Evolutionary roads leading to low effective spins, high black hole masses, and O1/O2 rates for LIGO/Virgo binary black holes^⋆

¹ Nicolaus Copernicus Astronomical Center, Polish Academy of Sciences, ul. Bartycka 18, 00-716 Warsaw, Poland
e-mail: chrisbelczynski@gmail.com
² Department of Astrophysics/IMAPP, Radboud University, PO Box 9010, 6500 GL Nijmegen, The Netherlands
³ Department of Physics and Astronomy, Michigan State University, East Lansing, MI 48824, USA
⁴ Astronomical Observatory, Warsaw University, Al. Ujazdowskie 4, 00-478 Warsaw, Poland
⁵ Center for Theoretical Physics, Polish Academy of Sciences, Al. Lotnikow 32/46, 02-668 Warsaw, Poland
⁶ Department of Physics and Astronomy, Johns Hopkins University, Baltimore, MD 21218, USA
⁷ Department of Astronomy, University of Geneva, Chemin des Maillettes 51, 1290 Versoix, Switzerland
⁸ CCS-2, MSD409, Los Alamos National Laboratory, Los Alamos, NM 87545, USA
⁹ University of Chicago, Chicago, IL 60637, USA
¹⁰ Center for Computational Relativity and Gravitation, Rochester Institute of Technology, Rochester, NY 14623, USA
¹¹ Department of Physics, Syracuse University, Syracuse, NY 13224, USA
¹² Kavli Institute for the Physics and Mathematics of the Universe (WPI), The University of Tokyo, Kashiwa, Chiba 277-8583, Japan
¹³ TAPIR, Walter Burke Institute for Theoretical Physics, Mailcode 350-17, Caltech, Pasadena, CA 91125, USA
¹⁴ Department of Astronomy & Astrophysics, University of California, 1156 High Street, Santa Cruz, CA 95064, USA
¹⁵ Lennard-Jones Laboratories, Keele University, Keele ST5 5BG, UK
¹⁶ School of Physics & Astronomy & Institute for Gravitational Wave Astronomy, University of Birmingham, Birmingham, UK
¹⁷ Lund Observatory, Department of Astronomy, and Theoretical Physics, Lund University, Box 43, 221 00 Lund, Sweden
¹⁸ Physics Department, Kenyon College, 201 North College RD, Gambier, OH 43022, USA
¹⁹ Department of Physics and Astronomy, Stony Brook University, Stony Brook, NY 11794, USA
²⁰ National Astronomical Observatories & University of the Chinese Academy of Sciences, Beijing, PR China
²¹ Department of Astronomy and Joint Space-Science Institute University of Maryland, College Park, MD 20742-2421, USA
²² Department of Physics, University of Oregon, Eugene, OR 97403, USA
²³ Institut d’Astrophysique de Paris, CNRS et Sorbonne Université, UMR 7095, 98bis Bd Arago, 75014 Paris, France

Received: 20 August 2019
Accepted: 5 March 2020

Abstract

All ten LIGO/Virgo binary black hole (BH-BH) coalescences reported following the O1/O2 runs have near-zero effective spins. There are only three potential explanations for this. If the BH spin magnitudes are large, then: (i) either both BH spin vectors must be nearly in the orbital plane or (ii) the spin angular momenta of the BHs must be oppositely directed and similar in magnitude. Then there is also the possibility that (iii) the BH spin magnitudes are small. We consider the third hypothesis within the framework of the classical isolated binary evolution scenario of the BH-BH merger formation. We test three models of angular momentum transport in massive stars: a mildly efficient transport by meridional currents (as employed in the Geneva code), an efficient transport by the Tayler-Spruit magnetic dynamo (as implemented in the MESA code), and a very-efficient transport (as proposed by Fuller et al.) to calculate natal BH spins. We allow for binary evolution to increase the BH spins through accretion and account for the potential spin-up of stars through tidal interactions. Additionally, we update the calculations of the stellar-origin BH masses, including revisions to the history of star formation and to the chemical evolution across cosmic time. We find that we can simultaneously match the observed BH-BH merger rate density and BH masses and BH-BH effective spins. Models with efficient angular momentum transport are favored. The updated stellar-mass weighted gas-phase metallicity evolution now used in our models appears to be key for obtaining an improved reproduction of the LIGO/Virgo merger rate estimate. Mass losses during the pair-instability pulsation supernova phase are likely to be overestimated if the merger GW170729 hosts a BH more massive than 50 M_⊙. We also estimate rates of black hole-neutron star (BH-NS) mergers from recent LIGO/Virgo observations. If, in fact. angular momentum transport in massive stars is efficient, then any (electromagnetic or gravitational wave) observation of a rapidly spinning BH would indicate either a very effective tidal spin up of the progenitor star (homogeneous evolution, high-mass X-ray binary formation through case A mass transfer, or a spin- up of a Wolf-Rayet star in a close binary by a close companion), significant mass accretion by the hole, or a BH formation through the merger of two or more BHs (in a dense stellar cluster).