The Distribution and Kinematics of Cold Near-Nuclear Gas in AGN

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Session 122 -- AGN: Accretion Disks, Tori and Gas
Oral presentation, Saturday, January 15, 2:15-3:45, Salon IV Room (Crystal Gateway)

[122.05] The Distribution and Kinematics of Cold Near-Nuclear Gas in AGN

J. Gallimore (UMd/STScI)

The kinematics and distribution of near nuclear cold gas in AGN is essentially unknown, in large part because the low emissivity of this gas precludes direct measurement. We have initiated a program to determine the kinematics and spatial distribution of cold nuclear gas in AGN using the technique of synthesis mapping of HI (and OH) in absorption against a spatially resolved radio continuum source. These measurements will allow us to address a number of key astrophysical questions; (1) What are the masses of the `central engines' in Seyfert galaxies, (2) Is there evidence for infalling neutral matter which could fuel the activity and if so, can we trace that inflow from the hundreds of parsec scale inward?, (3) How is the pc scale ionised and neutral gas related in Seyferts?, (4) Can we find evidence for `tori' of cold obscuring matter in Seyfert 2s, as predicted by the unified schemes?

We have recently completed HI VLA A array absorption studies of 12 Seyfert galaxies. We have obtained followup Merlin observations for NGC 1068 and NGC 3079. In NGC 1068 we have determined unambiguously the orientation of the linear radio structure; namely the NE lobe is pointed towards us. We have found supportive evidence for an AGN-driven outflow at the SW jet. We also find a kinematic disturbance and optical depth enhancement in the HI in the inner disk which suggests we are witnessing a bar-driven shock. In NGC 3079, the absorption profile is too broad to be explained by disk gas but must instead arise primarily in rapidly moving clouds located near the radio source. Slightly resolved, blue and redshifted absorption lines may be due to a ring of cold gas with a radius of $\sim 90$ parsecs. The mass interior to this postulated ring is $>10^{8}$ solar masses, implying an extremely dense stellar core or a compact central object.

We report here on the preliminary results for the sample as a whole, and on the more detailed results for NGC3079 and NGC 1068.

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