# Pulsar Wind Nebulae inside Supernova Remnants as Cosmic-Ray PeVatrons

## TL;DR

This paper proposes that pulsar wind nebulae within supernova remnants can act as cosmic-ray PeVatrons, accelerating particles to PeV energies through a combination of initial acceleration and adiabatic compression.

## Contribution

It introduces a new model where PWNe inside SNRs serve as PeVatrons, with detailed simulation of particle acceleration during different PWN evolutionary stages.

## Key findings

- Particles can be reaccelerated from 0.1 PeV to 1 PeV during PWN compression.
- Monte Carlo simulations support the PWN as a viable PeVatrons.
- The model explains how cosmic rays reach PeV energies in SNR environments.

## Abstract

We propose that cosmic-ray PeVatrons are pulsar wind nebulae (PWNe) inside supernova remnants (SNRs). The PWN initially expands into the freely expanding stellar ejecta. Then, the PWN catches up with the shocked region of the SNR, where particles can be slightly accelerated by the back and forth motion between the PWN and the SNR, and some particles diffuse into the PWN. Afterwards the PWN is compressed by the SNR, where the particles in the PWN are accelerated by the adiabatic compression. Using a Monte Carlo simulation, we show that particles accelerated by the SNR to 0.1 PeV can be reaccelerated to 1 PeV until the end of the PWN compression.