Greifswald 2024 – scientific programme
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P: Fachverband Plasmaphysik
P 12: Poster II
P 12.29: Poster
Tuesday, February 27, 2024, 16:30–18:30, ELP 6: Foyer
Influence of Plasma Instability for the Energy-loss of Relativistic Pair Beams from TeV Blazars — •Suman Dey and Günter Sigl — II. Institut für Theoretische Physik, Universität Hamburg, 22761 Hamburg
The interaction of TeV photons from blazars with the extragalactic background produces a relativistic beam of e− e+ pairs streaming through the intergalactic medium, producing a cascade through up-scattering low-energy photons. Plasma instability is considered one of the underlying energy-loss processes of the beams. This study aims to investigate the energy loss of beams due to plasma instability using a particle-in-cell (PIC) simulation. We extrapolated the instability growth trend observed in laboratory settings to the astrophysical scale, assuming no other important mechanisms. For relativistic jets, the beam undergoes a continuous influx of new particles by pair production, which persists in driving the instability. We estimated the saturated value of the energy-loss term and diffusion coefficient when equilibrium is achieved. Moreover, in extrapolating to astrophysical scales, we noted that the system started to develop secondary instability and emerged from a reactive to kinetic regime. Momentum broadening suppresses the secondary instability and saturates. We compared the energy-loss time scale (τloss) and diffusion time scale (τdiff) with inverse Compton (IC) cooling time (τIC). We observed that the τloss is almost comparable to τIC, whereas τdiff exceeds both. This opens a future scope to explore the effect of intergalactic magnetic field (IGMF) on instability using the modular structure of CRPropa code.
Keywords: Plasma instability; pic simulation; TeV blazars; cascades; gamma-rays