon. Then the inner remnant falls back to Earth, leaving the Moon.
These figures are screenshots from an impact simulation run at high resolution. It shows the impact at the upper left, then the material launched into space and separated into an outer remnant (green), an inner remnant (yellow), and the proto-Moon (purple.) The inner remnant falls back to Earth after imparting its angular momentum to the outer remnant. Image Credit: J. A. Kegerreis et al 2022 ApJL 937 L40.
The researchers released an animation of their impact simulations that illustrates the impact and the Moon’s formation. A new NASA and Durham University simulation puts forth a different theory of the Moon’s origin – the Moon may have formed in a matter of hours when material from the Earth and a Mars sized-body was launched directly into orbit after the impact. Credit: NASA/ Durham University/Jacob Kegerreis
Kegerreis and his research colleagues found that their immediate satellite scenario can answer some questions that the GIH can’t. The main roadblock to acceptance of the GIH is the isotopic similarity between Earth and the Moon. A cataclysmic impact with another planet from a distant part of the Solar System can’t produce the kind of isotopic similarity between the Earth and the Moon.
But the new scenario can explain it. Instead of melting and mixing the material from Theia and Earth, larger amounts of Earth material are contained in the Moon’s outer layers. And if the material ejected from Earth wasn’t entirely molten, then the early Moon wasn’t completely molten either. That could explain the Moon’s thin crust, another obstacle the GIH has to clear.
There’s also the issue of the Moon’s orbit. It’s tilted relative to Earth’s equator by about 5 degrees, and the instant satellite explanation can account for that. “In contrast,” the authors explain, “we find that an impact onto a spinning target with angular momentum misaligned to that of Theia’s orbit can readily produce significantly inclined debris, including a satellite, as illustrated in Figure 5.”
Figure 5 from the study shows how an impact onto a spinning proto-Earth misaligned to Theia’s orbital angular momentum can produce a satellite with an inclined or tilted orbit. Image Credit: J. A. Kegerreis et al 2022 ApJL 937 L40. The team’s simulations showed that instant satellite creation depends on several factors like impact angles and speed and spin of Theia and Earth. But interestingly, the temperature and internal structure of both bodies don’t change results much.
One of the problems with the GIH is that there’s no self-consistent model that starts with a giant impact and creates debris that results in a single Moon. But these higher resolution simulations have produced a single Moon. Will this be the final word?
“In conclusion,” the authors write, “high-resolution simulations reveal how giant impacts can immediately place a satellite into a wide orbit with a Moon-like mass and iron content. The resulting outer layers rich in proto-Earth material and the new options opened up for the initial lunar orbit, and internal structure could help to explain the isotopic composition of the Moon and other unsolved or debated lunar mysteries.”
While compelling in its ability to answer some long-standing questions, the instant satellite scenario doesn’t answer all of our questions. But supercomputers will keep getting more powerful, and scientists will keep improving their models. “The likelihood and potential of this and other Moon-formation scenarios will be constrained by: more reliable models for the long-term evolution of satellite orbits, magma oceans, post-impact planets, and disks,” the authors write. More:
Press Release: Supercomputer simulations reveal new possibilities for the Moon’s originNew Research: Immediate Origin of the Moon as a Post-impact SatelliteUniverse Today: This is How You Get Moons. An Earth-Sized World Just got Pummeled by Something Huge.
Like this:Like Loading...
|
Cosmology & The Universe
|
The presenters on the somewhat glitchy live broadcast from NASA seemed in awe of the images they introduced. “I’m beyond stoked to be sharing this with you,” said Dr. Nestor Espinoza, describing atmospheric data from a distant planet. The assembled astronomers watching along at Baltimore’s Space Telescope Science Institute ooh’d and aah’d, gasped and clapped.The five images — one released by President Biden on Monday and the rest showcased by NASA on Tuesday — document astonishing astronomical scenes from the universe and provide the first glimpse into the myriad capabilities of the much-anticipated telescope.“I’ve been waiting for Webb to sort of get its act together for 30 years. And there were a lot of times when I figured it would never happen,” said John McDowell, an astrophysicist at the Harvard-Smithsonian Center for Astrophysics. “But I’ve got to give them credit. They pulled it together and they’ve got a beautiful instrument. A real Swiss-army knife.”One image, titled SMACS 0723, revealed the deepest and sharpest image of the distant universe to date. The scintillating mosaic overflows with orange, blue, and white flecks that include glimpses into a galaxy cluster as it appeared 4.6 billion years ago. Webb can see much farther than its predecessor, the Hubble Space Telescope. And because light travels at a constant speed, seeing farther means looking further back in time.A video posted on Twitter by Alyssa Goodman, professor of applied astronomy at the Harvard-Smithsonian Center for Astrophysics, put the innovation in perspective by comparing an older image of the SMACS 0723 area to Webb’s latest snapshot, taken by the telescope in just 12-and-a-half hours.“A very blurry hint of something — nothing like what you see from this incredible image,” she says while toggling from the old image to the new.The Carina Nebula exhibited a similar grandeur. The image looks like a Van Gogh rendering of craggy orange mountains on a moonlit starry night. In reality, it is the edge of a turbulent cloud of gas and dust thousands of lightyears away, which serves as the crib and crypt for many of the brightest stars of the Milky Way. Unlike Hubble, which has documented the nebula before, the Webb telescope employs infrared radiation that can penetrate dust and create never-before-seen images of the stars within the cloud.But perhaps the image that showcases Webb’s greatest triumph was the unassuming WASP-96 b, squiggles and dots on a graph that document the atmospheric conditions of “hot gas giant exoplanet WASP-96 b.” The telescope measured light from the planet’s solar system over just 6.4 hours and found evidence of water vapor, hazes, and some previously unseen clouds.A still image from video provided by NASA shows a graph based on data from the James Webb Space Telescope. The telescope spotted the unambiguous signature of water, indications of haze and evidence of clouds in the exoplanet WASP-96b, the most detailed exoplanet spectrum to date.NASA/NYTFor Seager, the MIT astronomer who developed the equation used to create the WASP-96b graph, this speedy, in-depth analysis of exoplanets generates the most excitement — and consternation. Because so many scientists are angling to get research time on Webb, she will have to wait until next July to peer into TRAPPIST-1e, the exoplanet she and her team has been assigned that is widely considered to be potentially Earth-like and habitable.Seager’s research will be one of many efforts to reveal whether some promising exoplanets harbor atmospheres that might support life.The images — and the discoveries they predict — are the fruit of a decades-long project plagued by delays and cost overruns. An independent review of the program ordered by Congress in 2010 discovered a mess of mismanagement and oversight issues. Some lawmakers proposed a bill to cancel the project entirely. NASA vowed to make amends and completed construction in 2016, but then a series of human errors further jeopardized the project. Finally, after several launch delays, Webb and its 18 gold-plated mirrors hurdled into orbit on Christmas Day of 2021.And to nearly everyone’s surprise, the telescope has worked flawlessly since, a rarity in an era when just about everything — from airline travel to the baby formula market — seems broken.“To date, this is really an engineering feat. Now comes the science part. But the people we should be bowing down to are those that made this thing and made it work so seamlessly,” Goodman said.This image provided by NASA on Tuesday, July 12, 2022, shows Stephan's Quintet, a visual grouping of five galaxies, as observed from the Webb Telescope. HandoutIn a press conference Tuesday, Jane Rigby, the Webb operations project scientist, admitted she “went and had an ugly cry” when the early data revealed just how well the telescope worked.“We live in a time where we’re used to instantaneous feedback. Everything has to happen quickly. Otherwise, it becomes secondary and unworthy of money and attention,” said Mercedes Lopez-Morales, an astrophysicist at the Harvard-Smithsonian Center for Astrophysics.“Webb is an example of patience and perseverance. It was a little bit frustrating to watch. But I think now, everybody has stepped back and said, ‘You know, that was worth it.’”Astrophysics and astronomy are fields constantly seeking to answer questions of infinite doubt: Where do we come from? Are we alone? What happens next? The Webb telescope — with its speed, detail, and infrared capabilities — will play a crucial role in the quest to answer such inquiries.But the fields also sometimes raise the question of so what?“I’m not going to say that people shouldn’t be cynical at a time when gas prices are soaring and Ukraine is in shambles. But let this give people a little hope,” Lopez-Morales said. “We humans can’t necessarily disconnect from the day to day but we can think of more than one thing at the same time. Here, we can realize that there is occasional good.”The first tranche of data from Webb will be made available on Thursday to select scientists who collaborated in the telescope’s development. The sets will include information from and images of distant galaxies that are even older than the 4.6 billion-year-old one President Biden showed Monday in SMACS 0723.As Goodman said, “This is just the tip of the iceberg.”Hanna Krueger can be reached at hanna.krueger@globe.com. Follow her on Twitter @hannaskrueger.
