Name: Erin Hicks
Max-Planck-Institut fuer extraterrestrische Physik

University of Washington

Astrolunch

Abstract:
In a survey of a dozen nearby AGN the distribution and kinematics of the nuclear molecular hydrogen and stars are found to be consistent with an obscuring torus. Data obtained with the near infrared adaptive optics integral field spectrometers SINFONI on the VLT and OSIRIS on Keck used both natural and laser guide stars to achieve a spatial resolution down to 0".085, corresponding to less than 10 pc in some objects. The stellar and gas light profiles indicate they are in a disk-like distribution with size scales of 10-60 pc, consistent with obscuring torus models. The gas column density at these same radii, estimated to be at least 1023 cm^-2, is sufficient to provide the needed obscuration of the AGN. The stellar and gas kinematics in the nuclear region are measured to be in ordered rotation with velocity gradients of 60-120 km s^-1 across the central 50 pc. The 70-130 km s^-1 velocity dispersion of the gas is comparable to, or greater than, the rotational velocity on scales similar to that of the gas disk, suggesting a geometrically thick distribution consistent with obscuring torus models. This vertical structure is likely due to turbulence in the gas caused by heating from star formation (there is evidence of recent nuclear starburst activity) and/or the AGN. The similarity of the stellar and molecular hydrogen distributions and kinematics suggests a torus composed of mixed molecular gas and stars. In addition, modeling of both the stellar and molecular gas kinematics has provided direct measurements of the black holes masses, confirming that indirect measurement techniques, such as reverberation mapping, are accurate to within a factor of two.