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grs 1915+105 is a stellar-mass black hole that is well known for exhibiting at least 12 distinct classes of x-ray variability and correlated multi-wavelength behavior. despite such extraordinary variability, grs 1915+105 remained one of the brightest sources in the x-ray sky. however, in early 2019, the source became m... | the novel obscured state of the stellar-mass black hole grs 1915+105 |
the information content of crystalline materials becomes astronomical when collective electronic behavior and their fluctuations are taken into account. in the past decade, improvements in source brightness and detector technology at modern x-ray facilities have allowed a dramatically increased fraction of this informa... | harnessing interpretable and unsupervised machine learning to address big data from modern x-ray diffraction |
we performed the broadband (1-100 kev) spectral analysis of the first galactic be ultraluminous x-ray pulsar (beulx) swift j0243.6+6124 observed by insight-hxmt during the 2017-2018 outburst. the results show spectral transitions at two typical luminosities, roughly consistently with those reported previously via pure ... | two complete spectral transitions of swift j0243.6+6124 observed by insight-hxmt |
stellar ultraviolet (uv) radiation drives photochemistry, and extreme-ultraviolet (euv) radiation drives mass loss in exoplanet atmospheres. however, the uv flux is partly unobservable due to interstellar absorption, particularly in the euv range (100-912 å). it is therefore necessary to reconstruct the unobservable sp... | semiempirical modeling of the atmospheres of the m dwarf exoplanet hosts gj 832 and gj 581 |
we seek to explain both the seeming observation of dark matter by the seasonal variation of the dama-libra data and the observation of "electron recoil" events at xenon1t in which the liquid xe scintillator was excited by electrons - in excess to the expected background - by the same dark matter model. in our model the... | atomic size pearls being dark matter giving electron signal |
the hard x-ray modulation telescope (insight-hxmt) is china's first x-ray astronomy satellite. it was launched on 2017 june 15. the anticoincidence csi detectors of the high energy x-ray telescope (he) on board insight-hxmt could serve as an all-sky gamma-ray monitor in about 0.2-3 mev. in its first four years of opera... | the first insight-hxmt gamma-ray burst catalog: the first four years |
the identification and description of point sources is one of the oldest problems in astronomy, yet even today the correct statistical treatment for point sources remains one of the field's hardest problems. for dim or crowded sources, likelihood-based inference methods are required to estimate the uncertainty on the c... | a compound poisson generator approach to point-source inference in astrophysics |
imaging is one of the essential techniques to observe astronomical structures. while analyzing the observed images, it is a challenge in many scientific fields to reconstruct the 3-d structures from 2-d image(s). this report discusses this challenge in the context of reconstructing the structure of the earth's magnetos... | deriving the magnetopause position from the soft x-ray image by using the tangent fitting approach |
context. xmm-newton has observed the x-ray sky since early 2000. the xmm-newton survey science centre consortium has published catalogues of x-ray and ultraviolet sources found serendipitously in the individual observations. this series is now augmented by a catalogue dedicated to x-ray sources detected in spatially ov... | the xmm-newton serendipitous survey. viii. the first xmm-newton serendipitous source catalogue from overlapping observations |
since 1996 the blast wave driven by sn 1987a has been interacting with the dense circumstellar material, which provides us with a unique opportunity to study the early evolution of a newborn supernova remnant (snr). based on the xmm-newton rgs and epic-pn x-ray observations from 2007 to 2019, we investigated the post-i... | the post-impact evolution of the x-ray-emitting gas in snr 1987a as viewed by xmm-newton |
recent x-ray studies have revealed overionized recombining plasmas in a dozen mixed-morphology (mm) supernova remnants (snrs). however, the physical process of the overionization has not yet been fully understood. here we report on spatially resolved spectroscopy of x-ray emission from w44, one of the overionized mm sn... | deep xmm-newton observations reveal the origin of recombining plasma in the supernova remnant w44 |
we investigate the uncertainties of fitted x-ray model parameters and fluxes for relatively faint chandra acis-i source spectra. monte carlo (mc) simulations are employed to construct a large set of 150,000 fake x-ray spectra in the low photon count statistics regime (from 10 to 350 net counts) using the xspec spectral... | the statistical uncertainties on x-ray flux and spectral parameters from chandra acis-i observations of faint sources: application to the cygnus ob2 association |
