Resolving the Interstellar Medium in Ultraluminous Infrared QSO Hosts with ALMA

• Published in: The Astrophysical journal Vol. 887; no. 1; pp. 24 - 43
• Main Authors: Tan, Qing-Hua, Gao, Yu, Kohno, Kotaro, Xia, Xiao-Yang, Omont, Alain, Hao, Cai-Na, Mao, Shu-De, Daddi, Emanuele, Shi, Yong, Zhao, Ying-He, Cox, Pierre
• Format: Journal Article
• Language: English
• Published: Philadelphia The American Astronomical Society 10.12.2019; IOP Publishing; American Astronomical Society
• Subjects: Accretion; Active galactic nuclei; AGN host galaxies; Astrophysics; Bolometers; Continuum radiation; Deposition; Emissions; Galactic evolution; Galaxies; Interstellar matter; Interstellar medium; Kinematics; Luminosity; Molecular gases; Morphology; Quasars; Rotating disks; Rotation; Sciences of the Universe; Star & galaxy formation; Star formation; Star formation rate; Starburst galaxies; Stellar evolution; Velocity; Velocity gradient; AGN host galaxies; Astrophysics - Astrophysics of Galaxies; 1570; 2017; Starburst galaxies
• ISSN: 0004-637X; 1538-4357
• DOI: 10.3847/1538-4357/ab50be

We present ALMA observations of the CO(1−0) line and 3 mm continuum emission in eight ultraluminous infrared (IR) quasi-stellar objects (QSOs) at z = 0.06-0.19. All eight IR QSO hosts are clearly resolved in their CO molecular gas emission with a median source size of 3.2 kpc, and seven out of eight sources are detected in 3 mm continuum, which is found to be more centrally concentrated with respect to molecular gas with sizes of 0.4−1.0 kpc. Our observations reveal a diversity of CO morphology and kinematics for the IR QSO systems, which can be roughly classified into three categories: rotating gas disk with ordered velocity gradient, compact CO peak with disturbed velocity, and multiple CO distinct sources undergoing a merger between a luminous QSO and a companion galaxy separated by a few kpc. The molecular gas in three of the IR QSO hosts is found to be rotation-dominated with a ratio of the maximum rotation velocity to the local velocity dispersion of Vrot/ = 4-6. Basic estimates of the dynamical masses within the CO-emitting regions give masses between 7.4 × 109 and 6.9 × 1010 M . We find an increasing trend between black hole mass accretion rate and star formation rate (SFR) over 3 orders of magnitude in far-IR luminosity/SFR, in line with the correlation between QSO bolometric luminosity and star formation activity, indicative of a likely direct connection between active galactic nuclei and star formation activity over galaxy evolution timescales.