Low-Energy Supernovae Severely Constrain Radiative Particle Decays

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 → 2γ 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 B (bethe) = 10 51 erg. For 1-500 MeV-mass ALPs, this generic argument excludes ALP-photon couplings Gaγγ in the 10 −10 -10 −8 GeV −1 range.

Axion Instability Supernovae

“…The cosmological triangle received its name from its shape, and the fact that cosmologydependent constraints can be deduced given additional assumptions on exotic contributions to ∆N eff [19]. This region of parameter space has recently been criticized based on limiting the energy deposition in the mantle and the outer envelopes of low-energy supernovae [20,21]. These limits are suggestive that new optical phenomena are possible in this range of parameter space; however, until observational signatures of this type of energy deposition are better characterized, it is important to pursue additional probes of this parameter space.…”

Axion Searches at the LHC: FASER as a Light Shining through Walls Experiment

“…The supernova bounds are taken from Ref [36,105,106]. and should be considered conservative regarding the upper end of the bound that corresponds to the trapping limit[36].…”