Cataclysmic Variables in Globular Clusters, the Galactic Center, and Local Space

TL;DR

This study compares X-ray spectra of cataclysmic variables across different environments, revealing that brighter sources are likely magnetic CVs while fainter ones include normal CVs, with implications for understanding their populations.

Contribution

It provides a comparative analysis of CV populations in various environments using X-ray data, highlighting the magnetic nature of brighter sources and the diversity among fainter ones.

Findings

Brighter CVs are likely magnetic.

Fainter CVs include normal types.

Galactic Center sources have hard spectra due to extinction.

Abstract

We compare the X-ray spectra and luminosities, in the 2-8 keV band, of known and suspected cataclysmic variables (CVs) in different environments, assessing the nature of these source populations. These objects include nearby CVs observed with ASCA; the Galactic Center X-ray source population identified by Muno et al.; and likely CVs identified in globular clusters. Both of the latter have been suggested to be dominated by magnetic CVs. We find that the brighter objects in both categories are likely to be magnetic CVs, but that the fainter objects are likely to include a substantial contribution from normal CVs. The strangely hard spectra observed from the Galactic Center sources reflect the high and variable extinction, which is significantly greater than the canonical 6e22 /cm2 over much of the region, and the magnetic nature of many of the brightest CVs. The total numbers of faint Galactic Center sources are compatible with expectations of the numbers of CVs in this field.