V. Suleimanov e-mail: suleimanov@astro.uni-tuebingen.de
Suleimanov et al. Compton Scattering in Hot DA White Dwarfs
We re-examine the effects of Compton scattering on the
emergent spectra of hot DA white dwarfs in the soft X-ray range.
Earlier studies
have implied that sensitive X-ray observations at
wavelengths 
Å might be capable of probing the flux
deficits predicted by the redistribution of electron-scattered X-ray
photons toward longer wavelengths.
We adopt two independent numerical approaches to the inclusion of
Compton scattering in the computation of pure hydrogen atmospheres in
hydrostatic equilibrium. One employs the Kompaneets diffusion
approximation formalism,
while the other uses the cross-sections and redistribution functions
of Guilbert. Models and emergent spectra are computed for stellar
parameters representative of HZ 43 and Sirius B, and for models with
effective temperature
K.
The
differences between emergent spectra computed for Compton and Thomson
scattering cases are completely negligible in the case of both HZ 43
and Sirius B models, and are also negligible
for all practical purposes for models
with temperatures as high as
K.
Models of the soft X-ray flux from these stars
are instead dominated by uncertainties in their fundamental
parameters.
radiative transfer - scattering - methods: numerical - (stars:) white dwarfs - stars: atmospheres - X-rays: stars
V. Suleimanov1,2,5, J. Madej3, J.J. Drake4, T. Rauch1 and K. Werner1
Institut für Astronomie und Astrophysik, Universität Tübingen, Sand 1, 72076 Tübingen, Germany - Kazan State University, Kremlevskaya str., 18, Kazan 420008, Russia - Warsaw University Observatory, Al. Ujazdowskie 4, 00-478 Warsaw, Poland - Smithsonian Astrophysical Observatory, MS-3, 60 Garden Street, Cambridge, MA 02138, USA - Kazan Branch of Isaac Newton Institute, Santiago, Chile
Received xxx / Accepted xxx