Bremsstrahlung Energy Losses for Cosmic Ray Electrons and Positrons

TL;DR

This paper calculates the energy losses of ultra-relativistic cosmic ray electrons and positrons due to bremsstrahlung, including Thomson scattering and synchrotron radiation, to understand their propagation distances.

Contribution

It provides detailed calculations of bremsstrahlung energy losses for cosmic ray leptons considering cosmic microwave background and magnetic fields, aiding source distance estimations.

Findings

Energy losses are significant for leptons above 1 TeV.

Thomson scattering and synchrotron radiation are key loss mechanisms.

Lepton energies must be below about 1 TeV for galactic source distances.

Abstract

Recently cosmic ray electrons and positrons, i.e. cosmic ray charged leptons, have been observed. To understand the distances from our solar system to the sources of such lepton cosmic rays, it is important to understand energy losses from cosmic electrodynamic fields. Energy losses for ultra-relativistic electrons and/or positrons due to classical electrodynamic bremsstrahlung are computed. The energy losses considered are (i) due to Thompson scattering from fluctuating electromagnetic fields in the background cosmic thermal black body radiation and (ii) due to the synchrotron radiation losses from quasi-static domains of cosmic magnetic fields. For distances to sources of galactic length proportions, the lepton cosmic ray energy must be lass than about a TeV.