Resolving the dust tori in AGN with the VLT interferometer

Abstract

The MID-infrared Interferometric instrument (MIDI) at the VLT Interferometer (VLTI) is the ideal instrument to resolve the emission of the putative dust tori in nearby AGN. Indeed, the first successful MIDI observations of the brightest and nearest Seyfert II galaxies - NGC 1068 and the Circinus galaxy - already provided us with an unexpected wealth of information about the dust distribution and properties in the inner few parsec. Observations of the closest radio galaxy - Centaurus A - reveal a unresolved 10 μm source (< 0.2 pc) which presumably represents the base of the radio jet. About a dozen extragalactic sources will be accessible to MIDI, and will allow us to tackle two important issues of AGN physics: (1) are torus-shaped dust structures and our various viewing angles into them indeed responsible for the apparent differences in Seyfert I and II galaxies, and (2) how does the gas reservoir in these tori feed the accretion disks around the black holes? © 2008 Springer-Verlag Berlin Heidelberg.