|
Cosmology & The Universe
|
Published August 2, 2022 1:16PM NASA astrophysicist shares details on set of James Webb Space Telescope images NASA shared additional images from the $10 billion telescope’s initial outward gazes, including two images of nebulas where stars are born and die in spectacular beauty and another shot showing an update of a classic image of five tightly clustered galaxies that dance around each other. GREENBELT, Md. - NASA released a new image Tuesday from its James Webb Space Telescope, showing the Cartwheel Galaxy in stunning detail. While other telescopes, including the Hubble Space Telescope, have previously examined the Cartwheel Galaxy, located approximately 500 million light-years away in the Sculptor constellation, NASA said a large amount of dust has obscured the view. But its new James Webb telescope, which has an ability to detect infrared light, revealed new details about star formation and the galaxy's central black hole, NASA said. PREVIOUS: Groundbreaking Webb telescope images show new details of the universe The Cartwheel Galaxy's appearance, which resembles the wheel of a wagon, is the result of an "intense event," astronomers said, attributing it to a "high-speed collision between a large spiral galaxy and a smaller galaxy." The Cartwheel has two rings - a bright inner ring and an outer, colorful one - making it a "ring galaxy," which is a structure less common than spiral galaxies like the Milky Way. Left image: A large pink, speckled galaxy resembling a wheel with with a small, inner oval, with dusty blue in between on the right, with two smaller spiral galaxies about the same size to the left against a black background. Right image taken from J Astronomers noted that the new image shows how the bright core contains a "tremendous amount of hot dust with the brightest areas being the home to gigantic young star clusters." Meanwhile, they said the outer ring, which has expanded for about 440 million years, is dominated by star formation and supernovas. "As this ring expands, it plows into surrounding gas and triggers star formation," NASA astronomers wrote. RELATED: ‘Heartbeat’ radio signal detected billions of light-years from Earth But they said the telescope's image shows that the Cartwheel galaxy is in a transitory stage, and was presumably a normal spiral galaxy like the Milky Way before its collision. "While Webb gives us a snapshot of the current state of the Cartwheel, it also provides insight into what happened to this galaxy in the past and how it will evolve in the future," astronomers said. NASA’s James Webb Space Telescope reveals emerging stellar nurseries and individual stars in the Carina Nebula that were previously obscured. Images of "Cosmic Cliffs" showcase Webb’s cameras’ capabilities to peer through cosmic dust, shedding new light on how stars form. Image credit: NASA, ESA, CSA, and STScI What is the James Webb Space Telescope? The world’s biggest and most powerful space telescope rocketed away last December from French Guiana in South America. In January, it reached its lookout point of 1 million miles from Earth. That’s when the lengthy process began to align the mirrors, get the infrared detectors cold enough to operate, and calibrate the science instruments — all protected by a sunshade the size of a tennis court that keeps the telescope cool. The plan is to use the telescope to peer back so far that scientists will get a glimpse of the early days of the universe about 13.7 billion years ago and zoom in on closer cosmic objects, even our own solar system, with a sharper focus. NASA's James Webb Telescope launches into space After years of delays, NASA's James Webb Telescope blasted off into space on Dec. 25, 2021. It's now the biggest and most powerful tool for exploring space that's ever been built. How does James Webb Space Telescope compare to Hubble Space Telescope? The Hubble Space Telescope was launched into orbit by space shuttle Discovery in 1990, helping scientists to better understand how planets and galaxies form with its own awe-inspiring images. The James Webb Space Telescope is Hubble’s bigger, more powerful successor. Specifically, Webb is designed to peer deeper into space to see the earliest stars and galaxies that formed in the universe and to look deep into nearby dust clouds to study the formation of stars and planets, NASA says. To do this, Webb has a much larger primary mirror than Hubble — 2.7 times larger in diameter — which gives it more light-gathering power. RELATED: Moon caves might provide year-round comfortable temperatures for astronauts living on the moon Its infrared instruments also have longer wavelength coverage and more improved sensitivity compared to Hubble. Hubble has stared as far back as 13.4 billion years, disclosing a clumpy runt of a galaxy that is currently the oldest and farthest object ever observed. Astronomers are eager to close the 300 million-year gap with Webb and draw ever closer in time to the Big Bang, the moment the universe formed 13.8 billion years ago. How far back past 13 billion years did that first image look? NASA didn't provide any estimate on Monday. Outside scientists said those calculations will take time, but they are fairly certain somewhere in the busy image is a galaxy older than humanity has ever seen, probably back to 500 million or 600 million years after the Big Bang. "It takes a little bit of time to dig out those galaxies," University of California, Santa Cruz, astrophysicist Garth Illingworth said. "It's the things you almost can't see here, the tiniest little red dots." RELATED: James Webb Space Telescope to be featured on US postage stamp "This is absolutely spectacular, absolutely amazing," he added. "This is everything we’ve dreamed of in a telescope like this." The deepest view of the cosmos "is not a record that will stand for very long," project scientist Klaus Pontoppidan said during the briefing, since scientists are expected to use the Webb telescope to go even deeper. The Associated Press contributed to this report.
|
Cosmology & The Universe
|
Pulsars are one of the strangest celestial bodies in space. These cosmic lighthouses emit periodic bursts of radiation from their magnetic poles, and now a team of researchers claim they have detected the largest burst ever recorded from a pulsar.
A global collaboration of scientists used the H.E.S.S. Observatory in Namibia to observe a pulsar emitting bursts of gamma-rays with energies as high as 20 tera-electronvolts, which is about 10 trillion times more energetic than visible light. The emissions are coming from a pulsar known as Vela nearly 1,000 light-years from Earth. This massive object spins 11 times per second, flashing at us like a rapidly blinking light. The researchers say the bursts they recorded are a whopping 200 times more energetic than any pulsar beam previously documented. Their work is published today in Nature Astronomy.
“This result challenges our previous knowledge of pulsars and requires a rethinking of how these natural accelerators work,” said the team’s leader, Arache Djannati-Atai from the Astroparticle & Cosmology Laboratory in France, in a DESY press release. “The traditional scheme according to which particles are accelerated along magnetic field lines within or slightly outside the magnetosphere cannot sufficiently explain our observations.”
A pulsar is a type of neutron star, which is one of the new lives a star can take on when it implodes, assuming it doesn’t collapse all the way into a black hole. A pulsar is incredibly dense and features a highly active magnetosphere, through which electrons accelerate only to be ejected in a beam from one of the star’s poles. These jets then sweep across the universe as the pulsar spins, appearing as flashes in regular intervals to viewers on Earth, much like a lighthouse would appear to a sailor at sea.
“These dead stars are almost entirely made up of neutrons and are incredibly dense: a teaspoon of their material has a mass of more than five billion tonnes, or about 900 times the mass of the Great Pyramid of Giza,” said co-author and H.E.S.S. scientist Emma de Oña Wilhelmi in the release.
In August, researchers studying a pulsar 4,500 light-years from Earth cracked its bizarre behavior. The pulsar, named PSR J1023+0038 or J1023 for short, has been switching between two modes over the past decade: One in which the star emits high frequency visible light, ultraviolet light, and X-rays, and another in which it dims and emits lower frequency radio waves. The scientists deduced that, during the lower frequency mode, matter falls toward the pulsar’s surface and is pushed back out through its jet. In this process, matter surrounding the star heats up, triggering J1023's higher frequency mode.
|
Cosmology & The Universe
|
The Tarantula Nebula gets its name from its appearance, which is similar to that of a burrowing tarantula’s hole covered in spider silk. Image: NASA, ESA, CSA, and STScIThe latest wonder from the Webb Space Telescope is a new look at the Tarantula Nebula, a swirling mass of infantile and yet-to-be conceived stars. What looks like spider silk surrounds a hollowed-out center, where material has been blasted away by radiation, according to a NASA release. A nebula is a massive cloud of dust occupying the interstellar medium that could be the cradle of life for new stars, and the Tarantula Nebula gets its particular name for its resemblance to a tarantula’s burrow, covered in webbing.The Tarantula Nebula is located 161,000 light-years away from us Earthlings in the Large Magellanic Cloud, one of the Milky Way’s neighbors. Webb scientists were able to capture the nebula in all its glory using the telescope’s suite of infrared instruments, with the main view from the Near-Infrared Camera. According to NASA, the sparkling blue stars located right of center are responsible for the central cavity, as radiation emitted by the cluster of stars has hollowed out the area via intense stellar winds. The surrounding areas are incredibly dense and have formed pillars that are birthing young stars called “protostars.” Webb’s Mid-infrared Instrument, or MIRI, was able to see through the interstellar dust, since the longer wavelengths MIRI captures are able to penetrate the clouds of particulate matter. Scientists are excited to learn more about the Tarantula Nebula, especially because it shares a similar chemical composition to that of the “cosmic noon,” a time when the universe was only a few billion years old. By observing the Tarantula Nebula, astronomers can, in a way, peer into the universe’s past.
|
Cosmology & The Universe
|
Light from space always reaches us after a delay. For example, the light from our nearest star system, Alpha Centauri, takes four years to reach Earth, so when we look at Alpha Centauri, we see it as it was four years ago. The James Webb Space Telescope (JWST) will take this idea to the extreme, studying objects so distant that the telescope will essentially be looking back 13.5 billion years — close to the start of the universe.Early LightThe Big Bang occurred 13.8 billion years ago. One second afterward, the universe consisted of radiation, hydrogen, helium and high energy particles at a temperature of 18 billion degrees Fahrenheit. Around 400,000 years later, the temperature had cooled to 5,500 degrees Fahrenheit and the universe was glowing dull red. As the universe continued to expand and cool, that glow disappeared and the universe became completely dark, the so-called Dark Ages. The particles from the Big Bang grouped together due to gravity and formed the first atoms. Those atoms grouped together in clumps, eventually becoming stars. When the first stars formed they also began to emit the first light, which JWST was built to detect.The Hubble telescope can also look back in time to a certain extent, but not as far as JWST does. Hubble has been orbiting the Earth and giving us both amazing images of the universe and important scientific results for more than 30 years, but its mirror is only 8 feet in diameter, which limits its ability to observe the most distant objects. What’s more, light from the most distant objects is stretched due to the expansion of the universe, becoming infrared wavelengths, which Hubble cannot easily detect.By comparison, JWST is designed to collect infrared radiation, thanks to its much larger 21-foot diameter mirror. There are other benefits in collecting infrared radiation besides viewing faraway objects. Stars and planets that are just forming are surrounded by dust, which absorbs visible light; however, infrared radiation can penetrate that dust. Thus, JWST can see both farther and fainter objects than Hubble ever could.Back to the Beginning To do that deep stargazing, JWST must look at one patch of the universe for a long time in order to collect as much light as possible from the distant objects astronomers seek to view. “We are trying to build up the story of how the first galaxies ever emerged and how those evolved into galaxies we see today and we live in today,” said Marusa Bradac, an astronomer at the University of California, Davis, in an interview with NPR. “If you don’t get the beginning right, it’s really difficult to figure out what the whole evolution looked like”.Unlike Hubble, JWST will be able to see right into stellar nurseries, where stars and their planetary systems are born. The observations will answer questions about how clouds of dust and gas collapsed to form stars and how the planetary systems formed around them.A further goal for JWST is to try to understand the formation of the elements. After the Big Bang, the very high temperature and density produced the simplest elements, mostly helium and hydrogen. We know that all the other elements — carbon, gold, silicon and more — were created in nuclear reactions in the stars and in the huge stellar explosions we call supernovas, which scattered the elements into the galaxy. But we don’t entirely understand the processes involved.Seeing FurtherAstronomers from around the world will be able to apply for time using JWST to support their research and much of the new research will be the study of exoplanets. Twenty years ago, no other planets were known apart from those in our solar system. Since then thousands of planets, the exoplanets, have been discovered in orbit around stars. The plan is for JWST to study the atmospheres of the exoplanets to determine whether they could support life — or the telescope might even detect the presence of life itself.“The James Webb Space Telescope represents the ambition that NASA and our partners maintain to propel us forward into the future,” said NASA Administrator Bill Nelson in a NASA news release. “The promise of Webb is not what we know we will discover; it’s what we don’t yet understand or can’t yet fathom about our universe …. We are poised on the edge of a truly exciting time of discovery, of things we’ve never before seen or imagined.”
|
Cosmology & The Universe
|
Astronomers have long assumed that two black holes that circle close to each other are always destined to become one in a cataclysmic merger that spans eons.
