Abstract
The vertical structure of optically thick accretion disks is investigated in the two-zone approximation. The disk is divided into an underlying disk and a corona, where the latter is defined as the upper surface layers for which the effective optical depth is unity. It is found that a significant part of the accretion flow (or dissipation rate) can take place in the corona if the scale height of the magnetic field is larger than that of the disk. The presence of such a dissipative corona leads to a modification in the topology of local disk solutions. For example, these solutions are found from local stability analysis to be both secularly and thermally stable, for accretion rates that are a factor of ≈4 higher than those inferred from the stability of standard disk solutions. Thus, the applicability of optically thick disks with dissipative coronas are not as restrictive as disks without such coronas and can provide an attractive explanation for the origin of the soft spectral component observed in black hole X-ray binary systems.
Original language | English (US) |
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Pages (from-to) | 764-769 |
Number of pages | 6 |
Journal | Astrophysical Journal |
Volume | 573 |
Issue number | 2 I |
DOIs | |
State | Published - Jul 10 2002 |
Keywords
- Accretion, accretion disks
- Black hole physics
- Hydrodynamics
ASJC Scopus subject areas
- Astronomy and Astrophysics
- Space and Planetary Science