arXiv subjects

M-C. Chu

Publications and source records attributed to M-C. Chu.

3 recordsLinked to original sources

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↗

arXiv2012

Daya Bay Antineutrino Detector Gas System

The Daya Bay Antineutrino Detector gas system is designed to protect the liquid scintillator targets of the antineutrino detectors against degradation and contamination from exposure to ambient laboratory air. The gas system is also used to monitor the leak tightness of the antineutrino detector assembly. The cover gas system constantly flushes the gas volumes above the liquid scintillator with dry nitrogen to minimize oxidation of the scintillator over the five year lifetime of the experiment. This constant flush also prevents the infiltration of radon or other contaminants into these detecting liquids keeping the internal backgrounds low. Since the Daya Bay antineutrino detectors are immersed in the large water pools of the muon veto system, other gas volumes are needed to protect vital detector cables or gas lines. These volumes are also purged with dry gas. Return gas is monitored for oxygen content and humidity to provide early warning of potentially damaging leaks. The design and performance of the Daya Bay Antineutrino Detector gas system is described.

physics.ins-det↗