Some properties of doubly-degenerate stars

Abstract

We investigate critical masses of and circular geodesics around doubly-degenerate stars (DDSs) which are composed of cold nuclear matter as well as cold Fermionic dark matter (DM). We here consider asymmetric dark Fermion with self-interaction as a DM candidate. These stars have core-envelope structures and are categorized into baryon-enveloped and DM-enveloped, according to the composition of their envelope. It is seen that the baryon-enveloped and DM-enveloped classes have their own critical masses determined mainly by the dominant component in their envelope. For a typical parameter sets, we see that a balanced mixture of two species may lead to smaller masses than if the either of the species is dominant. We also show that for a highly DM-enveloped case circular orbits in the vacuum region terminates at the innermost stable circular orbit (ISCO) in vacuum, but circular orbits of smaller radius are possible in the DM-envelope forming a gap between the ISCO and the inner orbits.

arXiv comment8 pages, 12 figures

References in corpus (17)

• Where are the missing galactic satellites?
• The equation of state for nucleon matter and neutron star structure
• A direct empirical proof of the existence of dark matter
• Too big to fail? The puzzling darkness of massive Milky Way subhaloes
• A unified equation of state of dense matter and neutron star structure
• Dark Matter Self-interactions and Small Scale Structure
• The large-scale structure of the Universe
• Subhaloes in Self-Interacting Galactic Dark Matter Haloes
• WIMP Annihilation and Cooling of Neutron Stars
• Dark-Matter Admixed Neutron Stars
• Have neutron stars a dark matter core?
• Asymmetric Dark Stars and Neutron Star Stability
• Asymmetric Dark Matter Stars
• Limits on Self-Interacting Dark Matter
• Dark stars: gravitational and electromagnetic observables
• Magnetic neutron star cooling and microphysics
• Equilibrium Structure and Radial Oscillations of Dark Matter Admixed Neutron Stars