Description:

Title:   Winds, Winds Every Where: Radiatively Driven Outflows from Supermassive Black Holes?

Speaker: Sarah Gallagher, University of Western Ontario

Host: John Everett

Abstract: Supermassive black holes reside in the centers of every massive galaxy. In relatively brief spurts, black holes grow as luminous quasars through the infall of material through an accretion disk. Remarkably, the light from the accretion disk can outshine all of the stars in the host galaxy by a factor of a thousand, and this radiation can also drive energetic mass outflows. Mass ejection in the form of winds or jets appears to be as fundamental to quasar activity as accretion, and can be directly observed in many objects with broadened and blue-shifted UV emission and absorption features. A convincing argument for radiation pressure driving this ionized outflow can be made within the dust sublimation radius. Beyond, radiation pressure is still important, but high energy photons from the central engine can now push on dust grains. This physics underlies the dusty wind picture for the putative obscuring torus. I'll describe our model of the dusty wind and evaluate its success in accounting for observed properties of quasars such their mid-infrared spectral energy distributions, fractions of hidden objects, and column densities of important ions.

Keywords: Physics, Astronomy, Astrophysics