Observational constraints on the angular and spectral distributions of photons in gamma-ray burst sources |
| |
Authors: | V V Sokolov G S Bisnovatyi-Kogan V G Kurt Yu N Gnedin Yu V Baryshev |
| |
Institution: | (1) Special Astrophysical Observatory, Russian Academy of Sciences, Nizhniĭ Arkhyz, Karachaĭ-Cherkessian Republic, 357147, Russia;(2) Space Research Institute, Profsoyuznaya ul. 84/32, Moscow, 117997, Russia;(3) Astro Space Center, Lebedev Physical Institute, Russian Academy of Sciences, Profsoyuznaya ul. 84/32, Moscow, 117997, Russia;(4) Main Astronomical Observatory, Pulkovo, St. Petersburg, Russia;(5) Astronomical Institute, St. Petersburg State University, Staryi Petergof, St. Petersburg, Russia |
| |
Abstract: | The typical spectra of gamma-ray bursts (GRBs) are discussed in the context of the compactness problem for GRB sources and how it is resolved in the popular fireball model. In particular, observational (model-independent) constraints on the collimation of the gamma-rays and the dependence of the collimation angle on the photon energy are considered. The fact that the threshold for the creation of e ? e + pairs depends on the angle between the momenta of the annihilating photons in the GRB source provides an alternative solution to the compactness problem. A new approach to explaining GRBs, taking into account the angular dependence for pair creation, is proposed, and the main features of a scenario describing a GRB source with a total (photon) energy smaller or of the order of 1049 erg are laid out. Thus, we are dealing with an alternative to an ultra-relativistic fireball, if it turns out (as follows from observations) that all “long” GRBs are associated with normal (not peculiar) core-collapse supernovae. The effects of radiation pressure and the formation of jets as a consequence of even a small amount of anisotropy in the total radiation field in a (compact) GRB source are examined in this alternative model. Possible energy-release mechanisms acting in regions smaller or of the order of 108 cm in size (a compact model for a GRB) are discussed. New observational evidence for such compact energy release in the burst source is considered. |
| |
Keywords: | |
本文献已被 SpringerLink 等数据库收录! |
|