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arXiv · 0704.0659

Long Gamma-Ray Burst Progenitors: Boundary Conditions and Binary Models

E. P. J. van den Heuvel·S. -C. Yoon
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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.

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E. P. J. van den Heuvel, S. -C. Yoon. 2007-04-04. Long Gamma-Ray Burst Progenitors: Boundary Conditions and Binary Models. https://doi.org/10.1007/s10509-007-9583-8

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