We report CO detections in 17 out of 19 infrared ultraluminous QSO ( IR QSO ) hosts observed with the IRAM 30m telescope .
The cold molecular gas reservoir in these objects is in a range of 0.2–2.1 \times 10 ^ { 10 } M _ { \odot } ( adopting a CO-to- { H _ { 2 } } conversion factor \alpha _ { CO } = 0.8 M _ { \odot } { ( K~ { } km s ^ { -1 } ~ { } pc ^ { 2 } ) ^ { -1 } } ) .
We find that the molecular gas properties of IR QSOs , such as the molecular gas mass , star formation efficiency ( L _ { FIR } / L ^ { \prime } _ { CO } ) and the CO ( 1-0 ) line widths , are indistinguishable from those of local ultraluminous infrared galaxies ( ULIRGs ) .
A comparison of low- and high-redshift CO detected QSOs reveals a tight correlation between L _ { FIR } and L ^ { \prime } _ { CO ( 1 - 0 ) } for all QSOs .
This suggests that , similar to ULIRGs , the far-infrared emissions of all QSOs are mainly from dust heated by star formation rather than by active galactic nuclei ( AGNs ) , confirming similar findings from mid-infrared spectroscopic observations by Spitzer .
A correlation between the AGN-associated bolometric luminosities and the CO line luminosities suggests that star formation and AGNs draw from the same reservoir of gas and there is a link between star formation on \sim kpc scale and the central black hole accretion process on much smaller scales .