2025/04/10 by Nishizawa, Atsushi, Taruya, Atsushi, Himemoto, Yoshiaki · 8 citations
#Cosmology and Nongalactic Astrophysics (astro-ph.CO) #FOS: Physical sciences #High Energy Physics - Phenomenology (hep-ph)
paper · doi:10.48550/arxiv.2504.07559
The natural environment of the Earth can act as a sensitive detector for dark matter in ultralight axions. When axions with masses between 1×10-15 \rm eV and 1×10-13 \rm eV pass through the Earth, they interact with the global geomagnetic field, generating electromagnetic (EM) waves in the extremely low-frequency range (0.3--30 \rm Hz) through axion-photon coupling. This paper is one of a series of companion papers for~\citeTaruya:2025zql, focusing on the data analysis method and search results for an axion signal. Utilizing the theoretical predictions of axion-induced EM spectra from a companion study, we analyzed long-term observational data of terrestrial magnetic fields in this frequency band to search for axion-induced signals. Our analysis identified 65 persistent signal candidates with a signal-to-noise ratio (SNR) greater than 3. Aside from these candidates, we placed a new upper bound on the axion-photon coupling parameter, significantly refining the previous constraint from CAST by at most two orders of magnitude down to gaγ \lesssim 4×10-13 \rm GeV-1 for the axion mass around 3 × 10-14 \rm eV.