Low-Energy Supernovae Severely Constrain Radiative Particle Decays

TL;DR

This paper uses low-energy supernovae as sensitive detectors to constrain the decay of hypothetical particles like axion-like particles, setting new limits on their properties based on supernova energy deposition constraints.

Contribution

It introduces a novel method of using low-energy supernovae to place the first constraints on radiative decays of feebly-interacting particles such as ALPs.

Findings

Excludes ALP-photon couplings in the range 10^{-10} to 10^{-8} GeV^{-1}.

Demonstrates low-energy supernovae as effective calorimeters for particle decay energy.

Provides new bounds on particle properties based on supernova energy limits.

Abstract

The hot and dense core formed in the collapse of a massive star is a powerful source of hypothetical feebly-interacting particles such as sterile neutrinos, dark photons, axion-like particles (ALPs), and others. Radiative decays such as $a\to2\gamma$ deposit this energy in the surrounding material if the mean free path is less than the radius of the progenitor star. For the first time, we use a supernova (SN) population with particularly low explosion energies as the most sensitive calorimeters to constrain this possibility. These SNe are observationally identified as low-luminosity events with low ejecta velocities and low masses of ejected $^{56}$Ni. Their low energies limit the energy deposition from particle decays to less than about 0.1 B, where $1~{\rm B~(bethe)}=10^{51}~{\rm erg}$. For 1-500 MeV-mass ALPs, this generic argument excludes ALP-photon couplings $G_{a\gamma\gamma}$ in the $10^{-10}$-$10^{-8}~{\rm GeV}^{-1}$ range.