phase 1 of the colorado plateau coring project (cpcp-i) recovered a total of over 850 m of stratigraphically overlapping core from three coreholes at two sites in the early to middle and late triassic age largely fluvial moenkopi and chinle formations in petrified forest national park (pfnp), northeastern arizona, usa.... | colorado plateau coring project, phase i (cpcp-i): a continuously cored, globally exportable chronology of triassic continental environmental change from western north america |
a clearly defined geochronology and stratigraphic interpretation will enhance our understanding of the evolution of paleo water depth and transitional facies, contributing to hydrocarbon exploration. transitional deposition is extensively observed in the upper paleozoic of the ordos basin. nevertheless, the correlation... | the shanxi formation responses to astronomically forced climate changes during the upper paleozoic in the eastern ordos basin, nw china |
drilling for the international continental scientific drilling program (icdp) early jurassic earth system and timescale project (jet) was undertaken between october 2020 and january 2021. the drill site is situated in a small-scale synformal basin of the latest triassic to early jurassic age that formed above the major... | initial results of coring at prees, cheshire basin, uk (icdp jet project): towards an integrated stratigraphy, timescale, and earth system understanding for the early jurassic |
the accretion-powered x-ray pulsar gx 301-2 was observed with the balloon-borne x-calibur hard x-ray polarimeter during late 2018 december, with contiguous observations by the neutron star interior composition explorer mission (nicer) x-ray telescope, the swift x-ray telescope and burst alert telescope, and the fermi g... | observations of a gx 301-2 apastron flare with the x-calibur hard x-ray polarimeter supported by nicer, the swift xrt and bat, and fermi gbm |
microcalorimeters have shown remarkable success in delivering high-spectral-resolution observations of the hot and energetic universe, and have paved the way to revolutionary new science possibilities in x-ray astronomy. there are several research areas in compact-object science that can only be addressed with energy r... | frontiers in accretion physics at high x-ray spectral resolution |
one of the central goals of the laser interferometer space antenna (lisa) is the detection of gravitational waves from the merger of supermassive black holes. contrary to stellar-mass black hole mergers, such events are expected to be rich x-ray sources due to the accretion of material from the circumbinary disks onto ... | detectability of modulated x-rays from lisa’s supermassive black hole mergers |
temporal variability in flux and spectral shape is ubiquitous in the x-ray sky and carries crucial information about the nature and emission physics of the sources. the epic instrument on board the xmm-newton observatory is the most powerful tool for studying variability even in faint sources. each day, it collects a l... | the extras project: exploring the x-ray transient and variable sky |
we present our velocity measurements of 59 clumpy, metal-rich ejecta knots in the supernova remnant (snr) of sn 1572 (tycho). we use our 450 ks chandra high energy transmission grating spectrometer observation to measure the doppler shift of the he-like si kα line-center wavelength emitted from these knots to find thei... | the 3d x-ray ejecta structure of tycho's supernova remnant |
despite the impressive progress achieved both by x-ray and gamma-ray observatories in the last few decades, the energy range between ~ 200 kev and ~ 50 mev remains poorly explored. comptel, on-board the compton gamma-ray observatory (cgro, 1991-2000), opened the mev gamma-ray band as a new window to astronomy, performi... | introducing the mevcube concept: a cubesat for mev observations |
the x-ray imaging and spectroscopy mission (xrism) is a jaxa/nasa x-ray observatory with collaboration from esa and several institutes and academic institutions worldwide. it is proposed to fulfill the promise of high-resolution x-ray spectroscopy with imaging once realized but unexpectedly terminated by a mishap of as... | xrism: x-ray imaging and spectroscopy mission |
cyclostratigraphic studies are used to create relative and high-resolution time scales for sedimentary successions based on identification of regular cycles in climate proxy data. this method typically requires the construction of long, high-resolution data sets. in this study, we have demonstrated the efficacy of port... | portable x-ray fluorescence spectroscopy as a tool for cyclostratigraphy |
we present observations of thermonuclear (type-i) x-ray bursts, selected for comparison with numerical models. we provide examples of four distinct cases of ignition: he-ignition in mixed h/he fuel (case 1); he-ignition in pure he fuel, following exhaustion of accreted h by steady burning (case 2); ignition in (almost)... | thermonuclear burst observations for model comparisons: a reference sample |
scientific complementary metal oxide semiconductor (scmos) sensors are finding increasingly more applications in astronomical observations, thanks to their advantages over charge-coupled devices such as a higher readout frame rate, higher radiation tolerance, and higher working temperature. in this work, we investigate... | improving the x-ray energy resolution of a scientific cmos detector by pixel-level gain correction |
