Constraints on millicharged particles by neutron stars

TL;DR

This paper constrains the charge and mass of millicharged particles by simulating neutron star spin-down, showing bounds compatible with existing limits and exploring effects of magnetic fields and dark matter density.

Contribution

It introduces a novel method to constrain millicharged particles using neutron star rotational evolution simulations.

Findings

Established upper limits on millicharged particle charge for neutron stars.

Demonstrated the impact of magnetic field strength on constraints.

Explored the influence of local dark matter density on phase space bounds.

Abstract

We have constrained the charge-mass ($\varepsilon-m$) phase space of millicharged particles through the simulation of the rotational evolution of neutron stars, where an extra slow-down effect due to the accretions of millicharged dark matter particles is considered. For a canonical neutron star of $M=1.4~M_{\odot}$ and $R=10~{\rm km}$ with typical magnetic field strength $B_{0}=10^{12}$ G, we have shown an upper limit of millicharged particles, which is compatible with recently experimental and observational bounds. Meanwhile, we have also explored the influences on the $\varepsilon-m$ phase space of millicharged particles for different magnetic fields $B_{0}$ and dark matter density $\rho_{\rm{DM}}$ in the vicinity of the neutron star.