H-S. Chan | Searcharxiv

arXiv2022

Dark Matter-admixed Rotating White Dwarfs as Peculiar Compact Objects

The discoveries of anomalous compact objects challenge our understanding of the standard theory of stellar structures and evolution. They serve as an excellent laboratory to search for new physics. Earlier studies on spherically symmetric dark matter-admixed compact stars could explain a handful of anomalies. In this paper, we investigate the observational signatures of dark matter (DM)-admixed rotating white dwarfs and make connections to observed peculiar white dwarfs. We compute the equilibrium structures of DM-admixed rotating white dwarfs using a self-consistent, two-fluid method, with the DM component being a non-rotating degenerate fermi gas. We find that the admixture of DM in rotating white dwarfs could: (1) account for some peculiar white dwarfs that do not follow their usual mass-radius relation, (2) allow the existence of stable, rapid-rotating white dwarfs that are free from thermonuclear runaway, which could explain some anomalous x-ray pulsars/soft gamma-ray repeaters, and (3) produce universal $I$ (moment of inertia)-Love (tidal Love number)-$Q$ (quadrupole moment) relations that span bands above those without DM admixture, thus providing an indirect way to search for DM in white dwarfs through gravitational-wave detection. DM-admixed rotating white dwarfs can account for some peculiar compact objects. Our results suggest a systematic approach to account for unusual compact objects that could be discovered by upcoming surveys.

astro-ph.HE↗

arXiv2020

Delayed Detonation Thermonuclear Supernovae With An Extended Dark Matter Component

We present simulations of thermonuclear supernovae admixed with an extended component of fermionic cold dark matter. We consider the explosion of a Chandrasekhar-mass white dwarf using the deflagration model with deflagration-detonation transition with spherical symmetry. The dark matter component is comparable in size with that of the normal matter, and so the system is described by two-fluid, one-dimensional Eulerian hydrodynamics. The explosion leaves all the dark matter trapped as a remnant compact dark star in all of our considered models. The presence of dark matter lengthens the deflagration phase to produce more thermo-neutrinos and similar amounts of iron-group elements compared to those of ordinary explosions with no dark matter admixture. The dark matter admixed models produce dimmer and broader light curves, which challenge the role of thermonuclear supernovae as standard candles in cosmic distance measurement. Our results also suggest a formation path of dark compact objects which mimic sub-solar-mass black holes as dark gravitational sources, through near-solar-mass dark matter admixed thermonuclear supernovae.

astro-ph.HE↗