Related papers: GRB afterglows: deep Newtonian phase and its appli…
Whether gamma-ray bursts are highly beamed or not is a very difficult but important problem that we are confronted with. Some theorists suggest that beaming effect usually leads to a sharp break in the afterglow light curve during the…
The discovery of X-ray, optical and radio afterglows of GRBs provides an important tool for understanding these sources. Most current models envisage GRB as arising in a cataclysmic stellar event leading to a relativistically expanding…
The discovery of GRBs' afterglows has allowed us to establish several facts: their distance and energy scales, the fact that they are due to explosions, that the explosions are relativistic, and that the afterglow emission mechanism is…
Gamma-ray burst (GRB) afterglows have provided important clues to the nature of these massive explosive events, providing direct information on the nearby environment and indirect information on the central engine that powers the burst. We…
If the efficiency for producing $\gamma$-rays is the same in short duration ($\siml 2$ s) Gamma-Ray Bursts (GRBs) as in long duration GRBs, then the average kinetic energy of short GRBs must be $\sim 20$ times less than that of long GRBs.…
Gamma-ray bursts (GRB) are sudden, intense flashes of gamma-rays which, for a few blinding seconds, light up in an otherwise fairly dark gamma-ray sky. They are detected at the rate of about once a day, and while they are on, they outshine…
Extended, fading emissions in multi-wavelength are observed following Gamma-ray bursts (GRBs). Recent broad-band observational campaigns led by the Swift Observatory reveal rich features of these GRB afterglows. Here we review the latest…
In models for gamma ray burst afterglows, it is normally assumed that the external shock strongly amplifies the magnetic field and that this field maintains a steady value throughout the shocked region. We discuss the effects of modifying…
Recent particle-in-cell simulations suggest that a large fraction of the energy dissipated in a relativistic shock is deposited into a Maxwellian distribution of electrons that is connected to the high-energy power-law tail. Here, we…
We have found that the conventional generic dynamical model for gamma-ray bursts (GRBs) cannot reproduce the Sedov solution in the non-relativistic limit. Based on our refined generic dynamical model, we investigate afterglows from jetted…
The afterglow emission has become the main stream of Gamma-Ray burst research since its discovery three years ago. With the distance-scale enigma solved, the study of the late-time GRB emission is now the most promising approach to disclose…
The energy requirements of gamma ray bursts have in past been poorly constrained because of three major uncertainties: The distances to bursts, the degree of burst beaming, and the efficiency of gamma ray production. The first of these has…
We present numerical simulations of Gamma-Ray Bursts arising from external shocks in the impulsive and wind models, including a weak or a strong coupling between electrons and protons plus magnetic fields, and analyze the burst features in…
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…
The shallow decay phase and flares in the afterglows of gamma-ray bursts (GRBs) is widely believed to be associated with the later activation of central engine. Some models of energy injection involve with a continuous energy flow since the…
When does a GRB stop and its afterglow begin? A GRB may be defined as emission by internal shocks and its afterglow as emission by an external shock, but it is necessary to distinguish them observationally. With these definitions…
Particle-in-cell simulations have unveiled that shock-accelerated electrons do not follow a pure power-law distribution, but have an additional low-energy "thermal" part, which owns a considerable portion of the total energy of electrons.…
The afterglow emission that follows gamma-ray bursts (GRBs) contains valuable information about the circumburst medium and, therefore, about the GRB progenitor. Theoretical studies of GRB blast waves, however, are often limited to simple…
The recently discovered GRB afterglow is believed to be described reasonably well by synchrotron emission from a slowing down relativistic shell that collides with an external medium. To compare theoretical models with afterglow…
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…