Asymmetric Dark Stars and Neutron Star Stability

TL;DR

This paper investigates the properties and stability of asymmetric dark matter stars and their influence on neutron star stability, providing new models for exotic compact objects and challenging previous assumptions about attractive self-interactions.

Contribution

It derives the equation of state for ADM with various interactions and solves TOV equations, offering new insights into ADM star stability and neutron star destabilization mechanisms.

Findings

Attractive interactions in fermionic ADM do not destabilize neutron stars more than non-interacting ADM.

New equilibrium sequences for ADM stars are computed using TOV equations.

Results can aid gravitational wave searches for exotic compact objects.

Abstract

We consider gravitationally bound states of asymmetric dark matter (ADM stars), and the impact of ADM capture on the stability of neutron stars. We derive and interpret the equation of state for ADM with both attractive and repulsive interactions, and solve the Tolman-Oppenheimer-Volkoff equations to find equilibrium sequences and maximum masses of ADM stars. Gravitational wave searches can utilize our solutions to model exotic compact objects (ECOs). Our results for attractive interactions differ substantially from those in the literature, where fermionic ADM with attractive self-interactions was employed to destabilize neutron stars more effectively than non-interacting fermionic ADM. By contrast, we argue that fermionic ADM with an attractive force is no more effective in destabilizing neutron stars than fermionic ADM with no self-interactions.