Related papers: Gamma Ray Bursts: open problems
In the standard internal shock model, the observed X and gamma-ray radiation is assumed to be produced by synchrotron emission. I will show that there are serious problems with this interpretation, calling for other radiation mechanisms,…
If the emission of gamma-ray bursts were due to the synchrotron process in the standard internal shock scenario, then the typical observed spectrum should have a slope F(nu) \propto nu^{-1/2}, which strongly conflicts with the much harder…
Major advances have been made in the field of gamma-ray bursts in the last two years. The successful discovery of X-ray, optical and radio afterglows, which were predicted by theory, has made possible the identification of host galaxies at…
The prompt emission of gamma-ray bursts probably comes from a highly relativistic wind which converts part of its kinetic energy into radiation via the formation of shocks within the wind itself. Such "internal shocks" can occur if the wind…
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…
The principal paradigm for the prompt emission of gamma-ray bursts invokes diffusive acceleration at shocks internal to the dynamic ultrarelativistic outflow. This paper explores expectations for burst emission spectra arising from shock…
The cosmological gamma-ray burst (GRB) phenomenon is reviewed. The broad observational facts and empirical phenomenological relations of the GRB prompt emission and afterglow are outlined. A well-tested, successful fireball shock model is…
In the standard scenario of the fireball model of gamma-ray bursts(GRBs), the huge initial energy release produces a relativistic blast wave expanding into the external medium and a reverse shock moving into and heating the fireball ejecta.…
The gamma ray burst phenomenon is reviewed from a theoretical point of view, with emphasis on the fireball shock scenario of the prompt emission and the longer wavelenght afterglow. Recent progress and issues are discussed, including…
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…
The properties of the ambient medium in which GRBs go off are an important piece of the puzzle, not only as an issue in itself, but because of their link with the nature of the progenitor. In this review, I describe and critically comment…
A pedagogical derivation is presented of the ``fireball'' model of gamma-ray bursts, according to which the observable effects are due to the dissipation of the kinetic energy of a relativistically expanding wind, a ``fireball.'' The main…
Despite the dramatic improvement of our knowledge of the phenomenology of Gamma Ray Bursts, we still do not know several fundamental aspects of their physics. One of the puzzles concerns the nature of the radiative process originating the…
Recent results of the hectic research activity about gamma-ray bursts will be reviewed, with emphasis about the emission processes at the origin of the observed gamma-rays. The conventional synchrotron shock scenario is found to have…
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…
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…
Gamma-ray bursts are thought to be the outcome of a cataclysmic event leading to a relativistically expanding fireball, in which particles are accelerated at shocks and produce nonthermal radiation. We discuss the theoretical predictions of…
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…
The successful discovery of X-ray, optical and radio afterglows of GRB has made possible the identification of host galaxies at cosmological distances. The energy release inferred in these outbursts place them among the most energetic and…
The association of a supernova with a gamma-ray burst (GRB 030329) implies a massive star progenitor, which is expected to have an environment formed by pre-burst stellar winds. Although some sources are consistent with the expected wind…