Detecting Dark Matter with Neutron Stars

Neutron stars offer powerful astrophysical laboratories to probe the properties of dark matter. Gradual accumulation of heavy, non-annihilating dark matter in neutron stars can lead to the formation of comparable-mass black holes, and non-detection of gravitational waves from mergers of such low-mass black holes can constrain such dark matter interactions with nucleons. These constraints, though dependent on the currently uncertain binary neutron star merger rate density, are significantly more stringent than those from direct detection experiments and provide some of the strongest limits on heavy, non-annihilating dark matter interactions. Additionally, dark matter with baryon number-violating interactions can induce excess heating in cold neutron stars and is thus significantly constrained by thermal observations of cold neutron stars.