abstract stringlengths 3 192k | title stringlengths 4 857 |
|---|---|
aims: here we aim to characterise submillimetre water masers at 437, 439, 471, and 474 ghz towards a sample of evolved stars.methods: we used the atacama pathfinder experiment (apex1) to observe submillimetre water transitions and the co (4-3) line towards 11 evolved stars. the sample included semi-regular and mira var... | submillimetre water masers at 437, 439, 471, and 474 ghz towards evolved stars. apex observations and radiative transfer modelling |
an innovative mixing unit of the proposed mixer named joint-injection-mixer (jim) features both wide if and rf bandwidths (bws) for next-generation advanced heterodyne receivers of millimeter-wave astronomy. this proposed mixer demonstrates an rf frequency range from 60 to 148 ghz and an if frequency range from dc to 3... | an innovative joint-injection mixer with broadband if and rf for advanced heterodyne receivers of millimeter-wave astronomy |
as the next-generation radio astronomical telescopes continuously improve and develop, the pulsar survey will produce millions of pulsar candidates, which pose considerable challenges for pulsar identification and classification. the rapidly evolving artificial intelligence (ai) techniques are being used for pulsar ide... | research on pulsar candidate identification method based on deep residual neural network |
interferometric measurements with arrays of radio antennas are a powerful and widely used technique in astronomy. recently, this technique has been revisited for the reconstruction of extensive air showers [1]. this "radio-interferometric technique" exploits the coherence in the radio emission emitted by billions of se... | expected performance of air-shower measurements with the radio-interferometric technique |
radio timing observations of a millisecond pulsar in orbit around the galactic centre black hole (bh) or a bh at the centre of globular clusters could answer foundational questions in astrophysics and fundamental physics. pulsar radio astronomy typically employs the post-keplerian approximation to determine the system ... | radio timing in a millisecond pulsar - extreme/intermediate mass ratio binary system |
cosmic-ray (cr) sources temporarily enhance the relativistic particle density in their vicinity over the background distribution accumulated from the galaxy-wide past injection activity and propagation. if individual sources are close enough to the solar system, their localized enhancements may present as features in t... | signatures of recent cosmic-ray acceleration in the high-latitude gamma-ray sky |
following a report of bright radio flaring of the magnetar xte j1809-197 detected with the 76-m lovell telescope at jodrell bank (atel #12284), observations of this neutron star were conducted with the 100-m effelsberg radio telescope of the max planck institute for radio astronomy. | high-frequency observations of the radio magnetar xte j1810-197 |
the critical performance indicators of the tm65 m radio telescope are described. we report the antenna efficiency, sensitivity, and system noise temperature performance measurements in ku, k, ka, and q bands. the key indicators of the four bands' receiving systems are introduced firstly. the issues which are critical t... | antenna performance measurements in ku, k, ka, and q bands for the tm65 m radio telescope |
prominence temperatures have so far mainly been determined by analyzing spectral line shapes, which is difficult when the spectral lines are optically thick. the radio spectra in the millimeter range offer a unique possibility to measure the kinetic temperature. however, studies in the past used data with insufficient ... | on the visibility of prominence fine structures at radio millimeter wavelengths |
what happens to space and matter near a black hole? where did the moon come from? how do we know what stars are made of? are we alone in the universe? in exploding stars and invisible planets, fred watson, an award-winning astronomer, presents the most up-to-date knowledge on hot topics in astronomy and space science, ... | exploding stars and invisible planets: the science of what's out there |
the south african meerkat radio telescope, a precursor to the square kilometre array (ska) will be incorporated into the mid-frequency component of ska phase 1. after a decade of planning, designing and construction, the meerkat radio antenna was officially inaugurated in july of 2018. several exciting astronomical phe... | a proposed optical frequency synchronization system for the south african meerkat radio telescope |
recently, astronomy has witnessed great advancements in detectors and telescopes. imaging data collected by these instruments are organized into very large datasets that form data-oriented astronomy. the imaging data contain many radio galaxies (rgs) that are interesting to astronomers. however, considering that the sc... | research on morphological detection of fr i and fr ii radio galaxies based on improved yolov5 |
