Physical Society Colloquium

The Biggest Blowhards: Windy Supermassive Black Holes

Sarah Gallagher

Department of Physics and Astronomy
University of Western Ontario

Supermassive black holes reside in the centres of every massive galaxy. In brief spurts, black holes grow as luminous quasars via 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, though dust must play an important role beyond the dust sublimation radius. We apply unsupervised and hierarchical clustering algorithms on quasar spectra to test this “dusty wind” picture. I'll describe our model of the dusty wind and evaluate its successes and shortcomings in accounting for observed properties of quasars such their mid-infrared power, fractions of hidden objects, and column densities of important ions.