Related papers: GRB afterglow light curves from realistic density …
Short-duration Gamma-ray bursts (GRBs) (\leq 2{\rm s}) have remained a mystery due to the lack of afterglow detection until recently. The models to interpret short GRBs invoke distinct progenitor scenarios. Here we present a generic…
Afterglows of gamma-ray bursts are observed to produce light curves with the flux following power law evolution in time. However, recent observations reveal bright flares at times on the order of minutes to days. One proposed explanation…
Gamma-ray bursts may occur within pulsar wind bubbles (PWBs) under a number of scenarios, such as the supranova-like models in which the progenitor pulsar drives a powerful wind shocking against the ambient medium before it comes to death…
The afterglows of gamma-ray bursts (GRBs) have commonly been assumed to be due to shocks sweeping up the circum-stellar medium. However, most GRBs have been found in dense star-forming regions where a significant fraction of the prompt…
Radio observations of gamma-ray burst (GRB) afterglows are essential for our understanding of the physics of relativistic blast waves, as they enable us to follow the evolution of GRB explosions much longer than the afterglows in any other…
We review interaction models for GRB afterglows, with an eye on constraining the nature of their progenitors and the geometry of explosion. Evidence is presented for two types of progenitors. The radio afterglow of GRB 980425/SN 1998bw and…
By now there is substantial evidence that Gamma-Ray Bursts (GRBs) originate at cosmological distances from very powerful explosions. The interaction between a GRB and its surrounding environment has dramatic consequences on the environment…
A scenario is proposed that explains both the observed high pulsar velocities and extragalactic gamma-ray bursts (GRBs). The model involves an ultra- relativistic jet from a supernova (SN), that produces a GRB and its afterglow, whose…
Gamma Ray Burst (GRB) afterglows close to their peak intensity are among the brightest X-ray sources in the sky. Despite their fast power-law like decay, when fluxes are integrated from minutes up to hours after the GRB event, the…
The detection of x-ray afterglows of gamma-ray burst (GRB) sources has enabled the optical discovery that GRBs are at cosmological distances, which confirms that the enormous luminosities required must produce a relativistically expanding…
Direct multi-dimensional numerical simulation is the most reliable approach for calculating the fluid dynamics and observational signatures of relativistic jets in gamma-ray bursts (GRBs). We present a two-dimensional relativistic…
I show here that the time-delay between the gamma ray burst proper and the onset of the afterglow is a sensitive function of the surrounding density, going from ~10s for typical disk densities to several hours for IGM densities. Since bulk…
The optical and X-ray light-curves of long Gamma Ray Bursts (GRBs) often show a complex evolution and in most cases do not track each other. This behaviour can not be easily explained by the simplest standard afterglow models. A possible…
We continue our systematic statistical study on optical afterglow data of gamma-ray bursts (GRBs). We present the apparent magnitude distributions of early optical afterglows at different epochs (t= 10^2 s, t = 10^3 s, and 1 hour) for the…
We report a multi-wavelength analysis of the prompt emission and early afterglow of GRB051111 and discuss its properties in the context of current fireball models. The detection of GRB051111 by the Burst Alert Telescope on-board Swift…
A strong correlation is reported between gamma-ray burst (GRB) pulse lags and afterglow jet-break times for the set of bursts (seven) with known redshifts, luminosities, pulse lags, and jet-break times. This may be a valuable clue toward…
We present results for a large number of gamma-ray burst (GRB) afterglow light curve calculations, done by combining high resolution two-dimensional relativistic hydrodynamics simulations using RAM with a synchrotron radiation code. Results…
Gamma-ray burst (GRB) afterglows are likely produced in the shock that is driven as the GRB jet interacts with the external medium. Long-duration GRBs are also associated with powerful supernovae (SNe). We consider the optical and radio…
We analyze in detail the hydrodynamics and afterglow emission of an ultrarelativistic blast wave when it expands in a density-jump medium. Such a medium is likely to appear in the vicinity of gamma-ray bursts (GRBs) associated with massive…
Radio observations of gamma-ray burst (GRB) afterglows provide both complementary and unique diagnostics of the afterglow physics and environment of the burst. Here we concentrate on three unique aspects of GRB energetics and environments…