Dark matter self-annihilation as a hidden energy source in white dwarfs
Abstract
White dwarfs (WDs) are compact remnants of stars, supported by electron degeneracy pressure, and their structures are generally considered to be well understood. Significant discrepancies exist between the theoretical and observed white dwarf mass-radius (MR) relations, especially for hot Q-branch white dwarfs with unexplained heating sources. In this study, we explore the potential of WDs as a portal to dark matter (DM) physics by investigating the effect of self-annihilating DM (SADM) admixed in WDs, solving the set of two-fluid hydrostatic equilibrium and heat diffusion equations self-consistently. We obtain empirical formulae for the WD luminosity L and effective temperature Teff as functions of the DM mass fraction fd, annihilation cross section ⟨σv⟩, and particle mass mχ, as well as the WD's total mass Mt. We also compare the WD MR relations for various L, fd, and both Fermionic and Bosonic DM particle statistics, with the observational data. We show that the majority of observed deviations in the WD MR relation can be accounted for by having SADM admixed with fd ≤ 10−5 and ⟨σv⟩ ≪ 3×10−26 cm3 s−1, the thermal relic cross section. Therefore, our results suggest that WDs can be sensitive DM detectors, and DM self-annihilation could provide additional heating in WDs, accounting for their observed extra luminosities.
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BibTeX
@misc{chu2026dark,
title = {{Dark matter self-annihilation as a hidden energy source in white dwarfs}},
author = {Alvin Cheuk-Nam Chu and Cheuk-Man Yiu and Ching-Hui Lam and Peter Siu-Hei Cheung and Fong-Ching Ho and Ming-chung Chu},
howpublished = {arXiv},
year = {2026},
month = sep,
doi = {10.48550/arxiv.2609.22873},
eprint = {2609.22873},
archivePrefix = {arXiv},
url = {https://arxiv.org/abs/2609.22873},
note = {CC BY 4.0},
}
RIS
TY - UNPB
TI - Dark matter self-annihilation as a hidden energy source in white dwarfs
AU - Alvin Cheuk-Nam Chu
AU - Cheuk-Man Yiu
AU - Ching-Hui Lam
AU - Peter Siu-Hei Cheung
AU - Fong-Ching Ho
AU - Ming-chung Chu
PY - 2026
DA - 2026/09/19
PB - arXiv
DO - 10.48550/arxiv.2609.22873
UR - https://arxiv.org/abs/2609.22873
AB - White dwarfs (WDs) are compact remnants of stars, supported by electron degeneracy pressure, and their structures are generally considered to be well understood. Significant discrepancies exist between the theoretical and observed white dwarf mass-radius (MR) relations, especially for hot Q-branch white dwarfs with unexplained heating sources. In this study, we explore the potential of WDs as a portal to dark matter (DM) physics by investigating the effect of self-annihilating DM (SADM) admixed in WDs, solving the set of two-fluid hydrostatic equilibrium and heat diffusion equations self-consistently. We obtain empirical formulae for the WD luminosity L and effective temperature T_eff as functions of the DM mass fraction f_d, annihilation cross section ⟨σv⟩, and particle mass m_χ, as well as the WD's total mass M_t. We also compare the WD MR relations for various L, f_d, and both Fermionic and Bosonic DM particle statistics, with the observational data. We show that the majority of observed deviations in the WD MR relation can be accounted for by having SADM admixed with f_d ≤ 10^−5 and ⟨σv⟩ ≪ 3×10^−26 cm^3 s^−1, the thermal relic cross section. Therefore, our results suggest that WDs can be sensitive DM detectors, and DM self-annihilation could provide additional heating in WDs, accounting for their observed extra luminosities.
ER -