Energy loss of intergalactic pair beams: Particle-in-Cell simulation

TL;DR

This study uses Particle-in-Cell simulations to investigate plasma instabilities driven by intergalactic pair beams and their impact on secondary gamma-ray production, finding negligible effects in typical blazar conditions.

Contribution

First simulation-based analysis of plasma instabilities' effects on pair beams in intergalactic space using Particle-in-Cell methods.

Findings

Plasma instabilities can be recovered in simulations.

Instabilities have negligible impact on pair distribution in typical blazar conditions.

Simulation results align with theoretical growth rate orderings.

Abstract

The change of the distribution function of electron-positron pair beams determines whether GeV photons can be produced as secondary radiation from TeV photons. We will discuss the instabilities driven by pair beams. The system of a thermal proton-electron plasma and the electron-positron beam is collision free. We have, therefore, used the Particle-in-Cell simulation approach. It was necessary to alter the physical parameters, but the ordering of growth rates has been retained. We were able to show that plasma instabilities can be recovered in particle-in-cell simulations, but their effect on the pair distribution function is negligible for beam-background energy density ratios typically found in blazars.