the imaging x-ray polarimetry explorer (ixpe) is a nasa small explorer mission-in partnership with the italian space agency-dedicated to x-ray polarimetry in the 2-8 kev energy band. the ixpe telescope comprises three grazing incidence mirror modules coupled to three detector units hosting each one a gas pixel detector... | calibration of the ixpe focal plane x-ray polarimeters to polarized radiation |
we report a detailed study of an unidentified gamma-ray source located in the region of the compact stellar cluster ngc 3603. this is a star-forming region (sfr) powered by a massive cluster of ob stars. a dedicated analysis of about 10 yr of data from 10 gev to 1 tev, provided by the large area telescope on board the ... | morphological and spectral study of 4fgl j1115.1-6118 in the region of the young massive stellar cluster ngc 3603 |
we report x-ray spectroscopic results for four giant solar flares that occurred on 2005 september 7 (x17.0), 2005 september 8 (x5.4), 2005 september 9 (x6.2), and 2006 december 5 (x9.0), obtained from earth albedo data with the x-ray imaging spectrometer (xis) on board suzaku. the good energy resolution of the xis (fwh... | inverse first ionization potential effects in giant solar flares found from earth x-ray albedo with suzaku/xis |
the recurrent nova (rn) v3890 sgr was observed during the seventh day after the onset of its most recent outburst, with the chandra acis-s camera and high energy transmission gratings. a rich emission line spectrum was detected, due to transitions of fe-l and k-shell ions ranging from neon to iron. the measured absorbe... | chandra high energy transmission gratings spectra of v3890 sgr |
classifying catalogue objects as stars, galaxies, or active galactic nuclei (agns) is a crucial part of any statistical study of galaxies. we describe our pipeline for binary (star/galaxy) and multiclass (star/galaxy/type i agn/type ii agn) classification developed for the very deep clauds + hsc-ssp u*grizy data set. o... | classifying stars, galaxies, and agns in clauds + hsc-ssp using gradient boosted decision trees |
the distribution and kinematics of the circumstellar medium (csm) around a supernova remnant (snr) tell us useful information about the explosion of its natal supernova (sn). kepler's snr, the remnant of sn 1604, is widely regarded to be of type ia origin. its shock is moving through a dense, asymmetric csm. the presen... | spatially resolved rgs analysis of kepler's supernova remnant |
we present deep chandra observations of the pre-merger galaxy cluster abell 98 (a98). a98 is a complex merging system. while the northern (a98n) and central subclusters (a98s) are merging along the north-south direction, a98s is undergoing a separate late-stage merger, with two distinct x-ray cores. we report the detec... | gas sloshing and cold fronts in pre-merging galaxy cluster a98 |
it has been shown that the gas velocities within the intracluster medium (icm) can be measured by applying the novel xmm-newton epic-pn energy scale calibration, which uses instrumental cu kα as reference for the line emission. using this technique, we have measured the velocity distribution of the icm for clusters inv... | measuring the hot icm velocity structure function using xmm-newton observations |
owing to the narrow energy band of the swift burst alert telescope (bat), several urgent issues remain unsolved. we systematically study the properties of a refined sample of 283 swift/bat gamma-ray bursts (grbs) with well-measured spectral peak energy (ep) at a high confidence level greater than 3σ. we find that the d... | on the spectral peak energy of swift gamma-ray bursts |
in a previous paper, we presented an extension of our reflection model relxill_nk to include the finite thickness of the accretion disk following the prescription in taylor & reynolds. in this paper, we apply our model to fit the 2013 simultaneous observations by the nuclear spectroscopic telescope array (nustar) a... | impact of the disk thickness on x-ray reflection spectroscopy measurements |
observations collected with the atacama large millimeter/submillimeter array (alma) and analysis of broadband x-ray spectra have recently suggested the presence of a central compact object (cco) in sn 1987a. however, no direct evidence of the cco has been found yet. here we analyze chandra x-ray observations of sn 1987... | investigating the time evolution of the thermal emission from the putative neutron star in sn 1987a for 50+ years |
using suzaku data, we had found a 3.4σ evidence for the x-ray emitting warm-hot circumgalactic medium (cgm) in the l⋆ galaxy ngc 3221. here we present xmm-newton data and outline an efficient, rigorous, and well-defined method to extract the faint cgm signal. we confirm the cgm detection at 4σ significance within 30-20... | the warm-hot, extended, massive circumgalactic medium of ngc 3221: an xmm-newton discovery |