new deep vla d array hi observations of the highly inclined nearby spiral galaxy ngc 2683 are presented. archival c array data were processed and added to the new observations. to investigate the 3d structure of the atomic gas disk, we made different 3d models for which we produced model hi data cubes. the main ingredi... | the flaring hi disk of the nearby spiral galaxy ngc 2683 |
extragalactic jets launched from the immediate vicinity of supermassive black holes in radio-loud active galactic nuclei (agn) are key objects in modern astronomy and astroparticle physics. agn jets carry a fraction of the total gravitational energy released during the accretion of matter onto supermassive black holes ... | tanami:multiwavelength and multimessenger observations of active galaxies |
digital channelization decomposes a wideband signal into multiple adjacent sub-bands using parallel technology. channelization can effectively reduce the pressure on the radio astronomy digital backends system and make wideband signal processing possible. aiming at the problems of signal attenuation at sub-band edge, s... | research on channelization techniques of radio astronomical wideband signal with oversampled polyphase filter banks |
superconducting detectors, such as microwave kinetic inductance detectors (mkids), are sensitive to the effects of ambient magnetic fields. there are two effects magnetic fields have on the response of mkids; the trapping of magnetic fields inside the superconducting materials degrades the resonator quality, and the ti... | optimization of geomagnetic shielding for mkids mounted on a rotating cryostat |
we experience a golden era in testing and exploring relativistic gravity. whether it is results from gravitational wave detectors, satellite or lab experiments, radio astronomy plays an important complementary role. here one can mention the cosmic microwave background, black hole imaging and, obviously, binary pulsars.... | new results from testing relativistic gravity with radio pulsars |
we present a new set of measurements obtained with the combined array for research in millimeter-wave astronomy (carma) of jupiter’s microwave thermal emission near the 1.3 cm ammonia (nh3) absorption band. we use these observations to investigate the ammonia mole fraction in the upper troposphere, near 0.3 < p <... | a wideband self-consistent disk-averaged spectrum of jupiter near 30 ghz and its implications for nh3 saturation in the upper troposphere |
beam propagation at millimeter and submillimeter wavelengths is well described by gaussian beams and quasi-optical theory. due to the general progress in thz technology, receiver and other quasi-optical systems in the thz range demand increasingly larger bandwidths. in this context, this paper presents a general design... | frequency independent design of quasi-optical systems |
this dissertation spans two topics relating to optical to near-infrared astronomical cameras built around microwave kinetic inductance detectors (mkids). the first topic is the development of a digital readout system for 10- to 30-kilopixel arrays of mkids. mkids are superconducting detectors that can detect individual... | digitial readout for microwave kinetic inductance detectors and applications in high time resolution astronomy |
galaxy clusters are known to host a variety of extended radio sources: tailed radio galaxies whose shape is modelled by the interaction with the intra-cluster medium (icm); radio bubbles filling cavities in the icm distribution and rising buoyantly through the thermal gas; diffuse giant radio sources ("halos" and "reli... | non-thermal emission from galaxy clusters: feasibility study with ska |
maser (measurements, analysis, and simulation of emission in the radio range) is a com- prehensive infrastructure dedicated to time-dependent low frequency radio astronomy (up to about 50 mhz). the main radio sources observed in this spectral range are the sun, the magnetized planets (earth, jupiter, saturn), and our g... | maser: a science ready toolbox for low frequency radio astronomy |
the discovery of diffuse radio emission in galaxy clusters proved the existence of energetic cosmic-ray electrons and cosmic magnetic fields on mpc-scales in the universe. furthermore, both magnetic fields and cosmic-ray electrons are predicted to exist beyond galaxy clusters, namely, in the filaments and voids of the ... | cosmic-ray acceleration and magnetic fields in galaxy clusters and beyond: insights from radio observations |
context. very long baseline interferometry (vlbi) data are extremely sensitive to the phase stability of the vlbi array. this is especially important when we reach μjy rms sensitivities. calibration using standard phase-referencing techniques is often used to improve the phase stability of vlbi data, but the results ar... | multi-source self-calibration: unveiling the microjy population of compact radio sources |
internal shocks between propagating plasma shells, originally ejected at different times with different velocities, are believed to play a major role in dissipating the kinetic energy, thereby explaining the observed light curves and spectra in a large range of transient objects. even if initially the colliding plasmas... | dynamical properties of internal shocks revisited |
