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the x-ray afterglow of grb 130831a shows an “internal plateau” with a decay slope of ∼0.8, followed by a steep drop at around 105 s with a slope of ∼6. after the drop, the x-ray afterglow continues with a much shallower decay. the optical afterglow exhibits two segments of plateaus separated by a luminous optical flare... | modeling the multi-band afterglow of grb 130831a: evidence for a spinning-down magnetar dominated by gravitational wave losses? |
aims: we investigate the long gamma-ray burst (grb) 140629a through multiwavelength observations to derive the properties of the dominant jet and its host galaxy.methods: the afterglow and host galaxy observations were taken in the optical (swift/uvot and various facilities worldwide), infrared (spitzer), and x-rays (s... | multiwavelength observations of grb 140629a. a long burst with an achromatic jet break in the optical and x-ray afterglow |
the short hard gamma ray burst (shb) 170817a that followed gw170817, the first neutron stars merger (nsm) detected in gravitational waves (gws), has shown beyond doubt that nsms produce shbs. its low luminosity and other properties that differ from those of ordinary shbs were predicted by the cannonball model for relat... | the smoking guns of neutron stars mergers |
we systematically analyze the properties of the x-ray shallow decay phase in swift grbs observed from 2004 december to 2021 march. these events have at least the three obvious emission phases: the steep decay, shallow decay and the following decay. we find that the distributions of the characteristic properties of the ... | statistical properties of the x-ray afterglow shallow decay phase and their relationships with the prompt gamma-ray emission of gamma-ray bursts |
we present a detailed analysis of grb 151006a, the first gamma-ray burst (grb) detected by astrosat cadmium-zinc-telluride imager (czti). we study the long-term spectral evolution by exploiting the capabilities of fermi and swift satellites at different phases, which is complemented by the polarization measurement with... | surprise in simplicity: an unusual spectral evolution of a single pulse grb 151006a |
violations of both the weak equivalence principle (wep) and lorentz invariance can produce vacuum birefringence, which leads to an energy-dependent rotation of the polarization vector of linearly polarized emission from a given astrophysical source. however, the search for the birefringent effect has been hindered by o... | testing the weak equivalence principle and lorentz invariance with multiwavelength polarization observations of grb optical afterglows |
strong downstream magnetic fields of the order of ∼1 g, with large correlation lengths, are believed to cause the large synchrotron emission at the afterglow phase of gamma-ray bursts (grbs). despite the recent theoretical efforts, models have failed to fully explain the amplification of the magnetic field, particularl... | ambient magnetic field amplification in shock fronts of relativistic jets: an application to grb afterglows |
considered here is the acceleration and heating of relativistic outflow by local magnetic energy dissipation process in poynting-flux dominated outflow. adopting the standard assumption that the reconnection rate scales with the alfvén speed, i show here that the fraction of energy dissipated as thermal photons cannot ... | constraining magnetization of gamma-ray bursts outflows using prompt emission fluence |
multiwavelength observation of the gamma-ray burst, grb 190114c, opens a new window for studying the emission mechanism of grb afterglows. its very high energy (vhe; ≳ 100 gev) detection has motivated an inverse compton interpretation for the emission, but this has not been tested. here, we revisit the early afterglow ... | probing the multiwavelength emission scenario of grb 190114c |
gamma-ray bursts (grbs) are known to be the most violent explosions in the universe, and a variety of correlations between observable grb properties have been proposed in the literature, but none of these correlations are valid for both long and short grbs. in this paper we report the discovery of a universal correlati... | discovery of a universal correlation for long and short grbs and its application for the study of luminosity function and formation rate |
spectropolarimetric measurements of gamma-ray burst (grb) optical afterglows contain polarization information for both continuum and absorption lines. based on the zeeman effect, an absorption line in a strong magnetic field is polarized and split into a triplet. in this paper, we solve the polarization radiative trans... | on the polarized absorption lines in gamma-ray burst optical afterglows |
sub-relativistic materials launched during the merger of binary compact objects and the core collapse of massive stars acquire velocity structures when expanding in a stratified environment. the remnant (either a spinning magnetized neutron star (ns) or a central black hole) from the compact object or core collapse cou... | grb afterglow of the sub-relativistic materials with energy injection |
