Nuclear Activity in Nearby Galaxies

Understand

A significant fraction of nearby galaxies show evidence of weak nuclear activity unrelated to normal stellar processes.

• Recent high-resolution, multiwavelength observations indicate that the bulk of this activity derives from black hole accretion with a wide range of accretion rates.
• The low accretion rates that typify most low-luminosity active galactic nuclei induce significant modifications to their central engine.
• The broad-line region and obscuring torus disappear in some of the faintest sources, and the optically thick accretion disk transforms into a three-component structure consisting of an inner radiatively inefficient accretion flow, a truncated outer thin disk, and a jet or outflow.