Rapid population synthesis of black hole high-mass X-ray binaries: implications for binary stellar evolution

Romero-Shaw, Isobel, Hirai, Ryosuke, Bahramian, Arash, Willcox, Reinhold and Mandel, Ilya 2023. Rapid population synthesis of black hole high-mass X-ray binaries: implications for binary stellar evolution. Monthly Notices of the Royal Astronomical Society 524 (1) , pp. 245-259. 10.1093/mnras/stad1732

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Abstract

We conduct binary population synthesis to investigate the formation of wind-fed high-mass X-ray binaries containing black holes (BH-HMXBs). We evolve multiple populations of high-mass binary stars and consider BH-HMXB formation rates, masses, spins, and separations. We find that systems similar to Cygnus X-1 likely form after stable Case A mass transfer (MT) from the main-sequence progenitors of BHs, provided such MT is characterized by low accretion efficiency, β ≲ 0.1, with modest orbital angular momentum losses from the non-accreted material. Additionally, efficient BH-HMXB formation relies on a new simple treatment for Case A MT that allows donors to retain larger core masses compared to traditional rapid population-synthesis assumptions. At solar metallicity, our Preferred model yields observable BH-HMXBs in the Galaxy today, consistent with observations. In this simulation, 8 per cent of BH-HMXBs go on to merge as binary black holes or neutron star-black hole binaries within a Hubble time; however, none of the merging binaries have BH-HMXB progenitors with properties similar to Cygnus X-1. With our preferred settings for core mass growth, mass transfer efficiency, and angular momentum loss, accounting for an evolving metallicity, and integrating over the metallicity-specific star formation history of the Universe, we find that BH-HMXBs may have contributed ≈2–5 BBH merger signals to detections reported in the third gravitational-wave transient catalogue of the LIGO–Virgo–KAGRA Collaboration. We also suggest MT efficiency should be higher during stable Case B MT than during Case A MT.

Item Type:	Article
Date Type:	Publication
Status:	Published
Schools:	Schools > Physics and Astronomy
Publisher:	Oxford University Press
ISSN:	1365-2966
Date of First Compliant Deposit:	19 February 2026
Date of Acceptance:	6 June 2023
Last Modified:	19 Feb 2026 15:16
URI:	https://orca.cardiff.ac.uk/id/eprint/185049

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