A Time-dependent Spectral Analysis of γ Cassiopeiae
Nichols, Joy S.; Huenemoerder, David P.; Ignace, Richard; Pollock, A. M. T.; Torrejón, José M.; Pradhan, Pragati; Gunderson, Sean J.; Schulz, Norbert S.; Swarm, Dustin K.; Guenther, Hans Moritz
United States, Spain, United Kingdom
Abstract
We investigated the temporal and spectral features of γ Cassiopeiae's X-ray emission within the context of the white dwarf (WD) accretion hypothesis. We find that the variabilities present in the X-ray data show two different signals, one primarily due to absorption and the other due to flickering like in nonmagnetic cataclysmic variables. We then use this two-component insight to investigate previously unreported simultaneous XMM and NuSTAR data. The results of model fitting find WD properties consistent with optical studies alongside a significant secondary, thermal source. We propose a secondary shock between the Be decretion disk and WD accretion disk as the source. Finally, we analyzed a unique, low-count-rate event of the XMM light curve as potential evidence for the WD encountering Be decretion disk structures.