Using LISA-like Gravitational Wave Detectors to Search for Primordial Black Holes

TL;DR

This paper explores how LISA-like gravitational wave detectors can be used to detect primordial black holes, providing a new method to investigate their role as dark matter candidates through extreme mass ratio inspirals.

Contribution

The study introduces a novel approach to estimate event rates of PBH-SMBH mergers using GW detectors, highlighting their potential to probe PBH dark matter fractions and mass ranges.

Findings

LISA-like detectors can explore PBH fractions as low as 10^{-3} to 10^{-4}.

LISA can detect PBHs with masses up to 0.01-0.1 solar masses.

Other GW detectors can probe lower PBH mass regimes.

Abstract

Primordial black hole (PBH), which can be naturally produced in the early universe, remains a promising dark matter candidate . It can merge with a supermassive black hole (SMBH) in the center of a galaxy and generate gravitational wave (GW) signals in the favored frequency region of LISA-like experiments. In this work, we initiate the study on the event rate calculation for such extreme mass ratio inspirals (EMRI). Including the sensitivities of various proposed GW detectors, we find that such experiments offer a novel and outstanding tool to test the scenario where PBH constitutes (fraction of) dark matter. The PBH energy density fraction of DM ($f_\text{PBH}$) could potentially be explored as small as $10^{-3} \sim 10^{-4}$. Further, LISA has the capability to search for PBH mass upto $10^{-2} \sim 10^{-1} M_\odot$. Other proposed GW experiments can probe lower PBH mass regime.