AAS 203rd Meeting, January 2004
Session 104 Black Holes
Oral, Wednesday, January 7, 2004, 2:00-3:30pm, Centennial IV

## [104.06] The Origin of Supermassive Black Holes from Mestel Disks and the Rossby Instability

S.A. Colgate (LANL), R. Cen (Princeton), H. Li, N. Currier, M.S. Warren (LANL)

CHECKING The formation of supermassive black holes at the centers of galaxies starts with inviscid gravitational collapse forming a flat rotation curve, Mestel disk with M<r \propto r and \Sigma \propto 1/r . Such disks should form from the collapse of any uniformly rotating, isolated, gaseous cloud, either proto-galactic, galaxy-mass damped Lyman-\alpha clouds or the gas which survives galaxy mergers. In either case the disk will be unstable to the Rossby vortex instability (RVI). This instability grows from any large, steep pressure gradient in an optically thick and geometrically thin disk. The non-linear vortices initiated by the RVI can transport angular momentum with transport length ~r far more efficiently than turbulence with transport length, H << r, the disk thickness. Compared to a viscosity-based Shakura-Sunyaev disk the RVI transports angular momentum out to a much larger radius, r ~10 pc in an L* galaxy, so more mass is accreted into the central black hole. A typical galaxy rotational velocity is vrot = 200 km/s and the critical column density (CCD) necessary to initiate the RVI is \SigmaCCD ~100 gm cm-2. For M<r = 2 \pi r2 \Sigma we have rCCD = vrot2/ ( 2 \pi \SigmaCCD G) , and the mass accreted becomes MBH = vrot4/(2 \pi \SigmaCCD G2) = 3 \times 107 M\odot. Both the black hole mass MBH and its vrot4 dependence are in good agreement with recent observations, because vrot = \sqrt 3 \; \sigmac, where \sigmac is the velocity dispersion of the bulge at the radius of mutual contact. (Supported by the DOE)