Constraints on millicharged particles by neutron stars

We have constrained the charge-mass ($\epsilon -m$) 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 $M=1.4M_{\odot }$ and $R=10\mathrm{k}\mathrm{m}$ 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 $\epsilon -m$ phase space of millicharged particles for different magnetic fields $B_0$ and dark matter density ${\rho }_{\mathrm{D}\mathrm{M}}$ in the vicinity of the neutron star.