we report a 3.4σ detection of the warm-hot, massive, extended circumgalactic medium (cgm) around an l ⋆ star-forming spiral galaxy ngc 3221, using deep suzaku observations. the temperature of the gas is 106.1 k, comparable to that of the milky way cgm. the spatial extent of the gas is at least 150 kpc. for a β-model of... | evidence for a massive warm-hot circumgalactic medium around ngc 3221 |
since its discovery, 1e 1048.1-5937 has been one of the most active magnetars, both in terms of radiative outbursts, and changes to its spin properties. here we report on a continuing monitoring campaign with the neil gehrels swift observatory x-ray telescope in which we observe two new outbursts from this source. the ... | two new outbursts and transient hard x-rays from 1e 1048.1-5937 |
high spectral resolution with a resolving power, e /δ e ≳1000 at 6 kev, is now available in x-ray astronomy. x-ray observations are particularly effective for plasma studies since major atomic transitions appear as spectral features in the x-ray band. high-resolution spectroscopy enables us to probe a wide variety of a... | high-resolution x-ray spectroscopy of astrophysical plasmas with x-ray microcalorimeters |
young stellar objects are observed to have large x-ray fluxes and are thought to produce commensurate luminosities in energetic particles (cosmic rays). this particle radiation, in turn, can synthesize short-lived radioactive nuclei through spallation. with a focus on 26al, this paper estimates the expected abundances ... | radioactive planet formation |
we propose the difference of reaction rates of the weak interaction between enantiomers produces the small imbalance of the number density between pairs of enantiomers, which may be the origin of the homochirality in nature. since left-handed particles have larger reaction rate of the weak interaction than right-handed... | asymmetry of electron chirality between enantiomeric pair molecules and the origin of homochirality in nature |
we spectroscopically measure multiple hydrogen balmer line profiles from laboratory plasmas to investigate the theoretical line profiles used in white dwarf (wd) atmosphere models. x-ray radiation produced at the z pulsed power facility at sandia national laboratories initiates plasma formation in a hydrogen-filled gas... | laboratory measurements of white dwarf photospheric spectral lines: hβ |
h1504+65 is an extremely hot white dwarf (effective temperature teff = 200 000 k) with a carbon-oxygen dominated atmosphere devoid of hydrogen and helium. this atmospheric composition was hitherto unique among hot white dwarfs (wds), and it could be related to recently detected cooler wds with c or o dominated spectra.... | analysis of hst/cos spectra of the bare c-o stellar core h1504+65 and a high-velocity twin in the galactic halo |
multi-messenger observations of the transient sky to detect cosmic explosions and counterparts of gravitational wave mergers critically rely on orbiting wide-fov telescopes to cover the wide range of wavelengths where atmospheric absorption and emission limit the use of ground facilities. thanks to continuing technolog... | localisation of gamma-ray bursts from the combined spirit+hermes-tp/sp nano-satellite constellation |
we report the multiwavelength properties of millimeter galaxies hosting x-ray detected active galactic nuclei (agns) from the alma lensing cluster survey (alcs). alcs is an extensive survey of well-studied lensing clusters with alma, covering an area of 133 arcmin2 over 33 clusters with a 1.2 mm flux-density limit of ~... | alma lensing cluster survey: properties of millimeter galaxies hosting x-ray-detected active galactic nuclei |
in the framework of a national funded program for nuclear safety, a first prototype of portable gamma camera was built and tested. it integrates a caliste-hd cdte-hybrid detector designed for space x-ray astronomy coupled with a new system-on-chip based acquisition system (fpga and arm microprocessor) and thermo-electr... | second generation of portable gamma camera based on caliste cdte hybrid technology |
modern multimessenger astronomy delivers unique opportunity for performing crucial observations that allow for testing the physics of the gravitational interaction. these tests include detection of gravitational waves by advanced ligo-virgo antennas, event horizon telescope observations of central relativistic compact ... | einstein's geometrical versus feynman's quantum-field approaches to gravity physics: testing by modern multimessenger astronomy |
we investigate prolonged engine activities of short gamma-ray bursts (sgrbs), such as extended and/or plateau emissions, as high-energy gamma-ray counterparts to gravitational waves (gws). binary neutron-star mergers lead to relativistic jets and merger ejecta with r-process nucleosynthesis, which are observed as sgrbs... | upscattered cocoon emission in short gamma-ray bursts as high-energy gamma-ray counterparts to gravitational waves |
context. methanol in the interstellar medium mainly forms upon sequential hydrogenation of solid co. with typical abundances of up to 15% (with respect to water) it is an important constituent of interstellar ices where it is considered as a precursor in the formation of large and complex organic molecules (coms), e.g.... | laser desorption time-of-flight mass spectrometry of vacuum uv photo-processed methanol ice |
