Fermi acceleration at supernova remnant shocks

TL;DR

This paper combines semi-analytic models and hybrid plasma simulations to study particle acceleration at supernova remnant shocks, revealing efficient magnetic field amplification and significant energy transfer to non-thermal particles.

Contribution

It introduces large hybrid simulations to analyze shock transition, particle spectra, and magnetic field amplification in supernova remnants, advancing understanding of cosmic-ray acceleration.

Findings

Over 20% of shock energy converts to non-thermal particles

Particle spectrum follows a power-law as predicted by Fermi acceleration

Magnetic field amplification significantly influences shock dynamics

Abstract

We investigate the physics of particle acceleration at non-relativistic shocks exploiting two different and complementary approaches, namely a semi-analytic modeling of cosmic-ray modified shocks and large hybrid (kinetic protons/fluid electrons) simulations. The former technique allows us to extract some information from the multi-wavelength observations of supernova remnants, especially in the gamma-ray band, while the latter returns fundamental insights into the details of particle injection and magnetic field amplification via plasma instabilities. In particular, we present the results of large hybrid simulations of non-relativistic shocks, discussing the properties of the transition from the thermal to the non-thermal component, the spectrum of which turns out to be the power-law predicted by first-order Fermi acceleration. Along with a rather effective magnetic field amplification, we find that more than 20% of the bulk energy is converted in non-thermal particles, altering significantly the dynamics of the shock and leading to the formation of a precursor.