The Fermi Large Area Telescope as a Galactic Supernovae Axionscope

TL;DR

This paper proposes using the Fermi LAT to detect gamma rays from axionlike particles emitted during a galactic supernova, potentially probing new regions of ALP parameter space beyond laboratory experiments.

Contribution

It introduces a data-driven sensitivity estimate for Fermi LAT to detect ALPs from galactic supernovae, extending current bounds significantly.

Findings

Fermi LAT can probe photon-ALP coupling down to 2×10⁻¹³ GeV⁻¹ for low-mass ALPs.

Detection would explore ALP parameter space relevant to cosmic transparency and dark matter.

Non-detection would improve existing supernova bounds by over an order of magnitude.

Abstract

In a Galactic core-collapse supernova (SN), axionlike particles (ALPs) could be emitted via the Primakoff process and eventually convert into $\gamma$ rays in the magnetic field of the Milky Way. From a data-driven sensitivity estimate, we find that, for a SN exploding in our Galaxy, the Fermi Large Area Telescope (LAT) would be able to explore the photon-ALP coupling down to $g_{a\gamma} \simeq 2 \times 10^{-13}\,$GeV$^{-1}$ for an ALP mass $m_a \lesssim 10^{-9}\,$eV. These values are out of reach of next generation laboratory experiments. In this event, the Fermi LAT would probe large regions of the ALP parameter space invoked to explain the anomalous transparency of the Universe to $\gamma$ rays, stellar cooling anomalies, and cold dark matter. If no $\gamma$-ray emission were to be detected, Fermi-LAT observations would improve current bounds derived from SN1987A by more than one order of magnitude.