Formation of Inner Cool Disks in Black Hole Low State

摘要

We present our recent study on the formation of a cool disk in the in nermost region of accreting black holes in the low hard state. By taking into account the exchange of energy and mass between the corona and disk promoted by thermal conduction, it is found that a weak disk can be maintained by condensation of matter from a corona to the disk for luminosities in the range of 0.001-0.03 Eddington lumi nosity. Properties of the inner disk, for instance, the disk temperature as a function of X-ray luminosity, are present. The model is applied to the X-ray observations of the black hole candidate source GX 339-4 in the low hard state for which evidence is provided pointing to the possible existence of a cool inner disk (Miller et al. 2006b; Tomsick et al. 2008). Application to supermassive black holes are also discussed. It is suggested that such inner cool disks may contribute to the optical and ultraviolet emission of low lumin08ity active galactic nuclei.