A Reanalysis of XMM-Newton Data of the Classical Nova V2491 Cyg Using Hot Collisionally Ionized Absorber Model
Abstract
We present a reanalysis of a selection of archival XMM-Newton RGS (Reflection Grating Spectrometer) data of the classical nova; V2491 Cyg obtained on 2008 May 20.6 and May 30.3. Our aim is to model the complex absorption features in the high resolution spectra assuming these can be due to different components of absorption from warm photo-ionized or hot collisionally ionized plasma originating from the wind/ejecta along with the features of the stellar emission. Here, we focus on absorption from a hot collisionally ionized plasma model. We utilise SRON software SPEX version 2.05.04 for the analysis and use a blackbody (BB) plus collisional ionization equilibrium (CIE) model for the continuum, modified by a collisionally ionized hot absorber (HOT) along with interstellar gas and dust absorption. We consider that the hot collisonally ionized plasma absorption is effective only on the BB emission whereas the cold interstellar gas and dust absorption modifies both BB and CIE emission. Our fits model the ionized absorption features simultaneously and show that hot collisionally ionized absorption model improves the fits upon warm photo-ionized absorption models considerably. We find that the X-ray spectrum shows deep and complex absorption features blue shifted by 2630-3700 km/s consistent with ejecta/wind speeds. We derive C, N, O abundances of V2491 Cyg which shows a typical signature of H-burning with a nitrogen and oxygen overabundance (ratio to solar abundance) of N ≃ 6, O ≃ 38, and carbon depletion of C ≃ 0.4. Our fits yield two collisonally ionized hot plasma absorption components with temperatures T_1≃1.1-2.7, T_{2}≃0.6-0.9 keV and rms velocities σ_{v1}∼850, σ_{v2}∼55 km/s. The different temperatures, column densities and corresponding rms velocities of the absorbers may indicate the existence of high and low density regions with less and high strongly ionized material in the ejecta/wind that might cause the complex absorbed spectra of V2491 Cyg.
- Publication:
-
41st COSPAR Scientific Assembly
- Pub Date:
- July 2016
- Bibcode:
- 2016cosp...41E.643G