Lenté Dreyer from North-West University, Potchefstroom Campus, South Africa presented the astrophysics seminar on September 24, 2021.
Understanding the emission processes in blazar jets is important for studying astrophysical jets. The jet radiation and particle acceleration mechanisms of the high-energy emission from blazars can be modelled in many ways. High-energy polarimetry can probe the most active jet regions with the most efficient particle accelerations, and thus serve as a powerful tool to distinguish between models. In a model where a thermal and a non-thermal particle distribution scatters an external radiation field, hard X-ray/γ-ray radiation results from relativistic electrons, and the radiation is predicted to be unpolarized. Contrarily, Ultraviolet (UV)/X-ray radiation, resulting from scattering by thermal electrons, is predicted to be polarized. In this seminar, I will summarize the scientific potential for using high-energy polarimetry to constrain open questions in jet-physics. The advantages of using Monte Carlo methods to study high-energy polarization from anisotropic Compton scattering, by thermal and non-thermal particles, will be discussed. I will conclude by presenting a new Monte-Carlo code - MAPPIES (Monte-Carlo Applications for Partially Polarized Inverse External-Compton Scattering) - for polarization-dependent Compton scattering. I will present the code by showing results of the polarization signatures in a model where the Big Blue Bump (BBB; UV/soft X-ray excess) seen in some blazar spectra arises from the bulk Compton process.
