Stripped-Envelope Supernovae for QCD Axion Detection

QCD axions would be copiously produced in the protoneutron star formed in a core-collapse supernova (SN). After escaping, they would convert into gamma rays in the Galactic magnetic field and, as recently shown, in that of the progenitor star itself. Here, we show that Type Ibc SNe—whose progenitors have lost their hydrogen or even helium envelopes—are the optimal targets for this search. The stripped progenitors are much more compact, and they show larger magnetic fields than both red and blue supergiants, the progenitors of Type IIP/L SNe. If the next galactic SN is of Type Ibc, Fermi-LAT or a similar gamma-ray satellite might be able to discover the QCD axion down to masses as small as ma≃10-4 eV (Peccei-Quinn scale fa≃1011 GeV).