Long GRBs from binary stars: runaway, Wolf-Rayet progenitors

TL;DR

This paper explores how massive close binary stars can produce rapidly rotating Wolf-Rayet stars through mass transfer, potentially explaining the origins of long gamma-ray bursts and their association with runaway stars.

Contribution

It introduces a binary evolution channel for forming rapidly rotating Wolf-Rayet stars, expanding the possible progenitors of long gamma-ray bursts beyond single-star models.

Findings

Binary mass transfer can spin up Wolf-Rayet progenitors.

Runaway stars may be common long gamma-ray burst progenitors.

The proposed channel operates across a range of metallicities.

Abstract

The collapsar model for long gamma-ray bursts requires a rapidly rotating Wolf-Rayet star as progenitor. We test the idea of producing rapidly rotating Wolf-Rayet stars in massive close binaries through mass accretion and consecutive quasi-chemically homogeneous evolution; the latter had previously been shown to provide collapsars below a certain metallicity threshold for single stars. The binary channel presented here may provide a means for massive stars to obtain the high rotation rates required to evolve quasi-chemically homogeneous and fulfill the collapsar scenario. Moreover, it suggests that a possibly large fraction of long gamma-ray bursts occurs in runaway stars.