VERITAS and Fermi-LAT constraints on the Gamma-ray Emission from Superluminous Supernovae SN2015bn and SN2017egm

TL;DR

This study searches for gamma-ray emissions from two superluminous supernovae using Fermi-LAT and VERITAS data, setting upper limits that challenge magnetar-based models and discussing future detection prospects.

Contribution

It provides the first combined gamma-ray constraints on SLSNe-I from 100 MeV to 30 TeV, informing models of magnetar-powered supernovae.

Findings

No gamma-ray emission detected from SN2015bn and SN2017egm.

Upper limits approach the magnetar spin-down luminosity.

Future observations could detect VHE gamma rays from SLSNe-I.

Abstract

Superluminous supernovae (SLSNe) are a rare class of stellar explosions with luminosities ~10-100 times greater than ordinary core-collapse supernovae. One popular model to explain the enhanced optical output of hydrogen-poor (Type I) SLSNe invokes energy injection from a rapidly spinning magnetar. A prediction in this case is that high-energy gamma rays, generated in the wind nebula of the magnetar, could escape through the expanding supernova ejecta at late times (months or more after optical peak). This paper presents a search for gamma-ray emission in the broad energy band from 100 MeV to 30 TeV from two Type I SLSNe, SN2015bn, and SN2017egm, using observations from Fermi-LAT and VERITAS. Although no gamma-ray emission was detected from either source, the derived upper limits approach the putative magnetar's spin-down luminosity. Prospects are explored for detecting very-high-energy (VHE; 100 GeV - 100 TeV) emission from SLSNe-I with existing and planned facilities such as VERITAS and CTA.