Gamma ray bursts, their afterglows, and soft gamma repeaters

by Gennady S. Bisnovatyy-Kogan (Space Research Institute (IKI), Moscow, Russia)

Thursday 22 Nov 2012, 16:00 → 17:30 Europe/Rome

Aula Conversi (Dipartimento di Fisica - Ed. G. Marconi)

The conclusion, that cosmic gamma-ray bursts (GRBs) are of cosmological origin, is based on the statistical analysis of GRBs and the measurements of line redshifts in GRB optical afterglows. In most of these models, if not in all of them, the isotropic radiation cannot provide the energy release necessary for the appearance of a cosmological GRB. Observations of bright optical GRB afterglows point to the fact that an initially bright optical flare is directly related to the GRB itself, and the subsequent weak and much more continuous optical radiation is of a different nature. The interaction of the cosmological GRB radiation with a dense surrounding molecular cloud results in the appearance of long-duration (up to 10 years) weak optical afterglows associated with the heating and reradiation of gas. Results of 2D numerical simulation of the heating and reradiation of gas in various variants of the relative disposition of GRB and molecular clouds are presented. The possible relation between the short GRBs and soft gamma repeaters (SGR) is discussed. The model of SGR activity, based on nuclear explosion in the nonequilibrium layer in the neutron star crust, is discussed.