The emergence of structure in the binary black hole mass distribution

Tiwari, Vaibhav and Fairhurst, Stephen ORCID: https://orcid.org/0000-0001-8480-1961 2021. The emergence of structure in the binary black hole mass distribution. Astrophysical Journal Letters 913 (2) , L19. 10.3847/2041-8213/abfbe7

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Abstract

We use the gravitational wave signals from binary black hole merger events observed by LIGO and Virgo to reconstruct the underlying mass and spin distributions of the population of merging black holes. We reconstruct the population using the mixture model framework VAMANA using observations in GWTC-2 occurring during the first two observing runs and the first half of the third run (O1, O2, and O3a). Our analysis identifies a structure in the chirp mass distribution of the observed population. Specifically, we identify peaks in the chirp mass distribution at 8, 14, 26, and 45 M⊙ and a complementary structure in the component mass distribution with an excess of black holes at masses of 9, 16, 45, and 57 M⊙. Intriguingly, for both the distributions, the location of subsequent peaks are separated by a factor of around two and there is a lack of mergers with chirp masses of 10–12 M⊙. The appearance of multiple peaks is a feature of a hierarchical merger scenario when, due to a gap in the black hole mass spectrum, a pile-up occurs at the first peak followed by mergers of lower mass black holes to hierarchically produce higher mass black holes. However, cross-generation merger peaks and observations with high spins are also predicted to occur in such a scenario that we are not currently observing. The results presented are limited in measurement accuracy due to small numbers of observations but if corroborated by future gravitational wave observations these features have far-reaching implications.

Item Type:	Article
Date Type:	Publication
Status:	Published
Schools:	Physics and Astronomy
Publisher:	American Astronomical Society
ISSN:	2041-8213
Date of First Compliant Deposit:	23 July 2021
Date of Acceptance:	26 April 2021
Last Modified:	05 Jan 2024 19:09
URI:	https://orca.cardiff.ac.uk/id/eprint/142338

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