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Astrophysics, High Energy Astrophysical Phenomena, astro-ph.HE
Abstract:
Neutron stars (NSs) can capture dark matter (DM) particles because of their
deep gravitational potential and high density. The accumulated DM can affect
the properties of NSs. In this work we use a general relativistic two-fluid
formalism to solve the structure of DM-admixed NSs (DANSs) and the surrounding
spacetime. Specifically, we pay attention to the situation where those DANSs
possess DM halos. Due to the gravitational effect of the DM halo, the pulse
profile of an X-ray pulsar is changed. Our study finds a universal relation
between the peak flux deviation of the pulse profile and $M_{\rm halo}/R_{\rm
BM}$, which is the ratio of the DM halo mass, $M_{\rm halo}$, to the baryonic
matter (BM) core radius, $R_{\rm BM}$. Our results show that, when $M_{\rm
halo}/R_{\rm BM}=0.292$ and the DM particle mass $m_f = 0.3\,$GeV, the maximum
deviation of the profile can be larger than 100$\%$, which has implication in
X-ray pulsar observation.
