| Authors Affiliation: | Affiliations:
1. Astronomy and Astrophysics Group, Raman Research Institute, Sadashivnagar, Bangalore, Karnataka-560094, India
2. CRESST II and X-ray Astrophysics Laboratory, NASA/GSFC, Greenbelt, MD 20771, USA
3. Department of Physics, University of Maryland Baltimore County, 1000 Hilltop Circle, Baltimore, MD 21250, USA
4. Departamento de Física, Universidade Federal de Sergipe, Av. Marechal Rondon, S/N, 49100-000, São Cristóvão, SE, Brazil
5. Observatório Nacional, Rua Gal. José Cristino 77, 20921-400, Rio de Janeiro, RJ, Brazil |
| Abstract : | SS Cyg is one of the brightest dwarf novae that undergoes outbursts every 40-50 days and lasts 10-12 days. The outburst is associated with thermal-viscous instability in the accretion disk, which changes the geometry and properties of the X-ray-emitting boundary layer (BL). Using simultaneous broadband X-ray data (0.3-50 keV) from XMM-Newton and NuSTAR observatories, we present a comparative study on how the nature of the X-ray emitting plasma changes during the quiescent and outburst phases of SS Cyg. We notice significantly hard X-ray spectra during quiescence and copious amounts of very soft X-ray emissions in the form of blackbody during outburst, highlighting the changes in the BL’s opacity and mass accretion rate. Furthermore, we delve into the emissions of hard X-rays during outbursts, which has puzzling origin other than the BL. Our study conclusively confirms the presence of the Compton reflection hump in the hard X-rays. We discuss the differences in the reflection parameters during the two phases and what are the potential reflection sites of the emitted X-rays, i.e., white dwarf surface and/or accretion disk. Additionally, we explore the impact of intrinsic absorbers near the source, resulting from outflowing winds, on X-ray photons. |
