Dark stars: Gravitational and electromagnetic observables

Abstract

Theoretical models of self-interacting dark matter represent a promising answer to a series of open problems within the so-called collisionless cold dark matter (CCDM) paradigm. In case of asymmetric dark matter, self-interactions might facilitate gravitational collapse and potentially lead to formation of compact objects predominantly made of dark matter. Considering both fermionic and bosonic equations of state, we construct the equilibrium structure of rotating dark stars, focusing on their bulk properties, and comparing them with baryonic neutron stars. We also show that these dark objects admit the I-Love-Q universal relations, which link their moments of inertia, tidal deformabilities, and quadrupole moments. Finally, we prove that stars built with a dark matter equation of state are not compact enough to mimic black holes in general relativity, thus making them distinguishable in potential events of gravitational interferometers.

Testing the nature of dark compact objects: a status report

“…Interaction of the core with the surrounding star may lead to characteristic EM signatures [55,123]. Alternatively, a more generic imprint of such ECOs is GW emission, either via standard inspiralling processes [421,422] or by small oscillations of such ECOs inside neutron stars or white dwarfs [422,423].…”

Effect of scalar boson on fermionic dark stars

“…1, the corresponding parameters in Table 1 are still compatible with the total cross section constraint at low energies. 5,6 It can be seen that for fixedᾱ p value the cross-section increases by raising α s but for the case of fixedᾱ ǫ the cross-section is relative constant by raising α s . Both are evaluated for fixed dark particle mass.…”

“…Further studied has been done by Masseli et .al . 6 They studied the bulk properties of slow rotating DSs including the moment of inertia, tidal deformability and quadrupole moments using the fermionic and bosonic equation of states (EOSs). They using the same model as the one used in 5 for fermionic DM case but they considered only the non-relativistic repulsive Yukawa-type interaction and neglected the contribution of corresponding attractive Yukawa-type interaction because the contribution is irrelevant in the frame of the used model.…”

“…(11)- (12) in Ref. 5,6 The non-relativistic limit of Eqs. (5)- (6) can be derived easily and they can be expressed as…”

“…The DM particles in ΛCDM model are assumed to be cold and collision-less (CCDM). [4][5][6] However, it is reported recently that the CCDM paradigm is not too compatible with some astrophysical observations. The corresponding issues are the flatness of DM density profile at the core of dwarf galaxies, the incompatibility of the number of satellite galaxies between prediction by numerical simulations of CCDM and the observed ones, as well as the unobserved massive dwarf galaxies predicted by the CCDM.…”