Probing the accretion processes in soft X-ray selected polars

TL;DR

This study uses XMM-Newton data to analyze accretion processes in soft X-ray selected polars, modeling their emission regions considering physical parameters, and confirming their soft X-ray nature.

Contribution

It introduces comprehensive models of accretion emission regions in polars, incorporating multi-temperature structures and stellar contributions for broad spectral analysis.

Findings

Confirmed the soft X-ray nature of three polars

Developed models considering mass-flow density, magnetic field, and white-dwarf mass

Established composite spectral models from infrared to X-rays

Abstract

High-energy data of accreting white dwarfs give access to the regime of the primary accretion-induced energy release and the different proposed accretion scenarios. We perform XMM-Newton observations of polars selected due to their ROSAT hardness ratios close to -1.0 and model the emission processes in accretion column and accretion region. Our models consider the multi-temperature structure of the emission regions and are mainly determined by mass-flow density, magnetic field strength, and white-dwarf mass. To describe the full spectral energy distribution from infrared to X-rays in a physically consistent way, we include the stellar contributions and establish composite models, which will also be of relevance for future X-ray missions. We confirm the X-ray soft nature of three polars.