upcoming multiwavelength astronomical surveys will soon discover all massive galaxy clusters and provide unprecedented constraints on cosmology and cluster astrophysics. in this paper, we investigate the constraining power of the multiband cluster surveys, through a joint analysis of three observables associated with c... | probing cosmology and cluster astrophysics with multiwavelength surveys - i. correlation statistics |
the timing properties of x-ray binaries are still not understood, particularly the presence of quasi-periodic oscillations (qpos) in their x-ray power spectra. the solid-body regime of lense-thirring precession is one prominent model invoked to explain the most common type of qpos, type c. however, solid-body precessio... | can lense-thirring precession produce qpos in supersonic accretion flows? |
the data-oriented astronomy has allowed classifying the astroinformatics as a new academic research field, which covers various multi-disciplinary applications of the e-astronomy. among them are the data modeling, data mining, metadata standards development, data access, digital astronomical databases, image archives a... | astroinformatics as a new research field. ukrvo astroinformation resources: tasks and prospective |
direct detection of black hole-neutron star pairs is anticipated with the advent of aligo. electromagnetic counterparts may be crucial for a confident gravitational-wave detection as well as for extraction of astronomical information. yet black hole-neutron star pairs are notoriously dark and so inaccessible to telesco... | bright transients from strongly-magnetized neutron star-black hole mergers |
we present the supernova x-ray database (snax), a compilation of the x-ray data from young supernovae (sne). the database includes the x-ray fluxes and luminosities of young sne, from days to years after outburst. the original goal and intent of this study was to present a database of type iin sne (sne iin), which we h... | snax: a database of supernova x-ray light curves |
we have examined 13 pointed observations of the tev-emitting high synchrotron peak blazar pks 2155-304, taken by the suzaku satellite throughout its operational period. we found that the blazar showed large-amplitude intraday variabilities in the soft (0.8-1.5 kev) and the hard (1.5-8.0 kev) bands in the light curves. ... | x-ray intraday variability of the tev blazar pks 2155-304 with suzaku during 2005-2014 |
galaxy clusters are the most recently formed and most massive, gravitationally bound structures in the universe. the number of galaxy clusters formed is highly dependent on cosmological parameters, such as the dark matter density, σ 8, and ω m . the number density is a function of the cluster mass, which can be estimat... | the hydrostatic mass of a478: discrepant results from chandra, nustar, and xmm-newton |
x-ray observations are limited by the background, due to the intrinsic faintness or diffuse nature of the sources. the future athena x-ray observatory has among its goals the characterization of these sources. we aim at characterizing the particle-induced background of the athena microcalorimeter, in both its low- (sof... | review of the particle background of the athena x-ifu instrument |
this study presents a cyclostratigraphic investigation of the mesoproterozoic hongshuizhuang formation (about 1.45 ga) in north china. high-resolution, continuous magnetic susceptibility and x-ray fluorescence elemental data were obtained from the yuanji-2 drillcore. we tested the present astronomical age models using ... | an astronomically calibrated stratigraphy of the mesoproterozoic hongshuizhuang formation, north china: implications for pre-phanerozoic changes in milankovitch orbital parameters |
the origin of the idea of astrosat multi wavelength satellite mission and how it evolved over the next 15 years from a concept to the successful development of instruments for giving concrete shape to this mission, is recounted in this article. astrosat is the outcome of intense deliberations in the indian astronomy co... | astrosat: from inception to realization and launch |
astronomical data often suffer from noise and incompleteness. we extend the common mixtures-of-gaussians density estimation approach to account for situations with a known sample incompleteness by simultaneous imputation from the current model. the method, called gmmis, generalizes existing expectation-maximization tec... | filling the gaps: gaussian mixture models from noisy, truncated or incomplete samples |
we analyse the performance of a gas time projection chamber (tpc) as a high-performance gamma-ray telescope and polarimeter in the e+e- pair-creation regime. we use data collected at a gamma-ray beam of known polarisation. the tpc provides two orthogonal projections (x, z) and (y, z) of the tracks induced by each conve... | performance measurement of harpo: a time projection chamber as a gamma-ray telescope and polarimeter |