That needn't always be the case, new research finds.
In a new study, physicists found that it is theoretically possible for two black holes to remain at a fixed distance from each other, thanks to their mutual gravitational pull being perfectly counterbalanced by the speed at which the universe is expanding.
"Viewed from a distance, a pair of black holes whose attraction is offset by cosmic expansion would look like a single black hole," study co-author Óscar Dias, a physicist at the University of Southampton in the U.K., said in a statement. "It might be hard to detect whether it is a single black hole or a pair of them."
The team reported their findings Sept. 25 in the journal Physical Review Letters. They demonstrate that two black holes could be delicately balanced, despite conventional theories predicting otherwise, by pointing out "a logical inconsistency in the proof of one theorem and a limiting assumption in another," Toby Wiseman, a professor of theoretical physics at Imperial College London who was not involved with the new work, said in a different statement.
One of the key assumptions in those theorems is that the region around black hole pairs is empty. However, according to the standard model of cosmology — our current best description of the universe — dark energy causes the universe to expand at an accelerated rate. This dark energy is sometimes considered equivalent to the puzzling cosmological constant in the theory of general relativity.
In the new study, Días and colleagues show that two black holes can be positioned such that their mutual gravitational attraction is offset by acceleration due to the cosmological constant. "If these black holes are set up in precisely the correct way, they sit in an unstable equilibrium, akin to a pen balanced on its pointed end," Wiseman said. "Any disturbance will ruin this perfect balance."
Physicists say that wobbly balance could be made more stable when black holes are rotating. For instance, the gravitational attraction of two such identical black holes rotating in opposite directions could be balanced by their spins, although this possibility is yet to be proved.
The study only considered a pair of static black holes, so follow-up studies should address how stable spinning black holes could be.
"Our theory is proven for a pair of static black holes, but we believe it could be applied to spinning ones too," said study co-author Jorge Santos, a professor of theoretical physics at the University of Cambridge in England. "Also, it seems plausible that our solution could hold true for three or even four black holes, opening up a whole range of possibilities."
Live Science newsletter
Stay up to date on the latest science news by signing up for our Essentials newsletter.
Sharmila is a Seattle-based science journalist. She found her love for astronomy in Carl Sagan's The Pale Blue Dot and has been hooked ever since. She holds an MA in Journalism from Northeastern University and has been a contributing writer for Astronomy Magazine since 2017. Follow her on Twitter at @Sharmilakg.
|
Cosmology & The Universe
|
Our ideas about the Universe are based on a century-old simplification known as the cosmological principle. It suggests that when averaged on large scales, the Cosmos is homogeneous and matter is distributed evenly throughout.
This allows a mathematical description of space-time that simplifies the application of Einstein’s general theory of relativity to the Universe as a whole.
Our cosmological models are based on this assumption. But as new telescopes, both on Earth and in space, deliver ever more precise images, and astronomers discover massive objects such as the giant arc of quasars, this foundation is increasingly challenged.
In our recent review, we discuss how these new discoveries force us to radically re-examine our assumptions and change our understanding of the Universe.
Einstein’s legacy
Albert Einstein faced huge dilemmas 106 years ago when he first applied his equations for gravity to the Universe as a whole. No physicist had ever attempted something so bold, but it was a natural consequence of his key idea. As a 50-year-old textbook reminds us:
Matter tells space how to curve, and space tells matter how to move.
Data were almost completely lacking in 1917 and the idea that galaxies were objects at vast distances was a minority view among astronomers.
The conventional viewpoint, accepted by Einstein, was that the whole Universe looked like the inside of our galaxy. This suggested stars should be treated as pressure-less fluids, distributed randomly but with a well defined average density – the same, or homogeneous, anywhere in space.
Based on the idea that the Universe is the same everywhere, Einstein introduced his cosmological constant Λ, now known as “dark energy”.
On small scales, Einstein’s equations tell us that space never stands still. But forcing this on the Universe on a large scale was unnatural. Einstein was therefore relieved by the discovery of the expanding universe in the late 1920s. He even described Λ as his biggest blunder.
Ideas about matter have evolved, but not geometry
We now have amazingly detailed models of the physics of stars and galaxies embedded in the evolving Universe. We can trace the astrophysics of “stuff” from tiny seed ripples in the primordial fireball all the way to complex structures today.
Our telescopes are wonderful time machines. They look back all the way to when the first atoms formed, and the Universe first became transparent.
Beyond is the primordial plasma, opaque like the interior and surface of the Sun. The light that left the Universe’s “surface of last scattering” was very hot back then, about 2,700℃.
We receive that same light today, but cooled to minus 270℃ and diluted by the expansion of the Universe. This is the cosmic microwave background and it is remarkably uniform in all directions.
This is strong evidence the Universe was very close to spatially uniform when it was a fireball. But there is no direct evidence for such uniformity today.
A ‘lumpy’ Universe
Far back in time, our telescopes reveal small merging galaxies, growing into ever larger structures until the present day.
The expansion of the Universe has been halted entirely within the largest matter concentrations known as galaxy clusters. Where space is expanding, the clusters are stretched in filaments and sheets that thread and surround vast empty voids, all growing with time but at different rates. Rather than being smooth, matter forms a “cosmic web”.
But the idea that the Universe is spatially homogeneous endures.
There would be a gross inconsistency between the observed cosmic web and an average curved geometry of space if all we see is all there is. Evidence for missing matter has been around since the first observations of galaxy clusters in 1933.
Our first observations of the cosmic microwave background radiation and its ripples in the decade from 1965 changed that idea.
Our models of nuclear physics are wonderfully predictive. But they are only consistent with observations if the missing mass in galaxy clusters is something like neutrinos that cannot emit light. Thus we invented cold dark matter, which makes gravity stronger within galaxy clusters.
Billions have been spent trying to directly detect dark matter, but decades of such efforts have yielded no definitive detection of what makes up 80% of all matter and 20% of all the energy in the Universe today.
An anomalous sky
The cosmic microwave background radiation is not perfectly uniform. Superimposed on it are fluctuations, one of which is abnormally large and has the shape of a dipole: a yin-yang diagram covering the whole sky.
We can interpret this as an effect due to relative motion, provided we define the cosmic microwave background radiation as the rest frame of the Universe. If we didn’t do this, we would need a physical explanation for the large dipole.
Much of the puzzle boils down to a power asymmetry – a lopsided Universe. The temperatures of the hemispheres above and below the plane of the Milky Way are slightly different to expectation.
These anomalies have long been explained as a result of unaccounted physical processes in modelling microwave emissions from the Milky Way.
Matter within the sky
The cosmic microwave background radiation is not the only all-sky observation to show a dipole. Last year, researchers used observations of 1.36 million distant quasars and 1.7 million radio sources to test the cosmological principle. They found that matter, too, is unevenly distributed.
Another even more widely discussed mystery is the “Hubble tension”. Conventionally, we assume that an all-sky average of the Universe’s present expansion rate gives one well defined value: the Hubble constant. But the measured value differs from expectation, given a standard expansion history based on the cosmic microwave background radiation. If we allowed for inhomogeneous cosmologies, this problem may simply disappear.
Using cosmic microwave background data from individual opposing hemispheres, a standard expansion history implies different Hubble “constants” on each side of the sky today.
These puzzles are compounded by an ever-growing list of unexpected discoveries: a vast giant arc of quasars and a complex, bright and element-filled early Universe unveiled by the James Webb Space Telescope.
If matter is much more varied and interesting than expected, then maybe the geometry is too.
