Long Gamma-Ray Burst Progenitors: Boundary Conditions and Binary Models
Abstract
The observed association of Long Gamma-Ray Bursts (LGRBs) with peculiar Type Ic supernovae gives support to Woosley`s collapsar/hypernova model, in which the GRB is produced by the collapse of the rapidly rotating core of a massive star to a black hole. The association of LGRBs with small star-forming galaxies suggests low-metallicity to be a condition for a massive star to evolve to the collapsar stage. Both completely-mixed single star models and binary star models are possible. In binary models the progenitor of the GRB is a massive helium star with a close companion. We find that tidal synchronization during core-helium burning is reached on a short timescale (less than a few millennia). However, the strong core-envelope coupling in the subsequent evolutionary stages is likely to rule out helium stars with main-sequence companions as progenitors of hypernovae/GRBs. On the other hand, helium stars in close binaries with a neutron-star or black-hole companion can, despite the strong core-envelope coupling in the post-helium burning phase, retain sufficient core angular momentum to produce a hypernova/GRB.
Keywords
Cite
@article{arxiv.0704.0659,
title = {Long Gamma-Ray Burst Progenitors: Boundary Conditions and Binary Models},
author = {E. P. J. van den Heuvel and S. -C. Yoon},
journal= {arXiv preprint arXiv:0704.0659},
year = {2009}
}
Comments
8 pp., 2 figs, Proceedings of 5th Stromlo Symposium