Particle Spectra from Acceleration at Forward and Reverse Shocks of Young Type Ia Supernova Remnants

TL;DR

This paper investigates cosmic-ray acceleration at both forward and reverse shocks in young Type Ia supernova remnants, analyzing how magnetic fields and shock dynamics influence particle spectra and emission across multiple wavelengths.

Contribution

It introduces a comprehensive model including reverse shock acceleration and magnetic field evolution, highlighting their effects on particle spectra and emission morphology.

Findings

Reverse shock significantly influences cosmic-ray populations.

Spectral structures can mimic non-linear shock modifications.

Emission spectra and morphology evolve distinctly from forward-shock-only models.

Abstract

We study cosmic-ray acceleration in young Type Ia Supernova Remnants (SNRs) by means of test-particle diffusive shock acceleration theory and 1-D hydrodynamical simulations of their evolution. In addition to acceleration at the forward shock, we explore the particle acceleration at the reverse shock in the presence of a possible substantial magnetic field, and consequently the impact of this acceleration on the particle spectra in the remnant. We investigate the time evolution of the spectra for various time-dependent profiles of the magnetic field in the shocked region of the remnant. We test a possible influence on particle spectra of the Alfv\'enic drift of scattering centers in the precursor regions of the shocks. In addition, we study the radiation spectra and morphology in a broad band from radio to gamma-rays. It is demonstrated that the reverse shock contribution to the cosmic-ray particle population of young Type Ia SNRs may be significant, modifying the spatial distribution of particles and noticeably affecting the volume-integrated particle spectra in young SNRs. In particular spectral structures may arise in test-particle calculations that are often discussed as signatures of non-linear cosmic-ray modification of shocks. Therefore, the spectrum and morphology of emission, and their time evolution, differ from pure forward-shock solutions.