einstein's theory of general relativity predicts that the only stationary configuration of an isolated black hole is the kerr spacetime, which has a unique multipolar structure and a spherical shape when nonspinning. this is in striking contrast to the case of other self-gravitating objects, which instead can in princi... | axisymmetric deformations of neutron stars and gravitational-wave astronomy |
we have analyzed astrosat observations of the galactic microquasar system grs 1915+105, when the system exhibited c-type quasi-periodic oscillations (qpos) in the frequency range of 3.4-5.4 hz. the broadband spectra (1-50 kev) obtained simultaneously from the large area x-ray proportional counter and soft x-ray telesco... | identification of qpo frequency of grs 1915+105 as the relativistic dynamic frequency of a truncated accretion disk |
context. the mass loss from massive stars is not understood well. η carinae is a unique object for studying the massive stellar wind during the luminous blue variable phase. it is also an eccentric binary with a period of 5.54 yr. the nature of both stars is uncertain, although we know from x-ray studies that there is ... | vlti-amber velocity-resolved aperture-synthesis imaging of η carinae with a spectral resolution of 12 000. studies of the primary star wind and innermost wind-wind collision zone |
i introduce the consequences of neutrino mass and mixing in the dense environments of the early universe and in astrophysical environments. thermal and matter effects are reviewed in the context of a two-neutrino formalism, with methods of extension to multiple neutrinos. the observed large neutrino mixing angles place... | neutrinos in astrophysics and cosmology: theoretical advanced study institute (tasi) 2020 lectures |
we present here the results of the first broadband simultaneous spectral and temporal studies of the newly detected black hole binary maxi j1820+070 as seen by soft x-ray telescope and large area x-ray proportional counter (laxpc) on board astrosat. the observed combined spectra in the energy range 0.7-80 kev were well... | unveiling the temporal properties of maxi j1820+070 through astrosat observations |
we have been developing a new type of active pixel sensor, referred to as "xrpix" for future x-ray astronomy satellites on the basis of silicon-on-insulator cmos technology. the problem on our previous device, xrpix1b, was degradation of the charge-collection efficiency (cce) at pixel borders. in order to investigate t... | improving charge-collection efficiency of soi pixel sensors for x-ray astronomy |
one of the five great mass extinctions of the phanerozoic is the frasnian-famennian (fsbnd f) mass extinction, for which the causes have not yet been identified. in this study, cyclostratigraphic analysis of two fsbnd f transition sections was carried out in south china: the yangdi section, a marine slope facies, and t... | astronomical climate changes trigger late devonian bio- and environmental events in south china |
x-ray studies of jellyfish galaxies opened a window into the physics of the interplay between the intracluster medium (icm) and interstellar medium (ism). in this paper, we present the study of an archival chandra observation of the gasp jellyfish galaxy jo194. we observe x-ray emission extending from the stellar disk ... | unveiling the interplay between the gasp jellyfish galaxy jo194 and its environment with chandra |
wasp-18 hosts a massive, very close-in jupiter-like planet. despite its young age (<1 gyr), the star presents an anomalously low stellar activity level: the measured {log}{r}hk}{\prime } activity parameter lies slightly below the basal level; there is no significant time-variability in the {log}{r}hk}{\prime } value... | suppressed far-uv stellar activity and low planetary mass loss in the wasp-18 system |
the particle-induced background of x-ray observatories is produced by galactic cosmic ray (gcr) primary protons, electrons, and he ions. events due to direct interaction with the detector are usually removed by onboard processing. the interactions of these primary particles with the detector environment produce seconda... | characterization of the particle-induced background of xmm-newton epic-pn: short- and long-term variability |
we present x-ray flux and spectral analyses of the three pointed suzaku observations of the tev high synchrotron peak blazar mrk 421 taken throughout its complete operational duration. the observation taken on 2008 may 5 is, at 364.6 ks (i.e., 101.3 hr), the longest and most evenly sampled continuous observation of thi... | x-ray intraday variability of the tev blazar mrk 421 with suzaku |
the detection of a high-energy neutrino from the flaring blazar txs 0506+056 and the subsequent discovery of a neutrino excess from the same direction have strengthened the hypothesis that blazars are cosmic neutrino sources. the lack, however, of γ-ray flaring activity during the latter period challenges the standard ... | hadronic x-ray flares from blazars |
previous detections of an x-ray emission line near 3.5 kev in galaxy clusters and other dark-matter-dominated objects have been interpreted as observational evidence for the decay of sterile neutrino dark matter. motivated by this, we report on a search for a 3.5 kev emission line from the milky way's galactic dark mat... | a search for the 3.5 kev line from the milky way's dark matter halo with halosat |