synchrotron and inverse compton emission successfully explain the observed spectra of gamma-ray burst (grb) afterglows. it is thought that most grbs are products of extremely relativistic outflows and the afterglow marks the interaction of that ejecta with the surrounding matter. a faster decay of afterglow light curve... | on the theory of ring afterglows |
gamma-ray bursts (grbs) are the most luminous objects known: they outshine their host galaxies, making them ideal candidates for probing large-scale structure. our aim is to determine the spatial two-point correlation function of the grbs with spectroscopic redshifts. we used all observations till 4 june 2021, and we a... | the spatial distribution of gamma-ray bursts with measured redshifts from 24 years of observation |
using deep and high-cadence gamma-ray burst (grb) afterglow data from the reionization and transients infra-red/optical camera, we observe a sharp and achromatic light curve break 12.6 days after the grb, accompanied by an approximately achromatic bump. fitting of the optical, near-infrared, and x-ray data suggest a ve... | evidence for a bright-edged jet in the optical/near-infrared afterglow of grb 160625b |
the potential existence of two separate classes of long-duration gamma-ray bursts (lgrbs) with and without radio afterglow emission, corresponding to radio-bright/loud and radio-dark/quiet populations, has been recently argued and favoured in the grb literature. the radio-quiet lgrbs have been found to have, on average... | are there radio-loud and radio-quiet gamma-ray bursts? |
we describe the implementation of a remotely operated telescope on the skynet robotic telescope network, a system developed and run by the university of north carolina-chapel hill. our telescope, operated by appalachian state university at its dark sky observatory, runs robotically on this queue-scheduled system, autom... | implementation and operation of a robotic telescope on skynet |
aims: the aim of the study is to constrain the physics of gamma-ray bursts (grbs) by analysing the multi-wavelength afterglow data set of grb 121024a that covers the full range from radio to x-rays.methods: using multi-epoch broad-band observations of the grb 121024a afterglow, we measured the three characteristic brea... | microphysics and dynamics of the gamma-ray burst 121024a |
utilizing more than 100 long gamma-ray bursts (lgrbs) in the swift-ryan-2012 sample that includes the observed redshifts and jet angles, le & mehta performed a timely study of the rate density of lgrbs with an assumed broken power-law grb spectrum and obtained a grb-burst-rate functional form that gives acceptable ... | resolving the excess of long grb's at low redshift in the swift era |
a variety of scientific results have been achieved over the last 10 years with the grond simultaneous 7-channel imager at the 2.2 m telescope of the max-planck society at eso/la silla. while designed primarily for rapid observations of gamma-ray burst afterglows, the combination of simultaneous imaging in the sloan g‧r... | the benefit of simultaneous seven-filter imaging: 10 years of grond observations |
we extend the standard model of forward-reverse shock (fs-rs) for gamma-ray burst (grb) afterglow to more general cases. on one hand, we derive the analytical solution to the hydrodynamics of the shocks in two limiting cases, i.e. an ultrarelativistic reverse shock case and a newtonian reverse shock case. based on the ... | a semi-analytical solution to the forward-reverse shock hydrodynamics of the gamma-ray burst afterglow |
in recent years, more and more gamma-ray bursts (grbs) with late rebrightenings in their multi-band afterglows have revealed the late-time activity of their central engines. grb 100814a is a special case among the well-sampled events, with complex temporal and spectral evolution. the single power-law shallow decay inde... | signature of a spin-up magnetar from multi-band afterglow rebrightening of grb 100814a |
a planned rapid submillimeter (submm) gamma ray burst (grbs) follow-up observations conducted using the greenland telescope (glt) is presented. the glt is a 12-m submm telescope to be located at the top of the greenland ice sheet, where the high-altitude and dry weather porvides excellent conditions for observations at... | a new era of submillimeter grb afterglow follow-ups with the greenland telescope |
at2018cow is a recently detected transient (smartt et al. atel #11727), associated with a galaxy cgcg 137-068 at z = 0.014. its physical nature is debatable, with possible scenarios including the type ic supernova (e.g., xu et al. atel#11740, izzo et al. atel#11753), an off-axis gamma-ray burst afterglow (e.g., rivera ... | the evn detection of at2018cow at 1.67ghz |
the long gamma-ray burst grb 161017a was detected by fermi and swift, and its afterglow was observed by the mitsume 50 cm optical telescope promptly, about 50 s after the burst. early optical observations revealed that the optical light curve exhibits a plateau and rebrightening in the early afterglow phase about 500 a... | late engine activity of grb 161017a revealed by early optical observations |
