  Integral field optical spectroscopy with the INTEGRAL fiber-based systemis
used to map the extended ionized regions and gas flows in Mrk 273, one of the
closest Ultraluminous Infrared galaxies (ULIRGs).
  The Hbeta and [OIII]5007 maps show the presence of two distinct regions
separated by 4'' (3.1 kpc) along position angle (PA) 240. The northeastern
region coincides with the optical nucleus of the galaxy and shows the spectral
characteristics of LINERs. The southwestern region is dominated by [OIII]
emission and is classified as a Seyfert 2. Therefore, in the optical, Mrk 273
is an ultraluminous infrared galaxy with a LINER nucleus and an extended
off-nucleus Seyfert 2 nebula.
  The kinematics of the [OIII] ionized gas shows (i) the presence of highly
disturbed gas in the regions around the LINER nucleus, (ii) a high-velocity gas
flow with a peak-to-peak amplitude of 2.4 x 10^3 km/s, and (iii) quiescent gas
in the outer regions (at 3 kpc). We hypothesize that the high-velocity flow is
the starburst-driven superwind generated in an optically obscured nuclear
starburst, and that the quiescent gas is directly ionized by a nuclear source,
like the ionization cones typically seen in Seyfert galaxies.

Astrophysics