Binary black hole mergers from Population III star clusters

Fuente: arXiv
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Auteurs principaux: Mestichelli, Benedetta, Mapelli, Michela, Torniamenti, Stefano, Sedda, Manuel Arca, Branchesi, Marica, Costa, Guglielmo, Iorio, Giuliano, Santoliquido, Filippo
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Publié: 2024
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author Mestichelli, Benedetta
Mapelli, Michela
Torniamenti, Stefano
Sedda, Manuel Arca
Branchesi, Marica
Costa, Guglielmo
Iorio, Giuliano
Santoliquido, Filippo
author_facet Mestichelli, Benedetta
Mapelli, Michela
Torniamenti, Stefano
Sedda, Manuel Arca
Branchesi, Marica
Costa, Guglielmo
Iorio, Giuliano
Santoliquido, Filippo
contents Binary black holes (BBHs) born from the evolution of Population III (Pop. III) stars are one of the main high-redshift targets for next-generation ground-based gravitational-wave (GW) detectors. Their predicted initial mass function and lack of metals make them the ideal progenitors of black holes above the upper edge of the pair-instability mass gap, i.e. with a mass higher than $\approx{}134$ (241) M$_\odot$ for stars that become (do not become) chemically homogeneous during their evolution. Here, we investigate the effects of cluster dynamics on the mass function of BBHs born from Pop. III stars, by considering the main uncertainties on Pop. III star mass function, orbital properties of binary systems, star cluster's mass and disruption time. In our dynamical models, at least $\sim$5% and up to 100% BBH mergers in Pop. III star clusters have primary mass $m_1$ above the upper edge of the pair-instability mass gap. In contrast, only $\lesssim {} 3$% isolated BBH mergers have primary mass above the gap, unless their progenitors evolved as chemically homogeneous stars. The lack of systems with primary and/or secondary mass inside the gap defines a zone of avoidance with sharp boundaries in the primary mass - mass ratio plane. Finally, we estimate the merger rate density of BBHs and, in the most optimistic case, we find a maximum of $\mathcal{R}\approx200\,{\rm Gpc^{-3}\,yr^{-1}}$ at $z\sim15$ for BBHs formed via dynamical capture. For comparison, the merger rate density of isolated Pop. III BBHs is $\mathcal{R}\leq{}10\,{\rm Gpc^{-3}\,yr^{-1}}$, for the same model of Pop. III star formation history.
format Preprint
id arxiv_https___arxiv_org_abs_2405_06037
institution arXiv
publishDate 2024
record_format arxiv
spellingShingle Binary black hole mergers from Population III star clusters
Mestichelli, Benedetta
Mapelli, Michela
Torniamenti, Stefano
Sedda, Manuel Arca
Branchesi, Marica
Costa, Guglielmo
Iorio, Giuliano
Santoliquido, Filippo
Astrophysics of Galaxies
High Energy Astrophysical Phenomena
Binary black holes (BBHs) born from the evolution of Population III (Pop. III) stars are one of the main high-redshift targets for next-generation ground-based gravitational-wave (GW) detectors. Their predicted initial mass function and lack of metals make them the ideal progenitors of black holes above the upper edge of the pair-instability mass gap, i.e. with a mass higher than $\approx{}134$ (241) M$_\odot$ for stars that become (do not become) chemically homogeneous during their evolution. Here, we investigate the effects of cluster dynamics on the mass function of BBHs born from Pop. III stars, by considering the main uncertainties on Pop. III star mass function, orbital properties of binary systems, star cluster's mass and disruption time. In our dynamical models, at least $\sim$5% and up to 100% BBH mergers in Pop. III star clusters have primary mass $m_1$ above the upper edge of the pair-instability mass gap. In contrast, only $\lesssim {} 3$% isolated BBH mergers have primary mass above the gap, unless their progenitors evolved as chemically homogeneous stars. The lack of systems with primary and/or secondary mass inside the gap defines a zone of avoidance with sharp boundaries in the primary mass - mass ratio plane. Finally, we estimate the merger rate density of BBHs and, in the most optimistic case, we find a maximum of $\mathcal{R}\approx200\,{\rm Gpc^{-3}\,yr^{-1}}$ at $z\sim15$ for BBHs formed via dynamical capture. For comparison, the merger rate density of isolated Pop. III BBHs is $\mathcal{R}\leq{}10\,{\rm Gpc^{-3}\,yr^{-1}}$, for the same model of Pop. III star formation history.
title Binary black hole mergers from Population III star clusters
topic Astrophysics of Galaxies
High Energy Astrophysical Phenomena
url https://arxiv.org/abs/2405.06037