New Spectral Features from Bound Dark Matter

TL;DR

This paper predicts a universal spectral feature in direct detection experiments caused by Earth-bound dark matter, which could serve as a definitive signature for dark matter discovery.

Contribution

It introduces a new spectral feature from bound dark matter particles that is independent of the dark matter-nucleon cross section, aiding in unambiguous detection.

Findings

Bound dark matter induces a distinct low-energy recoil signal.

The spectral feature's ratio is independent of cross section.

This feature can serve as a definitive dark matter signature.

Abstract

We demonstrate that dark matter particles gravitationally bound to the Earth can induce a characteristic nuclear recoil signal at low energies in direct detection experiments. The new spectral feature we predict can provide the ultimate smoking gun for dark matter discovery for experiments with positive signal but unclear background. The new feature is universal, in that the ratio of bound over halo dark matter event rates at detectors is independent of the dark matter-nucleon cross section.