Merger rates in primordial black hole clusters without initial binaries

Korol, ValeriyaLeiden University,University of Birmingham,University of Copenhagen (författare)

Primordial black holes formed through the collapse of cosmological density fluctuations have been hypothesized as contributors to the dark matter content of the Universe. At the same time, their mergers could contribute to the recently observed population of gravitational-wave sources. We investigate the scenario in which primordial black holes form binaries at late times in the Universe. Specifically, we re-examine the mergers of primordial black holes in small clusters of ∼30 objects in the absence of initial binaries. Binaries form dynamically through Newtonian gravitational interactions. These binaries act as heat sources for the cluster, increasing the cluster's velocity dispersion, which inhibits direct mergers through gravitational-wave two-body captures. Meanwhile, three-body encounters of tight binaries are too rare to tighten binaries sufficiently to allow them to merge through gravitational-wave emission. We conclude that in the absence of initial binaries, merger rates of primordial black holes in the considered scenario are at least an order of magnitude lower than previously suggested, which makes gravitational-wave detections of such sources improbable.

Mandel, IlyaMonash University,University of Copenhagen,University of Birmingham,Swinburne University of Technology (författare)
Coleman Miller, M.University of Maryland,University of Copenhagen (författare)
Church, Ross P.Lund University,Lunds universitet,Astronomi - Genomgår omorganisation,Institutionen för astronomi och teoretisk fysik - Genomgår omorganisation,Naturvetenskapliga fakulteten,Lund Observatory - Undergoing reorganization,Department of Astronomy and Theoretical Physics - Undergoing reorganization,Faculty of Science,University of Copenhagen(Swepub:lu)astr-rch (författare)
Davies, Melvyn B.Lund University,Lunds universitet,Astronomi - Genomgår omorganisation,Institutionen för astronomi och teoretisk fysik - Genomgår omorganisation,Naturvetenskapliga fakulteten,Lund Observatory - Undergoing reorganization,Department of Astronomy and Theoretical Physics - Undergoing reorganization,Faculty of Science,University of Copenhagen(Swepub:lu)astr-mda (författare)
Leiden UniversityUniversity of Birmingham (creator_code:org_t)

Ingår i:Monthly Notices of the Royal Astronomical Society: Oxford University Press (OUP)496:1, s. 994-10000035-87111365-2966

Av författaren/redakt...: Korol, Valeriya; Mandel, Ilya; Coleman Miller, ...; Church, Ross P.; Davies, Melvyn B ...

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