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the x-ray afterglow of short hard bursts (shbs) of gamma rays provides compelling evidence that shbs are produced by highly relativistic jets launched in the birth of rotationally powered millisecond pulsars in merger of neutron stars and/or in mass accretion on neutron stars in low mass x-ray binaries. gravitational w... | the smoking guns of short hard gamma ray bursts |
a bright long gamma-ray burst grb 141207a was observed by the fermi gamma-ray space telescope and detected by both instruments onboard. the observations show that the spectrum in the prompt phase is not well described by the canonical empirical band function alone, and that an additional power-law component is needed. ... | high-energy non-thermal and thermal emission from grb141207a detected by fermi |
we report on the x-ray dust-scattering features observed around the afterglow of the gamma-ray burst grb 160623a. with an xmm-newton observation carried out ∼2 d after the burst, we found evidence of at least six rings, with angular size expanding between ∼2 and 9 arcmin, as expected for x-ray scattering of the prompt ... | behind the dust curtain: the spectacular case of grb 160623a |
we present multi-wavelength observations of the hyper-energetic gamma-ray burst (grb) 130907a, a swift-discovered burst with early radio observations starting at ≈4 hr after the γ-ray trigger. grb 130907a was also detected by the fermi/lat instrument and at late times showed a strong spectral evolution in x-rays. we fo... | early-time vla observations and broadband afterglow analysis of the fermi/lat detected grb 130907a |
we present our extensive observational campaign on the swift-discovered grb 141121a, almost 10 years after its launch. our observations cover radio through x-rays and extend for more than 30 days after discovery. the prompt phase of grb 141121a lasted 1410 s and, at the derived redshift of z = 1.469, the isotropic ener... | happy birthday swift: ultra-long grb 141121a and its broadband afterglow |
extended emission in short gamma-ray bursts (sgrbs) is a mystery. by conducting time-resolved spectral analyses of the nine brightest events observed by the swift-xrt, we classify the early x-ray emission of sgrbs into two types. one is the extended emission with exponentially rapid decay, which shows significant spect... | x-raying extended emission and rapid decay of short gamma-ray bursts |
the nature of the shallow decay phase in the x-ray afterglow of the gamma-ray burst (grb) is not yet clarified. we analyse the data of early x-ray afterglows of 26 grbs triggered by burst alert telescope onboard neil gehrels swift observatory and subsequently detected by fermi large area telescope (lat) and/or imaging ... | less noticeable shallow decay phase in early x-ray afterglows of gev/tev-detected gamma-ray bursts |
the physical origins of gamma-ray burst (grb) prompt emission (photosphere or synchrotron) are still subject to debate, after more than five decades. here, we find that many of the observed characteristics of 15 long grbs, which have the highest prompt emission efficiency ϵγ(ϵγ≳ 80%), strongly support photosphere (ther... | evidence of photosphere emission origin for gamma-ray burst prompt emission |
recently, the magic collaboration reported a ~5σ statistical significance of the very-high-energy (vhe) emission from a distant gamma-ray burst (grb), grb 201216c. such distant grb may be effectively absorbed by the extragalactic background light (ebl). the origin of the vhe emission from such distant objects is still ... | time-dependent numerical model for studying the very-high-energy emissions of distant gamma-ray burst grb 201216c |
we present the spectroscopic and photometric late-time follow-up of the host galaxy of the long-duration swift γ-ray burst grb 140506a at z = 0.889. the optical and near-infrared afterglow of this grb had a peculiar spectral energy distribution (sed) with a strong flux-drop at 8000 å (4000 å rest-frame) suggesting an u... | steep extinction towards grb 140506a reconciled from host galaxy observations: evidence that steep reddening laws are local |
it is largely recognized that gamma-ray burst (grb) jets involve ultrarelativistic motion. however, the value of the lorentz factor γ0 is still not clear and only lower limits are known for most bursts. we suggest here a new method to obtain upper limits on γ0. the early high-energy synchrotron afterglow flux depends s... | constraints on the bulk lorentz factor of gamma-ray burst jets from fermi /lat upper limits |
correlations between intrinsic properties of gamma-ray burst (grb) light curves provide clues to the nature of the central engine, the jet, and a possible means to standardize grbs for cosmological use. here, we report on the discovery of a correlation between the intrinsic early-time luminosity, lg,10 s, measured at r... | evidence for a luminosity-decay correlation in grb gev light curves |
