Stellar cooling, inelastic dark matter, and XENON

TL;DR

This paper proposes a dark photon-mediated inelastic dark matter model to explain both white dwarf cooling excess and XENON1T electron recoil events, suggesting potential signals for future detection and discussing astrophysical constraints.

Contribution

It introduces a novel inelastic dark matter scenario involving dark photons that links stellar cooling anomalies with direct detection signals, highlighting new parameter space and observational signatures.

Findings

Dark photon-mediated inelastic dark matter can explain XENON1T excess.

White dwarf cooling excess can be accommodated by dark photon emission.

Potential double peak in XENON1T spectrum could be detectable at XENONnT.

Abstract

We consider a novel scenario of dark photon-mediated inelastic dark matter to explain the white dwarf cooling excess suggested by its luminosity function, and the excess in electron recoil events at XENON1T. In the Sun, the dark photon $A'$ is produced mainly via thermal processes, and the heavier dark matter $\chi_2$ is produced by the scattering of halo dark matter $\chi_1$ with electrons. The XENON1T signal arises primarily by solar $A'$ scattering, and $A'$ emission by white dwarfs accommodates the extra cooling while maintaining consistency with other stellar cooling observations. A tritium component in the XENON1T detector is also required. We show for parameters that explain the XENON1T data, but not the white dwarf cooling anomaly, that a second signal peak may be buried in the XENON1T data and revealable at XENONnT. However, the parameters that give the double peak in the spectrum are incompatible with constraints from horizontal branch stars.