Astrophysical and Astrobiological effects of Gamma-Ray Bursts

Author(s)

Douglas Galante

• Document type: Doctoral Thesis
• Press: São Paulo. , gráficos, ilustrações, tabelas.
• Institution: Universidade de São Paulo (USP). Instituto Astronômico e Geofísico (IAG/SBD)
• Defense date: 2009-05-04

Examining board members

Jorge Ernesto Horvath; Amancio Cesar Santos Friaca; Claudia de Alencar Santos Lage; Eduardo Janot Pacheco; Carlos Alexandre Wuensche de Souza

• Advisor: Jorge Ernesto Horvath
• Field of knowledge: Physical Sciences and Mathematics - Astronomy
• Indexed in: Banco de Dados Bibliográficos da USP-DEDALUS
• Location: Universidade de São Paulo. Biblioteca do Instituto de Astronomia, Geofísica e Ciências Atmosféricas (IAG)

Abstract

The present work has the main goal of understanding the possible effects of the hard gamma radiation produced during a Gamma-Ray Burst (GRB) event both on the interstellar medium surrounding the source of the burst and on planets possibly illuminated. Gamma-Ray Bursts were first detected on the 60s and quickly have attracted the attention of the astrophysical community, since the energies emitted just in could reach 1054erg, the rest mass of the Sun. No mechanism was known to be so efficient in extracting gravitational energy to produce such emission. Later on, the possibility of the emission being collimated has lowered the energy of the to 5x1051erg, but the central engine has not yet been completely understood, and there is still ample room for exotic alternatives. We have studied the effects of GRB on the ISM, in an attempt to distinguish the candidates of GRB remnants from those generated by multiple supernovae. We have used both energetic arguments and the possibility of chemical alterations due to photonuclear reactions. We have also worked on the biological implications of the illumination of planets by a GRB, concluding that the effects of such event could seriously harm the biosphere of a planet even at distances of ~10kpc. (AU)