Diurnal modulation signal from dissipative hidden sector dark matter

TL;DR

This paper explores a dissipative hidden sector dark matter model with kinetic mixing, predicting a significant diurnal modulation signal in Earth-based detectors due to dark matter capture and shielding effects.

Contribution

It introduces a simple dissipative dark matter model with kinetic mixing that explains galactic phenomena and predicts a detectable diurnal modulation in direct detection experiments.

Findings

Diurnal modulation can exceed 10% in Southern hemisphere detectors.

Dark matter can be captured within Earth, affecting detection signals.

Model links galactic dynamics with terrestrial detection signatures.

Abstract

We consider a simple generic dissipative dark matter model: a hidden sector featuring two dark matter particles charged under an unbroken $U(1)'$ interaction. Previous work has shown that such a model has the potential to explain dark matter phenomena on both large and small scales. In this framework, the dark matter halo in spiral galaxies features nontrivial dynamics, with the halo energy loss due to dissipative interactions balanced by a heat source. Ordinary supernovae can potentially supply this heat provided kinetic mixing interaction exists with strength $\epsilon \sim 10^{-9}$. This type of kinetically mixed dark matter can be probed in direct detection experiments. Importantly, this self-interacting dark matter can be captured within the Earth and shield a dark matter detector from the halo wind, giving rise to a diurnal modulation effect. We estimate the size of this effect for detectors located in the Southern hemisphere, and find that the modulation is large ($\gtrsim 10\%$) for a wide range of parameters.