XMM-Newton Observations of the Cataclysmic Variable GW Lib

TL;DR

This study used XMM-Newton to observe the white dwarf in GW Librae, finding no X-ray pulsations despite optical signals, and suggesting the boundary layer does not reach the white dwarf surface.

Contribution

First X-ray analysis of GW Librae showing absence of pulsations and spectral characteristics indicating boundary layer structure.

Findings

No X-ray pulsations detected with upper limit of 0.092 mags.

X-ray spectrum fits a low temperature diffuse gas or cooling flow model.

Boundary layer likely does not extend to the white dwarf surface.

Abstract

XMM-Newton observations of the accreting, pulsating white dwarf in the quiescent dwarf nova GW Librae were conducted to determine if the non-radial pulsations present in previous UV and optical data affect the X-ray emission. The non-radial pulsations are evident in the simultaneous Optical Monitor data but are not detected in X-ray with an upper limit on the pulsation amplitude of 0.092 mags. The best fits to the X-ray spectrum are with a low temperature diffuse gas model or a multi-temperature cooling flow model, with a strong OVIII line, similar to other short period dwarf novae, but with a lower temperature range than evident in normal short period dwarf novae. The lack of pulsations and the spectrum likely indicate that the boundary layer does not extend to the surface of the white dwarf.