Related papers: GRBs Light Curves - Another Clue on the Inner Engi…
We present a detailed study of the spectral and temporal properties of the X-ray flares emission of several GRBs. We select a sample of GRBs which X-ray light curve exhibits large amplitude variations with several rebrightenings superposed…
It is now generally accepted that long-duration gamma ray bursts (GRBs) are due to the collapse of massive rotating stars. The precise collapse process itself, however, is not yet fully understood. Strong winds, outbursts, and intense…
Using a theoretical model describing pulse shapes, we have clarified the relations between the observed pulses and their corresponding timescales, such as the angular spreading time, the dynamic time as well as the cooling time. We find…
The explosion that results in a cosmic gamma-ray burst (GRB) is thought to produce emission from two physical processes -- the activity of the central engine gives rise to the high-energy emission of the burst through internal shocking and…
We present a formalism of the dynamics of internal shocks in relativistic jets where the source has a time-dependent injection velocity and mass-loss rate. The variation of the injection velocity produces a two-shock wave structure, the…
In the external shock model, gamma-ray burst (GRB) emissions are produced by the energization and deceleration of a thin relativistic blast wave due to its interactions with the circumburst medium (CBM). We study the physical properties of…
A temporal analysis has been performed on a sample of 100 bright gamma-ray bursts (GRBs) with T90<2s from the BATSE current catalog. The GRBs were denoised using a median filter and subjected to an automated pulse selection algorithm as an…
An extreme Kerr black hole (BH) surrounded by a precessing disk is invoked to explain the light curves of gamma-ray bursts (GRBs) based on the coexistence of the Blandford-Znajek (BZ) and the magnetic coupling (MC) processes. The overall…
Gamma Ray Bursts (GRBs) are notorious for their diversity. Yet, they have a series of common features. The typical energy of their $\gamma$ rays is a fraction of an MeV. The energy distributions are well described by a ``Band spectrum'',…
We present the results of hydrodynamical simulations of gamma-ray burst jets propagating through their stellar progenitor material and subsequently through the surrounding circumstellar medium. We consider both jets that are injected with…
A simple mathematical model for GRB pulses is postulated in both time and energy. The model breaks GRB pulses up into component functions, one general light curve function exclusively in the time dimension and four component functions…
We study the structure and evolution of the accreting plasma in gamma ray burst central engines. The models are based on the general relativistic MHD simulations. The nuclear equation of state adequate for dense and degenerate plasma, is…
Highly variable gamma-ray pulses and X-ray flares in GRB light curves can result from external shocks rather than central engine activity under the assumption that the GRB blast-wave shell does not spread. Acceleration of cosmic rays to…
Recently, two empirical correlations related to the minimum variability timescale ($\rm MTS$) of the lightcures are discovered in gamma-ray bursts (GRBs). One is the anti-correlation between $\rm MTS$ and Lorentz factor $\Gamma$, the other…
We construct models for gamma-ray bursts where the emission comes from internal shocks in a relativistic wind with a highly non uniform distribution of the Lorentz factor. We follow the evolution of the wind using a very simplified approach…
We show that if the intrinsic break energy of Gamma-Ray Bursts (GRBs) is determined by the product of more than three random variables the observed break energy distribution becomes almost lognormal including the redshift effect because of…
Several patterns have been discovered in how some spectral characteristics change during the decaying phase of long (> few s.) GRB pulses. We compare these observed signatures with those expected from a relativistically expanding shell.…
Internal shocks are a leading candidate for the dissipation mechanism that powers the prompt $\gamma$-ray emission in gamma-ray bursts (GRBs). In this scenario a compact central source produces an ultra-relativistic outflow with varying…
Recent studies have found that the spectral evolution of pulses within gamma-ray bursts (GRBs) is consistent with simple radiative cooling. Perhaps more interesting was a report that some bursts may have a single cooling rate for the…
The variable activity of a gamma-ray burst (GRB) source is thought to be correlated with its absolute peak luminosity - a relation that, if confirmed, can be used to derive an independent estimate of the redshift of a GRB. We find that…