Establishing the Non-Primordial Origin of Black Hole-Neutron Star Mergers

Abstract

Primordial black holes (PBHs) from the early Universe constitute an attractive dark matter candidate. First detections of black hole-neutron star (BH-NS) candidate gravitational wave events by the LIGO/Virgo collaboration, GW200105 and GW200115, already prompted speculations about non-astrophysical origin. We analyze, for the first time, the total volumetric merger rates of PBH-NS binaries formed via two-body gravitational scattering, finding them to be subdominant to the astrophysical BH-NS rates. In contrast to binary black holes, a significant fraction of which can be of primordial origin, either formed in dark matter halos or in the early Universe, PBH-NS rates cannot be significantly enhanced by contributions preceding star formation. Our findings imply that the identified BH-NS events are of astrophysical origin, even when PBH-PBH events significantly contribute to the GW observations.

7 pages, 2 figures, published in APJ

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Cited by in corpus (16)

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• PBH formation from spherically symmetric hydrodynamical perturbations: a review
• Primordial Black Holes
• Probing primordial black holes with anisotropies in stochastic gravitational-wave background
• General-Relativistic Hydrodynamics Simulation of a Neutron Star - Sub-Solar-Mass Black Hole Merger
• Coexistence Test of Primordial Black Holes and Particle Dark Matter from Diffractive Lensing
• Impacts of Jets and Winds From Primordial Black Holes
• GW230529_181500: A Potential Primordial Binary Black Hole Merger in the Mass Gap
• Constraining extended cosmologies with GW$\times$LSS cross-correlations
• Compact Binary Merger Rate in Dark-Matter Spikes
• The Merger Rate of Primordial Black Hole-Neutron Star Binaries in Ellipsoidal-Collapse Dark Matter Halo Models
• Primordial Black Hole-Neutron Star Merger Rate in Modified Gravity
• Compact Binary Merger Rate with Modified Gravity in Dark-Matter Spikes
• Primordial Black Hole Mergers as Probes of Dark Matter in Galactic Center
• Is PSR J0514$-$4002E in a PBH-NS binary?
• Dynamics and merger rate of primordial black holes in a cluster