Primordial black hole collision with neutron stars and astrophysical black holes and the observational signatures

TL;DR

This paper explores the potential of primordial black holes as dark matter candidates by analyzing their collision rates with neutron stars and black holes, and assesses the detectability of resulting gravitational waves.

Contribution

It derives relativistic dynamics of PBHs around compact objects and evaluates collision rates and gravitational wave signals, providing insights into observational prospects.

Findings

Collision rate in the Milky Way is about one per hundred years.

Gravitational wave signals from PBH mergers are below current detector sensitivity.

Future observations may detect these events on cosmological scales.

Abstract

In this paper, we examine whether low-mass Primordial Black Holes (PBHs) can be considered a plausible dark matter candidate in galactic halos. We derive the relativistic dynamics of PBHs around the heavy compact objects and evaluate their collision rate, as well as the likelihood of PBH capture in neutron stars and black holes. Although the rate of these collisions in the Milky Way is lower than our lifetime (i.e. almost one collision per hundred years), it may still be observable on cosmological scales. Additionally, we investigate the gravitational wave emission as an important observable window for PBH-astrophysical black hole merging. For the allowed range of PBH mass, gravitational wave signal is smaller than the sensitivity of present gravitational wave detectors. We provide observational prospect for detection of these events in future.