Ponente
Descripción
We propose a novel scenario for the detection of radio signals from axionic halo dark matter. Axions or axion-like particles produce radio waves via spontaneous decay into two photons. In addition, stimulated emission by a background containing photons of identical wavelength enhances the rate of photon emission by axionic decay. A photon background generated by a bright radio source should produce a countersource that we designate as axion gegenschein, a phenomenon characterised by an echo wave of the photons emitted by an astrophysical source observable in the sky direction opposite to the source. We discuss the expected flux of this signal which future-generation radio facilities, such as SKA and HIRAX, could be sensitive to, and show relevant bounds for the gegenschein emission that can be obtained.
