Determine whether black holes in high-mass X-ray binaries are truly rapidly rotating

Determine whether the black holes in high-mass X-ray binaries proposed to result from weak core–envelope coupling are truly rapidly rotating.

Background

The paper notes that weak core–envelope coupling has been proposed as an explanation for the high spins inferred in black-hole high-mass X-ray binaries. However, the actual spin measurements or interpretations of these systems remain uncertain, making their relevance to the formation of high-spin black holes in isolated binaries unresolved.