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Session 56 - Active Galaxies: The Central Engine.
Oral session, Tuesday, January 16
Corte Real, Hilton
We have resolved the water maser in the well-known active nucleus of NGC 1068, using the VLBA. The maser sources exhibit emission at the systemic velocity of the galaxy and in emission complexes that are red and blueshifted by up to about 300 km s^-1. We observed the systemic and redshifted emission. We use the water maser emission to probe the dynamics of nuclear gas within 2 pc of the AGN central engine.
The maser emission is distributed roughly along a line at a position angle of about -45^\circ, over about 1.5 pc. The emission displays strong velocity gradients and turbulence. The position angle is close to that of the wall of the ionization cone associated with the radio jet in this nucleus. The masers emission probably arises on the surface of a thick molecular disk, surrounding the axis of the jet. The emission may be excited by interaction of the jet and the surrounding medium. We contrast this scenario with the thin edge-on disk traced by water masers in NGC 4258.
