Related papers: Standard GRB, Dirty Fireballs, and the Excluded Mi…
Gamma-ray bursts are believed to be some catastrophic event in which material is ejected at a relativistic velocity, and internal collisions within this ejecta produce the observed $\gamma$-ray flash. The angular size of a causally…
We predict the rate at which Gamma-Ray Burst (GRB) afterglows should be detected in supernova searches as a function of limiting flux. Although GRB afterglows are rarer than supernovae, they are detectable at greater distances because of…
The degree of beaming in Gamma-Ray Bursts (GRBs) is currently unknown. The uncertainty in the gamma-ray beaming angle, theta, leaves the total energy release (proportional to theta^2) and the event rate per galaxy (proportional to…
We present the results of the spectral analysis of a sample of short bright $\gamma$--ray bursts (GRB) detected by BATSE and compare them with the average and time resolved spectral properties of long bright bursts. While the spectral…
The possibility that gamma-ray bursts (GRBs) were not isotropic emissions was devised theoretically as a way to ameliorate the huge energetic budget implied by the standard fireball model for these powerful phenomena. However, the mechanism…
The detection of delayed X-ray, optical and radio emission, "afterglow", associated with $\gamma$-ray bursts (GRBs) is consistent with fireball models, where the emission are produced by relativistic expanding blast wave, driven by…
A thermal component is suggested to be the physical composition of the ejecta of several bright gamma-ray bursts (GRBs). Such a thermal component is discovered in the time-integrated spectra of several short GRBs as well as long GRBs. In…
Gamma-ray bursts are cosmological sources emitting radiation from the gamma-rays to the radio band. Substantial observational efforts have been devoted to the study of GRBs during the prompt phase, i.e. the initial burst of high-energy…
The electron antinuetrino flux limits are presented for the brightest gamma-ray burst (GRB) of all time, GRB221009A, over a range of 1.8-200 MeV using the Kamioka Liquid Scintillator Anti Neutrino Detector (KamLAND). Using a variety of time…
The gamma-ray burst (GRB) model for production of ultra-high-energy cosmic-rays (UHECRs) is based on the hypothesis that GRBs arise from the dissipation of the kinetic energy of relativistic fireballs at cosmological distances. Recent GRB…
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…
The emission processes active in the highly relativistic jets of gamma-ray bursts (GRBs) remain unknown. In this paper we propose a new measure to describe spectra: the width of the $EF_E$ spectrum, a quantity dependent only on finding a…
The Gamma-Ray Bursts (GRBs) offer the unprecedented opportunity to observe for the first time the blackholic energy extracted by the vacuum polarization during the process of gravitational collapse to a black hole leading to the formation…
If Gamma-ray Bursts (GRBs) are generally associated with supernovae like 1998bw, a relatively wide intrinsic luminosity function is implied, which indicates the existence of a large amount of undetected dim bursts, and a much higher…
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…
The gamma ray burst apparent average isotropic power versus their red-shift of all known GRB (Sept.2009) is reported. It calls for an unrealistic Gamma Ray Burst Evolution around us or it just probe the need of a very thin gamma…
Results of a phenomenological model to estimate the GRB detection rate by the Fermi Gamma ray Space Telescope are reported. This estimate is based on the BATSE 4B GRB fluence distribution, the mean ratio of fluences measured at 100 MeV - 5…
In explaining the physical origin of the jet composition of gamma-ray bursts (GRBs), a more general picture, i.e. the hybrid jet model (which introduced another magnetization parameter $\sigma_{0}$ on the basis of the traditional fireball…
Gamma-ray bursts have the potential to produce the particle energies (up to $10^{21}$ eV) and the energy budget ($10^{44} \rm{erg yr^{-1} Mpc^{-3}}$) to accommodate the spectrum of the highest energy cosmic rays; on the other hand, there is…
Observations of GRB host galaxies and their environments in general can provide valuable clues about the nature of progenitors. Bursts are associated with faint, <R> ~ 25 mag, galaxies at cosmological redshifts, <z> ~ 1. The host galaxies…