Primordial Black Holes in Dark Matter Halos: Merger Rate Simulations and Limits from the LIGO-Virgo-KAGRA Observations

We investigate primordial black holes (PBHs) as significant component of dark matter and evaluate the rate by which PBH mergers can contribute to the gravitational wave events detected by LIGO/Virgo/KAGRA (LVK). We first simulate the evolution of PBH binaries within dark matter halos, estimating PBH merger rate up to redshift 10, with a focus on two main merging channels: two-body captures and binary-single interactions. In our study, we find that the latter can dominate under reasonable assumptions on the abundance of PBH binaries. We explore monochromatic and lognormal PBH mass distributions. For a monochromatic PBH mass-distribution, the merger rate increases with the PBH mass. There is a similar pattern for non-monochromatic mass distributions. Finally, we explore how the LVK observations can provide limits on the abundance of PBHs in the universe.