we present the micro-channel x-ray telescope (mxt), a new narrow-field (about 1°) telescope that will be flying on the sino-french svom mission dedicated to gamma-ray burst science, scheduled for launch in 2021. mxt is based on square micro pore optics (mpos), coupled with a low noise ccd. the optics are based on a "lo... | the microchannel x-ray telescope on board the svom satellite |
recent observations have confirmed that gamma-ray burst (grb) afterglows produce very high-energy radiation (vhe, e>100gev). this highly anticipated discovery opens new scenarios in the interpretation of grbs and in their role as probes of extragalactic background light (ebl) and lorentz invariance violation (liv). ... | probing gamma-ray burst vhe emission with the southern wide-field-of-view gamma-ray observatory |
we present the results of a spectroscopic search for narrow emission and absorption features in the x-ray spectra of long gamma-ray burst (grb) afterglows. using xmm-newton data, both epic and rgs spectra, of six bright (fluence > 10-7 erg cm-2) and relatively nearby (z = 0.54-1.41) grbs, we performed a blind search... | searching for narrow absorption and emission lines in xmm-newton spectra of gamma-ray bursts |
current models suggest gamma-ray bursts could be used as a way of probing population-iii stars - the first stars in the early universe. in this paper, we use numerical simulations to demonstrate that late-time radio observations of gamma-ray burst afterglows could provide a means of identifying bursts that originate fr... | gamma-ray bursts from massive population-iii stars: clues from the radio band |
we examine the emission from optically bright gamma-ray burst (grb) afterglows, as the ultraviolet and optical telescope (uvot) on the neil gehrels swift observatory first begins observing, following the slew to target the grb, while the pointing of the swift satellite is still settling. we verify the photometric quali... | a study of gamma-ray burst afterglows as they first come into view of the swiftultraviolet and optical telescope |
aims: we present a comprehensive temporal and spectral analysis of the long swift grb 120327a afterglow data to investigate possible causes of the observed early-time colour variations.methods: we collected data from various instruments and telescopes in x-ray, ultraviolet, optical, and near-infrared bands, and determi... | colour variations in the grb 120327a afterglow |
we present the high-energy emission properties of grb 160509a, from its prompt mission to late afterglow phase. grb 160509a contains two emission episodes: 0-40 s and 280-420 s after the burst onset ({t}0). the relatively high fluence of grb 160509a allows us to establish an evolving spectrum above 100 mev. during the ... | an evolving gev spectrum from prompt to afterglow: the case of grb 160509a |
a significant number of the parameters of a gamma-ray burst (grb) and its host galaxy are calculated from the afterglow. there are various methods obtaining extinction values for the necessary correction for galactic foreground. these are: galaxy counts, from hi 21 cm surveys, from spectroscopic measurements and colors... | foreground of gamma-ray bursts (grbs) from akari fis data |
different forms of long gamma-ray burst (grb) luminosity functions are considered on the basis of an explicit physical model. the inferred flux distributions are compared with the observed ones from two samples of grbs, swift and fermi gbm. the best-fit parameters of the luminosity functions are found, and the physical... | differential source count for gamma-ray bursts |
a number of gamma-ray bursts (grbs) exhibit the simultaneous bumps in their optical and x-ray afterglows around the jet break. these bumps are similar to the afterglows of grb 170817a, except preceded by a long shallow decay. its origin is unclear. we suggest that these late simultaneous bumps may sound a transition of... | late afterglow bump/plateau around the jet break: signature of a free-to-shocked wind environment in gamma-ray burst |
two types of emission can be observed from gamma-ray bursts (grbs): the prompt emission from the central engine which can be observed in gamma or x-ray (as a low energy tail) and the afterglow from the environment in x-ray and at shorter frequencies. we examined the swift xrt spectra with the xspec software. the correc... | galactic and extragalactic hydrogen in the x-ray spectra of gamma ray bursts |
photospheric emission may originate from relativistic outflows in two qualitatively different regimes: last scattering of photons inside the outflow at the photospheric radius or radiative diffusion to the boundary of the outflow. in this work, the measurement of temperature and flux of the thermal component in the ear... | diffusive photospheres in gamma-ray bursts |
