Using X-ray observations to identify the particle acceleration mechanisms in VHE SNRs and "dark" VHE sources

TL;DR

This paper reviews how X-ray observations help identify the particle acceleration mechanisms in very high energy supernova remnants and dark VHE sources, clarifying their nature and contribution to cosmic rays.

Contribution

It provides an overview of the current status of identifying Galactic VHE sources and discusses how X-ray data inform the understanding of their particle acceleration processes.

Findings

X-ray observations are crucial for distinguishing hadronic and leptonic processes.

Many VHE sources remain unidentified without X-ray data.

X-ray data help determine the astrophysical nature of dark VHE sources.

Abstract

Very high energy (VHE) gamma-ray observations have proven to be very successful in localizing Galactic acceleration sites of VHE particles. Observations of shell-type supernova remnants have confirmed that particles are accelerated to VHE energies in supernova blast waves; the interpretation of the gamma-ray data in terms of hadronic or leptonic particle components in these objects relies nevertheless strongly on input from X-ray observations. The largest identified Galactic VHE source class consists of pulsar wind nebulae, as detected in X-rays. Many of the remaining VHE sources remain however unidentified until now. With X-ray observations of these enigmatic "dark" objects one hopes to solve the following questions: What is the astrophysical nature of these sources? Are they predominantly electron or hadron accelerators? And what is their contribution to the overall cosmic ray energy budget? The paper aims to provide an overview over the identification status of the Galactic VHE source population.