Isolated Binary Black Hole Formation and Merger Rates from Galaxy Evolution

Fuente: arXiv
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Auteurs principaux: Smith, Tyler B., Kaplinghat, Manoj
Format: Preprint
Publié: 2024
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author Smith, Tyler B.
Kaplinghat, Manoj
author_facet Smith, Tyler B.
Kaplinghat, Manoj
contents The LIGO-Virgo-KAGRA (LVK) collaboration has detected over 150 confirmed gravitational wave events through O4a. Binary black hole (BBH) systems represent the overwhelming majority of these observations. We construct a model for the population of the BBHs based on the distribution of metallicities in galaxies and state-of-the-art stellar evolution models implemented through the Stellar EVolution N-body (SEVN) code. We calculate the redshift evolution of the total merger rate of BBHs and the differential rates with respect to primary mass, secondary mass, and the mass ratio. We explore variations in the delay-time distribution's (DTD) power-law index and show that it affects the total merger rate's spectral shape, but primarily acts as an amplitude shift on the differential rates. When comparing to the primary mass distribution, our results indicate that either the average IMF in dwarf galaxies must be top heavy, or most of the 30-40 $\rm M_\odot$ black holes must be formed through a dynamical capture mechanism. For masses greater than about $50 \, \rm M_\odot$, the predicted number of BBH systems plummet to zero, revealing the well-known mass gap due to the pair instability mechanism and mass loss in binary systems.
format Preprint
id arxiv_https___arxiv_org_abs_2412_13318
institution arXiv
publishDate 2024
record_format arxiv
spellingShingle Isolated Binary Black Hole Formation and Merger Rates from Galaxy Evolution
Smith, Tyler B.
Kaplinghat, Manoj
High Energy Astrophysical Phenomena
Astrophysics of Galaxies
The LIGO-Virgo-KAGRA (LVK) collaboration has detected over 150 confirmed gravitational wave events through O4a. Binary black hole (BBH) systems represent the overwhelming majority of these observations. We construct a model for the population of the BBHs based on the distribution of metallicities in galaxies and state-of-the-art stellar evolution models implemented through the Stellar EVolution N-body (SEVN) code. We calculate the redshift evolution of the total merger rate of BBHs and the differential rates with respect to primary mass, secondary mass, and the mass ratio. We explore variations in the delay-time distribution's (DTD) power-law index and show that it affects the total merger rate's spectral shape, but primarily acts as an amplitude shift on the differential rates. When comparing to the primary mass distribution, our results indicate that either the average IMF in dwarf galaxies must be top heavy, or most of the 30-40 $\rm M_\odot$ black holes must be formed through a dynamical capture mechanism. For masses greater than about $50 \, \rm M_\odot$, the predicted number of BBH systems plummet to zero, revealing the well-known mass gap due to the pair instability mechanism and mass loss in binary systems.
title Isolated Binary Black Hole Formation and Merger Rates from Galaxy Evolution
topic High Energy Astrophysical Phenomena
Astrophysics of Galaxies
url https://arxiv.org/abs/2412.13318