# Point-source and diffuse high-energy neutrino emission from Type IIn supernovae

## TL;DR

This paper investigates the potential of Type IIn supernovae to produce high-energy neutrinos, estimating their contribution to IceCube's observed flux and exploring their detectability as point sources.

## Contribution

It provides the first detailed Monte Carlo-based estimate of the diffuse neutrino emission from Type IIn supernovae and assesses their role in the astrophysical neutrino flux.

## Key findings

- Type IIn SNe contribute about 10% of IceCube's neutrino flux above 60 TeV.
- Detection of individual Type IIn SNe as neutrino sources is feasible within 20 Mpc.
- A small fraction of core collapse SNe being Type IIn could dominate the diffuse neutrino background.

## Abstract

Type IIn supernovae (SNe), a rare subclass of core collapse SNe, explode in dense circumstellar media that have been modified by the SNe progenitors at their last evolutionary stages. The interaction of the freely expanding SN ejecta with the circumstellar medium gives rise to a shock wave propagating in the dense SN environment, which may accelerate protons to multi-PeV energies. Inelastic proton-proton collisions between the shock-accelerated protons and those of the circumstellar medium lead to multi-messenger signatures. Here, we evaluate the possible neutrino signal of type IIn SNe and compare with IceCube observations. We employ a Monte Carlo method for the calculation of the diffuse neutrino emission from the SN IIn class to account for the spread in their properties. The cumulative neutrino emission is found to be ~ 10 per cent of the observed IceCube neutrino flux above 60 TeV. Type IIn SNe would be the dominant component of the diffuse astrophysical flux, only if 4 per cent of all core collapse SNe were of this type and 20 to 30 per cent of the shock energy was channeled to accelerated protons. Lower values of the acceleration efficiency are accessible by the observation of a single type IIn SN as a neutrino point source with IceCube using up-going muon neutrinos. Such an identification is possible in the first year following the SN shock breakout for sources within 20 Mpc.