C.D.S. - SIMBAD4 rel 1.7 - 2020.10.26CET14:56:17

2020A&A...640L..20B - Astronomy and Astrophysics, volume 640, L20-20 (2020/8-1)

Formation of low-spinning 100 M black holes.


Abstract (from CDS):

Aims. It is speculated that a merger of two massive stellar-origin black holes in a dense stellar environment may lead to the formation of a massive black hole in the pair-instability mass gap (∼50-135M). Such a merger-formed black hole is expected to typically have a high spin (a∼0.7). If such a massive black hole acquires another black hole it may lead to another merger detectable by LIGO/Virgo in gravitational waves. Acquiring a companion may be hindered by gravitational-wave kick/recoil, which accompanies the first merger and may quickly remove the massive black hole from its parent globular or nuclear cluster. We test whether it is possible for a massive merger-formed black hole in the pair-instability gap to be retained in its parent cluster and have low spin. Such a black hole would be indistinguishable from a primordial black hole.
Methods. We employed results from numerical relativity calculations of black hole mergers to explore the range of gravitational-wave recoil velocities for various combinations of merging black hole masses and spins. We compared merger-formed massive black hole speeds with typical escape velocities from globular and nuclear clusters.
Results. We show that a globular cluster is highly unlikely to form and retain a∼100M black hole if the spin of the black hole is low (a≤0.3). Massive merger-formed black holes with low spins acquire high recoil speeds (≥200km/s) from gravitational-wave kick during formation that exceed typical escape speeds from globular clusters (∼50km/s). However, a very low-spinning (a∼0.1) and massive (∼100M) black hole could be formed and retained in a galactic nuclear star cluster. Even though such massive merger-formed black holes with such low spins acquire high speeds during formation (∼400km/s), they may avoid ejection since massive nuclear clusters have high escape velocities (∼300-500km/s). A future detection of a massive black hole in the pair-instability mass gap with low spin would therefore not be proof of the existence of primordial black holes, which are sometimes claimed to have low spins and arbitrarily high masses.

Abstract Copyright: © ESO 2020

Journal keyword(s): black hole physics - gravitational waves

Simbad objects: 5

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Number of rows : 5

N Identifier Otype ICRS (J2000)
ICRS (J2000)
Mag U Mag B Mag V Mag R Mag I Sp type #ref
1850 - 2020
1 NAME M33 X-7 HXB 01 33 34.13 +30 32 11.3 17.50 18.80 18.70     O 130 2
2 X LMC X-1 HXB 05 39 38.8285930597 -69 44 35.533031148   14.8 14.5     O8(f)p 564 2
3 HD 226868 HXB 19 58 21.6758193269 +35 12 05.782512305 9.38 9.72 8.91 8.42   O9.7Iabpvar 3948 0
4 GrW 190412 GWE ~ ~           ~ 17 0
5 GrW 170729 GWE ~ ~           ~ 57 0

    Equat.    Gal    SGal    Ecl

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