Self-Similar Solutions for ADAF with Toroidal Magnetic Fields

We examined the effect of toroidal magnetic fields on a viscous gaseous diskaround a central object under an advection dominated stage. We foundself-similar solutions for radial infall velocity, rotation velocity, soundspeed, with additional parameter $\beta$ [$=c_{\rm A}^2/(2c_{\rm s}^2)$], where$c_{\rm A}$ is the Alfv\'en speed and $c_{\rm s}$ is the isothermal soundspeed. Compared with the non-magnetic case, in general the disk becomes thickdue to the magnetic pressure, and the radial infall velocity and rotationvelocity become fast. In a particular case, where the magnetic field isdominant, on the other hand, the disk becomes to be magnetically supported, andthe nature of the disk is significantly different from that of the weaklymagnetized case.Comment: 5pages, 2figures, PASJ 58 (2006) in pres