Axion dark matter-induced echo of supernova remnants

• Main Authors: Sun, Yitian (Author), Schutz, Katelin (Author), Nambrath, Anjali (Author), Leung, Calvin (Author), Masui, Kiyoshi (Author)
• Format: Article
• Language: English
• Published: American Physical Society (APS), 2022-04-27T17:13:04Z.
• Subjects: Article
• Online Access: Get fulltext

 Axions are a theoretically promising dark matter (DM) candidate. In the presence of radiation from bright astrophysical sources at radio frequencies, nonrelativistic DM axions can undergo stimulated decay to two nearly back-to-back photons, meaning that bright sources of radio waves will have a counterimage ("gegenschein") in nearly the exact opposite spatial direction. The counterimage will be spectrally distinct from backgrounds, taking the form of a narrow radio line centered at $\nu = m_a/4\pi$ with a width determined by Doppler broadening in the DM halo, $\Delta \nu/\nu \sim 10^{-3}$. In this work, we show that the axion decay-induced echoes of supernova remnants may be bright enough to be detectable. Their non-detection may be able to set the strongest limits to date on axion DM in the $\sim 1-10 \, \mu$eV mass range where there are gaps in coverage from existing experiments.