Origin of TeV Galactic Cosmic Rays

TL;DR

This paper investigates the origins of TeV Galactic cosmic rays by analyzing gamma-ray emissions associated with recent supernovae and pulsars, supporting the supernova origin hypothesis for Galactic CRs.

Contribution

It demonstrates that degree-scale gamma-ray sources linked to young pulsars align with recent supernova activity, emphasizing pulsars' role in cosmic ray acceleration.

Findings

Most gamma-ray sources are associated with young pulsars under 30 kyr old.

The observed gamma-ray emission matches expected CR injection rates of ~1e50 erg every 100 years.

Pulsar presence is crucial for CR acceleration, unlike shell-like supernova remnants without pulsars.

Abstract

We consider a possibility of identification of sources of cosmic rays (CR) of the energy above 1 TeV via observation of degree-scale extended gamma-ray emission which traces the locations of recent sources in the Galaxy. Such emission in the energy band above 100 GeV is produced by CR nuclei and electrons released by the sources and spreading into the interstellar medium. We use the data from the Fermi gamma-ray telescope to locate the degree-scale 100 GeV gamma-ray sources. We find that the number of such sources and their overall power match to those expected when CRs injection events happen every ~100 yr in portions of ~1e50 erg. We find that most of the sources are associated to pulsars with spin down age less than ~30 kyr and hence to the recent supernova explosions. This supports the hypothesis of supernova origin of Galactic CRs. We notice that the degree-scale extended emission does not surround shell-like supernova remnants without pulsars. Based on this observation, we argue that the presence of the pulsar is essential for the CR acceleration process. We expect that a significant fraction of the degree-scale sources should be detectable as extended sources with km3-scale neutrino detectors.