we here present the spectroscopic follow-up observations with vlt/x-shooter of the swift long-duration gamma-ray burst grb 160804a at z = 0.737. typically, grbs are found in low-mass, metal-poor galaxies that constitute the sub-luminous population of star-forming galaxies. for the host galaxy of the grb presented here,... | the luminous, massive and solar metallicity galaxy hosting the swift γ-ray burst grb 160804a at z = 0.737 |
we discuss the inhomogeneous behavior of gamma-ray burst afterglow light curves in optic. we use well-sampled light curves based on mostly our own observations to find and identify deviations (inhomogeneities) from broken power law. by the inhomogeneous behavior we mean flashes, bumps, slow deviations from power law (w... | inhomogeneities in the light curves of gamma-ray bursts afterglow |
the x-ray plateaus observed in the afterglows of some short gamma-ray bursts (grbs) are usually interpreted as the contribution from newborn magnetars with magnetic dipole radiation. however, fan et al. re-examined that interpretation and found that a rapidly rotating magnetar might lose most of the angular momentum to... | signature of r-mode gravitational-wave emission in the x-ray afterglow of short grb 090510 |
we obtained well-sampled optical photometry of grb 110213a, including swift/uvot and xrt. combining our data from those of other ground-based telescopes, we present 15 optical multicolor light curves showing similar shapes with two peaks. in contrast, in the x-ray band, only a single peak is observed between the two op... | grb 110213a: a study of afterglow electromagnetic cascade radiation |
we present a time-resolved spectral analysis of bright x-ray flares observed by swift x-ray telescope from 2004 december to 2021 december. we selected 58 bright flares from 56 gamma-ray burst x-ray afterglows to perform time-resolved spectral analysis. we find that there is a strong spectral evolution in x-ray flares. ... | the spectral evolution patterns and implications of gamma-ray burst x-ray flares |
short gamma-ray bursts (sgrbs) are widely believed to be from mergers of binary compact objects involving at least one neutron star and hence have a broad range of spatial offsets from their host galaxies. in this work, we search for possible correlations between the emission properties of 18 sgrbs and their offsets fr... | possible correlations between the emission properties of sgrbs and their offsets from the host galaxies |
two-thirds of long duration gamma-ray bursts (grbs) show soft x-ray absorption in excess of the milky way. the column densities of metals inferred from uv and optical spectra differ from those derived from soft x-ray spectra, at times by an order of magnitude, with the latter being higher. the origin of the soft x-ray ... | soft x-ray absorption excess in gamma-ray burst afterglow spectra: absorption by turbulent ism |
the recent discovery of gravitational waves from gw170817, associated with a short gamma-ray burst (grb) at a distance of 40 mpc, has demonstrated that short grbs can occur locally and at a reasonable rate. furthermore, gravitational waves enable us to detect close-by grbs, even when we are observing at latitudes far f... | compton echoes from nearby gamma-ray bursts |
the statistics of x-ray flares in the afterglow of gamma-ray bursts (grbs) have been studied extensively without considering the possible different origins of each flare. by satisfying six observational criteria, we find a sample composed of 16 long grbs observed by \textit{swift} satellite may share a same origin. by ... | revisiting the statistics of x-ray flares in gamma-ray bursts. |
the infra-red telescope (irt) on board theseus will play a key role in identifying and characterizing moderate to high redshift gamma-ray bursts afterglows. the irt enables the on board grb autonomous redshift determination, thus allowing the ground based telescopes to be triggered on a redshift pre-selected sample and... | the infra-red telescope on board the theseus mission |
we show that the weibel or currente filamentation instability can lead to the emission of circularly polarized radiation. using particle-in-cell (pic) simulations and a radiation post-processing numerical algorithm, we demonstrate that the level of circular polarization increases with the initial plasma magnetization, ... | magnetized current filaments as a source of circularly polarized light |
we present the statistical analysis of the properties of gamma-ray bursts with measured host galaxy redshifts and peaked optical light curves in proper frames of reference. the optical transients are classified by comparing the time lag of the optical peak relative to the grb trigger with the duration of the gamma-ray ... | statistical analysis of the parameters of gamma-ray bursts with known redshifts and peaked optical light curves |
the x-ray afterglows of almost one-half of gamma-ray bursts have been discovered by the swift satellite to have a shallow decay phase of which the origin remains mysterious. two main models have been proposed to explain this phase: relativistic wind bubbles (rwbs) and structured ejecta, which could originate from milli... | testing models for the shallow decay phase of gamma-ray burst afterglows with polarization observations |
