Related papers: Are GRBs the most violent events in the Universe?
Considering a GRB event as a relativistic ejecta where the relativistic moving makes radiation become anisotropic, we are able to show that the required intrinsic energy associated with these events is significantly smaller than those…
Much of progress in gamma-ray bursts has come from the studies of distant events (redshift z~1). The brightest GRBs are the most collimated events and seen across the Universe due to their brilliance. It has long been suspected that nearest…
Gamma Ray Bursts (GRBs) are the most explosive events after the big bang: their energy output corresponds to a sizeable fraction of a solar mass entirely converted into energy in a few seconds. Although many questions about their…
A standard fireball/afterglow model of a gamma-ray burst relates the event to a merging neutron star binary, or a neutron star - black hole binary, which places the events far away from star forming regions, and is thought to have an energy…
Gamma ray bursts (GRBs) are the most luminous physical phenomena in the universe. The relativistic effect on the blast wave associated with the GRB introduces the gamma factor. Here we put an upper limit on the gamma factor via constraints…
Gamma-Ray Bursts (GRBs) are the brightest objects observed. They are also the most relativistic objects known so far. GRBs occur when an ultrarelativisitic ejecta is slowed down by internal shocks within the flow. Relativistic particles…
We estimate the fraction of the total energy in a Gamma-Ray Burst (GRB) that is radiated in photons during the main burst. Random internal collisions among different shells limit the efficiency for converting bulk kinetic energy to photons.…
The most energetic gamma-ray bursts (GRBs) are remarkable sources releasing huge amounts of energy on short timescales. Their prompt emission, which usually lasts few seconds, is so bright that it is visible across the whole observable…
GRBs are the most energetic electromagnetic events in the Universe. Those whose typical duration is longer than a few seconds are known as long GRBs and shorter than a few seconds are short GRBs. It is widely accepted that these events are…
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 extreme hypothesis that essentially all types of ultrarelativistic outflow -- specifically AGN jets, pulsar wind nebulae and GRB --are electromagnetic, rather than gas dynamical, phenomena is considered. Electromagnetic flows are…
There is growing evidence that long and hard gamma-ray bursts (GRBs), discovered at redshifts between 0.4 and 3.4, are related to some type of supernova (SN) explosions. The GRB ejecta are ultra-relativistic, and possibly beamed. There is a…
Gamma-Ray Bursts (GRBs) - short bursts of 100-1MeV photons arriving from random directions in the sky are probably the most relativistic objects discovered so far. Still, somehow they did not attract the attention of the relativistic…
The energy of a Gamma-Ray Burst is one of the most interesting factors that can help determining the origin of these mysterious explosions. After the discovery that GRBs are cosmological it was thought, for a while that they are standard…
GRBs are the most energetic events in the Universe, associated with the death of massive stars (core-collapse supernovae) or the merging of neutron stars or black holes. Discovered in the early 1970s, their cosmological origin was…
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.…
Gamma-ray bursts (GRBs) are the most luminous astrophysical events observed so far. They are conventionally classified into long and short ones depending on their time duration, $T_{90}$. Because of the advantage their high redshifts offer,…
It is generally believed that cosmological Gamma Ray Bursts (GRBs) are produced by the deceleration of relativistic objects with Lorentz factor (Gamma) >~ 100. We study the possibility that some GRBs are produced along with relativistic…
Recent three dimensional, high-resolution simulations of neutron star coalescences are analysed to assess whether short gamma-ray bursts (GRBs) could originate from such encounters. The two most popular modes of energy extraction -- namely…
Gamma-ray bursts (GRBs) are the most luminous electromagnetic explosions in the Universe, which emit up to $8.8\times10^{54}$ erg isotropic equivalent energy in the hard X-ray band. The high luminosity makes them detectable out to the…