Related papers: Time-dependent thermal effects in GRB afterglows
We report optical observations during the first hour of the gamma-ray burst (GRB) afterglow of GRB021004. Our observation revealed the existence of a short plateau phase, in which the afterglow remained at almost constant brightness, before…
BAT and XRT observations of two recent well-covered GRBs observed by Swift, GRB 050315 and GRB 050319, show clearly a prompt component joining the onset of the afterglow emission. By fitting a power law form to the gamma-ray spectrum, we…
We show that simple kinematic arguments can give limits on the timescale and amplitude of variabilities in gamma-ray burst (GRB) afterglows, especially when the variability timescale is shorter than the observed time since the burst \Delta…
An overview of the optical and near-IR observations of GRBs in the Afterglow Era is presented, covering the period 1997-2000. They have allowed to a better understanding of the underlying GRB physics as well as to constraint the progenitor…
We report the optical polarization of a gamma ray burst (GRB) afterglow, obtained 203 seconds after the initial burst of gamma rays from GRB 060418, using a ring polarimeter on the robotic Liverpool Telescope. Our robust (2-sigma) upper…
Gamma-ray bursts (GRBs), which are bright flashes of gamma rays from extragalactic sources followed by fading afterglow emission, are associated with stellar core collapse events. We report the detection of very-high-energy (VHE) gamma rays…
The time and angle dependent line and continuum emission from a dense torus around a cosmological gamma-ray burst source is simulated, taking into account photoionization, collisional ionization, recombination, and electron heating and…
The luminosity and the spectral distribution of the afterglow of GRB 031203 have been presented within our theoretical framework, which envisages the GRB structure as composed by a proper-GRB, emitted at the transparency of an…
The well-sampled afterglows of gamma ray bursts (GRBs) not associated with a supernova (SN) explosion, can be scaled down to a simple dimensionless universal formula, which describes well their temporal behavior. Such SN-less GRBs include…
Gamma-ray burst (GRB) afterglow emission can be observed from sub-TeV to radio wavelengths, though only 6.6\% of observed GRBs present radio afterglows. We examine GRB radio light curves (LCs) to look for the presence of radio plateaus,…
We present a set of seventeen Gamma-Ray Bursts (GRBs) with known redshifts and X-ray afterglow emission. We apply cosmological corrections in order to compare their fluxes normalized at a redshift of 1. Two classes of GRB can be defined…
Gamma Ray Bursts (GRB) observed up to redshifts $z>8$ are fascinating objects to study due to their still unexplained relativistic outburst mechanisms and a possible use to test cosmological models. Our analysis of 77 GRB afterglows with…
We have performed detailed calculations of spectra and light curves of GRB afterglows assuming that the observed GRBs can have a jet geometry. The calculations are based on an expanding relativistic shock GRB afterglow model where the…
The detection of delayed emission in X-ray, optical and radio wave length, ``afterglow'', following a gamma-ray burst can be described by the emission of a relativistic shell decelerating upon collision with the ISM. We show that the…
We show that the X-ray and $\gamma$-ray spectra of Swift GRBs and their afterglows are consistent with the emission characteristic of an expanding, relativistic fireball. The classical afterglow due to the impact of the fireball on the…
We present a comprehensive analysis of the optical and X-ray light curves (LCs) and spectral energy distributions (SEDs) of a large sample of gamma-ray burst (GRB) afterglows to investigate the relationship between the optical and X-ray…
Most GRB X-ray afterglow light curves are characterised by a plateau, followed by a normal power-law decay interpreted as afterglow emission. Despite the numerous alternative interpretations, the origin of the plateau remains unclear. In…
We present a multiwavelength analysis of 63 Gamma-Ray Bursts observed with the world's three largest robotic optical telescopes, the Liverpool and Faulkes Telescopes (North and South). Optical emission was detected for 24 GRBs with…
Based on the refined dynamical model proposed by us earlier for beamed $\gamma$-ray burst ejecta, we carry out detailed numerical procedure to study those $\gamma$-ray bursts with rapidly fading afterglows (i.e., $\sim t^{-2}$). It is found…
It is suggested that many $\gamma$-ray bursts (GRBs) are cloaked by an ultra-relativistic baryonic shell that has high optical depth when the photons are manufactured. Such a shell would not fully block photons reflected or emitted from its…