Models which abandon the cosmological principle do exist and make predictions. They are simply less studied than standard cosmology. The European Space Agency’s Euclid satellite will be launched this year. Will Euclid reveal that on average space is not Euclidean? If so, then a fundamental revolution in physics might be around the corner.
|
Cosmology & The Universe
|
Astronomers have detected an unusual radio signal from a far-off galaxy, according to MIT officials.The signal is a fast radio burst, an intensely strong burst of radio waves, the Massachusetts Institute of Technology said in a statement. Usually, the mysterious signals last for a few milliseconds at most. But this one lasted up to three seconds and included bursts of radio waves every 0.2 seconds, in a clear periodic pattern.The discovery was reported last week in the journal Nature by members of the CHIME/FRB Collaboration.The Canadian Hydrogen Intensity Mapping Experiment, or CHIME, is a radio telescope in British Columbia, Canada. CHIME is designed to pick up radio waves emitted by hydrogen in the earliest stages of the universe. It also can detect fast radio bursts, or FRBs, and it has found hundreds of them, MIT said.Coauthors of the paper include Calvin Leung, Juan Mena-Parra, Kaitlyn Shin, and Kiyoshi Masui at MIT, along with Daniele Michilli. Michilli led the discovery of the FRB, first as a researcher at McGill University and then as a postdoctoral researcher at MIT, the university said.CHIME picked up a signal of a potential FRB on Dec. 21, 2019, and it immediately drew the attention of Michilli, who was scanning the data, the university said.“It was unusual,” Michilli said in the statement. “Not only was it very long, lasting about three seconds, but there were periodic peaks that were remarkably precise, emitting every fraction of a second — boom, boom, boom — like a heartbeat.”The burst, designated FRB 20191221A, is the longest-lasting FRB, with the clearest periodic pattern, detected to date, MIT said.While the origin of FRBs is uncertain, astronomers suspect the signal could come from either a radio pulsar or a magnetar, two types of neutron stars, which are the collapsed cores of massive stars. The source is located in another galaxy, several billion light-years from earth.“There are not many things in the universe that emit strictly periodic signals,” Michilli said. “Examples that we know of in our own galaxy are radio pulsars and magnetars, which rotate and produce a beamed emission similar to a lighthouse. And we think this new signal could be a magnetar or pulsar on steroids.”The astronomers hope to observe more bursts from FRB 20191221A, which could help to refine their understanding of its source, and of neutron stars in general, the university said.“This detection raises the question of what could cause this extreme signal that we’ve never seen before, and how can we use this signal to study the universe,” Michilli said. “Future telescopes promise to discover thousands of FRBs a month, and at that point we may find many more of these periodic signals.”Martin Finucane can be reached at martin.finucane@globe.com.
|
Cosmology & The Universe
|
Science Updated on Jul 11, 2022 6:49 PM EDT — Published on Jul 11, 2022 1:32 PM EDT Our view of the universe just expanded: The first image from NASA’s new space telescope unveiled Monday is brimming with galaxies and offers the deepest look of the cosmos ever captured.
Watch in our the player above.
The first image from the $10 billion James Webb Space Telescope is the farthest humanity has ever seen in both time and distance, closer to the dawn of time and the edge of the universe. That image will be followed Tuesday by the release of four more galactic beauty shots from the telescope’s initial outward gazes.
The first image from NASA’s James Webb Space Telescope is the deepest and sharpest infrared image of the distant universe to date. Known as Webb’s First Deep Field, this image of galaxy cluster SMACS 0723 is overflowing with detail. Image courtesy of NASA, ESA, CSA, and STScI
The “deep field” image released at a White House event is filled with lots of stars, with massive galaxies in the foreground and faint and extremely distant galaxies peeking through here and there. Part of the image is light from not too long after the Big Bang, which was 13.8 billion years ago.
WATCH LIVE: Stunning new images from James Webb Space Telescope offer fuller picture of our universe
“We’re going to give humanity a new view of the cosmos,” NASA Administrator Bill Nelson told reporters last month in a briefing. “And it’s a view that we’ve never seen before.”
The images on tap for Tuesday include a view of a giant gaseous planet outside our solar system, two images of a nebula where stars are born and die in spectacular beauty and an update of a classic image of five tightly clustered galaxies that dance around each other.
The world’s biggest and most powerful space telescope rocketed away last December from French Guiana in South America. It reached its lookout point 1 million miles (1.6 million kilometers) from Earth in January. Then the lengthy process began to align the mirrors, get the infrared detectors cold enough to operate and calibrate the science instruments, all protected by a sunshade the size of a tennis court that keeps the telescope cool.
READ MORE: Bigger and more powerful than the Hubble, NASA’s new telescope will see the ‘awe-inspiring’
The plan is to use the telescope to peer back so far that scientists will get a glimpse of the early days of the universe about 13.7 billion years ago and zoom in on closer cosmic objects, even our own solar system, with sharper focus.
Webb is considered the successor to the highly successful, but aging Hubble Space Telescope. Hubble has stared as far back as 13.4 billion years. It found the light wave signature of an extremely bright galaxy in 2016. Astronomers measure how far back they look in light-years with one light-year being 5.8 trillion miles (9.3 trillion kilometers).
“Webb can see backwards in time to just after the Big Bang by looking for galaxies that are so far away that the light has taken many billions of years to get from those galaxies to our telescopes,” said Jonathan Gardner, Webb’s deputy project scientist said during the media briefing.
How far back did that first image look? Over the next few days, astronomers will do intricate calculations to figure out just how old those galaxies are, project scientist Klaus Pontoppidan said last month.
READ MORE: NASA’s new space telescope sees 1st starlight, takes selfie
The deepest view of the cosmos “is not a record that will stand for very long,” Pontoppidan said, since scientists are expected to use the telescope to go even deeper.
Thomas Zurbuchen, NASA’s science mission chief said when he saw the images he got emotional and so did his colleagues: “It’s really hard to not look at the universe in new light and not just have a moment that is deeply personal.”
At 21 feet, Webb’s gold-plated, flower-shaped mirror is the biggest and most sensitive ever sent into space. It’s comprised of 18 segments, one of which was smacked by a bigger than anticipated micrometeoroid in May. Four previous micrometeoroid strikes to the mirror were smaller. Despite the impacts, the telescope has continued to exceed mission requirements, with barely any data loss, according to NASA.
NASA is collaborating on Webb with the European and Canadian space agencies.
“I’m now really excited as this dramatic progress augurs well for reaching the ultimate prize for many astronomers like myself: pinpointing “Cosmic Dawn” — the moment when the universe was first bathed in starlight,” Richard Ellis, professor of astrophysics at University College London, said via email.
AP Aerospace Writer Marcia Dunn contributed.
|
Cosmology & The Universe
|
image: This shows a still image of the supermassive black hole Sagittarius A*, as seen by the Event Horizon Collaboration (EHT), with an artist’s illustration indicating where the modelling of the ALMA data predicts the hot spot to be and its orbit around the black hole. view more Credit: EHT Collaboration, ESO/M. Kornmesser (Acknowledgment: M. Wielgus) [[Credit must be given to the creator and the European Southern Observatory must be mentioned in the media article.]] Using the Atacama Large Millimeter/submillimeter Array (ALMA), astronomers have spotted signs of a ‘hot spot’ orbiting Sagittarius A*, the black hole at the centre of our galaxy. The finding helps us better understand the enigmatic and dynamic environment of our supermassive black hole. “We think we're looking at a hot bubble of gas zipping around Sagittarius A* on an orbit similar in size to that of the planet Mercury, but making a full loop in just around 70 minutes. This requires a mind blowing velocity of about 30% of the speed of light!” says Maciek Wielgus of the Max Planck Institute for Radio Astronomy in Bonn, Germany, who led the study published today in Astronomy & Astrophysics. The observations were made with ALMA in the Chilean Andes — a radio telescope co-owned by the European Southern Observatory (ESO) — during a campaign by the Event Horizon Telescope (EHT) Collaboration to image black holes. In April 2017 the EHT linked together eight existing radio telescopes worldwide, including ALMA, resulting in the recently released first ever image of Sagittarius A*. To calibrate the EHT data, Wielgus and his colleagues, who are members of the EHT Collaboration, used ALMA data recorded simultaneously with the EHT observations of Sagittarius A*. To the team's surprise, there were more clues to the nature of the black hole hidden in the ALMA-only measurements. By chance, some of the observations were done shortly after a burst or flare of X-ray energy was emitted from the centre of our galaxy, which was spotted by NASA’s Chandra Space Telescope. These kinds of flares, previously observed with X-ray and infrared telescopes, are thought to be associated with so-called ‘hot spots’, hot gas bubbles that orbit very fast and close to the black hole. “What is really new and interesting is that such flares were so far only clearly present in X-ray and infrared observations of Sagittarius A*. Here we see for the first time a very strong indication that orbiting hot spots are also present in radio observations,” says Wielgus, who is also affiliated with the Nicolaus Copernicus Astronomical Centre, Poland and the Black Hole Initiative