Keck OSIRIS AO LIRG Analysis: Feedback in the Nuclei of Luminous
  Infrared Galaxies
  The role of feedback in triggering or quenching star formation and hence
driving galaxy evolution can be directly studied with high resolution integral
field observations. The manifestation of feedback in shocks is particularly
important to examine in galaxy mergers, where violent interactions of gas takes
place in the interstellar medium during the course of the galactic collision.
As part of our effort to systematically study the local population of luminous
infrared galaxies within the Great Observatories All-Sky LIRG Survey, we
undertook the Keck OSIRIS AO LIRG Analysis observing campaign to study the gas
dynamics in the inner kiloparsec regions of these systems at spatial scales of
a few 10s of parsecs. With high-resolution near-infrared adaptive
optics-assisted integral-field observations taken with OSIRIS on the Keck
Telescopes, we employ near-infrared diagnostics such as Brg and the
ro-vibrationally excited H2 lines to quantify the nuclear star formation rate
and identify feedback associated with shocked molecular gas seen in 21 nearby
luminous infrared galaxies. Shocked molecular gas is preferentially found in
the ultraluminous infrared systems, but may also be triggered at a lower
luminosity, earlier merging stage. On circumnuclear scales, AGN have a strong
effect on heating the surrounding molecular gas, though their coupling is not
simply driven by AGN strength but rather is complicated by orientation, dust
shielding, density, and other factors. We find that the nuclear star formation
correlates with merger class and diminishing projected nuclear separations.
These trends are largely consistent with the picture of merger-induced
starbursts within the center of galaxy mergers.
