Integral field spectroscopy of Markarian 273: Mapping high-velocity gas flows and an off-nucleus Seyfert 2 nebula

Integral field optical spectroscopy with the INTEGRAL fiber-based system is used to map the extended ionized regions and gas flows in Mrk 273, one of the closest ultraluminous infrared galaxies. The H beta and [O III] lambda 5007 maps show the presence of two distinct regions separated by 4" (3.1 kp c) along position angle (P.A.) 240 degrees. The northeastern region coincid es with the optical nucleus of the galaxy and shows the spectral characteri stics of LINERs. The southwestern region is dominated by [O In] emission an d is classified as a Seyfert 2. Therefore, in the optical, Mrk 273 is an ul traluminous infrared galaxy with a LINER nucleus and an extended off-nucleu s Seyfert 2 nebula. The kinematics of the [O III] ionized gas shows (1) the presence of highly disturbed gas in the regions around the LINER nucleus, (2) a high-velocity gas flow with a peak-to-peak amplitude of 2.4 x 10(3) k m s(-1), and (3) quiescent gas in the outer regions (at 3 kpc). We hypothes ize that the high-velocity flow is the starburst-driven superwind generated in an optically obscured nuclear starburst and that the quiescent gas is d irectly ionized by a nuclear source, similar to the ionization cones typica lly seen in Seyfert galaxies.