we perform a comprehensive stacking analysis of data collected by the fermi large area telescope (lat) of γ-ray bursts (grbs) localized by the swift spacecraft, which were not detected by the lat but which fell within the instrument’s field of view at the time of trigger. we examine a total of 79 grbs by comparing the ... | fermi lat stacking analysis of swift localized grbs |
rapid spectroscopy of grb afterglows is an important and hard task. based on the archival xs-grb spectral database, we here perform a pilot study on the afterglow's spectroscopy in the forthcoming svom era in two aspects. first, our simulation indicates that the color acquired from the svom/vt blue and red channels is ... | a pilot study of catching high-z grbs and exploring circumburst environment in the forthcoming svom era |
aims: we present the updated census and statistics of lyman-α emitting long gamma-ray burst host galaxies (lae-lgrbs). we investigate the properties of a subsample of lae-lgrbs and test the shell model that is commonly used to fit lyman-α (lyα) emission line spectra.methods: we considered all lgrb host galaxies with re... | gamma-ray bursts as probes of high-redshift lyman-α emitters and radiative transfer models |
early shallow-decaying x-ray afterglows of gamma-ray bursts (grbs) may be attributed to the dipole radiations of newly born magnetars. assuming that the grb jets powered by magnetars are quasi-universal, we find that the jet structure can be parameterized as a uniform jet with a luminosity of $\mathrm{log}{l}_{{\rm{j}}... | magnetar as central engine of gamma-ray bursts: quasi-universal jet, event rate, and x-ray luminosity function of dipole radiations |
gamma-ray bursts, associated with the collapse of massive stars or the collisions of compact objects, are the most luminous events in our universe. however, there is still much to learn about the nature of the relativistic jets launched from the central engines of these objects. we examine how jet structure-that is, th... | understanding gamma-ray burst jet structures from afterglow light curves |
gamma-ray bursts (grbs) are among the most luminous sources in the universe. the nature of their emission at tev energies is one of the most relevant open issues related to these events. the temporal and spectral features inferred from the early and late emissions usually known as prompt and afterglow, respectively, ca... | constraints on the very high energy gamma-ray emission with hawc |
we study the gamma-ray burst (grb) afterglow light curves produced by an off-axis jet in a stratified circumburst medium and summarize the temporal indices of the coasting phase, the deceleration phase, the newtonian phase, and the deep newtonian phase for various viewing angles and power-law indices of medium density.... | afterglow light curves from off-axis grb jets in stratified circumburst medium |
giant flares are the brightest and rarest outbursts from magnetars, with isotropic energies of 1044-1046 erg. grb 200415a is suggested as a magnetar giant flare from ngc 253. fermi large area telescope detected the gev afterglow emission from the flare, which is the first time that the gev emission is detected from a g... | the multiwavelength afterglow emission of magnetar giant flare-like event grb 200415a |
at 23:59:25 ut, the swift burst alert telescope (bat) triggered and located grb 210619b (trigger=1056757). swift slewed immediately to the burst. the bat on-board calculated location is ra, dec 319.713, +33.860 which is ra(j2000) = 21h 18m 51s dec(j2000) = +33d 51' 35" with an uncertainty of 3 arcmin (radius, 90% conta... | grb 210619b: swift detection of a bright burst and optical counterpart |
we used the 1m jacobus kapteyn telescope (jkt) at la palma, remotely operated by the sara consortium, to obtain bvri photometry of the afterglow of grb 221009a (swift j1913.1+1946; atel #15650) on october 10 ut. in image series from oct. 10.83-10.88, 30 hours after the initial burst detection, we find b=22.3, v=19.6, r... | bvri photometry of the grb 220019a afterglow |
observations of very early multi-wavelength afterglows are critical to reveal the properties of the radiating fireball and its environment as well as the central engine of gamma-ray bursts (grbs). we report our optical observations of grb 111228a from 95 s to about 50 hr after the burst trigger and investigate its prop... | multi-wavelength observations of grb 111228a and implications for the fireball and its environment |
at 19:51:27 ut, the swift burst alert telescope (bat) triggered and located grb 210610b (trigger=1054681). swift slewed immediately to the burst. the bat on-board calculated location is ra, dec 243.939, +14.391 which is ra(j2000) = 16h 15m 45s dec(j2000) = +14d 23' 29" with an uncertainty of 3 arcmin (radius, 90% conta... | grb 210610b: swift detection of a burst with bright optical afterglow |
