Searching for Axion Ultralight Dark Matter with Terrestrial Electromagnetic Signals

by Martí Abella Cortés, Fatih Žgalj

Wednesday Oct 7, 2026, 1:00 PM → 2:00 PM Europe/Madrid

IFAE Seminar Room (In-person)

Axions are hypothetical particles that can make up dark matter and, through a coupling to photons, interact with the Earth’s geomagnetic field. This interaction induces oscillating electromagnetic fields, offering a way to search for axion dark matter by using the Earth itself as a natural detector. However, this terrestrial signal can be significantly modified by the density of the Earth if the axion also couples to matter. In this talk, we introduce the basic idea behind this dark matter signature and show how Earth's density affects it. In particular, we show that the induced electric field can be substantially larger than the magnetic field, contrary to many typical scenarios. We then discuss how this signal can be searched for by using terrestrial electromagnetic measurements and present constraints on the axion-photon coupling obtained by focusing on the electric-field component. This provides a complementary approach to existing searches based on geomagnetic signals and offers another handle on the hunt for dark matter.