Observing the thermalization of dark matter in neutron stars

Understand

A promising probe to unmask particle dark matter is to observe its effect on neutron stars, the prospects of which depend critically on whether captured dark matter thermalizes in a timely manner with the stellar core via repeated scattering with the Fermi-degenerate medium.

• In this work we estimate the timescales for thermalization for multiple scenarios.
• These include: (a) spin-0 and spin-$\frac{1}{2}$ dark matter, (b) scattering on non-relativistic neutron and relativistic electron targets accounting for the respective kinematics, (c) interactions via a range of Lorentz-invariant structures, (d) mediators both heavy and light in comparison to the typical transfer momenta in the problem.
• We discuss the analytic behavior of the thermalization time as a function of the dark matter and mediator masses, and the stellar temperature.