Geomagnetic constraints on Millicharged Dark Matter

TL;DR

This paper proposes a novel method to detect millicharged dark matter using Earth's geomagnetic field, setting new constraints on their properties by analyzing magnetic signals and null experimental results.

Contribution

It introduces a new astrophysical approach to constrain millicharged dark matter using geomagnetic signals and null results from existing experiments.

Findings

Upper bounds on bosonic millicharged dark matter charge exceed stellar cooling constraints by over thirteen orders of magnitude.

Constraints are effective in the mass range $10^{-18}$--$10^{-14}\,\text{eV}$.

Method demonstrates the power of geomagnetic signals in dark matter detection.

Abstract

Millicharged particles are well-motivated dark matter candidates arising in many extensions of the Standard Model. We show that, despite their tiny coupling $e_m$ to photons, millicharged dark matter (mDM) in the Earth's geomagnetic field can generate a quasi-static, monochromatic magnetic signal with angular frequency twice the mDM mass. Using null results from the SuperMAG and SNIPE Hunt collaborations, we constrain the effective charge of bosonic mDM in the mass range $10^{-18}$--$10^{-14}\,\text{eV}$. The resulting upper bounds exceed stellar cooling constraints by over thirteen orders of magnitude, demonstrating the power of this method.