Searching for relativistic axions in the sky

Abstract

Relativistic axions produced in decays of $\mathcal{O}(10^{-7}-10^{-2}$ $\text{eV})$ dark matter (DM) partially convert to photons after traversing the galactic magnetic field, giving rise to a signal observable by the Square Kilometer Array (SKA) radio telescope. We show that for axions lighter than a few $\times$ $10^{-13}$ eV a 100 h SKA observation of the local dwarf galaxy Seg I would probe parameter space not constrained by stellar cooling and cosmological observations, with sensitivity several orders of magnitude better than the planned dedicated axion dark matter search experiments. We quantify the uncertainties in the SKA sensitivity projections due to two effects that enhance the radio flux: the presence of turbulent magnetic fields inside the galaxy, and the Bose enhancement of the DM decays to axions, where the latter, in particular, warrants further study.

26 pages, 12 figures. Updated to the version published in JCAP

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Cited by in corpus (3)

• Constraining Axion-Like Particles Dark Matter in Coma Berenices with FAST
• Constraining eV-scale axion-like particle dark matter: insights from the M87 Galaxy
• Echoes in multi-ALP scenarios