aims: following the detection of the fast radio burst frb150418 by the superb project at the parkes radio telescope, we aim to search for very-high energy gamma-ray afterglow emission.methods: follow-up observations in the very-high energy gamma-ray domain were obtained with the h.e.s.s. imaging atmospheric cherenkov t... | first limits on the very-high energy gamma-ray afterglow emission of a fast radio burst. h.e.s.s. observations of frb 150418 |
the typical detection rate of ~1 gamma-ray burst (grb) per day by the fermi gamma-ray burst monitor (gbm) provides a valuable opportunity to further our understanding of grb physics. however, the large uncertainty of the fermi localization typically prevents rapid identification of multiwavelength counterparts. we repo... | searching for fermi grb optical counterparts with the prototype gravitational-wave optical transient observer (goto) |
grb 220426a is a bright gamma-ray burst (grb) dominated by the photospheric emission. we perform several tests to speculate the origin of this photospheric emission. the dimensionless entropy η is large, which is not usual if we assume that it is a pure hot fireball launched by neutrino-antineutrino annihilation mechan... | the origin of the photospheric emission of grb 220426a |
a relativistic electron-positron (e+e-) pair wind from a rapidly rotating, strongly magnetized neutron star (ns) would interact with a gamma-ray burst (grb) external shock and reshape afterglow emission signatures. assuming that the merger remnant of gw170817 is a long-lived ns, we show that a relativistic e+e- pair wi... | grb 170817a afterglow from a relativistic electron-positron pair wind observed off-axis |
the event gw170817/grb 170817a, discovered via the successful joint observation of its gravitational wave radiation and its multiwavelength electromagnetic counterparts, was the first definite `smoking-gun' from the merger of two neutron stars (nss). however, the remnant of the merger remains unknown. piro et al. recen... | diagnosing the remnants of binary neutron star merger from gw170817/grb170817a event |
the late-time high-resolution x-ray and radio observations of grb980425/sn1998bw, the closest known gamma ray burst (grb) associated with a supernova (sn) explosion, may have actually resolved the hyperluminal source that produced the grb and its afterglow. its hyperluminal speed ~350c is consistent with that expected ... | hyperluminal signatures in the afterglows of gamma-ray bursts 980425 and 030329 |
flares in the x-ray afterglow of gamma-ray bursts (grbs) share more characteristics with the prompt emission than the afterglow, such as pulse profile and contained fluence. as a result, they are believed to originate from late-time activity of the central engine and can be used to constrain the overall energy budget. ... | fallback accretion on to a newborn magnetar: long grbs with giant x-ray flares |
twenty years have already been elapsed from the bepposax discovery of the first afterglow of a gamma-ray burst (grb) in february 28, 1997. thanks to this discovery, it was possible to unveil the 30 year mystery about grb origin: grbs are huge explosions in galaxies at cosmological distances. starting from the first grb... | the key role of bepposax in the grb history |
a structured jet is invoked to explain the afterglows and also the prompt emission of grb 170817a. in this article, we stress that, for a precessing jet, the jet structure in the prompt emission phase and that in the afterglow phase may be different. the jet structure in the afterglow phase can be non-uniform even if a... | jet structure in the afterglow phase for gamma-ray bursts with a precessing jet |
we have developed a model of early x-ray afterglows of gamma-ray bursts originating from the reverse shock (rs) propagating through ultrarelativistic, highly magnetized pulsar-like winds produced by long-lasting central engines. we first performed fluid and magnetohydrodynamic numerical simulations of relativistic doub... | dynamics and emission of wind-powered afterglows of gamma-ray bursts: flares, plateaus, and steep decays |
very long and precise follow-up measurements of the x-ray afterglow of very intense gamma-ray bursts (grbs) allow a critical test of grb theories. here we show that the single power-law decay with time of the x-ray afterglow of grb 130427a, the record-long and most accurately measured x-ray afterglow of an intense grb ... | critical test of gamma-ray burst theories |
we present photometric and polarimetric measurements of gamma-ray burst (grb) optical afterglows observed by the ringo3 imaging polarimeter over its ~7 yr lifetime mounted on the liverpool telescope. during this time, ringo3 responded to 67 grb alerts. of these, 28 had optical afterglows and a further ten were sufficie... | polarimetry and photometry of gamma-ray bursts afterglows with ringo3 |
one of the cornerstones of modern physics is einstein's special relativity, with its constant speed of light and zero photon mass assumptions. constraint on the rest mass mγ of photons is a fundamental way to test einstein's theory, as well as other essential electromagnetic and particle theories. since non-zero photon... | constraining the mass of the photon with gamma-ray bursts |
