Unveiling axion signals in galactic supernovae with future MeV telescopes

Abstract：

Axion-like particles (ALPs) produced via the Primakoff process in the cores of galactic core-collapse supernovae (SNe) could convert into MeV-energy γ-rays through interactions with the magnetic field of the Milky Way. To evaluate the detection prospects for such signals, we perform sensitivity projections for next-generation MeV telescopes by combining hypothetical instrument responses with realistic background estimates. Our analysis incorporates detailed simulations of the expected ALP flux from nearby SNe, the energy-dependent conversion probability in galactic magnetic fields, and the telescope’s angular/energy resolution based on advanced detector designs. Background components are modeled using data from current MeV missions and extrapolated to future sensitivity regimes. Our simulations demonstrate that next-generation telescopes with improved effective areas and energy resolutions could achieve sensitivity to photon-ALP couplings as low as $ g_{a\gamma} \approx 1.61 \times 10^{-13}\; \mathrm{GeV}^{-1} $ for ALP masses $ m_a \lesssim 10^{-9}\; \mathrm{eV} $ in the galactic center. These results indicate that future MeV missions will probe unexplored regions of the ALP parameter space, with conservative estimates suggesting they could constrain $ g_{a\gamma} $ values two orders of magnitude below current astrophysical limits. Such observations would provide the most stringent tests to date for ALPs as dark matter candidates in the ultra-light mass regime.