Possible maximum mass of dark matter existing in compact stars based on the self-interacting fermionic model

Abstract

The dark matter admixed neutron stars (DANSs) are studied using the two-fluid TOV equations separately, in which the normal matter (NM) and dark matter (DM) are simulated by the relativistic mean field theory and self-interacting fermionic model, respectively. A universal relationship [Formula: see text] is suggested, where [Formula: see text] is the maximum mass of DM existing in DANSs, [Formula: see text] is the particle mass of DM ranging from 5[Formula: see text]GeV to 1[Formula: see text]TeV, [Formula: see text] is the interaction mass scale with the value 300[Formula: see text]GeV (0.1[Formula: see text]GeV) for weak (strong) interaction DM model. This simple formula connects directly the microcosmic nature of DM particle with its macrocosmic mass existing in DANSs. Meanwhile, such a formula exhibits that the existence of NM has little effect on [Formula: see text]. It is found that the ratio of radius of DM in DANSs over [Formula: see text] is a constant with the value about 12[Formula: see text] (7[Formula: see text]) for weak (strong) interaction DM cases. According to the calculated results, only for the strong interaction DM cases with [Formula: see text] to [Formula: see text][Formula: see text]GeV and central energy density [Formula: see text][Formula: see text]MeV/fm3, DM has obvious effect on the mass of compact star. Compared with the energy density of DM in the Milky Way galaxy, [Formula: see text][Formula: see text]MeV/fm3, the existence of DM might hardly affect the mass of compact stars in the Milky Way galaxy.