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

### Authors:

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)

### Abstract:

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.