出版社：SISSA, Scuola Internazionale Superiore di Studi Avanzati
摘要：Gamma-ray bursts (GRBs) are nowadays considered to be collimated ejecta with bulk velocities
very close to the speed of light. The mechanism by which after the quasy-isotropic energy release
of a few 1050 erg yields a collimated ejection of plasma has not been satisfactorily explained by
simple analytically developments. The reason being that the collimation of an outflow by its progenitor
system depends on a very complex and non-linear dynamics. That has made it necessary
to use numerical simulations in order to shed some light on the viability of some likely progenitors
of GRBs. Here we review the most relevant features shown by these numerical simulations and
how they have been used to validate the most popular progenitor models, namely, the collapsar
model (for long GRBs) and the model involving the merger of compact binaries (for short GRBs).
