# Time evolution of broadband non-thermal emission from supernova remnants in different circumstellar environments

## TL;DR

This study uses hydrodynamical simulations to analyze the evolution of non-thermal broadband emission from supernova remnants in various circumstellar environments, predicting detectability with CTA and implications for understanding progenitor star properties.

## Contribution

It provides a systematic simulation-based analysis of VHE emission evolution in SNRs across different environments, highlighting key factors influencing emission and future observational prospects.

## Key findings

- VHE emission evolution is mainly influenced by target particle density and magnetic field amplification.
- CTA can potentially detect VHE gamma-rays from most young SNRs within 5 kpc.
- Future CTA observations will help probe supernova progenitor environments and mass loss history.

## Abstract

Supernova remnants (SNRs) are thought to be one of the major acceleration sites of galactic cosmic rays (CRs) and an important class of objects for high-energy astrophysics. SNRs produce multi-wavelength, non-thermal emission via accelerated particles at collisionless shocks generated by the interactions between the SN ejecta and the circumstellar medium (CSM). Although it is expected that the rich diversities observed in supernovae (SNe) and their CSM can result in distinct very-high-energy (VHE) electromagnetic signals in the SNR phase, there are only a handful of SNRs observed in both GeV and TeV gamma-rays so far. A systematic understanding of particle acceleration at SNRs in different ambient environments is therefore limited. Here, we explore non-thermal emission from SNRs in various circumstellar environments up to 5000 yrs from explosion using hydrodynamical simulations coupled with efficient particle acceleration. We find that time-evolution of emission characteristics in the VHE regime is mainly dictated by two factors; the number density of the target particles and the amplified magnetic field in the shocked medium. We also predict that Cherenkov Telescope Array (CTA) will have a sufficient sensitivity to detect VHE gamma-rays from most young SNRs at distances <~ 5.0 kpc. Future SNR observations with CTA will thus be promising for probing the CSM environment of SNe and hence their progenitor properties, including the mass loss history of massive stars.