using the generic hydrodynamic model of gamma-ray burst (grb) afterglows, we calculate the radio afterglow light curves of low luminosity, high luminosity, failed and standard grbs in different observational bands of fast's energy window. the grbs are assumed to be located at different distances from us. our results ra... | detecting radio afterglows of gamma-ray bursts with fast |
the microchannel x-ray telescope (mxt) is part of the scientific payload of the svom sino-french space mission to observe the early afterglow of gamma-ray bursts in the 0.2-10 kev energy range and localize them within 2 arcmin. for a total mass of 42 kg and a total power of 60 w, this instrument is composed of an optic... | design and performance of the camera of the micro-channel x-ray telescope on-board the svom mission |
we investigate the afterglow of grb 140713a, a gamma-ray burst (grb) that was detected and relatively well sampled at x-ray and radio wavelengths, but was not present at optical and near-infrared wavelengths, despite searches to deep limits. we present the emission spectrum of the likely host galaxy at z = 0.935 ruling... | detailed multiwavelength modelling of the dark grb 140713a and its host galaxy |
gamma-ray burst (grb) 111215a was bright at x-ray and radio frequencies, but not detected in the optical or near-infrared (nir) down to deep limits. we have observed the grb afterglow with the westerbork synthesis radio telescope and arcminute microkelvin imager at radio frequencies, with the william herschel telescope... | detailed afterglow modelling and host galaxy properties of the dark grb 111215a |
we develop a model of early gamma-ray burst (grb) afterglows with dominant x-ray contribution from the reverse shock (rs) propagating in highly relativistic (lorentz factor γw ∼ 106) magnetized wind of a long-lasting central engine. the model reproduces, in a fairly natural way, the overall trends and yet allows for va... | early grb afterglows from reverse shocks in ultra-relativistic, long-lasting winds |
in order to explain rapid light-curve variability without invoking a variable source, several authors have proposed `minijets' that move relativistically relative to the main flow of the jet. here, we consider the possibility that these minijets, instead of being isotropically distributed in the comoving frame of the j... | an anisotropic minijets model for the grb prompt emission |
we present a correlation between the average temporal decay ({α }{{x},{avg},\gt 200{{s}}}) and early-time luminosity ({l}{{x},200{{s}}}) of x-ray afterglows of gamma-ray bursts as observed by the swift x-ray telescope. both quantities are measured relative to a rest-frame time of 200 s after the γ-ray trigger. the lumi... | a correlation between the intrinsic brightness and average decay rate of gamma-ray burst x-ray afterglow light curves |
we present a wide data set of gamma-ray, x-ray, uv/opt/ir (uvoir), and radio observations of the swift grb100814a. at the end of the slow decline phase of the x-ray and optical afterglow, this burst shows a sudden and prominent rebrightening in the optical band only, followed by a fast decay in both bands. the optical ... | the optical rebrightening of grb100814a: an interplay of forward and reverse shocks? |
the multiwavelength observations of grb afterglows, together with some high-performance particle-in-cell simulations, hint that the magnetic field may decay behind the shock front. in this work, we develop a numerical code to calculate the evolution of the accelerated electron distribution, their synchrotron and invers... | numerical study of synchrotron and inverse-compton radiation from gamma-ray burst afterglows with decaying microturbulence |
the jet composition of gamma-ray bursts (grbs), as well as how efficiently the jet converts its energy to radiation, are long-standing problems in grb physics. here, we reported a comprehensive temporal and spectral analysis of the tev-emitting bright grb 190114c. its high fluence ($\sim$ 4.436$\times$10$^{-4}$ erg cm$... | grb 190114c: fireball energy budget and radiative efficiency revisited |
in this paper, we compute and analyse synthetic radio images of gamma-ray bursts (grbs) and kilonova afterglows. for modelling the former, we consider grb170817a-inspired set of parameters, while for the latter, we employ ejecta profiles from numerical-relativity simulations. we find that the kilonova afterglow sky map... | synthetic radio images of structured grb and kilonova afterglows |
we compare the isotropic equivalent 15-2000 kev γ-ray energy, eγ , emitted by a sample of 91 swift gamma-ray bursts with known redshifts, with the isotropic equivalent fireball energy, e fb, as estimated within the fireball model framework from x-ray afterglow observations of these bursts. the uncertainty in eγ , which... | the energy budget of grbs based on a large sample of prompt and afterglow observations |
