# Bochum 2015 – wissenschaftliches Programm

## Bereiche | Tage | Auswahl | Suche | Aktualisierungen | Downloads | Hilfe

# P: Fachverband Plasmaphysik

## P 10: Theory and Modelling I

### P 10.2: Vortrag

### Dienstag, 3. März 2015, 11:00–11:15, HZO 50

**The reduction of distant blazars’ inverse Compton cascade emission by plasma instability induced beam plateauing** — •Ulf Menzler — Ruhr-Universität Bochum, Theoretische Physik IV

The attenuation of TeV γ-rays from distant blazars by the extragalactic background light produces collimated relativistic electron-positron pair beams. The pair beams
traversing the intergalactic medium are unstable to linear two-stream instabilities of both electrostatic and electromagnetic nature. We investigate the case of weak
blazars where the back reaction of generated electrostatic turbulence leads to a parallel plateauing of the electron energy spectrum. We determine the inverse-Compton cascade flux reduction above a certain normalized energy *x*_{l} resulting from the incorporation of plasma effects on the beam particles distribution functions. Deriving the exact reduction factors for a steady state and a flaring scenario, where we also investigate the influence of time averaging observations, we can show, that in most cases the reduction is well approximated with a function *R*(*x*_{l}) resulting in the steady state scenario. For a typical blazar scenario the cascade flux reduction factor above
10 GeV is ∼ 0.1. Application of our findings to the spectrum of 1ES 0229+200 show, that the incorporation
of plasma effects leads to a natural explanation of the reduced GeV flux. Claims on the lower bound of the intergalactic magnetic field strengths, made by several authors to explain the flux reduction while neglecting plasma effects, are thus put into question.