at Harvard University, USA. “Perhaps these hot spots detected at infrared wavelengths are a manifestation of the same physical phenomenon: as infrared-emitting hot spots cool down, they become visible at longer wavelengths, like the ones observed by ALMA and the EHT,” adds Jesse Vos, a PhD student at Radboud University, the Netherlands, who was also involved in this study. The flares were long thought to originate from magnetic interactions in the very hot gas orbiting very close to Sagittarius A*, and the new findings support this idea. “Now we find strong evidence for a magnetic origin of these flares and our observations give us a clue about the geometry of the process. The new data are extremely helpful for building a theoretical interpretation of these events,” says co-author Monika Mościbrodzka from Radboud University. ALMA allows astronomers to study polarised radio emission from Sagittarius A*, which can be used to unveil the black hole’s magnetic field. The team used these observations together with theoretical models to learn more about the formation of the hot spot and the environment it is embedded in, including the magnetic field around Sagittarius A*. Their research provides stronger constraints on the shape of this magnetic field than previous observations, helping astronomers uncover the nature of our black hole and its surroundings. The observations confirm some of the previous discoveries made by the GRAVITY instrument at ESO’s Very Large Telescope (VLT), which observes in the infrared. The data from GRAVITY and ALMA both suggest the flare originates in a clump of gas swirling around the black hole at about 30% of the speed of light in a clockwise direction in the sky, with the orbit of the hot spot being nearly face-on. “In the future we should be able to track hot spots across frequencies using coordinated multiwavelength observations with both GRAVITY and ALMA — the success of such an endeavour would be a true milestone for our understanding of the physics of flares in the Galactic centre,” says Ivan Marti-Vidal of the University of València in Spain, co-author of the study. The team is also hoping to be able to directly observe the orbiting gas clumps with the EHT, to probe ever closer to the black hole and learn more about it. “Hopefully, one day, we will be comfortable saying that we ‘know’ what is going on in Sagittarius A*,” Wielgus concludes. More information This research was presented in the paper “Orbital motion near Sagittarius A* – Constraints from polarimetric ALMA observations” to appear in Astronomy & Astrophysics (https://www.aanda.org/10.1051/0004-6361/202244493). The team is composed of M. Wielgus (Max-Planck-Institut für Radioastronomie, Germany [MPIfR]; Nicolaus Copernicus Astronomical Centre, Polish Academy of Sciences, Poland; Black Hole Initiative at Harvard University, USA [BHI]), M. Moscibrodzka (Department of Astrophysics, Radboud University, The Netherlands [Radboud]), J. Vos (Radboud), Z. Gelles (Center for Astrophysics | Harvard & Smithsonian, USA and BHI), I. Martí-Vidal (Universitat de València, Spain), J. Farah (Las Cumbres Observatory, USA; University of California, Santa Barbara, USA), N. Marchili (Italian ALMA Regional Centre, INAF-Istituto di Radioastronomia, Italy and MPIfR), C. Goddi (Dipartimento di Fisica, Università degli Studi di Cagliari, Italy and Universidade de São Paulo, Brazil), and H. Messias (Joint ALMA Observatory, Chile). The Atacama Large Millimeter/submillimeter Array (ALMA), an international astronomy facility, is a partnership of ESO, the U.S. National Science Foundation (NSF) and the National Institutes of Natural Sciences (NINS) of Japan in cooperation with the Republic of Chile. ALMA is funded by ESO on behalf of its Member States, by NSF in cooperation with the National Research Council of Canada (NRC) and the Ministry of Science and Technology (MOST) and by NINS in cooperation with the Academia Sinica (AS) in Taiwan and the Korea Astronomy and Space Science Institute (KASI). ALMA construction and operations are led by ESO on behalf of its Member States; by the National Radio Astronomy Observatory (NRAO), managed by Associated Universities, Inc. (AUI), on behalf of North America; and by the National Astronomical Observatory of Japan (NAOJ) on behalf of East Asia. The Joint ALMA Observatory (JAO) provides the unified leadership and management of the construction, commissioning and operation of ALMA. The European Southern Observatory (ESO) enables scientists worldwide to discover the secrets of the Universe for the benefit of all. We design, build and operate world-class observatories on the ground — which astronomers use to tackle exciting questions and spread the fascination of astronomy — and promote international collaboration in astronomy. Established as an intergovernmental organisation in 1962, today ESO is supported by 16 Member States (Austria, Belgium, the Czech Republic, Denmark, France, Finland, Germany, Ireland, Italy, the Netherlands, Poland, Portugal, Spain, Sweden, Switzerland and the United Kingdom), along with the host state of Chile and with Australia as a Strategic Partner. ESO’s headquarters and its visitor centre and planetarium, the ESO Supernova, are located close to Munich in Germany, while the Chilean Atacama Desert, a marvellous place with unique conditions to observe the sky, hosts our telescopes. ESO operates three observing sites: La Silla, Paranal and Chajnantor. At Paranal, ESO operates the Very Large Telescope and its Very Large Telescope Interferometer, as well as two survey telescopes, VISTA working in the infrared and the visible-light VLT Survey Telescope. Also at Paranal ESO will host and operate the Cherenkov Telescope Array South, the world’s largest and most sensitive gamma-ray observatory. Together with international partners, ESO operates APEX and ALMA on Chajnantor, two facilities that observe the skies in the millimetre and submillimetre range. At Cerro Armazones, near Paranal, we are building “the world’s biggest eye on the sky” — ESO’s Extremely Large Telescope. From our offices in Santiago, Chile we support our operations in the country and engage with Chilean partners and society. Links Research paper Photos of ALMA Press release about the first image of our black hole For journalists: subscribe to receive our releases under embargo in you language For scientists: got a story? Pitch your research Contacts Maciek Wielgus
Max Planck Institute for Radio Astronomy
Bonn, Germany
Tel: +48 602417268
Email: maciek.wielgus@gmail.com Monika Mościbrodzka
Radboud University
Nijmegen, The Netherlands
Tel: +31-24-36-52485
Email: m.moscibrodzka@astro.ru.nl Ivan Martí Vidal
University of Valencia
Valencia, Spain
Tel: +34 963 543 078
Email: i.marti-vidal@uv.es Jesse Vos
Radboud University
Nijmegen, The Netherlands
Cell: +31 6 34008019
Email: jt.vos@astro.ru.nl Bárbara Ferreira
ESO Media Manager
Garching bei München, Germany
Tel: +49 89 3200 6670
Cell: +49 151 241 664 00
Email: press@eso.org Disclaimer: AAAS and EurekAlert! are not responsible for the accuracy of news releases posted to EurekAlert! by contributing institutions or for the use of any information through the EurekAlert system.
|
Cosmology & The Universe
|
They are the highest resolution images of the distant universe ever taken.Last Updated: July 12, 2022, 2:00 PM ETThe first full-color image from NASA's James Webb Space Telescope has been released.The images, the full set of which will be released Tuesday morning, will be the deepest and highest resolution ever taken of the universe, according to NASA.The telescope will help scientists study the formation of the universe’s earliest galaxies, how they compare to today’s galaxies, how our solar system developed and if there is life on other planets.NASA scientists revealed more details about the image of the Southern Ring Nebula taken by the James Webb Space Telescope.The image shows a planetary nebula, or a cloud of gas that encircles a dying star.During a press conference Tuesday, Klaus Pontoppidan, one of the telescope's project scientists, explained why the image is important."It's not just any star, it's a star much like the sun, or like the sun will be in 5 billion years when the sun dies," he said.Pontoppidian said the star is pushing out its outer layers, including carbon and oxygen, which helps create other cosmic objects."There's a life cycle of stars," he added. "This is the end of this star, but it's the beginning of other stars and planetary systems."NASA scientists said the images and data that will be collected from the James Webb Space Telescope will be groundbreaking in our understanding of the universe."This going to be revolutionary," said Jane Rigby, the operations project scientist for the telescope, during a press conference Tuesday. "These are previous capabilities we’ve never had before."Her comments come after NASA released five new images with never-before-seen detail of exoplanets, stars, nebulae and galaxies in the universe.Rigby said she cried from happiness after seeing the first images that Webb captured."It was a combination of giddy like, 'Oh my gosh, this is great,' and having a sob like, 'Oh my God, this works,'" she said.NASA revealed the difference in images taken by the James Webb Space Telescope, the first of which were revealed Tuesday, and its predecessor, the Hubble Space Telescope.In a tweet, the space agency posted images of Stephan’s Quintet, a cluster of five galaxies -- four of which interact.The 2009 image taken by Hubble was captured over the span of several weeks and show the galaxies surrounded by several stars.Meanwhile, the 2022 image taken by Webb was captured in less than one week and reveals hundreds of star formations never seen before because the telescope uses infrared technology, which reveals objects invisible to the human eye due to being surrounded by clouds, gas and dust.The final image revealed Tuesday from the James Webb Space Telescope has revealed new details about the Carina Nebula, located in the Milky Way Galaxy.The image, which is actually just the edge of the nebula, shows hundreds of stars never seen before within the cloud.Because of the massive amounts of dust and gas that exist within the nebula, the stars were not visible to the human eye.The area, referred to as the Cosmic Cliffs, shows a "giant, gaseous cavity" as young stars that were recently born push down ultraviolet radiation and create the jagged-looking edge.
