Constraining dark matter interactions mediated by a light scalar with white dwarfs

TL;DR

This paper uses white dwarf observations to set new limits on dark matter interactions mediated by a light scalar, especially effective in the sub-GeV mass range, complementing direct detection methods.

Contribution

It applies an improved formalism for dark matter capture in white dwarfs to a general scalar-mediated interaction model, providing novel constraints on dark matter properties.

Findings

Capture rate depends on scalar mediator mass, varying significantly in certain ranges.

Bounds from white dwarf observations are strong in the sub-GeV dark matter mass regime.

Results are complementary to existing direct detection experiments.

Abstract

Observations of white dwarfs in dark matter-rich environments can provide strong limits on the strength of dark matter interactions. Here we apply the recently improved formalism of the dark matter capture rate in white dwarfs to a general model in which dark matter interacts with the white dwarf ion components via a light scalar mediator. We compute the dark matter capture rate in the optically thin limit in a cold white dwarf from the globular cluster Messier. We then estimate the threshold cross-section, which significantly varies as a function of the light scalar mediator mass $m_\phi$ in the range of $0.05\, m_\chi<m_\phi<m_\chi$ and becomes constant when $m_\phi>m_\chi$. We also show that the bounds obtained from the dark matter capture in a white dwarf from the globular cluster Messier 4 are complementary to direct detection experiments and particularly strong in the sub-GeV regime.