aims: we characterize a sample of gamma-ray bursts with low luminosity x-ray afterglows (lla grbs), and study their properties. method: we select a sample consisting of the 12\% faintest x-ray afterglows from the total population of long grbs (lgrbs) with known redshift. we study their intrinsic properties (spectral in... | properties of low luminosity afterglow gamma-ray bursts |
we report an optical spectrum on the afterglow of the extremely strong, long gamma-ray burst grb221009a/swift j1913.1+1946 (atel #15653, #15655, #15660, #15663, #15671, #15685) taken with the lrs2-r spectrograph (wavelength range: 6450-10500 angstroms, resolving power: 1800) of the 10m hobby-eberly telescope at mcdonal... | detection of the emerging supernova spectrum from the afterglow of grb221009a |
the immensely bright and intrinsically simple afterglow spectra of gamma-ray bursts (grbs) have proven to be highly effective probes of the interstellar dust and gas in distant, star forming galaxies. despite significant progress, many aspects of the host galaxy attenuating material are still poorly understood. there i... | gamma-ray burst afterglows as probes of the ism |
x-ray flares are the most common phenomena in the afterglow phase of gamma-ray bursts (grbs) in the swift era, and are known as a canonical component in x-ray afterglows. in this work, we constrain the lorentz factor of x-ray flares with an updated sample. we extensively search for x-ray light curves showing flare and ... | the updated bulk lorentz factors of gamma-ray burst x-ray flares |
burst alert robotic telescope (bart) is an autonomous robotic observatory located at the ondřejov observatory in the czech republic. it was constructed in 1996 in order to follow up satellite triggers in hope to provide early observations of gamma‑ray burst optical afterglows. we present the new telescope of the observ... | small binocular telescope: the new epoch of burst alert robotic telescope |
we use joint observations by the neil gehrels swift x-ray telescope (xrt) and the fermi large area telescope (lat) of gamma-ray burst (grb) afterglows to investigate the nature of the long-lived high-energy emission observed by fermi lat. joint broadband spectral modeling of xrt and lat data reveal that lat nondetectio... | investigating the nature of late-time high-energy grb emission through joint fermi\\swift observations |
a simplified one dimensional grid is used to model the evolution of magnetized plasma flow. we implement diffusion laws similar to those so-far used to model magnetic reconnection with cellular automata. as a novelty, we also explicitly superimpose a background flow. the aim is to numerically investigate the possibilit... | self organized criticality in an one dimensional magnetized grid. application to grb x-ray afterglows |
recent observations by the swift satellite have revealed long-lasting ($\sim 10^2-10^5\,\mathrm{s}$), "plateau-like" x-ray afterglows in the vast majority of short gamma-ray bursts events. this has put forward the idea of a long-lived millisecond magnetar central engine being generated in a binary neutron star (bns) me... | magnetically-induced outflows from binary neutron star merger remnants |
molecular species, most frequently h2, are present in a small, but growing, number of gamma-ray burst (grb) afterglow spectra at redshifts z ∼ 2-3, detected through their rest-frame uv absorption lines. in rare cases, lines of vibrationally excited states of h2 can be detected in the same spectra. the connection betwee... | infrared molecular hydrogen lines in grb host galaxies |
depletion studies provide a way to understand the chemical composition of interstellar dust grains. we here examine 23 gamma-ray bursts (grbs) optical afterglow spectra (spanning 0.6 ≤ z ≤ 5.0) and compare their silicon and iron dust-phase column densities with different extinction curve parameters to study the composi... | silicon and iron dust in gamma-ray burst host galaxy absorbers |
we propose a method to detect possible non-stationarities of gamma-ray burst jets. assuming that the dominant source of variability in the prompt gamma light curve is the non-stationarity of the jet, we show that there should be a connection between the variability measure and the characteristic angle of the jet derive... | a statistical method to detect non-stationarities of gamma-ray burst jets |
we report on master optical observations of an afterglow-like optical and x-ray transient at2021lfa/ztf21aayokph. we detected the initial steady brightening of the transient at 7σ confidence level. this allowed us to use smooth optical self-similar emission of grbs model to constrain the explosion time to better than 1... | orphan optical flare as soss emission afterglow, localization in time |
context. among the large variety of astrophysical sources that we can observe, gamma-ray bursts (grbs) are the most energetic of the whole universe. their emission peaks in the γ-ray band, with a duration from a fraction of a second to a few hundred seconds, and is followed by an afterglow covering the whole electromag... | grb 080928 afterglow imaging and spectro-polarimetry |
