Jul 18 – 22, 2022
Europe/Zurich timezone

Earth as a transducer for dark-photon and ALP dark-matter detection

Jul 21, 2022, 3:30 PM


Oral presentation (young scientists) Parallel 3B - Axions


Dr Michael A. Fedderke (Johns Hopkins University)


In this talk, I will discuss a novel electromagnetic signal for two well-motivated ultralight dark-matter (DM) candidates: dark photons and axion-like particles (ALPs). The signal is a small (but larger than expected) oscillating magnetic-field pattern that appears across the entire surface of the Earth, driven by the DM field. It is highly phase-coherent and has a frequency set by the DM mass, with the specific signal pattern depending on the DM candidate. I will discuss searches for this signal that leverage the exceptional utility that distributed magnetometer networks hold as fundamental-physics discovery tools. In particular, I will discuss how my collaborators and I searched for this signal using an existing dataset maintained by the SuperMAG Collaboration, consisting of unshielded magnetometer readings taken at O(500) geographically distributed geomagnetic ground stations. These data have one-minute time resolution, with the earliest data taken in 1970. Our search finds no robust evidence for either DM candidate. However, we place the first direct exclusion bounds on dark-photon DM in the mass-range from $2\times 10^{-18}$ eV to $7\times 10^{-17}$ eV; these limits are complementary to existing astrophysical bounds. For ALP DM, we place limits in the same mass range that at some masses rival existing laboratory constraints on axions. I will mention ongoing work and future plans to extend these searches.

Primary author

Dr Michael A. Fedderke (Johns Hopkins University)


Dr Ariel Arza Prof. Derek F. Jackson Kimball (California State University East Bay) Prof. Peter W. Graham (Stanford University) Dr Saarik Kalia (Stanford University)

Presentation materials