Bosonic Dark Matter in Light of the NICER Precise Mass-Radius Measurements

Abstract: We explore the presence of self-interacting bosonic dark matter (DM) within neutron stars (NSs) in light of the latest multi-messenger observations of the Neutron Star Interior Composition Explorer (NICER) and LIGO/Virgo detectors. The bosonic DM is distributed as a core inside the NS or as a halo around it leading to formation of a DM admixed NS. We focus on the variation of the visible and dark radius of the mixed object due to DM model parameters and fractions. It is shown that DM core formation reduces the visible radius and the total mass pushing them below observational limits while halo formation is in favor of the latest mass-radius observations. Moreover, we scan over the parameter space of the bosonic DM model considering two nuclear matter equation of states by applying the radius, maximum mass and tidal deformability constraints. Our investigation allows for the exclusion of a range of DM fractions, self-coupling constant and sub-GeV boson masses, which limits the amount of accumulated DM to relatively low values to be consistent with astrophysical bounds. In this paper, we introduce main features of the pulse profile corresponding to the DM admixed NS as a novel observable quantity. We find that the depth of minimum fluxes in the pulse profiles crucially depends on the amount of DM around NS and its compactness. The current/future astrophysics missions may test the possibility of the existence of DM within NSs and break the degeneracies between different scenarios via multiple observations.