grb 090618 is a bright gamma-ray burst (grb) with multiple pulses. it shows evidence of thermal emission in the initial pulses as well as in the early afterglow phase. because high-resolution spectral data from the swift/x-ray telescope (xrt) are available for the early afterglow, we investigate the shape and evolution... | discovery of smoothly evolving blackbodies in the early afterglow of grb 090618: evidence for a spine-sheath jet? |
we present predictions of centimeter and millimeter radio emission from reverse shocks (rss) in the early afterglows of gamma-ray bursts (grbs) with the goal of determining their detectability with current and future radio facilities. using a range of grb properties, such as peak optical brightness and time, isotropic ... | radio flares from gamma-ray bursts |
we have performed a systematic study of gamma-ray bursts (grbs), which have various values in the peak energy of the νfν spectrum of prompt emission, epeak, observed by the swift/burst alert telescope (bat) and fermi/gamma-ray burst monitor, investigating their prompt and x-ray afterglow emissions. we cataloged long-la... | systematic study of the peak energy of broadband gamma-ray burst spectra |
jet precessions are widely involved in astrophysical phenomena from galaxies to x-ray binaries and gamma-ray bursts (grbs). polarization presents a unique probe of the magnetic fields in grb jets. the precession of grb relativistic jets will change the geometry within the observable emitting region of the jet, which ca... | polarization in early optical afterglows of gamma-ray bursts driven by precessing jets |
the angular distribution of gamma-ray burst (grb) jets is not yet clear. the observed luminosity of grb 170817a is the lowest among all known short grbs, which is best explained by the fact that our line of sight is outside of the jet opening angle, θ obs > θj , where θ obs is the angle between our line of sight and... | grb 170817a: a short grb seen off-axis |
as we further our studies on gamma-ray bursts (grbs), via both theoretical models and observational tools, more and more options begin to open for exploration of its physical properties. as grbs are transient events primarily dominated by synchrotron radiation, it is expected that the synchrotron photons emitted by grb... | afterglow polarization from off-axis gamma-ray burst jets |
tev emissions from γ-ray bursts are very important to study their origin and the radiation mechanisms in detail. recent observations of tev photons in some of the grbs are challenging to be explained by the traditional synchrotron radiation mechanism. in this work, we present the results of a detailed investigation of ... | observational properties of tev detected grb 180720b, grb 190114c and grb 190829a |
previous studies have shown that the incidence rate of intervening strong mg ii absorbers towards gamma-ray bursts (grbs) were a factor of 2-4 higher than towards quasars. exploring the similar sized and uniformly selected legacy data sets xq-100 and xsgrb, each consisting of 100 quasar and 81 grb afterglow spectra obt... | solving the conundrum of intervening strong mg ii absorbers towards gamma-ray bursts and quasars |
it has recently become clear that in both short and long gamma-ray bursts (grbs) it coexists a sequence of different events, each characterized by specific physical processes and corresponding values of the lorentz gamma factors. the ultra-relativistic prompt emission (upe) phase, with lorentz factor $\gamma\leq10^4$, ... | on the short grb gev emission from a kerr black hole |
we investigate the expected radio emission from the reverse shock of short grbs, using the fitted afterglow parameters. in light of recent results suggesting that in some cases the radio afterglow is due to emission from the reverse shock, we examine the extent to which this component is detectable for short grbs. in s... | reverse shock emission from short grbs |
the rich and complex data obtained from multi-wavelength observations of shb170817a, the short hard gamma ray burst (shb) associated with gw170817 --the first neutron stars merger event detected in gravitational waves (gws)-- are analyzed in the framework of the cannonball model of shbs. in this model a highly relativi... | cannonball model diagnosis of the short gamma ray burst 170817a |
gamma-ray burst (grb) 120729a was detected by swift/bat and fermi/gbm, and then rapidly observed by swift/xrt, swift/uvot, and ground-based telescopes. it had a single long and smooth γ-ray emission pulse, which extends continuously to the x-rays. we report lick/kait observations of the source, and make temporal and sp... | grb 120729a: external shock origin for both the prompt gamma-ray emission and afterglow |
gamma-ray burst (grb) 150910a was detected by swift/burst alert telescope (bat), and then rapidly observed by swift/xrt, swift/ultraviolet-optical telescope, and ground-based telescopes. we report lick observatory spectroscopic and photometric observations of grb 150910a, and we investigate the physical origins of both... | early optical observations of grb 150910a: bright jet optical afterglow and x-ray dipole radiation from a magnetar central engine |
