Supernova Remnants in the Sedov Expansion Phase: Thermal X-Ray Emission
Abstract
Improved calculations of X-ray spectra for supernova remnants (SNRs) in the Sedov-Taylor phase are reported, which for the first time include reliable atomic data for Fe L-shell lines. This new set of Sedov models also allows for a partial collisionless heating of electrons at the blast wave and for energy transfer from ions to electrons through Coulomb collisions. X-ray emission calculations are based on the updated Hamilton-Sarazin spectral model. The calculated X-ray spectra are successfully interpreted in terms of three distribution functions: the electron temperature and ionization timescale distributions, and the ionization timescale-averaged electron temperature distribution. The comparison of Sedov models with a frequently used single nonequilibrium ionization (NEI) timescale model reveals that this simple model is generally not an appropriate approximation to X-ray spectra of SNRs. We find instead that plane-parallel shocks provide a useful approximation to X-ray spectra of SNRs, particularly for young SNRs. Sedov X-ray models described here, together with simpler plane shock and single-ionization timescale models, have been implemented as standard models in the widely used XSPEC v11 spectral software package.
- Publication:
-
The Astrophysical Journal
- Pub Date:
- February 2001
- DOI:
- arXiv:
- arXiv:astro-ph/0008066
- Bibcode:
- 2001ApJ...548..820B
- Keywords:
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- ISM: Supernova Remnants;
- X-Rays: ISM;
- Astrophysics
- E-Print:
- 19 pages, 11 figures, submitted to Astrophysical Journal