Transient Radio Signatures from Neutron Star Encounters with QCD Axion Miniclusters

Understand

The QCD axion is expected to form dense structures known as axion miniclusters if the Peccei-Quinn symmetry is broken after inflation.

• Miniclusters that have survived until today will interact with neutron stars (NSs) in the Milky Way to produce transient radio signals from axion-photon conversion in the NS magnetosphere.
• We quantify the properties of these encounters and find that they occur frequently ($\mathcal{O}(1-100)\,\mathrm{day}^{-1}$); last between a day and a few months; are spatially clustered towards the Galactic center; and can reach observable fluxes.
• These radio transients are within reach of current generation telescopes and therefore offer a promising pathway to discovering QCD axion dark matter.