The biconical outflow in the Seyfert galaxy NGC 2992

We report on a detailed kinematic study of the galactic-scale outflow in th e Seyfert galaxy NGC 2992. The TAURUS-2 imaging Fabry-Perot interferometer was used on the 3.9 m Anglo-Australian Telescope to derive the two-dimensio nal velocity field of the Ha-emitting gas over the central arcminute of NGC 2992. The complete two-dimensional coverage of the data combined with simp le kinematic models of rotating axisymmetric disks allow us to differentiat e the outflowing material from the line-emitting material associated with t he galactic disk. The kinematics of the disk component out to R = 3.0 kpc a re well modeled by pure circular rotation in a plane inclined at i = 68 deg rees +/- 3 degrees from the plane of the sky and with kinematic major axis along P.A. 32% +/- 3 degrees. The outflow component is distributed into two wide cones with opening angle =125 degrees -135 degrees and extending -2.8 kpc (18 ") on both sides of the nucleus at nearly right angles (Theta = 11 6 degrees +/- 5 degrees) to the disk kinematic major axis. The outflow on t he southeastern side of the nucleus is made of two distinct kinematic compo nents interpreted as the front and back walls of a cone. The azimuthal velo city gradient in the back-wall component reflects residual rotational motio n, which indicates either that the outflowing material was lifted from the disk or that the underlying galactic disk is contributing slightly to this component. A single outflow component is detected in the northwestern cone. A biconical outflow model with velocities ranging from 50 to 200 km s(1) a nd oriented nearly perpendicular to the galactic disk can explain the data. The broad-line profiles and asymmetries in the velocity fields suggest tha t some of the entrained line-emitting material may lie inside the biconical structure rather than only on the surface of the bicone. The mass involved in this outflow is of order 1 x 10(7) n(e,2)(1) M-., and the bulk and " tu rbulent" kinematic energies are 6 x 10(53) n(e,2)(1) ergs and 3 x 10(54) n( e,2)(1) ergs, respectively. The most likely energy source is a ot, bipolar, thermal wind powered on a subkiloparsec scale by the active galactic nucle us and diverted along the galaxyIs minor axis by the pressure gradient of t he ISM in the host galaxy. The data are not consistent with a starburstdriv en wind or a collimated outflow powered by radio jets.