Open AccessThermal conduction between an accretion disc and a corona in active galactic nuclei: vertical structure of the transition layer
Author(s) -
Różańska A.
Publication year - 1999
Publication title -
monthly notices of the royal astronomical society
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 2.058
H-Index - 383
eISSN - 1365-2966
pISSN - 0035-8711
DOI - 10.1046/j.1365-8711.1999.02752.x
Subject(s) - physics , thermal conduction , astrophysics , hydrostatic equilibrium , accretion (finance) , corona (planetary geology) , thermal , radiative transfer , mechanics , thermodynamics , optics , astronomy , astrobiology , venus
We study the vertical structure of the transition layer between an accretion disc and a corona in the context of the existence of a two‐phase medium in thermally unstable regions. The disc is illuminated by hard X‐ray radiation, and satisfies the condition of hydrostatic equilibrium. We take into account the energy exchange between the hot, Compton‐heated corona (∼10 8 K) and cool disc (∼10 4 K) arising from both radiative processes and thermal conduction. In the case including thermal conduction, we perform a local stability analysis, and conclude that thermal conduction does not suppress thermal instability. In spite of the continuous temperature profile T ( τ ) there are regions of strong temperature gradient, in which spontaneous perturbations can lead to cloud condensation in the transition layer. We determine the minimum size λ TC of such a perturbation.