MULTIWAVELENGTH MODELLING OF THE ACCRETION REGION IN POLARS

Abstract

This project focuses on the accretion-induced emission from polars, a sub-class of the magnetic cataclysmic variables. Most of the observed flux of these systems, from the optical to the hard X-ray energies, comes from the so called post-shock region: a small part of the accretion column near the white-dwarf surface. The stellar components and a large portion of the mass-transfer structure play a minor role in the emission from these systems. The main radiative processes are cyclotron, bremsstrahlung, and black body. We propose to develop a computational tool to simultaneously model the optical and X-ray emission of AM Her systems. Our group has already developed codes to calculate the cyclotron emission from the post-shock region and to adjust a model to a set of observational data. In this project, we aim to improve such a code, including the bremsstrahlung from the accretion region and a reprocessed component from the white-dwarf surface, the fundamental radiative processes in high energies. We are going to apply the model to objects having data on a broad range of wavelengths and covering different epochs in order to study the physical and geometrical properties of the post-shock regions of polars, including possible changes related to the different accretion rates.