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P: Fachverband Plasmaphysik
P 15: Astrophysical Plasmas
P 15.3: Talk
Wednesday, April 2, 2025, 16:45–17:00, ZHG102
Marginal Role of the Electrostatic Instability in the GeV Scale Cascade Flux from 1ES 0229+200 — •Martin Pohl1,2 and Mahmoud Alawashra1 — 1Deutsches Elektronen-Synchrotron DESY, Platanenallee 6, 15738 Zeuthen, Germany — 2Institute for Physics and Astronomy, University of Potsdam, D-14476 Potsdam, Germany
TeV gamma rays from blazars spawn relativistic pair beams that should generate detectable GeV-scale cascade emission, yet this component is absent in the observed spectra of some blazars. One interpretation is the deflection of the electron-positron pairs by a weak intergalactic magnetic field. Alternatively, electrostatic beam-plasma instabilities could drain the beam energy before the pairs produce the cascade emission. Recent studies suggest that particle scattering is the primary feedback of these plasma instabilities, rather than energy loss. In this work, we quantitatively assess the arrival time of secondary gamma rays at Earth as a function of the beam scattering by the electrostatic instability. Our findings reveal that the time delay of the GeV secondary cascade arrival due to instability broadening is on the order of a few months, which is insufficient to account for the missing cascade emission in blazar spectra. In this study, we have not yet included linear Landau damping of the plasma oscillations caused by the MeV-band cosmic-ray electrons. The impact of this damping on the nonlinear evolution of the beam-plasma system will be studied in future work.
Keywords: gamma rays; instabilities; Blazar; relativistic processes