many attempts have been made to provide catalogs of potential sources of ultra-high energy cosmic ray (uhecr) particles based on various astronomical tracers, such as observed radio or gamma-ray emission. a closer look reveals, however, that they all suffer from significant bias and selection effects. we present here a... | a parametrized catalog of radio galaxies as uhecr sources |
this chapter introduces the concepts of polarimetry in the case of low frequency radio astronomy. in this regime radio waves are usually not the signature of atomic or molecular transitions lines, but rather that of unstable particle distribution functions releasing their free energy through electromagnetic radiation. ... | polarization in low frequency radio astronomy |
short duration gamma ray bursts (sgrb) and their afterglows are among the most promising electromagnetic (em) counterparts of neutron star (ns) mergers. the afterglow emission is broad-band, visible across the entire electromagnetic window from γ-ray to radio frequencies. the flux evolution in these frequencies is sens... | exploring short-grb afterglow parameter space for observations in coincidence with gravitational waves |
a neutron star was first detected as a pulsar in 1967. it is one of the most mysterious compact objects in the universe, with a radius of the order of 10 km and masses that can reach two solar masses. in fact, neutron stars are star remnants, a kind of stellar zombies (they die, but do not disappear). in the last decad... | a neutron star is born |
we explore opportunities for multi-messenger astronomy using gravitational waves (gws) and prompt, transient low-frequency radio emission to study highly energetic astrophysical events. we review the literature on possible sources of correlated emission of gws and radio transients, highlighting proposed mechanisms that... | multi-messenger astronomy of gravitational-wave sources with flexible wide-area radio transient surveys |
the method to establish the pointing model of the 65-meter radio telescope of shanghai astronomical observatory (tm65 m) is described. the single-point data are collected by means of "cross scan", then, they are fitted with a model including both the gaussian and nonlinear terms. it is also simulated and analyzed how t... | the establishment of pointing model for the tm65 m radio telescope |
extreme outbursts in young stars may be a common stage of pre-main-sequence stellar evolution. these outbursts, caused by enhanced accretion and accompanied by increased luminosity, can also strongly impact the evolution of the circumstellar environment. we present atacama large millimeter array (alma) and very large a... | alma and vla observations of ex lupi in its quiescent state |
we propose a new observing method for single-dish millimeter and submillimeter spectroscopy using a heterodyne receiver equipped with a frequency-modulating local oscillator (fmlo). unlike conventional switching methods, which extract astronomical signals by subtracting the reference spectra of off-sources from those o... | a new off-point-less observing method for millimeter and submillimeter spectroscopy with a frequency-modulating local oscillator |
the present work is an effort to investigate possible radial variations in the solar coronal rotation by analysing the solar radio emission data at 15 different frequencies (275-1755 mhz) for the period starting from 1994 july to 1999 may. we used a time series of disc-integrated radio flux recorded daily at these freq... | radial differential rotation of solar corona using radio emissions |
aims: the sample of serendipitous sources detected in all swift-xrt images pointing at gamma ray bursts (grbs) constitutes the largest existing medium-deep survey of the x-ray sky. to build such dataset we analysed all swift x-ray images centred on grbs and observed over a period of 15 years using automatic tools that ... | open universe survey of swift-xrt grb fields: flux-limited sample of hbl blazars |
the green bank telescope diffuse ionized gas survey (gdigs) is a fully sampled radio recombination line (rrl) survey of the inner galaxy at c-band (4-8 ghz). we average together ∼15 hnα rrls within the receiver bandpass to improve the spectral signal-to-noise ratio. the average beam size for the rrl observations at the... | the gbt diffuse ionized gas survey: tracing the diffuse ionized gas around the giant hii region w43 |
fast radio transient search algorithms identify signals of interest by iterating and applying a threshold on a set of matched filters. these filters are defined by properties of the transient such as time and dispersion. a real transient can trigger hundreds of search trials, each of which has to be post-processed for ... | robust assessment of clustering methods for fast radio transient candidates |
the epoch of reionisation (eor) is the period within which the neutral universe transitioned to an ionised one. this period remains unobserved using low-frequency radio interferometers, which target the 21 cm signal of neutral hydrogen emitted in this era. the murchison widefield array (mwa) radio telescope was built w... | simulations of ionospheric refraction on radio interferometric data |
