Molecular Gas in Optically Bright QSOs

Testing the evolutionary connection between ULIRGs and QSO hosts has been a key component in the study of both galaxy types and suggests that optically bright QSOs might still reside in molecular gas-rich environments with ongoing star formation. We present here a study of the molecular gas properties of a sample of z < 0.3 luminous Palomar-Green (PG) QSO hosts. This study consists of two components: The first is an IRAM 30m Telescope survey of CO emission from the PG QSO hosts, which shows that a significant fraction (30%) of PG QSO hosts are indeed molecular gas-rich. The second is a pilot ALMA observational study of CO(3-2) emission from 4 PG QSO hosts with 200-500 pc spatial and 10km/s velocity resolution. Our high- resolution ALMA observations reveal a diverse morphology and kinematics of the molecular gas in these hosts and show that the properties of the star formation rate in the high-density region in the vicinity of AGN are similar to that of ULIRGs. However, the current high-resolution ALMA observation misses large scale diffuse faint emission and indicates that lower resolution ALMA observations are required to have a complete picture of the molecular gas in the QSO host