Common origin for black holes in both high mass X-ray binaries and gravitational-wave sources

Understand

Black-hole (BH) high-mass X-ray binary (HMXB) systems are likely to be the progenitors of BH-BH mergers detected by LIGO/Virgo/KAGRA (LVK).

• Yet merging BHs reach higher masses ($\sim 100M_{\odot}$) than BHs in HMXBs ($\sim 20 M_{\odot}$) and exhibit lower spins ($a_{\rm BH}\lesssim 0.25$ with a larger values tail) than what is often claimed for BHs in HMXBs ($a_{\rm BH}\gtrsim 0.9$).
• This could suggest that these two classes of systems belong to different populations, but here we show that this may not necessarily be the case.
• The difference in masses is easily explained as the known HMXB-BHs are in galaxies with relatively high metallicity, so their progenitor stars are subject to strong mass loss from winds, leading to relatively low-mass BH at core collapse.