we present a search for sterile neutrino dark matter decay signals in the milky way's dark matter halo by considering the entirety of the swift x-ray telescope (swift-xrt) data archive. after filtering the raw archive, we analyze a ~77 ms data set containing the full field of view, as well as a ~41 ms data set with poi... | constraining sterile neutrino dark matter in the milky way halo with swift-xrt |
massive binaries play an important role in fields ranging from gravitational-wave astronomy to stellar evolution. we provide several lines of evidence that classical obe stars in the small magellanic cloud (smc) obtain their rapid rotation from mass and angular momentum transfer in massive binaries, which predicts that... | classical obe stars as post-supernova runaways: confirming binary origins |
single electron sensitive read out (sisero) is a novel on-chip charge detector output stage for charge-coupled device (ccd) image sensors. developed at mit lincoln laboratory, this technology uses a p-mosfet transistor with a depleted internal gate beneath the transistor channel. the transistor source-drain current is ... | single electron sensitive readout (sisero) x-ray detectors: technological progress and characterization |
interstellar dust permeates our galaxy and plays an important role in many physical processes in the diffuse and dense regions of the interstellar medium (ism). high-resolution x-ray spectroscopy, coupled with modelling based on laboratory dust measurements, provides a unique probe for investigating the interstellar du... | interstellar oxygen along the line of sight of cygnus x-2 |
we present the first comprehensive search for high-energy neutrino emission from high- and low-mass x-ray binaries conducted by icecube. galactic x-ray binaries are long-standing candidates for the source of galactic hadronic cosmic rays and neutrinos. the compact object in these systems can be the site of cosmic-ray a... | search for high-energy neutrino emission from galactic x-ray binaries with icecube |
extending for 50-200 pc in all directions from the sun, the local cavity has been characterized as an old supernova bubble consisting of low-density million-degree plasma heated by supernova shocks. we summarize the arguments for and against this model and conclude that hydrogen in the local cavity is fully ionized, an... | could the local cavity be an irregularly shaped strömgren sphere? |
the neil gehrels swift observatory carried out prompt searches for gravitational-wave (gw) events detected by the ligo/virgo collaboration (lvc) during the second observing run (“o2”). swift performed extensive tiling of eight lvc triggers, two of which had very low false-alarm rates (gw170814 and the epochal gw170817)... | swift-xrt follow-up of gravitational-wave triggers in the second advanced ligo/virgo observing run |
supernova remnants (snrs) offer the means to study supernovae (sne) long after the original explosion and can provide a unique insight into the mechanism that governs these energetic events. in this work, we examine the morphologies of x-ray emission from different elements found in the youngest known core-collapse snr... | asymmetries of heavy elements in the young supernova remnant cassiopeia a |
global warming imposes us to reflect on the way we carry research, embarking on the obligation to minimize the environmental impact of our research programs, with the reduction of our travel footprint being one of the easiest actions to implement, thanks to the advance of digital technology. the x-ray integral field un... | estimating, monitoring and minimizing the travel footprint associated with the development of the athena x-ray integral field unit |
using the insight-hxmt observations of grs 1915+105 when it exhibits low-frequency quasiperiodic oscillations (qpos), we measure the evolution of the qpo frequency along with disk inner radius and mass accretion rate. we find a tight positive correlation between the qpo frequency and mass accretion rate. our results ex... | testing evolution of lfqpos with mass accretion rate in grs 1915+105 with insight-hxmt |
we present a tabulated version of our slim-disk model for fitting tidal disruption events (tdes). we create a synthetic x-ray spectral library by ray-tracing stationary general relativistic slim disks and including gravitational redshift, doppler, and lensing effects self-consistently. we introduce the library to reduc... | a library of synthetic x-ray spectra for fitting tidal disruption events |
this study focuses on high-energy proxies of stellar magnetic activity over long-term starspot cycles of three low-activity sun-like stars: α centauri a (hd 128620: g2 v), α cen b (hd 128621: k1 v), and the sun itself. data sets include: daily solar ultraviolet irradiance spectra and x-ray fluxes from the solar radiati... | in the trenches of the solar-stellar connection. i. ultraviolet and x-ray flux-flux correlations across the activity cycles of the sun and alpha centauri ab |