astronomy has always been propelled by the discovery of new phenomena lacking precedent, often followed by new theories to explain their existence and properties. in the modern era of large surveys tiling the sky at ever high precision and sampling rates, these serendipitous discoveries look set to continue, with recen... | black swans in astronomical data |
although fast radio bursts (frbs) have been an active field in astronomy and cosmology, their origin is still unknown to date. one of the interesting topics is the classification of frbs, which is closely related to the origin of frbs. different physical mechanisms are required by different classes of frbs. in the lite... | a possible subclassification of fast radio bursts |
using the fourier domain acceleration search (fdas) method to search for binary pulsars is a computationally costly process. next generation radio telescopes will have to perform fdas in real time, as data volumes are too large to store. fdas is a matched filtering approach for searching time-domain radio astronomy dat... | cutting the cost of pulsar astronomy: saving time and energy when searching for binary pulsars using nvidia gpus |
narrowband radio search for extraterrestrial intelligence (seti) in the 21st century suffers severely from radio frequency interference (rfi), resulting in a high number of false positives, and it could be the major reason why we have not yet received any messages from space. we thereby propose a novel observation stra... | a solution to continuous rfi in narrowband radio seti with fast: the multibeam point-source scanning strategy |
we investigate the conditions for the h i-to-h2 transition in the solar neighborhood by analyzing h i emission and absorption measurements toward 58 galactic lines of sight (loss) along with 12co(1-0) (co) and dust data. based on the accurate column densities of the cold and warm neutral medium (cnm and wnm), we first ... | probing the conditions for the h i-to-h2 transition in the interstellar medium |
radio frequency interference (rfi) is unwanted noise that swamps the desired astronomical signal. radio astronomers have always had to deal with rfi detection and excision around telescope sites, but little has been done to understand the full scope, nature and evolution of rfi in a unified way. we undertake this for t... | nature and evolution of uhf and l-band radio frequency interference at the meerkat radio telescope |
quasars show a remarkable degree of atomic emission-line broadening, an observational feature which, in conjunction with a radial distance estimate for this emission from the nucleus, is often used to infer the mass of the central supermassive black hole. the radius estimate depends on the structure and kinematics of t... | confronting a thin disk-wind launching mechanism of broad-line emission in active galactic nuclei with gravity observations of quasar 3c 273 |
we develop a process of image-plane self-calibration for interferometric imaging data. the process is based on shape-orientation-size (sos) conservation for the principal triangle in an image generated from the three fringes made from a triad of receiving elements, in situations where interferometric phase errors can b... | image-plane self-calibration in interferometry |
dual and off-nucleus active supermassive black holes are expected to be common in the hierarchical structure formation paradigm, but their identification at parsec scales remains a challenge due to strict angular resolution requirements. we conducted a systematic study using the very long baseline array (vlba) to exami... | varstrometry for off-nucleus and dual sub-kiloparsec active galactic nuclei (vodka): very long baseline array searches for dual or off-nucleus quasars and small-scale jets |
radio frequency interference (rfi) mitigation for pulsar signals is a long perplexing issue in astrophysical measurements. linear mitigation methods are often criticized for limited rfi excision range and weakness of rfi modeling. meanwhile, thresholding methods (e.g., the sumthreshold) suffer from empirical factors. i... | robust rfi excision for pulsar signals by a novel nonlinear m-type estimator with an application to pulsar timing |
the conversion of a former 100-foot (30-m) telecommunications antenna (earth station) in new zealand into a radio telescope is described. a specification of the antenna and the priorities for its actual conversion are initially presented. in describing the actual conversion, particular emphasis is given to mechanical a... | conversion of a new zealand 30-metre telecommunications antenna into a radio telescope |
we report the first wideband monitoring observations of psr j1803-3002a, a relatively bright millisecond pulsar (msp) in the globular cluster ngc 6522 with a spin period of 7.1 ms and no known binary companion. these observations were performed using the parkes 64 m radio telescope with the ultra-wideband low receiver ... | wideband monitoring observations of psr j1803-3002a in the globular cluster ngc 6522 |
