📝 SummarXiv

Abstract

We investigate the impact of dark matter (DM) on both hybrid and twin stars within a two-fluid framework, where DM and normal matter interact only through gravity. A self-interacting fermionic DM model is considered, while for nucleonic and quark matter we employ the relativistic mean-field model and the constant sound-speed parametrization, respectively. Our results show that DM significantly influences the formation of hybrid and twin stars, depending on the transition pressure and the discontinuity in energy density at a fixed sound speed. The presence of DM reduces the number of twin or hybrid stars compared to the case without DM, and this effect directly depends on the DM mass and fraction. We further find that the formation of DM-core or DM-halo configurations is mainly governed by DM parameters, whereas the realization of twin or hybrid star scenarios is primarily controlled by quark parameters. Using the $2M_\odot$ constraint, we demonstrate that the parameter space for twin stars can be further restricted in both DM-core and DM-halo scenarios.