Measurement of Cosmic-ray Electrons at TeV Energies by VERITAS

TL;DR

This paper presents the measurement of cosmic-ray electrons at TeV energies using VERITAS, revealing a broken power-law spectrum with a break at around 710 GeV, providing insights into local astrophysical sources and dark matter possibilities.

Contribution

First measurement of TeV cosmic-ray electron spectrum with VERITAS, showing a broken power-law shape and constraining models of local sources and dark matter.

Findings

Spectrum extends from 300 GeV to 5 TeV.

Single power-law fit is rejected.

Spectrum shows a break at approximately 710 GeV.

Abstract

Cosmic-ray electrons and positrons (CREs) at GeV-TeV energies are a unique probe of our local Galactic neighborhood. CREs lose energy rapidly via synchrotron radiation and inverse-Compton scattering processes while propagating within the Galaxy and these losses limit their propagation distance. For electrons with TeV energies, the limit is on the order of a kiloparsec. Within that distance there are only a few known astrophysical objects capable of accelerating electrons to such high energies. It is also possible that the CREs are the products of the annihilation or decay of heavy dark matter (DM) particles. VERITAS, an array of imaging air Cherenkov telescopes in southern Arizona, USA, is primarily utilized for gamma-ray astronomy, but also simultaneously collects CREs during all observations. We describe our methods of identifying CREs in VERITAS data and present an energy spectrum, extending from 300 GeV to 5 TeV, obtained from approximately 300 hours of observations. A single power-law fit is ruled out in VERITAS data. We find that the spectrum of CREs is consistent with a broken power law, with a break energy at 710 $\pm$ 40$_{stat}$ $\pm$ 140$_{syst}$ GeV.