# Cosmic ray acceleration by shocks: spectral steepening due to turbulent magnetic field amplification

## TL;DR

This paper demonstrates that turbulent magnetic field amplification during cosmic ray acceleration by shocks causes energy extraction from CRs, resulting in a steepened CR energy spectrum, which impacts our understanding of cosmic ray physics.

## Contribution

It introduces a mechanism where turbulent magnetic field amplification leads to spectral steepening by extracting energy from cosmic rays.

## Key findings

- Magnetic field amplification extracts energy from CRs.
- CR spectrum steepens due to turbulence-induced magnetic amplification.
- Implications for cosmic ray acceleration models.

## Abstract

We show that the energy required to turbulently amplify magnetic field during cosmic ray (CR) acceleration by shocks extracts energy from the CR and steepens the CR energy spectrum.