realizing the next generation of radio telescopes such as the square kilometre array (ska) requires both more efficient hardware and algorithms than today's technology provides. the image-domain gridding (idg) algorithm is a novel approach towards solving the most compute-intensive parts of creating sky images: griddin... | radio-astronomical imaging on graphics processors |
a crucial part of a space mission for very-long baseline interferometery (vlbi), which is the technique capable of providing the highest resolution images in astronomy, is orbit determination of the mission's space radio telescope(s). in order to successfully detect interference fringes that result from correlation of ... | radioastron orbit determination and evaluation of its results using correlation of space-vlbi observations |
in this research, we develop a new method of upgrading the radio pointing model of an important instrument of the caltech submillimeter observatory (cso) telescope, i.e., the submillimeter high angular resolution camera ii (sharc ii), by making three types of structural reconstruction of its existing model. first, the ... | an improved radio pointing model for sharc ii of the caltech submillimeter observatory telescope |
we present the design, implementation, and characterization of the optics of alma band 1, the lowest frequency band in the most advanced radio astronomical telescope. band 1 covers the broad frequency range from 35 to 50 ghz, with the goal of minor degradation up to 52 ghz. this is, up to now, the largest fractional ba... | high efficiency wideband refractive optics for alma band-1 (35-52 ghz). design, implementation, and measurement results |
radio-frequency interference (rfi) can significantly contaminate the measured radiometric signal of current spaceborne l-band passive microwave radiometers. these spaceborne radiometers operate within the protected passive remote sensing and radio-astronomy frequency allocation of 1400-1427 mhz but nonetheless are stil... | radio-frequency interference mitigating hyperspectral l-band radiometer |
the data recently accumulated by the kepler mission have demonstrated that small planets are quite common and that a significant fraction of all stars may have an earth-like planet within their habitable zone. these results are combined with a drake-equation formalism to derive the space density of biotic planets as a ... | on the abundance of extraterrestrial life after the kepler mission |
the issue of radio frequency interference (rfi) is a widespread problem in most microwave earth observation missions, and passive instruments are particularly sensitive to rfi. this is the case for smos, soil moisture and ocean salinity, a satellite of the european space agency, which operates in the 1400-1427 mhz band... | smos esa rfi monitoring and information tool: lessons learned |
the formation of the first stars and galaxies during `cosmic dawn' is thought to have imparted a faint signal onto the 21-cm spin temperature from atomic hydrogen gas in the early universe. observationally, an absorption feature should be measurable as a frequency dependence in the sky-averaged (i.e. global) temperatur... | beamforming approaches towards detecting the 21-cm global signal from cosmic dawn with radio array telescopes |
high-performance dual-polarization receiver optics is a key component of terahertz applications with stringent requirements, such as radio astronomy or planetary exploration. usually, such optics use corrugated horns due to their excellent wideband performance. however, this kind of horns is difficult to fabricate for ... | 1.25-1.57 thz dual-polarization receiver optics based on corrugated horns |
a high-performance low-loss high-reflection-loss compact double-ridged waveguide orthomode transducer (omt) for the 67-116 ghz band has been designed, fabricated, and tested. the focus in the design has been to achieve the best possible performance while keeping the design compact and fabrication as simple as possible.... | double-ridged waveguide orthomode transducer (omt) for the 67-116-ghz band |
pulsars are exotic objects which have yielded a bounty of important astrophysical results. as rapidly rotating, highly magnetized neutron stars, pulsars' stable rotation and beamed radio emission enables their use as interstellar laboratory clocks. the extraordinary timing regularity of the millisecond pulsar (msp) pop... | wideband observations of radio pulsars |
an exhaustive analysis of 9 yr optical r-band photopolarimetric data of the flat-spectrum radio quasar 3c 279 from 2008 february 27 to 2017 may 25 is presented, along with multiwavelength observing campaigns performed during the flaring activity exhibited in 2009 february/march, 2011 june, 2014 march/april, 2015 june, ... | optical polarimetric and multiwavelength flaring activity of blazar 3c 279 |
