Browsing by Author "Fei, Qinyue"

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    Constraining Quasar Feedback from Analysis of the Hydrostatic Equilibrium of the Molecular Gas in Their Host Galaxies
    (Institute of Physics, 2024) Fei, Qinyue; Wang, Ran; Molina, Juan; Ho, Luis C.; Shangguan, Jinyi; Bauer, Franz Erik; Treister, Ezequiel
    We investigate the kinematics and dynamics of the molecular and ionized gas in the host galaxies of three Palomar-Green quasars at low redshifts, benefiting from the archival millimeter-wave interferometric and optical integral field unit data. We study the kinematics of both cold molecular and hot ionized gas by analyzing the CO and Hα data cubes, and construct the mass distributions of our sample through gas dynamics, utilizing a priori knowledge regarding the galaxy light distribution. We find no systematic offset between the stellar mass derived from our dynamical method and that from the broadband photometry and mass-to-light ratio, suggesting the consistency of both methods. We then study the kinetic pressure and the weight of the interstellar medium (ISM) using our dynamical mass model. By studying the relationship between kinetic pressure and gravitational pressure of the quasar host galaxies, we find an equivalence in the hydrostatic equilibrium states of ISM in the quasar host galaxies, similar to the result of gas equilibrium in normal star-forming galaxies, suggesting minimal quasar feedback. Regarding noncircular motion as indicative of quasar-driven outflows, we observe an exceptionally low coupling efficiency between molecular gas outflow and active galactic nucleus bolometric luminosities. These results demonstrate the marginal influence of the central engine on the properties of cold molecular gas in quasar host galaxies.
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    Dynamics of Molecular Gas in the Central Region of the Quasar I Zwicky 1
    (2023) Fei, Qinyue; Wang, Ran; Molina, Juan; Shangguan, Jinyi; Ho, Luis C.; Bauer, Franz E.; Treister, Ezequiel
    We present a study of the molecular gas distribution and kinematics in the cicumnuclear region (radii less than or similar to 2 kpc) of the z approximate to 0.061 quasar I Zwicky 1 using a collection of available Atacama Large Millimeter/submillimeter Array observations of the carbon monoxide (CO) emission. With an angular resolution of similar to 0.'' 36 (corresponding to similar to 400 pc), the host-galaxy substructures including the nuclear molecular gas disk, spiral arms, and a compact bar-like component are resolved. We analyzed the gas kinematics based on the CO image cube and obtained the rotation curve and radial distribution of velocity dispersion. The velocity dispersion is about 30 km s(-1) in the outer CO disk region and rises up to greater than or similar to 100 km s(-1) at radius less than or similar to 1 kpc, suggesting that the central region of the disk is dynamically hot. We constrain the CO-to-H-2 conversion factor, alpha(CO), by modeling the cold gas disk dynamics. We find that, with prior knowledge about the stellar and dark matter components, the alpha(CO) value in the circumnuclear region of this quasar host galaxy is 1.55(-0.49)(+0.47) M-circle dot (K km s(-1) pc(2))(-1), which is between the value reported in ultraluminous infrared galaxies and in the Milky Way. The central 1 kpc region of this quasar host galaxy has significant star formation activity, which can be identified as a nuclear starburst. We further investigate the high-velocity dispersion in the central region. We find that the interstellar medium (ISM) turbulent pressure derived from the gas velocity dispersion is in equilibrium with the weight of the ISM. This argues against extra power from active galactic nuclei feedback that significantly affects the kinematics of the cold molecular gas.