Speaker
Description
The role of plasma instabilities in the development of electromagnetic cascades from extragalactic sources has gained importance as an alternative theory that seeks to explain the deviation of observed photon flux results from theoretical predictions at the GeV scale. This phenomenon is the result of the interaction between electron-positron pairs with the intergalactic medium (IGM). The development of these instabilities could cool down the electron-positron pairs more efficiently
than the inverse Compton scattering, being a possible cause of the observed suppression in the photon flux. For this reason, we studied the impact of instabilities in electromagnetic cascades through a parametric study in computer simulations, performed with the Monte Carlo code CRPropa. We developed a new interaction module in CRPropa for electrons and positrons that accounts for the energy losses due to these instabilities. A numerical methodology was created for the study
of the photon spectrum at Earth generated in electromagnetic cascades, coming from a blazar emitting very-high energy gamma-rays (VHEGR) with a given emission spectrum. This framework was used to reconstruct the spectrum at Earth for specific blazar emission and parametrization of the plasma instabilities. The results suggest a non-negligible effect of instabilities for the suppression of GeV-photon flux for some plasma parameters and injected spectra. This approach could also be used to
reformulate the preexisting bounds on intergalactic magnetic field (IGMF).
