Title: The Infrared Ultraluminous QSOs

Speaker: Xiaoyang Xia (Tianjin Normal University)

Time & Place: Thursday, 3.00pm, April 25th, Lecture Hall, 3rd floor

Abstract: In my talk I will introduce the multi-wavelength properties of infrared ultraluminous QSOs, discussing the growth of the central black hole and spheroid of the QSO host based on low and high redshift samples of infrared ultraluminous QSOs with CO detections. The gas reservoir of infrared ultraluminous QSOs ranges from several times 10^9 M_sun to a few times 10^10 M_sun, suggesting that sufficient cold molecular gas exists to sustain massive starbursts for these QSOs. There also exists tight correlations between L_FIR and L_CO and between L_FIR and 6.2mum PAH luminosity, implying that the FIR emissions of all QSOs are mainly from star formation. The correlation between AGN-associated bolometric luminosities and L_CO indicates a possible link between the cold molecular gas on kpc scales (disk/ring) and the central black hole accretion process. Furthermore, the Mdot/SFR values for local infrared ultraluminous QSOs and a few high-redshift, relatively faint QSOs are comparable to the local M_BH/M_sph value. These QSOs might be in the transition stage from gas-rich galaxy mergers to QSOs then to elliptical galaxies, exhibiting both high SFR and high accretion rates. However, the local M_ BH/M_sph relation could not be established in this short transition phase. If the black hole continues to grow vigorously after this transition period, then the M_BH/M_sph relation might be established afterwards. On the other hand, for both local and very bright high-redshift QSOs, the black hole appears to grow much faster than the spheroids.