Published in:
Publications of the Astronomical Society of Japan, 61 (2009) 2, Seite 213-226
Language:
English
DOI:
10.1093/pasj/61.2.213
ISSN:
0004-6264;
2053-051X
Origination:
Footnote:
Description:
Abstract Highly supercritical accretion discs are probable sources of dense optically thick axisymmetric winds. We introduce a new approach based on diffusion approximation radiative transfer in a funnel geometry, and obtain an analytical solution for the energy density distribution inside the wind, assuming that all of the mass, momentum and energy are injected well inside the spherization radius. This allows us to derive the spectrum of the emergent emission for various inclination angles. We show that self-irradiation effects play an important role in altering the temperature of the outcoming radiation by about 20%, and the apparent X-ray luminosity by a factor of 2–3. The model has been successfully applied to two ULXs. The basic properties of the high ionization He ii-regions found around some ULXs are also easily reproduced in our models.