Related papers: Gamma-Ray Burst without Baryonic and Magnetic Load…
Cosmological GRBs are discussed with an emphasis on their plausible connection with black holes. GRBs can be triggered by collapse of stellar-mass objects that leads to formation of a black hole and a transient debris disk with a huge…
Central engine of gamma-ray bursts (GRBs) may be intermittent and launch several episodes of ejecta separated by a long quiescent interval. In this scenario, an external shock is formed due to the propagation of the first launched ejecta…
Jets producing gamma-ray bursts (GRBs) are likely to carry a neutron component that drifts with respect to the proton component. The neutron-proton collisions strongly heat the jet and generate electron-positron pairs. We investigate…
In relativistic strongly magnetized winds outflowing from the fast-rotating compact progenitors of gamma-ray bursts (GRBs) there are three regions where powerful high-frequency emission may be generated: (i) the thermal photosphere, (ii)…
Gamma-ray bursts are produced by the dissipation of the kinetic energy of a highly relativistic fireball, via the formation of a collisionless shock. When this happens, Ultra High Energy Cosmic Rays up to 10^20 eV are produced. I show in…
The dominant component of the (100 MeV - 50 GeV) GRB emission detected by LAT starts with a delay relative to the prompt soft (sub-MeV) gamma-rays and lasts long after the soft component fades. This has lead to the intriguing suggestion…
Gamma-ray bursts (GRBs) are brief flashes of gamma rays, considered to be the most energetic explosive phenomena in the Universe. The emission from GRBs comprises a short (typically tens of seconds) and bright prompt emission, followed by a…
The prompt GRB emission is thought to arise from electrons accelerated in internal shocks propagating within a highly relativistic outflow. The launch of Fermi offers the prospect of observations with unprecedented sensitivity in…
According to the internal-external shocks model for $\gamma $-ray bursts (GRBs), the GRB is produced by internal shocks within a relativistic flow while the afterglow is produced by external shocks with the ISM. We explore the early…
Strong variability is a common characteristic of the prompt emission of gamma-ray bursts (GRB). This observed variability is widely attributed to an intermittency of the central engine, through formation of strong internal shocks in the…
We present an analysis of the Internal Shock Model of GRBs, where gamma-rays are produced by internal shocks within a relativistic wind. We show that observed GRB characteristics impose stringent constraints on wind and source parameters.…
The prompt $\gamma$-rays of gamma-ray bursts (GRBs) may originate from the photosphere of a relativistic jet. However, only a few GRBs have been observed with evident blackbody-like emission, for example, GRB~090902B. It has been…
We calculate the synchrotron self-Compton emission from internal shocks occurring in relativistic winds as a source of gamma-ray bursts, with allowance for self-absorption. For plausible model parameters most pulses within a Gamma-Ray Burst…
Forward shocks caused by the interaction between a relativistic blast wave and the circum-burst medium are thought to be responsible for the afterglow emission in Gamma-Ray Bursts (GRBs). We consider the hydrodynamics of a spherical…
Gamma-Ray Bursts (GRBs), short and intense pulses of low energy gamma-rays, have fascinated astronomers and astrophysicists since their unexpected discovery in the late sixties. During the last decade, several space missions: BATSE (Burst…
Long Gamma-Ray Bursts (GRBs) are produced by ultra-relativistic jets launched from core collapse of massive stars. Most massive stars form in binaries and/or in star clusters, which means that there may be a significant external photon…
Long Gamma-Ray Bursts (GRB) relativistic jets are surrounded by hot cocoons which confine jets during their punch out from the progenitor star. These cocoons are copious sources of X-ray photons that can be and are inverse-Compton (IC)…
The internal/external synchrotron shock scenario has proved very successful in interpreting the key observations about gamma ray bursts. There still remains, however, some big uncertainties. The hottest issue concerns the nature of the…
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…
We study afterglow flares of gamma-ray bursts (GRBs) in the framework of the late internal shock (LIS) model based on a careful description for the dynamics of a pair of shocks generated by a collision between two homogeneous shells,.…