|
Cosmology & The Universe
|
Space Updated on: July 10, 2022 / 8:56 PM / CBS News President Biden will unveil the first color image from the James Webb Space Telescope at the White House on Monday, heralding the end of tests and checkout and the beginning of science operations by the world's most powerful space observatory."We're going to give humanity a new view of the cosmos, and it's a view that we've never seen before," NASA Administrator Bill Nelson, who will join Biden at the White House, told reporters in a preview briefing."One of those images ... is the deepest image of our universe that has ever been taken," he said. "And we're only beginning to understand what Webb can and will do." An artist's impression of the James Webb Space Telescope. NASA NASA plans to release additional "first light" images Tuesday, photos designed to show off Webb's ability to capture light from the first generation of stars and galaxies; to chart the details of stellar evolution, from starbirth to death by supernova; and to study the chemical composition of exoplanet atmospheres. For the past 30 years, the Hubble Space Telescope has become one of the most iconic instruments in astronomical history, helping astronomers pin down the age of the universe, confirming the presence of supermassive black holes, capturing the deepest views of the cosmos ever collected and providing fly-by class images of planets in Earth's solar system.But Webb, operating at just a few degrees above absolute zero behind a tennis-court size sunshade, promises to push the boundaries of human knowledge even deeper with a 21.3-foot-wide segmented primary mirror capable of detecting the faint, stretched-out infrared light from the era when stars began "turning on" in the wake of the Big Bang. Launched on Christmas Day, Webb is stationed in a gravitationally stable orbit nearly 1 million miles from Earth. For the past six months, engineers and scientists have been working through a complex series of deployments, activations and checkouts, fine tuning the telescope's focus and optimizing the performance of its four science instruments. — NASA (@NASA) July 11, 2022 The initial images released Monday and Tuesday, selected by an international team of astronomers, will "demonstrate to the world that Webb is, in fact, ready for science, and that it produces excellent and spectacular results," said Klaus Pontoppidan, Webb project scientist at the Space Telescope Science Institute."And it's also to highlight the breadth, the sheer breadth of science that can be done with Webb and to highlight all of the four science instruments," he added. "And last but not least, to celebrate the beginning of normal science operations."The targets for Webb's first public images include:The Carina Nebula: A vast star-forming region in the constellation Carina some 7,600 light years from Earth that's four times as large as the Orion Nebula. The Carina Nebula is the home of the most luminous known star in the Milky Way as well as the Eta Carinae binary system, which includes a massive sun expected to explode in a supernova blast in the near future (astronomically speaking). The Carina Nebula, a vast stellar nursery featuring massive young stars in multiple clusters and the debris of supernova blasts, as seen by the Hubble Space Telescope. Webb's infrared view is expected to peer into the dusty clouds to reveal infant suns in the process of being born. Maicon Germiniani Southern Ring Nebula: An expanding cloud of gas a half light year across that was ejected from a dying star. Relatively low-mass stars like Earth's sun will end their lives by blowing off their outer layers, forming so-called "planetary nebulas" while their cores shrink and slowly cool.Stephen's Quintet: A collection of five galaxies in the constellation Pegasus 290 million light years from Earth that was discovered in 1877, the first such compact grouping of galaxies to be detected. Four of the five galaxies are gravitationally interacting in a slow-motion merger. A Hubble image of Stephen's Quintet, a group of five large galaxies in the constellation Pegasus. Four of the galaxies are gravitationally interacting while the fifth, at lower left, is not involved. NASA, ESA, Hubble Legacy Archive WASP-96b: An unusual cloudless exoplanet 1,150 light years away that's about half the size of Jupiter, orbiting its sun every 3.4 days. By spectroscopically analyzing light from the parent star as it passes through the exoplanet's atmosphere on the way to Earth, astronomers can tease out details about its chemical composition.SMACS J0723.3-7327: The combined gravity of countless stars in huge galaxy clusters like this one can act as a powerful lens if the alignment is just right, magnifying the light from more distant objects in the far background to provide a deeper look back across space and time than would otherwise be possible."The first images will include observations that span the range of Webb science themes," said Pontoppidan. "From the early universe, the deepest infrared view of the cosmos to date. We will also see an example of how galaxies interact and grow, and how these cataclysmic collisions between galaxies drive the process of star formation. "We'll see a couple of examples from the life cycle of stars, starting from the birth of stars, where Webb can reveal new, young stars emerging from their natal cloud of gas and dust, to the death of stars, like a dying star seeding the galaxy with new elements and new dust that may one day become part of new planetary systems."Last but not least, he said, the team will show off the first chemical fingerprints from the atmosphere of an exoplanet.One of the Hubble Space Telescope's most astonishing images was its initial "deep field" look at a tiny patch of seemingly empty sky over a 10-day period in 1995. To the amazement of professionals and the public alike, that long-exposure image revealed more than 3,000 galaxies of every shape, size and age, some of them the oldest, most distant ever seen. The original Hubble Deep Field revealed more than 3,000 galaxies in a small, seemingly empty region of space. The James Webb Space Telescope is expected to push well beyond Hubble in search of the first stars and galaxies to form after the Big Bang 13.8 billion years ago. NASA Subsequent Hubble deep fields pushed even farther back in time, detecting the faint light of galaxies that were shining within about 500 million years of the Big Bang. How stars formed and got organized so quickly into galactic structures is still a mystery, as is the development of the supermassive black holes at their cores.Webb's four instruments are expected to push the boundaries still closer to the beginning of galaxy formation. A test image from the telescope's Canadian-built Fine Guidance Sensor, an image that wasn't optimized for the detection of extremely faint objects, nonetheless revealed thousands of galaxies.Webb's look at SMACS 0723 is expected to demonstrate the enormous reach of the observatory."This is really only the beginning, we're only scratching the surface," Pontoppidan said. "We have in the first images, a few days worth of observations. Looking forward, we have many years of observation, so we can only imagine what that will be." In: James Webb Space Telescope NASA William Harwood Bill Harwood has been covering the U.S. space program full-time since 1984, first as Cape Canaveral bureau chief for United Press International and now as a consultant for CBS News. He covered 129 space shuttle missions, every interplanetary flight since Voyager 2's flyby of Neptune and scores of commercial and military launches. Based at the Kennedy Space Center in Florida, Harwood is a devoted amateur astronomer and co-author of "Comm Check: The Final Flight of Shuttle Columbia." Twitter Thanks for reading CBS NEWS. Create your free account or log in for more features. Please enter email address to continue Please enter valid email address to continue
|
Cosmology & The Universe
|
The James Webb Space Telescope (JWST) has discovered that nearly all of the universe's earliest galaxies were filled with dazzling gas clouds that blazed brighter than the emerging stars within them — and it could help solve a mystery that threatens to break cosmology.
Forming as early as 500 million years after the Big Bang, some early galaxies have been seen glowing so brightly that they shouldn't exist: Brightnesses of their magnitude should come only from massive galaxies with as many stars as the Milky Way, yet the galaxies took shape in a fraction of the time our galaxy took to form.
The discovery threatened to upend physicists' understanding of galaxy formation and even the standard model of cosmology, which states that a few million years after the Big Bang (13.8 billion years ago) energy condensed into matter from which the first stars slowly coalesced. Yet when the JWST came online, it saw far too many stars.
Now, astronomers have found a possible answer: a large group of 12 billion-year-old galaxies almost 90% of which were wreathed in bright gas that — after being ignited by light from the surrounding stars — triggered intense bursts of star formation as the gas cooled. The new research has been accepted for publication in The Astrophysical Journal.
"Our paper proves that interactions with the neighboring galaxies are responsible for the unusual brightness of early galaxies," lead author Anshu Gupta, an astrophysicist at Curtin University in Australia, told Live Science in an email. "The explosion of star formation triggered by the interactions could also explain the more massive nature of early galaxies."
Astronomers discovered the bright gas clouds in data collected as part of JWST's Advanced Deep Extragalactic Survey, which used three of the telescope's instruments to collect infrared images of galaxies before analyzing their spectra.
By peering at the frequencies of light the galaxies emitted, the researchers discovered spikes of "extreme emission features" — a clear sign that the gas was capturing light from nearby stars before reemitting it.
"Gas cannot emit light on its own," Gupta said. "But the young, massive stars emit just the right type of radiation to excite the gas — and the early galaxies have lots of young stars."
After comparing this emission spectrum with those found in newer galaxies populating today's universe, the researchers found that around 1% had similar features. The researchers said that by studying these later galaxies, which are easier to measure, they will gain important insight into the earlier galaxies and the beginnings of the universe's chemistry.
"The chemical elements that make up everything tangible on Earth and the universe, except hydrogen and helium, originated in the cores of distant stars," Gupta said. "So, it is critical to understand the conditions surrounding galaxies and stars in the early universe for us to better understand our own world today."
|
Cosmology & The Universe
|
By Gaurava Khanna - University of Massachusetts DartmouthThe concept of time travel has always captured the imagination of physicists and laypersons alike. But is it really possible? Of course it is. We’re doing it right now, aren’t we? We are all traveling into the future one second at a time. But that was not what you were thinking. Can we travel much further into the future? Absolutely. If we could travel close to the speed of light, or in the proximity of a black hole, time would slow down enabling us to travel arbitrarily far into the future. The really interesting question is whether we can travel back into the past.I am a physics professor at the University of Massachusetts, Dartmouth, and first heard about the notion of time travel when I was 7, from a 1980 episode of Carl Sagan’s classic TV series, “Cosmos.” I decided right then that someday, I was going to pursue a deep study of the theory that underlies such creative and remarkable ideas: Einstein’s relativity. Twenty years later, I emerged with a Ph.D. in the field and have been an active researcher in the theory ever since.Now, one of my doctoral students has just published a paper in the journal Classical and Quantum Gravity that describes how to build a time machine using a very simple construction.Closed time-like curvesEinstein’s general theory of relativity allows for the possibility of warping time to such a high degree that it actually folds upon itself, resulting in a time loop. Imagine you’re traveling along this loop; that means that at some point, you’d end up at a moment in the past and begin experiencing the same moments since, all over again – a bit like deja vu, except you wouldn’t realize it. Such constructs are often referred to as “closed time-like curves” or CTCs in the research literature, and popularly referred to as “time machines.” Time machines are a byproduct of effective faster-than-light travel schemes and understanding them can improve our understanding of how the universe works. Over the past few decades well-known physicists like Kip Thorne and Stephen Hawking produced seminal work on models related to time machines.The general conclusion that has emerged from previous research, including Thorne’s and Hawking’s, is that nature forbids time loops. This is perhaps best explained in Hawking’s “Chronology Protection Conjecture,” which essentially says that nature doesn’t allow for changes to its past history, thus sparing us from the paradoxes that can emerge if time travel were possible.Perhaps the most well-known amongst these paradoxes that emerge due to time travel into the past is the so-called “grandfather paradox” in which a traveler goes back into the past and murders his own grandfather. This alters the course of history in a way that a contradiction emerges: The traveler was never born and therefore cannot exist. There have been many movie and novel plots based on the paradoxes that result from time travel – perhaps some of the most popular ones being the “Back to the Future” movies and “Groundhog Day.”Exotic matterDepending on the details, different physical phenomena may intervene to prevent closed time-like curves from developing in physical systems. The most common is the requirement for a particular type of “exotic” matter that must be present in order for a time loop to exist. Loosely speaking, exotic matter is matter that has negative mass. The problem is negative mass is not known to exist in nature.Caroline Mallary, a doctoral student at the University of Massachusetts Dartmouth has published a new model for a time machine in the journal Classical & Quantum Gravity. This new model does not require any negative mass exotic material and offers a very simple design.Mallary’s model consists of two super long cars – built of material that is not exotic, and have positive mass – parked in parallel. One car moves forward rapidly, leaving the other parked. Mallary was able to show that in such a setup, a time loop can be found in the space between the cars. So can you build this in your backyard?If you suspect there is a catch, you are correct. Mallary’s model requires that the center of each car has infinite density. That means they contain objects – called singularities – with an infinite density, temperature and pressure. Moreover, unlike singularities that are present in the interior of black holes, which makes them totally inaccessible from the outside, the singularities in Mallary’s model are completely bare and observable, and therefore have true physical effects.Physicists don’t expect such peculiar objects to exist in nature either. So, unfortunately a time machine is not going to be available anytime soon. However, this work shows that physicists may have to refine their ideas about why closed time-like curves are forbidden.Source: The Conversation
