The X-ray continuum of Tycho's remnant measured with Ginga.
Abstract
The X-ray spectrum of Tycho's remant was observed in the energy range from 2 to 20 keV with Ginga in December, 1989. Fits of standard model spectra to the measured continuum above 4.5 keV showed that the spectrum of the remnant cannot satisfactorily be described by a single Bremsstrahlung component plus a Gaussian line for the Fe K-line blend. Such an approach was previously chosen to characterize Tycho's continuum measured with EXOSAT and Tenma up to 10 keV yielding divergent spectral parameters. Although the two-component modeling of the continuum yielded formally acceptable fits, the spectral parameters of the high energy component remained uncertain according to the very shallow chi2-valleys of the corresponding significance contours. The centroid of the Gaussian line is at 6.5 keV possibly indicating Fe line emssion from a hot plasma. A physical meaningful representation of Tycho's continuum is achieved by a multi-temperature spectrum provided by a numerical model. The 1-D model describes the hydrodynamical evolution of the remnant taking non-equilibrium ionization into account. The remarkable agreement between the model, and the measured continuum confirms the basic model assumption that a local temperature equilibrium between electrons and ions is almost instantaneously established in the remnant's X-ray emitting shell. From the model emissivity and the measured flux density a distance of Tycho of nearly 3 kpc is derived.
- Publication:
-
Astronomy and Astrophysics
- Pub Date:
- March 1994
- Bibcode:
- 1994A&A...283..635F
- Keywords:
-
- Computational Astrophysics;
- Hydrodynamics;
- Interstellar Matter;
- Line Spectra;
- Stellar Atmospheres;
- Supernova Remnants;
- Thermal Emission;
- X Ray Astronomy;
- X Rays;
- Bremsstrahlung;
- Exosat Satellite;
- Ginga Satellite;
- Iron Compounds;
- Mathematical Models;
- Potassium Compounds;
- Stellar Models;
- Astrophysics