The formation of 30 solar-mass merging black holes at solar metallicity


Simone S. Bavera; Tassos Fragos; Emmanouil Zapartas; Jeff J. Andrews; Vicky Kalogera; Christopher P. L. Berry; Matthias Kruckow; Aaron Dotter; Konstantinos Kovlakas; Devina Misra; Kyle A. Rocha; Philipp M. Srivastava; Meng Sun; and Zepei Xing (2022)


The maximum mass of black holes formed in isolated binaries is determined by stellar winds and the interactions between the binary components. We consider for the first time fully self-consistent detailed stellar structure and binary evolution calculations in population-synthesis models and a new, qualitatively different picture emerges for the formation of black-hole binaries, compared to studies employing rapid population synthesis models. We find merging binary black holes can form with a non-negligible rate (\sim 4\times10^{-7}\,M_\odot^{-1}) at solar metallicity. Their progenitor stars with initial masses \gtrsim 50\,M_\odot do not expand to supergiant radii, mostly avoiding significant dust-driven or luminous blue variable winds. Overall, the progenitor stars lose less mass in stellar winds, resulting in black holes as massive as \sim 30\,M_\odot, and, approximately half of them avoid a mass-transfer episode before forming the first-born black hole. Finally, binaries with initial periods of a few days, some of which may undergo episodes of Roche-lobe overflow mass transfer, result in mildly spinning first-born black holes, \chi_\mathrm{BH1} \lesssim 0.2, assuming efficient angular-momentum transport.

Merging binary black hole population at solar metallicity.  Filled bins indicate the underlying (intrinsic) binary black hole distribution, while dashed lines illustrate selection effects for a ground-based GW detector. Here, we assume Advanced LIGO at design sensitivity as an example. We distinguish with the indices 1,2 the first- and second-born black holes, respectively. (Left) binary black hole component mass distributions of merging binary black holes formed from binary stars at solar metallicity.  (Right) binary black hole component spin-magnitude distributions of merging binary black holes formed from binary stars at solar metallicity.  Systems with \chi_\mathrm{BH} > 0.4 are believed to be associated with a luminous long-duration gamma-ray burst at the time of black hole formation.