The true importance of the warm , AGN-driven outflows for the evolution of galaxies remains uncertain .
Measurements of the radial extents of the outflows are key for quantifying their masses and kinetic powers , and also establishing whether the AGN outflows are galaxy-wide .
Therefore , as part of a larger project to investigate the significance of warm , AGN-driven outflows in the most rapidly evolving galaxies in the local universe , here we present deep Hubble Space Telescope ( HST ) narrow-band [ OIII ] \lambda 5007 observations of a complete sample of 8 nearby ULIRGs with optical AGN nuclei .
Combined with the complementary information provided by our ground-based spectroscopy , the HST images show that the warm gas outflows are relatively compact for most of the objects in the sample : in three objects the outflow regions are barely resolved at the resolution of HST ( 0.065 < R _ { [ OIII ] } < 0.12 kpc ) ; in a further four cases the outflows are spatially resolved but with flux weighted mean radii in the range 0.65 < R _ { [ OIII ] } < 1.2 kpc ; and in only one object ( Mrk273 ) is there clear evidence for a more extended outflow , with a maximum extent of R _ { [ OIII ] } \sim 5 kpc .
Overall , our observations show little evidence for the galaxy-wide outflows predicted by some models of AGN feedback .