the meerkat radio telescope consists of 64 gregorian-offset antennas located in the karoo in the northern cape in south africa. the antenna system consists of multiple subsystems working collaboratively to form a cohesive instrument capable of operating in multiple modes for defined science cases. we focus on the chann... | meerkat correlator-beamformer: a real-time processing back-end for astronomical observations |
detecting single-pulse astronomical transients, such as pulsars or fast radio bursts, requires collecting and processing enormous amounts of data. amber is a software processing pipeline that makes it possible to detect these single-pulse phenomena in real-time. the software achieves this by offloading compute-intensiv... | amber: a real-time pipeline for the detection of single pulse astronomical transients |
fortesfit efficiently explores and discriminates between various spectral energy distributions (sed) models of astronomical sources. the python package adds bayesian inference to a framework that is designed for the easy incorporation and relative assessment of sed models, various fitting engines, and a powerful treatm... | fortesfit: flexible spectral energy distribution modelling with a bayesian backbone |
galaxy mergers play a crucial role in the formation of massive galaxies and the buildup of their bulges. an important aspect of the merging process is the in-spiral of the supermassive black-holes (smbhs) to the centre of the merger remnant and the eventual formation of a smbh binary. if both the smbhs are accreting th... | dual active galactic nuclei in nearby galaxies |
in radio astronomy, the ultra-long wavelengths (ulw) regime of longer than 10 m (frequencies below 30 mhz), remains the last virtually unexplored window of the celestial electromagnetic spectrum. the strength of the science case for extending radio astronomy into the ulw window is growing. however, the opaqueness of th... | antenna design and implementation for the future space ultra-long wavelength radio telescope |
many-degree-scale gamma-ray halos are expected to surround extragalactic high-energy gamma-ray sources. these arise from the inverse compton emission of an intergalactic population of relativistic electron/positron pairs generated by the annihilation of ≳ 100 {gev} gamma rays on the extragalactic background light. thes... | bow ties in the sky. ii. searching for gamma-ray halos in the fermisky using anisotropy |
the results of observations aimed at determining the spectra of standard radio sources in an "artificial-moon" absolute flux scale at epoch 2015.5 at wavelengths of 3.5-18 cm are presented. the sample includes sources with small angular sizes, used as flux-density standards for the calibration of various types of anten... | spectra of standard radio sources at the current epoch |
the vegas multi-beam spectrometer (vegas) was built for the green bank telescope (gbt) through a partnership between the national radio astronomy observatory (nrao) and the university of california at berkeley. vegas is based on a field programmable gate array (fpga) frontend and a heterogeneous computing backend compr... | the versatile gbt astronomical spectrometer (vegas): current status and future plans |
fast radio bursts (frbs) are one of the most mysterious astronomical phenomena nowadays. the identification of their origin requires more observations in the future and, importantly, deep understandings of the existing observational data. by fitting the redshift and energy distributions of 15 parkes frbs, we try to der... | modeling the redshift and energy distributions of fast radio bursts |
2hwc j1928+177 is a galactic tev gamma-ray source detected by the high altitude water cherenkov (hawc) observatory up to ∼56 tev. the hawc source, later confirmed by the high energy stereoscopic system, still remains unidentified as a dark accelerator since there is no apparent supernova remnant or pulsar wind nebula d... | multiwavelength observations of 2hwc j1928+177: dark accelerator or new tev gamma-ray binary? |
the future of radio astronomy will require instruments with large collecting areas for higher sensitivity, wide fields of view for faster survey speeds, and efficient computing and data rates relative to current capabilities. we describe the first successful deployment of the e-field parallel imaging correlator (epic) ... | a real-time, all-sky, high time resolution, direct imager for the long wavelength array |
the highest brightness temperature ever observed are from "nanoshots" from the crab pulsar which we argue could be the signature of bursts of vacuum $e^{\pm}$ pair production. if so this would be the first time the astronomical schwinger effect has been observed. these "schwinger sparks" would be an intermittent but ex... | are crab nanoshots schwinger sparks? |
many astronomical sources produce transient phenomena at radio frequencies, but the transient sky at low frequencies (<300 mhz) remains relatively unexplored. blind surveys with new wide-field radio instruments are setting increasingly stringent limits on the transient surface density on various timescales. although... | a matched filter technique for slow radio transient detection and first demonstration with the murchison widefield array |
