The Biconical Outflow in the Seyfert Galaxy NGC 2992

We report on a detailed kinematic study of the galactic-scale outflow in theSeyfert galaxy NGC 2992. The TAURUS-2 Imaging Fabry-Perot Interferometer wasused on the Anglo-Australian 3.9-m telescope to derive the two-dimensionalvelocity field of the Halpha-emitting gas over the central arcminute of NGC2992. The complete two-dimensional coverage of the data combined with simplekinematic models of rotating axisymmetric disks allows us to differentiate theoutflowing material from the line-emitting material associated with thegalactic disk. The kinematics of the disk component out to R = 3.0 kpc are wellmodeled by pure circular rotation. The outflow component is distributed intotwo wide cones with opening angle of 125 -- 135 degrees and extending 2.8 kpc(18") on both sides of the nucleus at nearly right angles to the disk kinematicmajor axis. The outflow on the SE side of the nucleus is made of two distinctkinematic components interpreted as the front and back walls of a cone. Theazimuthal velocity gradient in the back-wall component reflects residualrotational motion which indicates either that the outflowing material waslifted from the disk or that the underlying galactic disk is contributingslightly to this component. A single outflow component is detected in the NWcone. The most likely energy source for this outflow is a hot bipolar thermalwind powered on sub-kpc scale by the AGN and diverted along the galaxy minoraxis by the pressure gradient of the ISM in the host galaxy. The data are notconsistent with a starburst-driven wind or a collimated outflow powered byradio jets. (abridged)Comment: 28 pages including 8 figures (2 ps, 6 jpeg), Latex w/ aaspp4.st