|
Cosmology & The Universe
|
By Jonathan AmosBBC Science CorrespondentImage source, NASA/ESA/CSA/STScIStunning images of a "stellar nursery" and a "cosmic dance" have been acquired by Nasa's new $10bn space telescope.The James Webb observatory, billed as the successor to the famous Hubble telescope, is showcasing its first full-colour pictures of the cosmos. US President Joe Biden gave a teaser on Monday, with the release of a photo depicting very far-off galaxies.Scientists on the project are following up with further images that demonstrate Webb's diverse capabilities.Follow live as the new pictures are releasedThe new observatory has been tuned to see the sky in the infrared - that's light at longer wavelengths that can be sensed by our eyes.This will give it the ability to look deeper into the Universe than its predecessor and, as a consequence, detect events occurring further back in time - more than 13.5 billion years ago.Astronomers also expect to use its more advanced technologies to study the atmospheres of distant planets in the hope that signs of life might be detected.The initial batch of images are just a taster of what is to come, says Prof Gillian Wright, the British researcher who's co-led one of Webb's four infrared instruments."Whenever you look at the sky in a new way, you see things that you didn't expect," the director of the UK Astronomy Technology Centre told BBC News. "The fact that these new data are so good, that they're of such good quality, that they've been obtained in just a few hours of observations - that's telling you that the discoveries are just sitting out there waiting to be made."SMACS 0723SMACS 0723 is a huge cluster of galaxies. It's known to astronomers as a "gravitational lens" because the mass of the cluster bends and magnifies the light of objects that are much further away. Everywhere you see a red arc-like structure - that's something - a galaxy - way off in the distance and far further back in time. The light in some of those arcs has taken over 13 billion years to reach us. And here's the slightly bizarre thing - some of those arcs on either side of the image are actually the same object. Their light has been bent through SMACS 0723 on more than one path. The Southern RingImage source, NASA/ESA/CSA/STScIYou'll have seen versions of this in those coffee table books of stunning Hubble images. The Southern Ring, or "Eight-Burst" nebula, is a giant expanding sphere of gas and dust that's been lit up by a dying star in the centre. As stars age, they change the way they make energy and eject their outer layers. And then, when the star gets very hot again, it energises all that material it had previously spurned. The Southern Ring is nearly half a light-year in diameter and is located about 2,000 light-years from Earth. This type of structure is called a "planetary nebula", but it actually has nothing to do with planets. It's a misnomer from the early days of telescopes when they didn't have anything like the resolution they have today. Just as Webb wants to see how stars are born, it wants to see how they die, also.Stephan's QuintetImage source, NASA/ESA/CSA/STScIAbout 290 million light-years away, Stephan's Quintet is located in the constellation Pegasus. It's notable for being the first compact galaxy group ever discovered. Four of the five galaxies within the quintet are locked in a cosmic dance of repeated close encounters. This Webb image doesn't look that different from the Hubble version at first glance, but the new telescope's infrared sensitivity will pull out different features for astronomers to study. And this was the great hope - that we would have Webb working alongside Hubble. They have different strengths and being able to compare and contrast will give scientists a new dimension to their studies. We don't know for how much longer Hubble will operate. It's 32 years old and prone to technical glitches. But the officials at Nasa who are in charge of the old warhorse have just submitted a five-year budget plan. Keep your fingers crossed.Media caption, Amber Straughn: Why the James Webb telescope sees in the infraredViewers in the UK can watch a special programme on Webb - Super Telescope: Mission to the Edge of the Universe - on BBC Two, on Thursday at 20:00 BST, or afterwards on BBC iPlayer.AstronomyNasaThe UniverseJames Webb Space TelescopeHubble TelescopeSpace exploration
|
Cosmology & The Universe
|
NASA and the Department of Energy (DOE) are working together to develop a science instrument that will survive the harsh and unforgiving environment of the lunar surface at night on the far side of the Moon to attempt first-of-its-kind measurements of the Dark Ages of the Universe. The instrument, named the Lunar Surface Electromagnetics Experiment – Night (LuSEE-Night), is a collaboration between DOE’s Brookhaven National Laboratory, the DOE Office of Science, UC Berkeley’s Space Sciences Laboratory, and NASA’s Science Mission Directorate.
LuSEE-Night is a pathfinder to understand the Moon’s radio environment and to potentially take a first look at a previously unobserved era in our cosmic history. This collaboration further strengthens the longstanding partnership between NASA and the DOE to enable space innovation and exploration.
The Dark Ages is an important epoch in cosmological studies as it can provide new insights into the formation and evolution of our Universe. The Dark Ages occurred between approximately 380 thousand – 400 million years after the origin of the universe, known as the Big Bang, and are a time before the first luminous stars and galaxies appeared. Since radio waves present the only signal we can measure from the Dark Ages, LuSEE provides an opportunity to learn how the first non-luminous matter evolved into the stars and galaxies that we see dominating the observable Universe today.
Unfortunately, these important radio wave signals from the Dark Ages are impossible to measure from Earth’s surface due to our planet’s opaque ionosphere and the noise from Earth’s constant “pollution” of the inner solar system with radio waves. However, due to the Moon’s lack of an interfering ionosphere – and due to the far side of the Moon being constantly shielded from harmful radio emissions from Earth, as well as the Sun during the lunar night – the far side of the Moon offers a unique environment that allows for observations of sensitive radio astronomy signals that cannot be obtained anywhere else in the near-Earth space environment. LuSEE-Night, which will be delivered to the far side of the Moon on a future Commercial Lunar Payload Services (CLPS) flight, will utilize deployable antennas and radio receivers to potentially observe these sensitive radio waves from the Dark Ages for the first time. By physically being on the lunar surface and taking measurements at the right time, several external sources of radio interference will be removed, including radio noise from the Sun, Earth, Jupiter, and Saturn. ;
“LuSEE-Night is a fascinating experiment that will get us closer to observing something we’ve never been able to before - the Dark Ages signal,” said Asmeret Asefaw Berhe, DOE’s Director of the Office of Science. “With this collaboration, DOE and NASA are setting conditions for successful exploration of the Dark Ages cosmology in the decades to come.”
However, a significant challenge will be for the instrument to survive the harsh, cold, and dark environment of the lunar night on the far side of the Moon long enough to collect and return data to Earth. Throughout the day and night cycle on the Moon, temperatures swing between around 250°F (120°C) during the day and -280°F (-173°C) at night. This temperature range presents a significant challenge to not only taking and transmitting the data, but also in keeping the instrument from freezing and ending the mission prematurely. Thus, technology to survive the lunar night is critical for not only robotic activities, but for creating a sustained human presence on the lunar surface.
“LuSEE-Night will operate during the cold temperatures of the 14-day lunar night, when no sunlight is available to generate power or heat” said Joel Kearns, deputy associate administrator for exploration in NASA’s Science Mission Directorate. “In addition to the significant potential science return, demonstration of the LuSEE-Night lunar night survival technology is critical to performing long-term, high-priority science investigations from the lunar surface.”
If successful, LuSEE-Night will act as a pathfinder to help inform larger future instruments to further measure these otherwise undetectable radio frequencies, and help scientists better understand the earliest period of the Universe’s formation and evolution.
"This measurement is very challenging, radio emission from the galaxy is very bright and our Dark Ages signal is hiding behind it” said LuSEE-Night PI Stuart D. Bale. Anže Slosar, the LuSEE-Night science collaboration spokesperson, added "Every time we have opened a new frequency window in cosmology, we have unlocked new discoveries about the history of the Universe and our place within it."
LuSEE-Night is planned to be delivered to the Moon on a future CLPS flight. Through CLPS flights, NASA is buying a complete commercial robotic lunar delivery service and does not provide launch services, own the lander, or lead landing operations. Prof. Stuart D. Bale of University of California, Berkeley is the NASA Principal Investigator for LuSEE-Night with Anže Slosar and Sven Herrmann from Brookhaven National Laboratory as the DOE lead and project manager, respectively.
|
Cosmology & The Universe
|
Julian Muñoz has come up with a ruler to measure the early universe.
A theoretical physicist, Muñoz studies the distant, dim period in the universe’s history known as cosmic dawn. That’s when stars first began flickering on, a few hundred million years after the Big Bang, infusing the universe with initial glimmers of starlight and forming the first galaxies.
Before the first stars, the universe was cold and dark — as Muñoz describes it, “boring.” Then, starlight began to reshape the universe. “It is a very dramatic epoch,” says Muñoz, of the University of Texas at Austin.
That epoch is also poorly understood. Cosmic dawn is so unexplored that Muñoz compares it to an uncharted area on early maps of Earth. There, Muñoz says, “there could be dragons.” By studying this era, he hopes to reveal the behavior of one dragon of the cosmos, dark matter, the inscrutable substance whose mass binds galaxies.
But to understand the cosmos, scientists have to be able to measure it. Looking far into space means looking deep into the past. The trouble is our 2-D view of the sky doesn’t readily reveal how far away things are. “When we look at the night sky, we’ve got no depth perception,” says cosmologist Adrian Liu of McGill University in Montreal.
Scientists have devised a variety of methods to get a handle on distances, including standard candles and standard rulers — objects of known brightness or length. If you know how bright an object is (compared with how bright it appears) or you know how long a particular feature is on the sky (compared with its apparent length), you can tell how far away it is. A ruler looks smaller from 20 meters away than from 10 meters away, and a 20-watt lightbulb looks dimmer the farther away it is. The same applies over cosmic distances.
Scientists use certain types of exploding stars, for example, to estimate distances, because the blasts put out a predictable light show (SN: 5/8/12). Standard rulers or standard candles can be used to trace out how far away other objects of interest are and reveal how rapidly the universe has expanded over its history.
But none of the known standard objects reach back to the cosmic dawn era. That’s where Muñoz’s ruler comes in. “This ability to reach that far back,” Liu says, “that’s the really valuable thing.”
