Gravitational Waves from Mergers of Asymmetric Dark Stars

TL;DR

This paper explores how asymmetric dark matter can form dark stars with unique properties, and how their mergers produce gravitational waves that can reveal insights into dark matter physics.

Contribution

It introduces a model for dark star formation, calculates their merger rates, and discusses how their gravitational wave signals differ from known astrophysical sources.

Findings

Dark stars can significantly contribute to low-redshift merger rates.

Dark star mergers produce distinct gravitational wave signatures.

The mass distribution of dark star mergers extends beyond known astrophysical processes.

Abstract

A strongly self-interacting component of asymmetric dark matter (DM) particles can form compact dark stars (DSs). These objects have a broad spectrum of masses and radii, with distinct evolution histories from both neutron stars and black holes (BHs). We argue that these differences allow a population of DSs to contribute significantly to the astrophysical merger rate in unique and discernible ways. Specifically, their merger rate could dominate at low redshifts over other sources, while their mass function may populate windows outside known astrophysical processes. We investigate the structure and formation of DSs within a dissipative model, and calculate the enhancement of their merger cross-section due to tidal deformation effects. From this, we derive the present-day merger rate and its differential mass distribution. These findings open a new window to probe DM substructure and particle interactions through present and future gravitational wave (GW) observatories.