high-precision measurement of the isotropic diffuse γ-ray background (igrb) has been extrapolated to the tev energy region using the fermi-lat experiment. various kinds of astrophysical sources are candidates for its origin. however, a consensus on the dominant source has been difficult to reach. recent observations of... | contribution of high-energy grb emissions to the spectrum of the isotropic diffuse γ-ray background |
at 11:55:21 ut, the swift burst alert telescope (bat) triggered and located grb 220826a (trigger=1121751). swift slewed immediately to the burst. the bat on-board calculated location is ra, dec 206.431, -44.044 which is ra(j2000) = 13h 45m 44s dec(j2000) = -44d 02' 39" with an uncertainty of 3 arcmin (radius, 90% conta... | grb 220826a: swift detection of a burst with an optical counterpart |
x-ray flares are frequently detected in the x-ray afterglow light curves and are highly correlated with the prompt emission of gamma-ray bursts (grbs). we compile a comprehensive sample of x-ray flares up to 2021 april, comprising 697 flares. we classify the total sample into four types: early flares (tp≤103 s), late f... | statistical properties of x-ray flares in gamma-ray bursts |
context. a thermal x-ray component is observed in the early afterglow of some gamma-ray bursts. possible explanations include shockwave breakout, relativistic photosphere, or emission from cocoon. the difficulties of these models are discussed.aims: we propose an alternative model that attributes such a thermal compone... | thermal emission in the early afterglow of gamma-ray bursts from their interaction with supernova ejecta |
we study the electromagnetic radiation from a newborn magnetar whose magnetic tilt angle decreases rapidly. we calculate the evolution of the angular spin frequency, the perpendicular component of the surface magnetic field strength, and the energy loss rate through magnetic dipole radiation. we show that the spin-down... | effect of rapid evolution of magnetic tilt angle on a newborn magnetar's dipole radiation |
we show that observed properties of the low luminosity grb171205a and its afterglow, like those of most other low-luminosity (ll) gamma ray bursts (grbs) associate with a supernova (sn), indicate that it is an ordinary sn-grb, which was produced by inverse compton scattering of glory light by a highly relativistic narr... | origin of the far off-axis grb171205a |
the aim of the space mission concept theseus is to continue to collect and study the grb events like swift. it will allow us to study the early universe. moreover, it will offer us to study with unprecedented sensitivity grb emission and to measure the redshift for the bursts with z>5. in this work, we investigate t... | grb follow-up and science with theseus/irt . |
the number of long gamma-ray bursts (grbs) known to have occurred in the distant universe (z > 5) is small (∼15); however, these events provide a powerful way of probing star formation at the onset of galaxy evolution. in this paper, we present the case for grb 100205a being a largely overlooked high-redshift event.... | the case for a high-redshift origin of grb 100205a |
swift, chandra, and xmm have found a weak but nearly constant x-ray component from swift j1644+57 that appeared at ∼500 days and was visible at least until ∼1400 days after the stellar capture, which cannot be explained by standard tidal disruption theories. we suggest that this x-ray afterglow component may result fro... | x-ray afterglow of swift j1644+57: a compton echo? |
grb 120308a, a long duration γ-ray burst (grb) detected by swift, was distinguished by a highly polarized early optical afterglow emission that strongly suggests an ordered magnetic field component in the emitting region. in this work, we model the optical and x-ray emission in the reverse and forward shock scenario an... | the magnetization degree of the outflow powering the highly polarized reverse-shock emission of grb 120308a |
the detection of optical re-brightenings and x-ray plateaus in the afterglows of gamma-ray bursts (grbs) challenges the generic external shock model. recently, we have developed a numerical method to calculate the dynamic of the system consisting of a forward shock and a reverse shock. here, we briefly review the appli... | diverse features of the multiwavelength afterglows of gamma-ray bursts: natural or special? |
gamma-ray bursts (grbs) are the most violent explosions in the universe, releasing a huge amount of energy in few seconds. while our understanding of the prompt and the afterglow phases has increased with swift and fermi, we have very few information about their high energy (he, e <~ 100) emission components. this r... | search for high energy emission from grbs with magic |
we demonstrate the use of the akari fis all-sky survey maps in the study of extragalactic objects. a quick but reliable estimate of the galactic foreground is essential for extragalactic research in general. we explored the galactic foreground and calculated hydrogen column densities using akari fis and other recent al... | galactic foreground of gamma-ray bursts from akari far-infrared surveyor |
