2025/02/13 by W.-C. Yang, Yang, Wenxiu, Yitian Sun +17 · 1 citation
Physics and Astronomy · #Astrophysics and Cosmic Phenomena #Cosmology and Nongalactic Astrophysics (astro-ph.CO) #Dark Matter and Cosmic Phenomena #FOS: Physical sciences #High Energy Physics - Phenomenology (hep-ph) #Particle Detector Development and Performance
paper · pdf · doi:10.48550/arxiv.2502.08913
openalex publication_date 2025/02/13 · openalex created_date 2025/02/15 · openalex updated_date 2026/07/28
Axions are one of the leading dark matter candidates. If we are embedded in a Milky Way dark matter halo comprised of axions, their stimulated decay would enable us to observe a counterimage (``axion gegenschein") with a frequency equal to half the axion mass in the opposite direction of a bright radio source. This spectral line emission will be broadened to Δν/ν∼ σd/c ∼ 10-3 due to the velocity dispersion of dark matter, σd. In this pilot study, we perform the first search for the expected axion gegenschein image of Vela supernova remnant (SNR) with 26.4 hours of effective ON-OFF data from the Five-hundred-meter Aperture Spherical radio Telescope (FAST) L-band (1.0 - 1.5~GHz) 19-beam receiver. Our null detection limits the axion-photon coupling strength to be gaγγ \lesssim 2 × 10-10 GeV-1 in the mass ranges of 8.7 μeV ≤ ma ≤ 9.44 μeV and 10.85 μeV ≤ ma ≤ 12.01 μeV . These results provide a stronger constraint on gaγγ in this axion mass range than the current limits obtained by the direct search of axion decay signal from galaxy clusters which uses FAST observations, but is a factor of ∼ 3 times weaker than the current CAST limit.Based on our observation strategy, data processing methods, and results, the expected sensitivity will reach ∼ 10-11GeV-1 with ∼ 2000 hours of observation in the future.