2003ApJ...596..429O -
Astrophys. J., 596, 429-436 (2003/October-2)
Spectral energy distribution in supercritical disk accretion flows through photon-trapping effects.
OHSUGA K., MINESHIGE S. and WATARAI K.-Y.
Abstract (from CDS):
We investigate the spectral energy distribution (SED) of the supercritical disk accretion flows around black holes by solving the multifrequency zeroth-moment equation of the radiation transfer equation under the flux-limited diffusion approximation as well as the energy equation of gas. Special attention is paid to the photon-trapping effects, the effects that photons are trapped within accretion flow and are swallowed by a black hole, with little being radiated away. It is found that when flow luminosity is below about twice the Eddington luminosity (L≲2LE), photon trapping is ineffective and the SED shifts to the higher energy side as L increases. The peak frequency at which the SED reaches its peak becomes at maximum 3 times higher than that given by the standard-disk model, which might resolve the ``too hot accretion disk problem.'' When L≳2LE, in contrast, the peak frequency of the SED tends to decrease with increase of mass accretion rate. This is due to enhanced photon trapping. Since high-energy photons are generated near the equatorial plane, they can be more effectively trapped in flow than low-energy ones, and hence the high-energy part of radiation is suppressed. Finally, the observed time variation of IC 342 S1, which is an ultraluminous X-ray source, in the X-ray H-R diagram, can be explained by the modulation of the mass accretion rate. In comparison with the observational data, we estimate that the mass of black hole in IC 342 S1 is ∼100M☉.
Abstract Copyright:
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Journal keyword(s):
Accretion, Accretion Disks - Radiative Transfer - X-Rays: Individual: Alphanumeric: IC 342 S1
CDS comments:
IC 342 S1 = [FT87] IC 342 1, M 81 X-6 = [F88] X- 6 (= M81 S-6 in the legend of fig.6)
Simbad objects:
3
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