Speaker
Description
Axion-like particles (ALPs) coupled to nucleons can be efficiently produced in core-collapse supernovae (SNe) and then, if they couple to photons, convert into gamma rays in cosmic magnetic fields, generating short gamma-ray bursts. Though ALPs from a Galactic SN would induce an intense and easily detectable gamma-ray signal, such events are exceedingly rare. In contrast, a few SNe per year are expected {in nearby galaxies} within $\sim \mathcal{O}(10)$ Mpc, where strong magnetic fields can enable efficient ALP–photon conversions, offering a promising extragalactic target.
This motivates full-sky gamma-ray monitoring, ideally combined with deci-hertz gravitational-wave detectors to enable time-triggered searches from nearby galaxies. We show that, under realistic conditions, a decade of coverage could reach sensitivities {to ALP-photon coupling $g_{a\gamma} \gtrsim 10^{-15}~{\rm GeV}^{-1}$ for ALP masses $m_a \lesssim 10^{-9}$~eV,
probing a currently-unexplored large region of the parameter space below the longstanding SN 1987A bound.
