Resolving the Interstellar Medium in Ultraluminous Infrared QSO Hosts with ALMA

Abstract

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 luminous QSO and a companion galaxy separated by a few kpc. The molecular gas in three of IR QSO hosts are found to be rotation-dominated with the ratio of the maximum rotation velocity to the local velocity dispersion of V rot /σ = 4 − 6. Basic estimates of the dynamical masses within the CO-emitting regions give masses between 7.4 × 10 9 and 6.9 × 10 10 M . We find an increasing trend between BH mass accretion rate and star formation rate (SFR) over three orders of magnitude in far-IR luminosity/SFR, in line with the correlation between QSO bolometric luminosity and SF activity, indicative of a likely direct connection between AGN and SF activity over galaxy evolution timescales.

Unravelling the origin of extended radio emission in narrow-line Seyfert 1 galaxies with the JVLA

“…Its integrated flux density is 14.58 mJy, with the flux density of the tapered maps approximately similar. It exhibits starburst level star formation at a rate of 183 M yr −1 derived from the CO(1-0) luminosity (Tan et al 2019). This is evident also in our star formation diagnostics, as the W3-W4 colour is 2.88, q22 = 1.23, S W3 is 153.7 mJy higher than S 1.4GHz, JVLA (45.3 mJy).…”

“…However, its radio luminosity, log νL ν,int = 40.43 erg s −1 , would be high even for a starburst galaxy, and thus it is plausible that radio emission is a combination of nuclear and star formation related processes. Tan et al (2019) in ALMA observations found a rotating gas disk with ordered velocity gradient, indicating that the host (Figs. B.2e and B.2f) is a disk galaxy which has not undergone any recent merger.…”

Symbiosis of radio-emitting winds and a jet in a super-Eddington active galactic nucleus

“…The jet-ISM collision interpretation is supported by the parameter η < 1 (Figure 6), which suggests that a dense environment hinders the expansion of the jet plasma 45 . Further support is provided by recent observations of I Zw 1 at other bands: the direction of the kilo-parsec-scale molecular gas disc was found 46,47 to be approximately along the parsec-scale jet direction here, and a radius of ∼7 mas (∼8 pc) torus is also proposed 48 .…”

“…Our observations reveal that the jet direction in I Zw 1 is along the kpc-scale molecular disk 46,47 , which is suggesting that the kpc-scale molecular disk (direction of the axis) is tilted with the inner accretion disk axis or BH spin. 51 , following the standard procedure.…”

Past, Present, and Future of the Scaling Relations of Galaxies and Active Galactic Nuclei

“…CO emission profiles have been used to estimate dynamical masses for individual objects since the early 2000s (Walter et al, 2003) even at fairly high redshift, and nowadays ALMA is rapidly adding to the available dynamical mass measurements for the host galaxy [e.g. (Tan et al, 2019;Molina et al, 2021)], considering that the velocity field of the molecular gas is often regular and consistent with rotation. State-of-the-art surface photometry of the AGN host galaxies in the NIR achieves decomposition in spheroid, disk, and bar component, as most of the host of nearby Seyfert galaxies are of morphological type Sa/SBa.…”