Exploring the Gamma-Ray Emissivity of Young Supernova Remnants I: Hadronic Emission

TL;DR

This paper develops a simplified model to predict the time evolution of gamma-ray emission from young supernova remnants, revealing different behaviors based on the surrounding medium and suggesting future observability of SN 1987A.

Contribution

It introduces an analytical expression for hadronic luminosity evolution in young SNRs, accounting for different ambient density profiles, and applies it to real supernovae to predict gamma-ray visibility.

Findings

Hadronic emission decreases over time in wind environments for core-collapse SNe.

Hadronic emission increases over time in constant density environments for Type Ia SNe.

SN 1987A may become a detectable gamma-ray source in the next decade.

Abstract

Using a simplified model for the hadronic emission from young supernova remnants (SNRs), we derive an expression to calculate the hadronic luminosity with time, depending on the SN ejecta density profile and the density structure of the surrounding medium. Our analysis shows that the hadronic emission will decrease with time for core-collapse SNe expanding in the winds of their progenitor stars, but increase with time for SNe expanding into a constant density medium, typical of Type Ia SNe. Using our expressions, we can compute the time-dependent hadronic flux from some well-known young SNe and SNRs with time, and where applicable reproduce previous results in the appropriate parameter regime. Using our calculations, we also emphasize the exciting possibility that SN 1987A may become a visible gamma-ray source in the next decade.