we present the second swift ultra-violet/optical telescope (uvot) gamma-ray burst (grb) afterglow catalog, greatly expanding on the first swift uvot grb afterglow catalog. the second catalog is constructed from a database containing over 120,000 independent uvot observations of 538 grbs first detected by swift, the hig... | a large catalog of homogeneous ultra-violet/optical grb afterglows: temporal and spectral evolution |
recently, delaunay et al. (2016) discovered a gamma-ray transient, swift j0644.5-5111, associated with the fast radio burst (frb) 131104. they also reported follow-up broadband observations beginning two days after the frb and provided upper limits on a putative afterglow of this transient. in this paper, we show that ... | could frb 131104 originate from the merger of binary neutron stars? |
we derive basic analytical results for the timing and decay of the gamma-ray burst (grb) counterpart and delayed afterglow light curves for a brief emission episode from a relativistic surface endowed with angular structure, consisting of a uniform core of size ${\theta }_{c}$ (lorentz factor ${{\rm{\gamma }}}_{c}$ and... | x-ray afterglows from the gamma-ray burst "large-angle" emission |
the observed early x-ray plateau in the afterglow lightcurves of some gamma-ray bursts (grbs) is attributed to the dipole radiations (drs) of a newborn magnetar. a quasi-periodic oscillation (qpo) signal in the plateau would be strong evidence of the magnetar precession motion. by making a time-frequency domain analysi... | early evolution of a newborn magnetar with strong precession motion in grb 180620a |
gamma-ray bursts (grbs) can be divided into three subclasses: x-ray flash (xrf), x-ray rich (xrr), and classical grb (c-grb). an x-ray flare is the rebrightening emission shown in the early x-ray afterglow of some grbs. in this paper, we comprehensively examine the x-ray flare properties among xrf, xrr, and c-grb subcl... | grb x-ray flare properties among different grb subclasses |
the experimental study of the dynamics of neutral electron-positron beams is an emerging area of research, enabled by the recent results on the generation of this exotic state of matter in the laboratory. electron-positron beams and plasmas are believed to play a major role in the dynamics of extreme astrophysical obje... | general features of experiments on the dynamics of laser-driven electron-positron beams |
instruments, such as the rotse, tortora, pi of the sky, master-net, and others have recorded single-band optical flux measurements of gamma-ray bursts starting as early as ~ 10 s after gamma-ray trigger. the earliest measurements of optical spectral shape have been made only much later, typically on hour time-scales, n... | evolution of the afterglow optical spectral shape of grb 201015a in the first hour: evidence for dust destruction |
the recent radio observations of a superluminal radio afterglow following gamma-ray burst (grb) 179817a are interpreted in terms of a jet impacting a baryonic cloak, which is presumably the material caught at the front of the jet as the latter emerges from a denser ejected material. assuming that we, the observers, are... | short gamma-ray bursts viewed from far off-axis |
in this paper, we further investigate the relationship, reported by oates et al., between the optical/uv afterglow luminosity (measured at restframe 200 s) and average afterglow decay rate (measured from restframe 200 s onwards) of long duration gamma-ray bursts (grbs). we extend the analysis by examining the x-ray lig... | exploring the canonical behaviour of long gamma-ray bursts using an intrinsic multiwavelength afterglow correlation |
advances in our numerical and theoretical understanding of gamma-ray burst afterglow processes allow us to construct models capable of dealing with complex relativistic jet dynamics and non-thermal emission, that can be compared directly to data from instruments such as swift. because afterglow blast waves and power la... | simulation and physical model based gamma-ray burst afterglow analysis |
following the recently established "binary-driven hypernova" (bdhn) model, we here interpret grb 970828 in terms of the four episodes typical of such a model. the "episode 1," up to 40 s after the trigger time t 0, with a time varying thermal emission and a total energy of eiso,1st = 2.60 × 1053 erg, is interpreted as ... | induced gravitational collapse in the batse era: the case of grb 970828 |
advanced ligo and virgo (advligo/virgo) detectors reported the first binary neutron star merger candidate in the third observing run, s190425z, on 2019 april 25. a weak γ-ray excess was reported nearly coincidentally by the international gamma-ray astrophysics laboratory (integral) satellite, which accidentally covered... | on the energetics of a possible relativistic jet associated with the binary neutron star merger candidate s190425z |
