Early-time signatures of {\gamma}-ray emission from supernovae in dense circumstellar media

TL;DR

This study models gamma-ray emission from interaction-powered supernovae with dense circumstellar media, predicting detectable signals by Fermi-LAT within 10 Mpc, shortly after shock breakout.

Contribution

It introduces a comprehensive numerical model for gamma-ray emission from dense CSM supernovae, including various physical processes and temporal evolution.

Findings

Gamma-ray emission >100 MeV could be detectable by Fermi-LAT for nearby supernovae.

Dense CSM enhances gamma-ray production through proton-proton collisions.

Emission peaks shortly after shock breakout within 100-1000 days.

Abstract

We present our results on the {\gamma}-ray emission from interaction-powered supernovae (SNe), a recently discovered SN type that is suggested to be surrounded by a circumstellar medium (CSM) with densities 10^7-10^12~ cm^-3. Such high densities favor inelastic collisions between relativistic protons accelerated in the SN blast wave and CSM protons and the production of {\gamma}-ray photons through neutral pion decays. Using a numerical code that includes synchrotron radiation, adiabatic losses due to the expansion of the source, photon-photon interactions, proton-proton collisions and proton-photon interactions, we calculate the multi-wavelength non-thermal photon emission soon after the shock breakout and follow its temporal evolution until 100-1000 days. Focusing on the {\gamma}-ray emission at >100 MeV, we show that this could be detectable by the Fermi-LAT telescope for nearby (<10 Mpc) SNe with dense CSM (>10^11 cm^-3).