XMM-NewtonObservations of the Cataclysmic Variable GW Librae

Abstract

XMM-Newton observations of the accreting, pulsating white dwarf in the quiescent dwarf nova GW Librae were conducted to determine whether the nonradial pulsations present in previous UV and optical data affect the X-ray emission. The nonradial pulsations are evident in the simultaneous Optical Monitor data but are not detected in the X-ray with an upper limit on the pulsation amplitude of 0.092 mag. The best fits to the X-ray spectrum are with a low-temperature diffuse gas model or a multitemperature cooling flow model with a strong O VIII 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.