linear polarization measurements in the optical band show polarization degrees of a few per cent at late times. recently, polarization at sub-per-cent level was also detected in radio by alma, opening the window for multiwavelength polarimetry and stressing the importance of properly modelling polarization in grb after... | modelling the linear polarization of grb afterglows across the electromagnetic spectrum |
observations of gamma-ray bursts (grbs) at very high energy (vhe) offer a unique opportunity to investigate particle acceleration processes, magnetic fields and radiation fields in these events. very long baseline interferometry (vlbi) observations have been proven to be a powerful tool providing unique information on ... | east asia vlbi network observations of the tev gamma-ray burst 190114c |
the spectral index s of high-energy particles diffusively accelerated in a non-magnetized relativistic shock, such as in a γ-ray burst afterglow, depends on the unknown angular diffusion function $\mathcal {d}$ , which itself depends on the particle distribution function f if acceleration is efficient. we develop a rel... | diffusive acceleration in relativistic shocks: particle feedback |
the afterglow of grb 170817a has been detected for more than three years, but the origin of the multi-band afterglow light curves remains under debate. a classical top-hat jet model is faced with difficulties in producing a shallow rise of the afterglow light curves as observed (fν ∝ t0.8). here we reconsider the model... | the afterglow emission from a stratified jet in grb 170817a |
the gravitational waves from the binary neutron star merger gw170817 were accompanied by a multiwavelength electromagnetic counterpart, which confirms the association of the merger with a short gamma-ray burst (sgrb). the afterglow observations implied that the event was accompanied by a narrow, ~5°, and powerful, ~105... | the collimation of relativistic jets in post-neutron star binary merger simulations |
for an expanding spherical relativistic shock, we derive relations between the parameters of downstream emitting zone and the quantities measured by a distant observer. these relations are formulated in terms of dimensionless effective coefficients combined with self-evident dimensional estimates. our calculations take... | relating quasi-stationary one zone emission models to expanding relativistic shocks |
x-ray flares in gamma-ray bursts (grbs) are believed to be generated by the late activities of central engine, and thus provide an useful tool to diagnose the properties of central objects. in this paper, we work on a grb x-ray flare sample whose bulk lorentz factors are constrained by two different methods and the jet... | constraining properties of grb central engines with x-ray flares |
observations of afterglows of gamma-ray bursts (grbs) suggest that post-shock magnetic fields are strongly amplified to about 100 times the shock-compressed value. the weibel instability appears to play an important role in generating the magnetic field. however, recent simulations of collisionless shocks in homogeneou... | weibel instability driven by spatially anisotropic density structures |
here we present the conceptual design of a wide field imager onboard a 6u class cubesat platform for the study of grb prompt and afterglow emission and detection of electromagnetic counterparts of gravitational waves in soft x-rays. the planned instrument configuration consists of an array of x-ray hybrid cmos detector... | blackcat cubesat: a soft x-ray sky monitor, transient finder, and burst detector for high-energy and multimessenger astophysics |
context. deriving physical parameters from gamma-ray burst (grb) afterglow observations remains a challenge, even 20 years after the discovery of afterglows. the main reason for the lack of progress is that the peak of the synchrotron emission is in the sub-mm range, thus requiring radio observations in conjunction wit... | large-amplitude late-time radio variability in grb 151027b |
the x-ray light curves of the early afterglow phase from gamma-ray bursts (grbs) present a puzzling variability, including flares. the origin of these flares is still debated, and often associated with a late activity of the central engine. we discuss an alternative scenario where the central engine remains short-lived... | relativistic simulations of long-lived reverse shocks in stratified ejecta: the origin of flares in grb afterglows |
the observed light curves and estimated sky rate of fast extragalactic x-ray transients (xrts) discovered in archival chandra data indicate that they belong to two distinct xrt populations. the first population of relatively short duration pulses, which typically last less than few minutes seems to be pulses of x-ray f... | fast extragalactic x-ray transients from gamma-ray bursts viewed far off-axis |
the international gamma-ray astrophysics laboratory (integral) has detected the short gamma-ray burst (sgrb), grb170817a with a signal-to-noise ratio of 4.6 and demonstrated its association with the binary neutron star merging event gw170817 detected by the ligo and virgo gravitational wave observatories. the associati... | integral search for gw counterparts and the grb170817a/gw170817 detection |