we present a single-dish mapping algorithm with a number of advantages over traditional techniques. (1) our algorithm makes use of weighted modeling, instead of weighted averaging, to interpolate between signal measurements. this smooths the data, but without blurring the data beyond instrumental resolution. techniques... | skynet algorithm for single-dish radio mapping. i. contaminant-cleaning, mapping, and photometering small-scale structures |
while observations of many high-precision radio pulsars of order ≲1 μs across the sky are needed for the detection and characterization of a stochastic background of low-frequency gravitational waves (gws), sensitivity to single sources of gws requires even higher timing precision. the argentine institute of radio astr... | precision timing of psr j0437-4715 with the iar observatory and implications for low-frequency gravitational wave source sensitivity |
compressed sensing theory is slowly making its way to solve more and more astronomical inverse problems. we address here the application of sparse representations, convex optimization and proximal theory to radio interferometric imaging. first, we expose the theory behind interferometric imaging, sparse representations... | sparse representations and convex optimization as tools for lofar radio interferometric imaging |
comets are considered as the most primitive objects in the solar system. their composition provides information on the composition of the primitive solar nebula, 4.6 gyr ago. the radio domain is a privileged tool to study the composition of cometary ices. observations of the oh radical at 18 cm wavelength allow us to m... | comets at radio wavelengths |
the signal processing firmware that has been developed for the low frequency aperture array component of the square kilometre array (ska) is described. the firmware is implemented on a dual fpga board, that is capable of processing the streams from 16 dual polarization antennas. data processing includes channelization ... | the signal processing firmware for the low frequency aperture array |
we present the r-band polarimetric results towards two nebulae l1415 and l1389 containing low-luminosity stars. aim of this study is to understand the role played by magnetic fields in formation of low-luminosity objects. linear polarization arises due to dichroism of the background starlight projected on the cloud pro... | probing the magnetic fields in l1415 and l1389 |
we examine the robustness of the color-color selection of quiescent galaxies (qgs) against contamination of dusty star-forming galaxies using the latest submillimeter data. we selected 18,304 qg candidates out to z ∼ 3 using the commonly adopted nuv-r-j selection based on the high-quality multiwavelength cosmos2015 cat... | revisiting the color-color selection: submillimeter and agn properties of nuv-r-j selected quiescent galaxies |
radio frequency data in astronomy enable scientists to analyze astrophysical phenomena. however, these data can be corrupted by radio frequency interference (rfi) that limits the observation of underlying natural processes. in this study, we extend recent developments in deep learning algorithms to astronomy data. we r... | removing radio frequency interference from auroral kilometric radiation with stacked autoencoders |
we propose a new approach for large-scale high-dynamic range computational imaging. deep neural networks (dnns) trained end-to-end can solve linear inverse imaging problems almost instantaneously. while unfolded architectures provide robustness to measurement setting variations, embedding large-scale measurement operat... | deep network series for large-scale high-dynamic range imaging |
this brief review introduces the notion of a relativistic multifluid system---a multi-component system with identifiable relative flows---and outlines a set of models for scenarios relevant for different astronomical observation channels. the specific problems used to illustrate the key principles include superfluid hy... | a multifluid perspective on multimessenger modelling |
low-frequency radio observatories are reaching unprecedented levels of sensitivity in an effort to detect the 21 cm signal from the cosmic dawn. high precision is needed because the expected signal is overwhelmed by foreground contamination, largely from so-called diffuse emission-a nonlocalized glow comprising galacti... | validation solutions to the full-sky radio interferometry measurement equation for diffuse emission |
we present a measurement of the relativistic corrections to the thermal sunyaev-zel'dovich (sz) effect spectrum, the rsz effect, toward the massive galaxy cluster rx j1347.5-1145 by combining submillimeter images from herschel-spire with millimeter wavelength bolocam maps. our analysis simultaneously models the sz effe... | measurement of the relativistic sunyaev-zeldovich correction in rx j1347.5-1145 |
we have used x-ray data from the neutron star interior composition explorer (nicer) to search for long-timescale temporal correlations ("red noise") in the pulse times of arrival (toas) from the millisecond pulsars psr j1824-2452a and psr b1937+21. these data more closely track intrinsic noise because x-rays are unaffe... | a detection of red noise in psr j1824-2452a and projections for psr b1937+21 using nicer x-ray timing data |
