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[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 v_rot = 200 km/s and the critical column density (CCD) necessary to initiate the RVI is \Sigma_CCD ~100 gm cm^-2. For M_<r = 2 \pi r² \Sigma we have r_CCD = v_rot²/ ( 2 \pi \Sigma_CCD G) , and the mass accreted becomes M_BH = v_rot⁴/(2 \pi \Sigma_CCD G²) = 3 \times 10⁷ M_\odot. Both the black hole mass M_BH and its v_rot⁴ dependence are in good agreement with recent observations, because v_rot = \sqrt 3 \; \sigma_c, where \sigma_c is the velocity dispersion of the bulge at the radius of mutual contact. (Supported by the DOE)

The author(s) of this abstract have provided an email address for comments about the abstract: colgate@lanl.gov

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Bulletin of the American Astronomical Society, 35 #5
© 2003. The American Astronomical Soceity.