sdss j2222+2745 is a galaxy cluster at z = 0.49, strongly lensing a quasar at z = 2.805 into six widely separated images. in recent hubble space telescope imaging of the field, we identify additional multiply lensed galaxies and confirm the sixth quasar image that was identified by dahle et al. we used the gemini-north... | lens model and time delay predictions for the sextuply lensed quasar sdss j2222+2745 |
nuclear astrophysics, and particularly nuclear emission line diagnostics from a variety of cosmic sites, has remained one of the least developed fields in experimental astronomy, despite its central role in addressing a number of outstanding questions in modern astrophysics. radioactive isotopes are co-produced with st... | understanding the origin of the positron annihilation line and the physics of supernova explosions |
x-ray astronomy provides information regarding the electromagnetic emission of active galactic nuclei and x-ray binaries. these events provide details regarding the astrophysical environment of black holes and stars, and help us understand gamma-ray bursts. they produce estimates for the maximum mass of neutron stars a... | slowly-rotating compact objects: the nonintegrability of hartle-thorne particle geodesics |
frequency-domain multiplexing (fdm) is the baseline readout system for the x-ray integral field unit on board the athena mission. under the fdm scheme, tess are coupled to a passive lc filter and biased with alternating current (ac bias) at mhz frequencies. using high-quality-factor lc filters and room-temperature elec... | progress in the development of frequency-domain multiplexing for the x-ray integral field unit on board the athena mission |
we report on the results of x-ray observations of 4xmm j111816.0-324910, a transient ultraluminous x-ray source located in the galaxy ngc 3621. this system is characterized by a transient nature and marked variability with a characteristic timescale of ≈3500 s, in contract with other ultraluminous x-ray sources, which ... | the slow heartbeats of an ultraluminous x-ray source in ngc 3621 |
to fully characterize the atmospheres, or lack thereof, of terrestrial exoplanets, we must include the high-energy environments provided by their host stars. the nearby mid-m dwarf lhs 3844 hosts a terrestrial world that lacks a substantial atmosphere. we present a time-series uv spectrum of lhs 3844 from 1131 to 3215 ... | the high-energy spectrum of the nearby planet-hosting inactive mid-m dwarf lhs 3844 |
massive stars can shed material via steady, line-driven winds, eruptive outflows, or mass transfer onto a binary companion. in the case of single stars, the mass is deposited by the stellar wind into the nearby environment. after the massive star explodes, the stellar ejecta interact with this circumstellar material (c... | a grid of core-collapse supernova remnant models. i. the effect of wind-driven mass loss |
relativistically broadened and redshifted 6.4-6.9 kev iron k lines are observed from many accretion powered objects, including x-ray binaries and active galactic nuclei. the existence of gas close to the central engine implies large radiation intensities and correspondingly large gas densities if the gas is to remain p... | photoionization models for high-density gas |
x-ray reflection spectroscopy is currently one of the leading techniques for studying the inner part of accretion disks around black holes, measuring black hole spins, and even testing fundamental physics in strong gravitational fields. however, the accuracy of these measurements depends on the reflection models employ... | testing relativistic reflection models with grmhd simulations of accreting black holes |
the first detection of a binary neutron star merger through gravitational waves and photons marked the dawn of multimessenger astronomy with gravitational waves, and it greatly increased our insight in different fields of astrophysics and fundamental physics. however, many open questions on the physical process involve... | electromagnetic counterparts of compact binary mergers |
due to the peculiar properties of ultra-diffuse galaxies (udgs), understanding their origin presents a major challenge. previous x-ray studies demonstrated that the bulk of udgs lack substantial x-ray emission, implying that they reside in low-mass dark matter halos. this result, in concert with other observational and... | the archetypal ultra-diffuse galaxy, dragonfly 44, is not a dark milky way |
we analyze x-ray light curves of the blazars mrk 421, pks 2155-304, and 3c 273 using observations by the soft x-ray telescope on board astrosat and archival xmm-newton data. we use light curves of length 30-90 ks from three to four epochs for all three blazars. we apply the autoregressive integrated moving average mode... | blazar variability: a study of nonstationarity and the flux-rms relation |
jet precession is considered to universally exist in different-scale astronomical phenomena, including gamma-ray bursts (grbs). for the long-lived grb central engine, the relativistic precessing jets will periodically inject kinetic energy into the external shocks, then significantly modulate the shapes of the light cu... | energy injection driven by precessing jets in gamma-ray burst afterglows |
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