Direct Detection of Atomic Dark Matter in White Dwarfs

TL;DR

This paper demonstrates how white dwarf cooling observations can set strong constraints on atomic dark matter models, especially on the kinetic mixing parameter, providing a novel astrophysical probe of dark matter properties.

Contribution

It introduces a new method using white dwarf luminosity functions to constrain atomic dark matter and kinetic mixing, extending the range of detectable dark matter scenarios.

Findings

Constraints on kinetic mixing down to ε ~ 10^{-12}

Limits on atomic dark matter fraction as low as 0.1%

Complementary to other dark matter detection methods

Abstract

Dark matter could have a dissipative asymmetric subcomponent in the form of atomic dark matter (aDM). This arises in many scenarios of dark complexity, and is a prediction of neutral naturalness, such as the Mirror Twin Higgs model. We show for the first time how White Dwarf cooling provides strong bounds on aDM. In the presence of a small kinetic mixing between the dark and SM photon, stars are expected to accumulate atomic dark matter in their cores, which then radiates away energy in the form of dark photons. In the case of white dwarfs, this energy loss can have a detectable impact on their cooling rate. We use measurements of the white dwarf luminosity function to tightly constrain the kinetic mixing parameter between the dark and visible photons, across many orders of magnitude in DM mass, down to values of $\epsilon \sim 10^{-12}$. Using this method we can constrain scenarios in which aDM constitutes fractions as small as $10^{-3}$ of the total dark matter density. Our methods are highly complementary to other methods of probing aDM, especially in scenarios where the aDM is arranged in a dark disk, which can make direct detection extremely difficult but actually slightly enhances our cooling constraints.