scholarly journals Sensitivity of the lower edge of the pair-instability black hole mass gap to the treatment of time-dependent convection

2020 ◽  
Vol 493 (3) ◽  
pp. 4333-4341 ◽  
Author(s):  
M Renzo ◽  
R J Farmer ◽  
S Justham ◽  
S E de Mink ◽  
Y Götberg ◽  
...  
Keyword(s):  
Black Hole ◽  
Gravitational Wave ◽  
Time Scale ◽  
Turnover Time ◽  
Black Hole Mass ◽  
The Third ◽  
Mass Gap ◽  
Mixing Length Theory ◽  
State Assumption ◽  
Additional Equation

ABSTRACT Gravitational-wave detections are now probing the black hole (BH) mass distribution, including the predicted pair-instability mass gap. These data require robust quantitative predictions, which are challenging to obtain. The most massive BH progenitors experience episodic mass ejections on time-scales shorter than the convective turnover time-scale. This invalidates the steady-state assumption on which the classic mixing length theory relies. We compare the final BH masses computed with two different versions of the stellar evolutionary code $\tt{MESA}$: (i) using the default implementation of Paxton et al. (2018) and (ii) solving an additional equation accounting for the time-scale for convective deceleration. In the second grid, where stronger convection develops during the pulses and carries part of the energy, we find weaker pulses. This leads to lower amounts of mass being ejected and thus higher final BH masses of up to ∼$5\, \mathrm{M}_\odot$. The differences are much smaller for the progenitors that determine the maximum mass of BHs below the gap. This prediction is robust at $M_{\rm BH, max}\simeq 48\, \mathrm{M}_\odot$, at least within the idealized context of this study. This is an encouraging indication that current models are robust enough for comparison with the present-day gravitational-wave detections. However, the large differences between individual models emphasize the importance of improving the treatment of convection in stellar models, especially in the light of the data anticipated from the third generation of gravitational-wave detectors.

scholarly journals Mind the Gap: The Location of the Lower Edge of the Pair-instability Supernova Black Hole Mass Gap

2019 ◽  
Vol 887 (1) ◽  
pp. 53 ◽  
Author(s):  
R. Farmer ◽  
M. Renzo ◽  
S. E. de Mink ◽  
P. Marchant ◽  
S. Justham
Keyword(s):  
Black Hole ◽  
Lower Edge ◽  
Black Hole Mass ◽  
Mass Gap

scholarly journals New physics and the black hole mass gap

2020 ◽  
Vol 102 (11) ◽  
Author(s):  
Djuna Croon ◽  
Samuel D. McDermott ◽  
Jeremy Sakstein
Keyword(s):  
Black Hole ◽  
New Physics ◽  
Black Hole Mass ◽  
Mass Gap

scholarly journals Black hole mass function from gravitational wave measurements

2017 ◽  
Vol 95 (10) ◽  
Author(s):  
Ely D. Kovetz ◽  
Ilias Cholis ◽  
Patrick C. Breysse ◽  
Marc Kamionkowski
Keyword(s):  
Black Hole ◽  
Gravitational Wave ◽  
Mass Function ◽  
Black Hole Mass ◽  
Wave Measurements

scholarly journals Implications of recoil kicks for black hole mergers from LIGO/Virgo catalogs

2021 ◽  
Vol 502 (3) ◽  
pp. 3879-3884
Author(s):  
Giacomo Fragione ◽  
Abraham Loeb
Keyword(s):  
Black Hole ◽  
Gravitational Wave ◽  
Globular Clusters ◽  
Star Clusters ◽  
Star Cluster ◽  
Effective Spin ◽  
The Third ◽  
Binary Black Hole ◽  
Super Star Clusters ◽  
Escape Speed

ABSTRACT The first and second Gravitational Wave Transient Catalogs by the LIGO/Virgo Collaboration include 50 confirmed merger events from the first, second, and first half of the third observational runs. We compute the distribution of recoil kicks imparted to the merger remnants and estimate their retention probability within various astrophysical environments as a function of the maximum progenitor spin (χmax), assuming that the LIGO/Virgo binary black hole (BBH) mergers were catalyzed by dynamical assembly in a dense star cluster. We find that the distributions of average recoil kicks are peaked at about $150\, \rm km\, s^{-1}$, $250\, \rm km\, s^{-1}$, $350\, \rm km\, s^{-1}$, $600\, \rm km\, s^{-1}$, for maximum progenitor spins of 0.1, 0.3, 0.5, 0.8, respectively. Only environments with escape speed ${\gtrsim}100\, \rm km\, s^{-1}$, as found in galactic nuclear star clusters as well as in the most massive globular clusters and super star clusters, could efficiently retain the merger remnants of the LIGO/Virgo BBH population even for low progenitor spins (χmax = 0.1). In the case of high progenitor spins (χmax ≳ 0.5), only the most massive nuclear star clusters can retain the merger products. We also show that the estimated values of the effective spin and of the remnant spin of GW170729, GW190412, GW190519_153544, and GW190620_030421 can be reproduced if their progenitors were moderately spinning (χmax ≳ 0.3), while for GW190517_055101 if the progenitors were rapidly spinning (χmax ≳ 0.8). Alternatively, some of these events could be explained if at least one of the progenitors is already a second-generation BH, originated from a previous merger.

scholarly journals Formation of low-spinning 100 M⊙ black holes

2020 ◽  
Vol 640 ◽  
pp. L20
Author(s):  
K. Belczynski ◽  
S. Banerjee
Keyword(s):  
Black Holes ◽  
Black Hole ◽  
Gravitational Wave ◽  
Globular Clusters ◽  
Primordial Black Hole ◽  
Massive Black Hole ◽  
Mass Gap ◽  
High Speeds ◽  
Nuclear Clusters ◽  
Nuclear Cluster

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 (∼50−135 M⊙). 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 ∼100 M⊙ 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 (≳ 200 km s−1) from gravitational-wave kick during formation that exceed typical escape speeds from globular clusters (∼ 50 km s−1). However, a very low-spinning (a ∼ 0.1) and massive (∼100 M⊙) 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 (∼ 400 km s−1), they may avoid ejection since massive nuclear clusters have high escape velocities (∼ 300−500 km s−1). 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.

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