Event Details

Supermassive black holes lurk in the cores of most large galaxies, perturbing stars and gas that venture into their neighborhoods. During the quasar era high rates of accretion onto these black holes power Active Galactic Nuclei (AGN) at luminosities exceeding all the stars in their host galaxies. The resulting accretion flows are thought to form thin flattened disks of gas spiralling inward under the influence of an anomalous viscosity, probably related to a magnetorotational instability (MRI) in the highly sheared accretion disk. The micro-arcsecond angular sizes of AGN are too small to be resolved by conventional methods. Echo Mapping uses observations of spectral variations, exploiting light travel time delays to resolve structure of the optical and UV emission line and continuum regions associated with the black hole accretion flows. Dr. Horne will discuss the Echo Mapping methods and show some results obtained to measure the black hole masses and accretion rates

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