Search for Gamma-ray Production in Supernovae Located in a Dense Circumstellar Medium with the Fermi-LAT

TL;DR

This study conducted a systematic search for gamma-ray emission from supernovae in dense circumstellar media using Fermi-LAT data, finding no significant excess and setting upper limits on gamma-ray luminosity.

Contribution

First comprehensive search for gamma-ray signals from supernovae in dense CSM with Fermi-LAT, establishing constraints on gamma-ray emission models.

Findings

No gamma-ray excess detected in the sample.

Upper limits set on gamma-ray luminosity.

Joint analysis constrains gamma-ray to optical luminosity ratio.

Abstract

Supernovae (SNe) exploding in a dense circumstellar medium (CSM) are predicted to accelerate cosmic rays in collisionless shocks and emit GeV gamma rays and TeV neutrinos on a time scale of several months. Here we summarize the results of the first systematic search for gamma-ray emission in Fermi-LAT data in the energy range from 100 MeV to 300 GeV from a large sample of SNe exploding in dense CSM. We search for a gamma-ray excess at the position of 147 SNe Type IIn in a one year time window after the optical peak time. In addition we combine the closest and optically brightest sources of our sample in a joint likelihood analysis in three different time windows (3, 6 and 12 months). No excess gamma-ray emission is found and limits on the gamma-ray luminosity and the ratio of gamma-ray to optical luminosity are presented.