Axion-photon multimessenger astronomy with giant flares

Javier De Miguel, Chiko Otani

Published 2022-01-11Version 1

We treat prospects for multimessenger astronomy with giant flares (GFs), a rare transient event featured by magnetars that can be as luminous as a hundred of the brightest supernovae ever observed. The beamed photons correlate with an axion counterpart via resonant conversion in the magnetosphere. Relying on orthodox idealizations, we find the sensitivity to galactic GFs of viable experiments $\mathrm{g}_{\phi \gamma}\!\gtrsim\!4\!\times\!10^{-12}$ GeV$^{-1}$& $\mathrm{g}_{\phi e}\!\gtrsim\!10^{-10}$ at 95% confidence level over a broad mass range. We rule out the compatibility of axion flares with the recent XENON1T excess only due to the time persistence of the signal.