Faint light of old neutron stars and detectability at the James Webb Space Telescope

Understand

Isolated ideal neutron stars (NS) of age $>10^9$ yrs exhaust thermal and rotational energies and cool down to temperatures below $\mathcal{O}(100)$ K.

• Accretion of particle dark matter (DM) by such NS can heat them up through kinetic and annihilation processes.
• This increases the NS surface temperature to a maximum of $\sim 2550$ K in the best case scenario.
• The maximum accretion rate depends on the DM ambient density and velocity dispersion, and on the NS equation of state and their velocity distributions.