Millimeter CO ( 1 \to 0 ) interferometry and high resolution , Hubble Space Telescope ( HST ) 1.1 , 1.6 , and 2.2 \mu m imaging of the radio compact galaxy PKS 1345+12 are presented .
With an infrared luminosity of \sim 2 \times 10 ^ { 12 } L _ { \odot } , PKS 1345+12 is a prime candidate for studying the link between the ultraluminous infrared galaxy phenomenon and radio galaxies .
These new observations probe the molecular gas distribution and obscured nuclear regions of PKS 1345+12 and provide morphological support for the idea that the radio activity in powerful radio galaxies is triggered by the merger of gas rich galaxies .
Two nuclei separated by 2 \arcsec ( 4.0 kpc ) are observed in the near-infrared ; the extended southeastern nucleus has colors consistent with reddened starlight , and the compact northwestern nucleus has extremely red colors indicative of an optical quasar with a warm dust component .
Further , the molecular gas , 3mm continuum , and radio emission are coincident with the redder nucleus , confirming that the northwestern nucleus is the site of the AGN and that the molecular gas is the likely fuel source .