Primordial Black Hole Merger Rate in Self-Interacting Dark Matter Halo Models

TL;DR

This paper investigates the merger rate of primordial black holes within self-interacting dark matter halos, proposing new models for halo density evolution and comparing merger rates with observational data from gravitational wave detectors.

Contribution

It introduces a novel approach to modeling SIDM halo density profiles and calculates PBH merger rates, highlighting conditions where SIDM models produce higher merger rates than CDM models.

Findings

SIDM halos can produce higher PBH merger rates than CDM halos for certain PBH fractions.

The merger rate of 10 solar mass PBHs can match LIGO-Virgo observations within SIDM models.

A relation between PBH fraction and mass is consistent with observational constraints.

Abstract

We study the merger rate of primordial black holes (PBHs) in self-interacting dark matter (SIDM) halo models. To explore a numerical description for the density profile of SIDM halo models, we use the result of a previously performed simulation for SIDM halo models with $\sigma/m=10~{\rm cm^{2}g^{-1}}$. We also propose a concentration-mass-time relation that can explain the evolution of the halo density profile related to SIDM models. Furthermore, we investigate the encounter condition of PBHs that may have been randomly distributed in the medium of dark matter halos. Under these assumptions, we calculate the merger rate of PBHs within each halo considering SIDM halo models and compare the results with that obtained for cold dark matter (CDM) halo models. To do this, we employ the definition of the time after halo virialization as a function of halo mass. We indicate that SIDM halo models for $f_{\rm PBH}>0.32$ can generate sufficient PBH mergers in such a way that those exceed the one resulted from CDM halo models. By considering the spherical-collapse halo mass function, we obtain similar results for the cumulative merger rate of PBHs. Moreover, we calculate the redshift evolution of the PBH total merger rate. To determine a constraint on the PBH abundance, we study the merger rate of PBHs in terms of their fraction and masses and compare those with the black hole merger rate estimated by the Advanced LIGO (aLIGO)-Advanced Virgo (aVirgo) detectors during the third observing run. The results demonstrate that within the context of SIDM halo models, the merger rate of $10~M_{\odot}-10~M_{\odot}$ events can potentially fall within the aLIGO-aVirgo window. We also estimate a relation between the fraction of PBHs and their masses, which is well consistent with our findings.