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MOCCA-SURVEY Database I: Assessing GW kick retention fractions for BH-BH mergers in globular clusters

Morawski, Jakub ; Giersz, M ; Askar, A LU orcid and Belczynski, K (2018) In Monthly Notices of the Royal Astronomical Society 481(2). p.2168-2179
Abstract
Anisotropy of gravitational wave (GW) emission results in a net momentum gained by the black hole (BH) merger product, leading to a recoil velocity up to ∼103 km s−1, which may kick it out of a globular cluster (GC). We estimate GW kick retention fractions of merger products assuming different models for BH spin magnitude and orientation. We check how they depend on BH–BH merger time and properties of the cluster. We analyse the implications of GW kick retention fractions on intermediate massive BH formation by repeated mergers in a GC. We also calculate final spin of the merger product, and investigate how it correlates with other parameters: effective spin of the binary and gravitational kick velocity. We used data from MOCCA (MOnte... (More)
Anisotropy of gravitational wave (GW) emission results in a net momentum gained by the black hole (BH) merger product, leading to a recoil velocity up to ∼103 km s−1, which may kick it out of a globular cluster (GC). We estimate GW kick retention fractions of merger products assuming different models for BH spin magnitude and orientation. We check how they depend on BH–BH merger time and properties of the cluster. We analyse the implications of GW kick retention fractions on intermediate massive BH formation by repeated mergers in a GC. We also calculate final spin of the merger product, and investigate how it correlates with other parameters: effective spin of the binary and gravitational kick velocity. We used data from MOCCA (MOnte Carlo Cluster simulAtor) GC simulations to get a realistic sample of BH–BH mergers, assigned each BH spin value according to a studied model, and calculated recoil velocity and final spin based on most recent theoretical formulas. We discovered that for physically motivated models, GW kick retention fractions are about 30 per cent
30 per cent
and display small dependence on assumptions about spin, but are much more prone to cluster properties. In particular, we discovered a strong dependence of GW kick retention fractions on cluster density. We also show that GW kick retention fractions are high in final life stages of the cluster, but low at the beginning. Finally, we derive formulas connecting final spin with effective spin for primordial binaries, and with maximal effective spin for dynamical binaries. (Less)
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author
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organization
publishing date
type
Contribution to journal
publication status
published
subject
in
Monthly Notices of the Royal Astronomical Society
volume
481
issue
2
pages
2168 - 2179
publisher
Oxford University Press
external identifiers
  • scopus:85060882279
ISSN
1365-2966
DOI
10.1093/mnras/sty2401
language
English
LU publication?
yes
id
1c63d86c-2895-4a6d-b3ba-69e2845384d3
date added to LUP
2018-10-30 17:54:20
date last changed
2024-04-15 16:40:31
@article{1c63d86c-2895-4a6d-b3ba-69e2845384d3,
  abstract     = {{Anisotropy of gravitational wave (GW) emission results in a net momentum gained by the black hole (BH) merger product, leading to a recoil velocity up to ∼103 km s−1, which may kick it out of a globular cluster (GC). We estimate GW kick retention fractions of merger products assuming different models for BH spin magnitude and orientation. We check how they depend on BH–BH merger time and properties of the cluster. We analyse the implications of GW kick retention fractions on intermediate massive BH formation by repeated mergers in a GC. We also calculate final spin of the merger product, and investigate how it correlates with other parameters: effective spin of the binary and gravitational kick velocity. We used data from MOCCA (MOnte Carlo Cluster simulAtor) GC simulations to get a realistic sample of BH–BH mergers, assigned each BH spin value according to a studied model, and calculated recoil velocity and final spin based on most recent theoretical formulas. We discovered that for physically motivated models, GW kick retention fractions are about 30 per cent <br/>30 per cent<br/> and display small dependence on assumptions about spin, but are much more prone to cluster properties. In particular, we discovered a strong dependence of GW kick retention fractions on cluster density. We also show that GW kick retention fractions are high in final life stages of the cluster, but low at the beginning. Finally, we derive formulas connecting final spin with effective spin for primordial binaries, and with maximal effective spin for dynamical binaries.}},
  author       = {{Morawski, Jakub and Giersz, M and Askar, A and Belczynski, K}},
  issn         = {{1365-2966}},
  language     = {{eng}},
  month        = {{09}},
  number       = {{2}},
  pages        = {{2168--2179}},
  publisher    = {{Oxford University Press}},
  series       = {{Monthly Notices of the Royal Astronomical Society}},
  title        = {{MOCCA-SURVEY Database I: Assessing GW kick retention fractions for BH-BH mergers in globular clusters}},
  url          = {{http://dx.doi.org/10.1093/mnras/sty2401}},
  doi          = {{10.1093/mnras/sty2401}},
  volume       = {{481}},
  year         = {{2018}},
}