Related papers: How to Construct a GRB Engine?
Recent observations suggest that $\gamma$-ray bursts (GRBs) and their afterglows are produced by jets of highly relativistic cannonballs (CBs), emitted in supernova (SN) explosions. The CBs, reheated by their collision with the shell, emit…
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…
Observations suggest that gamma-ray bursts (GRBs) are produced by the dissipation of the kinetic energy of a relativistic fireball. In this talk, recent work on the production of high energy neutrinos by GRB fireballs is reviewed. A…
Gamma-ray bursts (GRBs) have puzzled astronomers since their accidental discovery in the late sixties. The BATSE detector on the COMPTON-GRO satellite has been detecting one burst per day for the last six years. Its findings have…
The IceCube Collaboration recently reported a stringent upper limit on the high energy neutrino flux from GRBs, which provides a meaningful constraint on the standard internal shock model. Recent broad band electromagnetic observations of…
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…
Gamma-ray bursts (GRBs) are a mixed class of sources consisting of, at least, the long duration and short-hard subclasses, the X-ray flashes, and the low-luminosity GRBs. In all cases, the release of enormous amounts of energy on a short…
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'',…
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…
The prompt emission of gamma-ray bursts (hereafter GRBs) probably comes from a highly relativistic wind which converts its kinetic energy into radiation via the formation of shocks within the wind itself. Such "internal shocks" can occur if…
Despite all the already existing observational data, current models still cannot explain completely the excessive energy output and the time variability of GRB. One of the reasons for this is the lack of a good model of the central engine…
The energetics of the long duration GRB phenomenon is compared with models of a rotating Black Hole (BH) in a strong magnetic field generated by an accreting torus. A rough estimate of the energy extracted from a rotating BH with the…
The dissipation mechanism that powers gamma-ray bursts (GRBs) remains uncertain almost half a century after their discovery. The two main competing mechanisms are the extensively studied internal shocks and the less studied magnetic…
The observed afterglows of gamma ray bursts, in particular that of GRB 970228 six months later, seem to rule out relativistic fireballs and relativistic firecones driven by merger or accretion induced collapse of compact stellar objects in…
Gamma-ray bursts (GRBs) are still an enigma. In particular the central engine, the total energy, and the very narrow distribution of peak energies challenge model builders. Motivated by recent theoretical developments (string theory,…
Observations suggest that $\gamma$-ray bursts (GRBs) are produced by the dissipation of the kinetic energy of a relativistic fireball. We show that a large fraction, $\ge 10%$, of the fireball energy is expected to be converted by…
Recent observations suggest that the long-duration gamma ray bursts (GRBs) and their afterglows are produced by highly relativistic jets emitted in supernova explosions. We propose that the result of the event is not just a compact object…
We investigate a "hypernova" model for gamma-ray bursts (GRBs), i.e., massive C+O star model with relativistic jets. In this model, non-thermal precursors can be produced by the "first" relativistic shell ejected from the star. Main GRBs…
Ultra-relativistic motion and efficient conversion of kinetic energy to radiation are required by gamma-ray burst (GRB) observations, yet they are difficult to simultaneously achieve. Three leading mechanisms have been proposed to explain…
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…