Axions are promising dark matter candidates and could form substructures such as miniclusters and axion stars, existing within our galaxy. Based on the mass distribution of miniclusters, we derive the mass distribution of axion stars and examine how many axion stars can reach the critical axion star mass set by axion-photon coupling. We refer to this critical axion star mass as decay mass, for which a mass excess converts into photons. We consider continuous accretion of these critical axion stars and their consequential emissions. Interestingly, the abundant axion stars and nearly monochromatic emissions from the axion stars provide a distinctive opportunity to search for axions against the radio backgrounds. We find that the axion-photon coupling around or even below ~1e-12/GeV can be probed for axion masses ranging from 1e-7 eV to 1e-2 eV, by using ongoing or upcoming radio telescopes, namely, LOFAR, FAST, ALMA, and SKA..