millisecond magnetars are often invoked as the central engine of some gamma-ray bursts (grbs), specifically the ones showing a plateau phase. we argue that an apparent plateau phase may not be realized if the magnetic field of the nascent magnetar is in a transient rapid decay stage. some grbs that lack a clear plateau... | the initial evolution of millisecond magnetars: an analytical solution |
we present a study of 21 dark gamma-ray burst (grb) host galaxies, predominantly using x-ray afterglows obtained with the chandra x-ray observatory (cxo) to precisely locate the burst in deep hubble space telescope (hst) imaging of the burst region. the host galaxies are well-detected in f160w in all but one case and i... | chandra and hubble space telescope observations of dark gamma-ray bursts and their host galaxies |
grb 131108a is a bright long gamma-ray burst (grb) detected by the large area telescope and the gamma-ray burst monitor on board the fermi gamma-ray space telescope. dedicated temporal and spectral analyses reveal three γ-ray flares dominating above 100 mev, which are not directly related to the prompt emission in the ... | bright gamma-ray flares observed in grb 131108a |
considering the contribution of emission from the host galaxies of gamma-ray bursts (grbs) to radio afterglows, we investigate the effect of host galaxies on observations statistically. for the three types of event, i.e. low-luminosity, standard and high-luminosity grbs, it is found that a tight correlation exists betw... | radio afterglows and host galaxies of gamma-ray bursts |
gw170817, the first neutron star merger event detected by advanced ligo/virgo detectors, was associated with the underluminous short-duration grb 170817a. in this letter we compare the forward shock afterglow emission of gw170817/grb 170817a to other luminous short gamma-ray bursts (sgrbs) with both a known redshift an... | late afterglow emission statistics: a clear link between gw170817 and bright short gamma-ray bursts |
the joint detection of the gravitational wave signal and the electromagnetic emission from a binary neutron star merger can place unprecedented constraint on the equation of state of supranuclear matter. although a variety of electromagnetic counterparts have been observed for gw170817, including a short gamma-ray burs... | protomagnetar research through an analysis of the x-ray plateau in the multi-messengar era |
synchrotron emission polarization is very sensitive to the magnetic field configuration. recently, polarization of synchrotron emission with a mixed (sm) magnetic field in the gamma-ray burst (grb) afterglow phase has been developed. here, we apply these sm models to the grb prompt phase and compare their polarization ... | polarization of grb prompt emission and its application to polar's data |
electromagnetic observations of the first binary neutron star (bns) merger detected in gravitational waves, gw170817, have established that relativistic jets can be successfully launched in bns mergers. typically, such jets produce emission in two phases: γ-ray prompt emission and multiwavelength afterglow. because of ... | detectability of electromagnetic counterparts from neutron star mergers: prompt emission versus afterglow |
we present a spectroscopic investigation with the very large telescope/x-shooter of seven candidate extremely strong damped lyman-α absorption systems [esdlas, n(h i) ≥ 5 × 1021 cm-2] observed along quasar sightlines. we confirm the extremely high column densities, albeit slightly (0.1 dex) lower than the original esdl... | extremely strong dlas at high redshift: gas cooling and h2 formation |
long gamma-ray bursts (grbs) are considered to originate from core collapse of massive stars. it is believed that the afterglow property is determined by the density of the material in the surrounding interstellar medium (ism). therefore, the circumburst density can be used to distinguish between an interstellar wind, ... | constraining the circumburst medium of gamma-ray bursts with x-ray afterglows |
studies of high-redshift gamma-ray bursts (grbs) provide important information about the early universe such as the rates of stellar collapsars and mergers, the metallicity content, constraints on the re-ionization period, and probes of the hubble expansion. rapid selection of high-z candidates from grb samples reporte... | machine-z: rapid machine-learned redshift indicator for swift gamma-ray bursts |
particle acceleration is expected to be different between relativistic and non-relativistic collisionless shocks. we show that electromagnetic counterparts to gravitational waves (gws), gamma-ray burst (grb) afterglows, are ideal targets for observing trans-relativistic evolution of accelerated electron distribution be... | probing particle acceleration at trans-relativistic shocks with off-axis gamma-ray burst afterglows |
grb 130925a is an ultra-long gamma-ray burst (grb), and it shows clear evidence for thermal emission in the soft x-ray data of the swift/x-ray telescope (xrt; ∼0.5 kev), lasting until the x-ray afterglow phase. due to the long duration of the grb, the burst could be studied in hard x-rays with high-resolution focusing ... | thermal emissions spanning the prompt and the afterglow phases of the ultra-long grb 130925a |
