VLT/VIMOS integral field spectroscopy of luminous and ultraluminous
  infrared galaxies: 2D kinematic properties
  We present and discuss the 2D kinematic properties of the ionized gas
(Halpha) in a sample of 38 local (ultra) luminous infrared galaxies [(U)LIRGs]
(31 LIRGs and 7 ULIRGs) observed with VIMOS at the VLT using integral field
spectroscopy. This sample covers well the less studied LIRG luminosity range
and includes isolated disks, interacting systems, and mergers. The majority of
the galaxies have two main kinematically distinct components. One component
(i.e., narrow or systemic) extends over the whole line-emitting region and is
characterized by small to intermediate velocity dispersions (i.e., sigma from
30 to 160 km s^-1). It traces the overall velocity field. The second component
(broad) has in general a larger velocity dispersion (up to 320 km s^-1), mainly
found in the inner regions and generally blueshifted with respect to the
systemic component. Most of the objects (76%) are dominated by rotation, more
relevant in LIRGs than in ULIRGs. Isolated disks, interacting galaxies, and
merging systems define a sequence of increasing mean velocity dispersion, and
decreasing velocity field amplitude.The LIRGs classified as isolated disks have
similar velocity amplitudes but larger mean velocity dispersions (44 vs. 24 km
s^-1) than local spirals, implying a larger turbulence and thicker disks.
Interacting systems and mergers have values closer to those of low velocity
dispersion ellipticals/lenticular galaxies (E/SOs). The (U)LIRGs classified as
mergers have kinematic properties similar to those shown by the Lyman break
analogs (LBAs). The dynamical masses range from \sim 0.04 m* to 1.4 m* (i.e.,
m* = 1.4x10^{11} Msun), with ULIRGs (M{dyn} sim 0.5 +/- 0.2 m*) being more
massive than LIRGs by, on average, a factor of about 2. The mass ratio of
individual pre-coalescence galaxies is <2.5 for most of the systems, confirming
that most (U)LIRG mergers involve sub-m* galaxies of similar mass.
