École Nationale Supérieure de
Techniques Avancées

Abstract

Gamma-ray bursts and their afterglows : Physical modelisation of burst GRB 030329 variability Gamma-ray bursts are the most energetic events known in the Universe. The most widely admited scenario explaining the phenomenon is that matter is ejected from a blackhole at ultra-relativistic speeds. Internal shocks are likely to happen if the speed is not uniform in the jet, emitting energy partly radiated by the synchrotron effect. GRB 030329 is an interesting case, as it was the first burst to be clearly identified with a supernova. Its light curve at visible wavelengths, just after the prompt emission in the gamma range, shows several irregularities, such as a slope break and a succession of bumps. The construction of a program modelising the propagation of a relativistic jet in an external environment allowed us to test some scenarii which could explain these distinguishing features. It was possible, with this code, to produce curves very similar to those measured, but none of the scenario allowed to reproduce all of the irregularities at once, except if ad-hoc prescriptions were added, whose physical justifications are debatable.