Sizing up cosmic dawn
No one has ever seen a conclusive signature of cosmic dawn — the very first galaxies are too distant to observe directly. But there’s another way to spot cosmic dawn’s effects, one that’s been a long-sought target for astronomers. As the first stars formed, their light heated the surrounding hydrogen gas, causing it to absorb light with a wavelength of 21 centimeters, a number that results from the separation between energy levels in hydrogen atoms. Observing that 21-centimeter absorption signal is the aim of the Hydrogen Epoch of Reionization Array, or HERA, collaboration, an effort that Muñoz and Liu both work on, using a radio telescope in South Africa.
If it can be detected, this absorption signal should have subtle, ring-shaped patterns imprinted in it, Muñoz reported in 2019 in Physical Review Letters.
Those patterns, the basis of his ruler, result from the differing behavior of dark matter and normal matter during an even earlier period, less than 400,000 years after the Big Bang. Sound waves careening through the plasma at that time would have pushed normal matter to high speeds while leaving dark matter at a standstill.
This mismatch in velocities affected where galaxies formed during the later cosmic dawn era. To create a galaxy, dark matter must gravitationally reel in normal matter. But where the velocities differed, the normal matter zipped right on by. The early universe was left with sparsely populated regions of the sky, arranged in ring-shaped patterns with a predictable distance scale. The rings, which are too subtle to pick out by eye from the data but show up in statistical analyses, have radii of half a billion light-years – that’s one long measuring stick.
The new standard ruler could reveal how fast the universe was expanding back then. That information can tell scientists what that youthful universe was made of, revealing the amount of dark matter, normal matter and dark energy, another hidden piece of the cosmic puzzle.
Subscribe to Science News
Get great science journalism, from the most trusted source, delivered to your doorstep.
A new expansion measurement could also add fuel to one of the fiercest debates in cosmology. Currently, different measurements of the universe’s expansion rate clash with one another, leaving scientists pondering whether there are flaws in our understanding of the cosmos.
Seeking to understand the unknown, including these shadowy cosmic realms, is “an integral component of human nature — like art and poetry,” Muñoz says. “You could live without it, but I really hope you don’t have to.”
Looking into dark corners
Muñoz’s interest in dark matter drew him to the cosmic dawn. The first galaxies grew off a scaffold of dark matter. So information about how and when those galaxies formed can reveal dark matter’s properties. In a report published in 2018 in Nature, for example, Muñoz and colleagues suggested that, if some of the universe’s dark matter had a tiny electric charge, a millionth of an electron’s, that could alter the expected cosmic dawn signal.
He has also developed important computational tools, like a new technique that allows for lightning-fast simulations of the cosmic dawn, reported February 16 at arXiv.org. The time it takes to perform these simulations has previously limited what scientists can study.
“He’s got an eye for interesting ideas,” says theoretical physicist Marc Kamionkowski of Johns Hopkins University, Muñoz’s Ph.D. adviser. But the cosmic ruler, “that’s probably the most singular idea that he’s had.”
Becoming a physicist, in itself, was uncharted territory for Muñoz. As a child, he liked science. He recalls being amazed by fossilized shark teeth that were millions of years old — perhaps his first experience grappling with such grand timescales.
But Muñoz didn’t have a scientific role model; his parents didn’t finish high school. He focused his attention on video games and coding until a high school physics teacher encouraged his scientific streak. He turned to physics, he says, where “it was possible to channel all this nerdy energy for knowledge.” That’s what drives Muñoz to explore the questions that swirl around dark corners of the cosmos. “I do it because I think the answers enrich the human experience.”
Julian Muñoz is one of this year’s SN 10: Scientists to Watch, our list of 10 early and mid-career scientists who are making extraordinary contributions to their field. We’ll be rolling out the full list throughout 2023.
Want to nominate someone for the SN 10? Send their name, affiliation and a few sentences about them and their work to sn10@sciencenews.org.
|
Cosmology & The Universe
|
Among the newly released images are breathtaking views of a distant galaxy group called Stephan’s Quintet that was discovered in 1877.The Webb telescope's view of the Carina Nebula reveals previously invisible areas of star birth.Space Telescope Science Institute / NASA, ESA, CSA, STScIJuly 12, 2022, 3:07 PM UTCA new era of astronomy has begun.NASA on Tuesday released a full batch of images and data from the James Webb Space Telescope, providing a tantalizing first look at the cosmic mysteries that could be untangled in the years ahead by humanity's largest and most powerful space observatory.Among the newly released images are breathtaking views of a distant galaxy group called Stephan's Quintet that was discovered in 1877, a stellar nursery called the Carina Nebula that plays host to many stars that are several times larger than the sun, and the Southern Ring Nebula, a huge expanding shell of gas around a dying star."Every image is a new discovery and each will give humanity a view of the universe that we've never seen before," NASA Administrator Bill Nelson said during an event held at the Goddard Space Flight Center to introduce the images.This group of five galaxies is known as Stephan's Quintet, located roughly 290 million light-years away in the constellation Pegasus.Space Telescope Science Institute / NASA, ESA, CSA, STScIThe long-awaited release of the Webb telescope's first images comes after NASA and the White House gave the public a sneak peek a day early, unveiling a stunning view captured of a patch of sky overflowing with bright galaxies.The so-called "deep field view" showed massive clusters of galaxies in the foreground that are magnifying and distorting light from fainter and much more distant celestial objects behind them.That image, along with the full series released Tuesday by the space agency, hint at the sheer power and unparalleled capabilities of the $10 billion-Webb telescope. Scientists have said the observatory, which will be able to see deeper into space and in greater detail than any telescope that has come before it, could revolutionize human understanding of the universe.The Webb telescope captured the Southern Ring Nebula, a huge expanding shell of gas around a dying star, in unprecedented detail.Space Telescope Science Institute / NASA, ESA, CSA, STScIThis week's release included the Webb telescope's first spectrum of an exoplanet, showing light emitted at different wavelengths from WASP-96b, a planet outside our solar system that was discovered in 2014. WASP-96b, located more than 1,000 light-years away from Earth, has roughly half the mass of Jupiter and is primarily made up of gas, according to NASA.While WASP-96b is too hot and located too close to its parent star to be considered habitable, Webb's spectrum revealed the presence of water vapor in the planet's atmosphere.Webb's observations of exoplanets, including with instruments sensitive enough to study the chemical fingerprints of their atmospheres, could help guide the search for potential life beyond Earth.The Webb telescope, a collaboration among NASA, the European Space Agency and the Canadian Space Agency, launched into space Dec. 25, 2021. After spending more than six months testing and configuring the spacecraft's various instruments, NASA officials said the observatory's science operations are now ready to begin in earnest.The spacecraft, which is the size of a tennis court, is equipped with infrared "eyes" that can pierce through dust and gas that might otherwise make some stars, galaxies and celestial targets undetectable. As such, the telescope is expected to provide first-of-its-kind infrared views of the universe, and capture some never-before-seen cosmic objects.The James Webb Space Telescope captured different wavelengths of light from an exoplanet known as WASP-96b, located more than 1,000 light-years away from Earth. The so-called spectrum revealed water vapor in the planet's atmosphere.Space Telescope Science Institute / NASA, ESA, CSA, and STScITelescopes like Webb can essentially peer back into the universe's history because it takes time for light to travel through space. This means that light detected by Webb from the most distant galaxies in the cosmos provides insight into the universe as it was billions of years ago.Billed as the successor to the prolific Hubble Space Telescope, the Webb observatory is designed to study the earliest stars and galaxies in the universe. Researchers have said that Webb could unlock mysteries from as far back as 100 million years after the Big Bang — observations that could help astronomers understand how the modern universe came to be.Denise Chow is a reporter for NBC News Science focused on general science and climate change.
|
Cosmology & The Universe
|
For the first time, scientists may have discovered indirect evidence that large amounts of invisible dark matter surround black holes. The discovery, if confirmed, could represent a major breakthrough in dark matter research. Space.com reports: Dark matter makes up around 85% of all matter in the universe, but it is almost completely invisible to astronomers. This is because, unlike the matter that comprises stars, planets and everything else around us, dark matter doesn't interact with light and can't be seen. Fortunately, dark matter does interact gravitationally, enabling researchers to infer the presence of dark matter by looking at its gravitational effects on ordinary matter "proxies." In the new research, a team of scientists from The Education University of Hong Kong (EdUHK) used stars orbiting black holes in binary systems as these proxies.
The team watched as the orbits of two stars decayed, or slightly slowed, by about 1 millisecond per year while moving around their companion black holes, designated A0620-00 and XTE J1118+480. The team concluded that the slow-down was the result of dark matter surrounding the black holes which generated significant friction and a drag on the stars as they whipped around their high-mass partners.
Using computer simulations of the black hole systems, the team applied a widely held model in cosmology called the dark matter dynamical friction model, which predicts a specific loss of momentum on objects interacting gravitationally with dark matter. The simulations revealed that the observed rates of orbital decay matched the predictions of the friction model. The observed rate of orbital decay is around 50 times greater than the theoretical estimation of about 0.02 milliseconds of orbital decay per year for binary systems lacking dark matter. The study has been published in The Astrophysical Journal Letters.
The team watched as the orbits of two stars decayed, or slightly slowed, by about 1 millisecond per year while moving around their companion black holes, designated A0620-00 and XTE J1118+480. The team concluded that the slow-down was the result of dark matter surrounding the black holes which generated significant friction and a drag on the stars as they whipped around their high-mass partners.
Using computer simulations of the black hole systems, the team applied a widely held model in cosmology called the dark matter dynamical friction model, which predicts a specific loss of momentum on objects interacting gravitationally with dark matter. The simulations revealed that the observed rates of orbital decay matched the predictions of the friction model. The observed rate of orbital decay is around 50 times greater than the theoretical estimation of about 0.02 milliseconds of orbital decay per year for binary systems lacking dark matter. The study has been published in The Astrophysical Journal Letters.
|
Cosmology & The Universe
|
Subsets and Splits
List Unique Topics
Simple retrieval of unique topics from the dataset, useful for basic exploration but lacks deeper insights.