Stripped-Envelope Supernovae for QCD Axion Detection

Abstract

QCD axions would be copiously produced in the proto-neutron 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 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 $m_a\simeq 10^{-4}\,\rm eV$ (Peccei-Quinn scale $f_a\simeq 10^{11} \,\rm GeV$).

Figures (4)

• Figure 1: Projected reach on $g_{a p}\times g_{a\gamma}$ for KSVZ axions as a function of $m_a$, assuming detection of 100-MeV $\gamma$ rays from a future galactic SN ($d=2$ kpc) with a satellite like Fermi-LAT. The sensitivity bands are for RSG, BSG and stripped-envelope progenitors, assuming the shown values for radius $R$ and dipole field $B$. We assume our hot one-zone SN model for axion production. The black upper bound is the SN 1987A cooling limit.
• Figure 2: Simulated Fermi-LAT spectra expected for KSVZ axions with different $m_a$ values, using both the hot model (thick histograms) and the cold model (dotted histograms). We used the celestial coordinates of HD 45166 at a period with an average off-axis angle of $\langle \theta \rangle \sim 52^{\circ}$. The energy bins match a resolution of 20% of the photon energy.
• Figure 3: Comparison between Fermi-LAT's on-axis effective area extracted from the P8R3_TRANSIENT020_V3 Instrument Response Functions (IRFs) and the average effective area obtained with gtexposure for our simulated observation at $\langle \theta \rangle \sim 52^{\circ}$.
• Figure 4: Like Fig. \ref{['fig:HotBounds']}, but assuming instead our cold SN model (see Table \ref{['tab:one_zone']}) for the production of axions from the core.