Impact of dark matter on the neutron star properties

• Violetta Sagun (University of Coimbra)

Despite intensive searches for the particle nature of dark matter (DM) its true nature still remains unknown. Until now, terrestrial experiments on nuclear recoil of DM, and direct searches of the DM annihilation have not yet found a suitable DM candidate. Hence, there is large interest to use astrophysical systems for the search for DM. Compact objects, such as neutron stars (NSs) are especially attractive in this context, because they can accumulate a sizable amount of DM in their stellar interior. The presence of DM inside the NS core might have a measurable effect considering NS masses and radii. I will discuss an impact of asymmetric DM on properties of NSs and their ability to reach the two solar masses limit. It allows us to present a new range of masses of DM particles and their fractions inside the star. An analysis is based on the observational fact of the existence of two pulsars reaching this limit and on the theoretically predicted reduction of the neutron star maximal mass caused by the accumulation of DM in its interior. I will demonstrate that light DM particles with masses below 0.2 GeV can create an extended halo around the NS leading not to decrease, but to increase of its visible gravitational mass. By using recent results on the spatial distribution of DM in the Milky Way, I will present an estimate of its fraction inside the neutron stars located in the Galaxy center. I will show how the detection of a 2 Msun NS in the most central region of the Galaxy will impose an upper constraint on the mass of DM particles of ∼60 GeV.