Molecuar Gas in Infrared Ultraluminous QSOs

摘要

We report the detections of molecular gas in 15/19 infrared ultraluminous QSOs (IR QSOs) using the IRAM 30m. The gas reservoir in these objects is several times 10~9M_☉ to 10~(10)M_☉ that is much higher than those of optically selected Palomar-Green QSOs. In addition, the star formation efficiency, indicating by LFIR and L′_(CO), and the CO (1-0) line widths for IR QSOs are similar to those of ULIRGs. With a typical star formation rate of few times 100M_☉yr~(-1), the cold molecular gas will be consumed within several times 10~7 to 10~8 years. By comparing with low-z and high-z CO detected QSOs, we find that there exists tight correlation between LFIR and L′_(CO) for all QSOs, implying that the far infrared emission is mainly from star formation for QSOs.