Related papers: The transition from a cool disk to an ion supporte…

It is commonly believed that accretion discs are truncated and their inner regions are described by advection dominated accretion flows (ADAFs) in the hard spectral state of black hole X-ray binaries. However, the increasing occurrence of a…

We investigate equilibrium accretion flows dominated by $e^+ e^-$ pairs. We consider one- and two-temperature accretion disk coronae above a thin disk, as well as hot optically thin two-temperature accretion flows without an underlying thin…

We investigate the thermal stability of optically thin, two-temperature, radiative cooling-dominated accretion disks. Our linear analysis shows that the disk is thermally unstable without magnetic fields, which agrees with previous…

The observation of the hot gas surrounding Sgr $A^*$ and a few other nearby galactic nuclei imply that electron and proton mean free paths are comparable to the gas capture radius. So, the hot accretion flows is likely to proceed under…

We show that, unlike the results presented previously in the literature, the transition from an outer Shakura-Sunyaev disk (SSD) to an advection-dominated accretion flow (ADAF) is possible for large values of the viscosity parameter $\alpha…

We apply the disk-corona evaporation model (Meyer & Meyer-Hofmeister) originally derived for dwarf novae to black hole systems. This model describes the transition of a thin cool outer disk to a hot coronal flow. The mass accretion rate…

We investigate the form of the momentum distribution function for protons and electrons in an advection-dominated accretion flow (ADAF). We show that for all accretion rates, Coulomb collisions are too inefficient to thermalize the protons.…

We study the torque acting on a planet embedded in an optically thick accretion disc, using global two-dimensional hydrodynamic simulations. The temperature of an optically thick accretion disc is determined by the energy balance between…

All high temperature accretion solutions including ADAF are physically thick, so outgoing radiation interacts with the incoming flow, sharing as much or more resemblance with classical spherical accretion flows as with disk flows. We…

In a previous paper, we described new analytic formulae for optically-thick supercritical accretion flows (Watarai 2006, hereafter paper 1). Here we present analytic formulae for optically-thin one-temperature accretion flows including the…

Recent papers discussing advection dominated accretion flows (ADAF) as a solution for astrophysical accretion problems should be treated with some caution because of their uncertain physical basis. The suggestions underlying ADAF involve…

We propose a variable ADAF disk model for X-ray binary systems. In this model, the accretion flow consists of an outer thin disk and an inner optically thick advection-dominated accretion flow (ADAF) torus. The size of the turbulent ADAF is…

We consider the interaction of a slowly rotating unmagnetized neutron star with a hot (ion supported, ADAF) accretion flow. The virialized protons of the ADAF penetrate into the neutron star atmosphere, heating a surface layer. Detailed…

Recent observations of two black hole candidates (GX 339-4 and J1753.5-0127) in the low-hard state (L_X/L_Edd ~ 0.003-0.05) suggest the presence of a cool accretion disk very close to the innermost stable orbit of the black hole. This runs…

Recently, Narayan & Raymond (1999) proposed that the thermal emission lines from the hot plasma in advection dominated accretion flows (ADAFs) are potentially observable with the next generation of X-ray observatories, with which the…

Using the black hole transient X-ray source A0620-00 as an example we study the physical interplay of three theoretical constituents for modelling these transient sources: (1) the advection-dominated accretion flow (ADAF) onto the central…

We examine heating and cooling in protostellar disks using 3-D radiation-MHD calculations of a patch of the Solar nebula at 1 AU, employing the shearing-box and flux-limited radiation diffusion approximations. The disk atmosphere is ionized…

Radiatively inefficient (or advection dominated) disks are discussed at an introductory level. Ion supported and radiation supported flows are discussed, the different consequences of advection dominated flows onto black holes vs. solid…

Aims: The hard and soft spectral states of black hole accretion are understood as connected with ADAF accretion (truncated disk) and standard disk accretion, respectively. However, observations indicate the existence of cool gas in the…

We analyze heating and cooling processes in accretion disks in binaries. For realistic parameters of the accretion disks in close binaries (with accretion rates from 1e-12 to 1e-7 Msun/year and \alpha from 0.1 to 0.01), the gas temperature…