the afterglow data of gamma ray bursts (grbs) can be used to constrain the physical properties of the fireball (e.g., the jet structure and opening angle) and the circumburst medium. with the peak time of the early afterglow light curve being taken as the deceleration time, one can estimate the initial lorentz factor o... | grb 181110a: constraining the jet structure, circumburst medium and the initial lorentz factor |
at 20:39:13 ut, the swift burst alert telescope (bat) triggered and located grb 191221b (trigger=945521). swift slewed immediately to the burst. the bat on-board calculated location is ra, dec 154.832, -38.141 which is ra(j2000) = 10h 19m 20s dec(j2000) = -38d 08' 28" with an uncertainty of 3 arcmin (radius, 90% contai... | grb 191221b: swift detection of a burst and a very bright optical candidate |
we present simulations of the detection probability for absorption lines from ions in the warm and hot ionized medium (whim) with athena in the spectra of gamma-ray burst afterglows. the simulations are based on swift xrt lightcurves of these afterglows and are performed using the end-to-end simulation framework sixte.... | observing the whim with athena |
the afterglows of gamma-ray bursts (grbs) are believed to originate from the synchrotron emission of shock-accelerated electrons produced by the interaction between the outflow and the external medium. the accelerated electrons are usually assumed to follow a power-law energy distribution with an index of p. observatio... | modeling the multi-band afterglow of grb 091127: evidence of a hard electron energy spectrum with an injection break |
the swift satellite has observed more than a thousand grbs with x-ray data. almost a third of them have redshift measurement, too. here we start to investigate the x-ray spectral fitting of the data considering the low energy part where the n(h) absorption happens. based on the available more accurate input data we exa... | studying the variability of the x-ray spectral parameters of high-redshift grbs' afterglows |
at 05:09:55 ut, the swift burst alert telescope (bat) triggered and located grb 220101a (trigger=1091101). swift slewed immediately to the burst. the bat on-board calculated location is ra, dec 1.380, +31.753 which is ra(j2000) = 00h 05m 31s dec(j2000) = +31d 45' 09" with an uncertainty of 3 arcmin (radius, 90% contain... | grb 220101a: swift detection of a burst with a bright optical counterpart |
we present our optical photometric and spectroscopical observations of grb 140629a. a redshift of z = 2.275 ±0.043 is measured through the metal absorption lines in our spectroscopic data. using our photometric data and multiple observational data from other telescopes, we show that its optical light curve is well inte... | photometric and spectroscopic observations of grb 140629a |
the first gamma-ray burst (grb) catalog presented by the fermi-large area telescope (lat) collaboration includes 28 grbs, detected above 100 mev over the first three years since the launch of the fermi mission. however, more than 100 grbs are expected to be found over a period of six years of data collection thanks to ... | prospects for gamma-ray bursts detection by the cherenkov telescope array |
context. the very high-energy (vhe; ≥100 gev) component from at least two gamma-ray bursts (grbs), that is, grb 180720b and grb 190114c, has been detected in the afterglow phase. it is widely discussed that the gev to tev emission originated from a synchrotron self-compton (ssc) process. the vhe component may cause an ... | searching for an additional high-energy component in fermi-lat grb afterglows |
we present the discovery and the subsequent follow up of radio emission from sdss j130402.36+293840.6 (j1304+2938), the candidate host galaxy of the gamma-ray burst (grb) grb 200716c. the galaxy is detected in the racs (0.89 ghz), the nvss, the apertif imaging survey, and the first (1.4 ghz), the vlass (3 ghz), and in ... | multi-scale vlbi observations of the candidate host galaxy of grb 200716c |
we present centimeter-band and millimeter-band afterglow observations of five long-duration γ-ray bursts (grbs; grb 130131a, 130420b, 130609a, 131229a, 140713a) with dust-obscured optical afterglow emission, known as "dark" grbs. we detect the radio afterglow of two of the dark grbs (grb 130131a and 140713a), along wit... | a radio-selected population of dark, long gamma-ray bursts: comparison to the long gamma-ray burst population and implications for host dust distributions |
it has been widely recognized that gamma-ray burst (grb) afterglows arise from interactions between the grb outflow and circumburst medium, while their evolution follows the behaviors of relativistic shock waves. assuming the distribution of circumburst medium follows a general power-law form, that is, n = a * r -k , w... | diagnosing the circumburst environment with multiband gamma-ray burst radio afterglows |
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