We confront the admixture of dark matter inside a neutron star using gravitational wave constraints coming from binary neutron star merger. We consider a relativistic mean field model including $\sigma -\omega -\rho$ meson interaction with NL3 parametrization. We study fermionic dark matter interacting with nucleonic matter via Higgs portal mechanism. We show that admixture of dark matter inside the neutron star softens the equation state and lowers the value of tidal deformability. Gravitational wave GW170817 observation puts an upper bound on tidal deformability of a binary neutron star with low spin prior at 90% confidence level, which disfavors stiff equation of state such as the Walecka model with NL3 parametrization. However, we show that the Walecka model with NL3 parametrization with a fermionic dark matter component satisfies the tidal deformability bound coming from the GW170817 observation.

• Received 2 August 2018

DOI:https://doi.org/10.1103/PhysRevD.99.043016

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Published by the American Physical Society