Searching for a dark matter induced galactic axion gradient

TL;DR

This paper proposes using spin precession experiments to detect a galactic axion gradient induced by dark matter, offering a new way to explore dark matter interactions with the Standard Model.

Contribution

It introduces a novel method to search for dark matter-induced axion gradients via spin precession, connecting astrophysical bounds with laboratory experiments.

Findings

Existing co-magnetometer data constrains relevant theories.

Future experiments will probe well-motivated models.

The interactions can originate from a confining hidden sector.

Abstract

An ultra-light axion with CP violating interactions with a dark sector and CP preserving interactions with the visible sector can act as a novel portal between dark matter and the Standard Model. In such theories, dark matter sources an axion field extending over the entire galaxy, the gradient of which can be searched for with precise spin precession experiments. A reinterpretation of existing co-magnetometer data already constrains theories that are consistent with astrophysical bounds, and near-future experiments will begin probing well-motivated models. The required interactions can arise from a confining hidden sector without necessitating fine-tuning of the axion's mass.