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High Energy Physics - Phenomenology
Title: On the Galactic radio signal from stimulated decay of axion dark matter
(Submitted on 22 Nov 2023 (v1), last revised 11 Apr 2024 (this version, v2))
Abstract: We study the full-sky distribution of the radio emission from the stimulated decay of axions which are assumed to compose the dark matter in the Galaxy. Besides the constant extragalactic and CMB components, the decays are stimulated by a Galactic radio emission with a spatial distribution that we empirically determine from observations. We compare the diffuse emission to the counterimages of the brightest supernovae remnants, and take into account the effects of free-free absorption. We show that, if the dark matter halo is described by a cuspy NFW profile, the expected signal from the Galactic center is the strongest. Interestingly, the emission from the Galactic anti-center provides competitive constraints that do not depend on assumptions on the uncertain dark matter density in the inner region. Furthermore, the anti-center of the Galaxy is the brightest spot if the Galactic dark matter density follows a cored profile. The expected signal from stimulated decays of axions of mass $m _{a} \sim 10 ^{-6}$ eV is within reach of the Square Kilometer Array for an axion-photon coupling $g _{a\gamma} \gtrsim (2-3) \times 10 ^{-11}$ GeV$^{-1}$.
Submission history
From: Takuya Okawa [view email][v1] Wed, 22 Nov 2023 19:10:43 GMT (2327kb,D)
[v2] Thu, 11 Apr 2024 23:09:07 GMT (1656kb,D)
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