we present a sample composed of the 41 faintest x-ray afterglows of the population of long gamma-ray bursts (lgrbs) with known redshift. we study their intrinsic properties (spectral index, decay index, distance, luminosity, isotropic radiated energy, and peak energy) and their luminosity distribution functions to asse... | a study of grbs with low-luminosity afterglows |
in this paper, we revisit the scenario that an internal gradual magnetic dissipation taking place within the wind from a newborn millisecond magnetar can be responsible for gamma-ray burst (grb) production. we show that a combination of two emission components in this model, i.e., the photospheric emission from the win... | prompt emission of gamma-ray bursts from the wind of newborn millisecond magnetars: a case study of grb 160804a |
using multiwavelength observations of radio afterglows, we confirm the hypothesis that the flux density of gamma-ray bursts (grbs) at a fixed observing frequency is invariable when the distance of the grbs increases, which means the detection rate will be approximately independent of redshift. we study this behavior th... | the redshift dependence of the radio flux of gamma-ray bursts and their host galaxies |
a generic synchrotron external shock model is the widely preferred paradigm used to interpret the broad-band afterglow data of gamma-ray bursts (grbs), including predicted observable signatures from a reverse shock which have been confirmed by observations. investigations of the nature of the reverse shock emission can... | reverse shock emission in gamma-ray bursts revisited |
from a comprehensive statistical analysis of swift x-ray light curves of gamma-ray bursts (grbs) collected from 2004 december to the end of 2010, we found a three-parameter correlation between the isotropic energy emitted in the rest-frame 1-104 kev energy band during the prompt emission (eγ,iso), the rest-frame peak o... | update on the grb universal scaling ex,iso-eγ,iso-epk with 10 years of swift data |
we present a brief history and the current status of research on gamma-ray bursts (grbs), including observations at various grb phases: the prompt emission, afterglow, supernova/kilonova, and the host galaxy. an overview of the known phenomenological features and theoretical models for grbs is given. problems, the solu... | gamma-ray bursts: multiwavelength investigations and models |
we present 5.5 ghz observations with the very large array of a sample of nearby galaxies with energetic nuclear outbursts at mid-infrared (mir) bands. these observations reach a uniform depth down to a median rms of ∼10 μjy, representing one of the most sensitive searches for radio emission associated with nuclear tran... | compact radio emission from nearby galaxies with mid-infrared nuclear outbursts |
the gamma-ray burst (grb) afterglows provide a unique opportunity to study the interstellar medium (ism) of star-forming galaxies at high-redshift. the grb-dlas (damped lyman-α absorbers) contain a large neutral hydrogen column density, n(h i), and are observed against the grb afterglow. a large fraction of grb-dlas sh... | physical conditions in two high-redshift h2-bearing grb-dlas, 120815a and 121024a |
we investigate the multi-band properties of the grb 161017a with z = 2.013, which was detected by swift and fermi satellites, and other instruments. the optical and x-ray afterglows were all detected at early times after the prompt emission. the optical light curve shows a very bright onset peak at about 100 s for 13 m... | grb 161017a, the circumburst environment is an intermediate regime between the homogeneous interstellar medium and wind-type medium |
observations of short-duration gamma-ray bursts and their afterglows show that a good fraction (perhaps ≳50%) of binary neutron star mergers lead to strongly magnetized, rapidly rotating pulsars (including millisecond magnetars), no matter whether the pulsar remnants are short- or long-lived. such compact objects are v... | gravitational waves from post-merger radially oscillating millisecond pulsars |
we use published data in radio, optical, and x-ray bands to analyse and model afterglows of gw/grb 170817a. our analysis is based on a phenomenological gamma-ray burst generator model, which we previously used to study the prompt gamma-ray emission of this important transient. we find a multicomponent model and a few o... | properties of jet and surrounding material of gw/grb 170817a |
there exists an inevitable scatter in intrinsic luminosity of gamma ray bursts(grbs). if there is relativistic beaming in the source, viewing angle variation necessarily introduces variation in the intrinsic luminosity function(ilf). scatter in the ilf can cause a selection bias where distant sources that are detected ... | luminosity selection for gamma ray bursts |
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