Most Black Holes Are Born Very Slowly Rotating
- Creators
- Fuller, Jim
- Ma, Linhao
Abstract
The age of gravitational-wave astronomy has begun, and black hole (BH) mergers detected by the Laser Interferometer Gravitational-Wave Observatory (LIGO) are providing novel constraints on massive star evolution. A major uncertainty in stellar theory is the angular momentum (AM) transport within the star that determines its core rotation rate and the resulting BH's spin. Internal rotation rates of low-mass stars measured from asteroseismology prove that AM transport is efficient, suggesting that massive stellar cores may rotate slower than prior expectations. We investigate AM transport via the magnetic Tayler instability, which can largely explain the rotation rates of low-mass stars and white dwarfs. Implementing an updated AM transport prescription into models of high-mass stars, we compute the spins of their BH remnants. We predict that BHs born from single stars rotate very slowly, with a ~ 10^(−2), regardless of initial rotation rate, possibly explaining the low χ_(eff) of most BH binaries detected by LIGO thus far. A limited set of binary models suggests slow rotation for many binary scenarios as well, although homogeneous evolution and tidal spin-up of post-common-envelope helium stars can create moderate or high BH spins. We make predictions for the values of χ_(eff) in future LIGO events, and we discuss implications for engine-powered transients.
Additional Information
© 2019 The American Astronomical Society. Received 2019 June 4; revised 2019 July 17; accepted 2019 July 18; published 2019 August 5. We thank Will Farr, Davide Gerosa, Greg Salvesen, and Christopher Berry for enlightening conversations. This research is funded in part by an Innovator Grant from The Rose Hills Foundation and the Sloan Foundation through grant FG-2018-10515.Attached Files
Published - Fuller_2019_ApJL_881_L1.pdf
Accepted Version - 1907.03714.pdf
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Additional details
- Eprint ID
- 97632
- Resolver ID
- CaltechAUTHORS:20190805-095631487
- Rose Hills Foundation
- FG-2018-10515
- Alfred P. Sloan Foundation
- Created
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2019-08-05Created from EPrint's datestamp field
- Updated
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2021-11-16Created from EPrint's last_modified field
- Caltech groups
- TAPIR, Astronomy Department