the atacama large millimeter/submillimeter array (alma) offers new diagnostic possibilities that complement other commonly used diagnostics for the study of our sun. in particular, alma's ability to serve as an essentially linear thermometer of the chromospheric gas at unprecedented spatial resolution at millimetre wav... | prospects and challenges of numerical modelling of the sun at millimetre wavelengths |
we demonstrate how radio pulsars can be used as random number generators. specifically, we focus on publicly verifiable randomness (pvr), in which the same sequence of trusted and verifiable random numbers is obtained by multiple parties. pvr is a critical building block for many processes and algorithms (including cry... | physical publicly verifiable randomness from pulsars |
context. we present a celestial reference frame (crf) based on the combination of independent, multifrequency radio source position catalogs using nearly 40 years of very long baseline interferometry observations at the standard geodetic frequencies at sx band and about 15 years of observations at higher frequencies (k... | realization of a multifrequency celestial reference frame through a combination of normal equation systems |
the formation and evolution of our solar system (and planetary systems around other stars) are among the most challenging and intriguing fields of modern science. as the product of a long history of cosmic matter evolution, this important branch of astrophysics is referred to as stellar-planetary cosmogony. interdiscip... | the formation and evolution of the solar system |
the lunar regolith penetrating radar (lrpr) onboard the chang'e 5 lander is the first antenna-array radar deployed for the exploration of an extraterrestrial object. it is able to measure the subsurface structure of the moon at a resolution of ∼10 cm. this work presents a method for calibrating the variable cable delay... | revealing regolith substructure by chang'e-5 lrpr with optimized cable delay calibration method |
this paper describes two small aperture array demonstrators called medicina and sardinia array demonstrators (mad and sad, respectively). the objectives of these instruments are to acquire experience and test new technologies for a possible application to the low-frequency aperture array of the low-frequency telescope ... | from mad to sad: the italian experience for the low-frequency aperture array of ska1-low |
we present neil gehrels swift observatory (hereafter swift) observations of 31 sources from the sms4 catalog, a sample of 137 bright radio sources originally designed to extend the well-studied 3crr radio sample to the southern hemisphere. all these sources had no chandra or xmm-newton observations: 24 of these were ob... | a swift x-ray view of the sms4 sample-x-ray properties of 31 quasars and radio galaxies |
lightning has been directly observed or inferred on all giant planets, generally accepted to be occurring in their water clouds. however, much as earth has both cloud-cloud and cloud-ground lightning, this does not mean all flashes occur in a narrow altitude range: on jupiter, the galileo spacecraft detected lightning ... | giant planet lightning in nonideal gases |
alongside its role in astronomical research, the newly commissioned 32-m radio telescope is being used as an outreach tool for astronomy education in ghana. the observatory also serves as a facility for international postgraduate programmes. | using ghana's 32-m radio telescope to promote astronomy outreach |
interferometry delivers the highest angular resolution. it is being used extensively in radio astronomy and, since about a decade, it is becoming an important player in infrared astronomy. however, infrared interferometry is restricted to sparse arrays and no full-phase information is recovered. while imaging is arguab... | cassini-automap: a novel image reconstruction algorithm for infrared interferometry |
a multiwavelength investigation of the southern infrared dust bubble cs51 is presented in this paper. we probe the associated ionized, cold dust, molecular and stellar components. radio continuum emission mapped at 610 and 1300 mhz, using the giant metrewave radio telescope, india, reveals the presence of three compact... | infrared dust bubble cs51 and its interaction with the surrounding interstellar medium |
the arianna pilot hexagonal radio array (hra), a seven station test-bed for the development of an ultra-high energy (uhe) neutrino telescope, using antarctica's ross ice shelf as a detector, was completed during the 2014-2015 antarctic summer season. in the more than three years since, the hra has demonstrated remarkab... | performance and simulation of the arianna pilot array, with implications for future ultra-high energy neutrino astronomy |
Subsets and Splits
No community queries yet
The top public SQL queries from the community will appear here once available.