The Kinematic Connection between absorbing Gas toward QSOs and Galaxies at Intermediate Redshift

By C. Steidel, Juna A. Kollmeier, A. Shapley, C. Churchill, Mark Dickinson, M. Pettini. 2002

160 citations recorded by the source corpus.

We present complementary data on five intermediate-redshift (0.44 ≤ z ≤ 0.66) Mg II-absorbing galaxies, combining high spatial resolution imaging from the Hubble Space Telescope, high-resolution quasi-stellar object (QSO) spectroscopy from the Keck High Resolution Echelle Spectrometer, and galaxy kinematics from intermediate-resolution spectroscopy using the Keck Low-Resolution Imaging Spectrometer. These data allow a direct comparison of the kinematics of gas at large galactocentric impact parameters with the galaxy kinematics obtained from the faint galaxy spectroscopy. All five galaxies appear to be relatively normal spirals, with measured rotation curves yielding circular velocities in the range 100 ≤ vc ≤ 260 km s-1. The QSO sight lines have projected impact parameters to the absorbing galaxies in the range 14.5 h-1 kpc ≤ d ≤ 75 h-1 kpc; the galaxies have inclination angles with respect to the line of sight ranging from 40° to 75°. We find that in four of the five cases examined, the velocities of all of the Mg II-absorption components lie entirely to one side of the galaxy systemic redshift. The fifth case, for which the galaxy is much less luminous than the other four, has narrow absorption centered at zero velocity with respect to systemic, despite having the largest disk inclination angle in the sample. These observations are consistent with rotation being dominant for the absorbing-gas kinematics; however, the total range of velocities observed is inconsistent with simple disk rotation in every case. Simple kinematic models that simultaneously explain both the systemic offset of the absorbing material relative to the galaxy redshifts and the total velocity width spanned by the absorption require either extremely thick rotating gas layers, rotation velocities that vary with z-height above the extrapolation of the galactic plane, or both. In any case, our small sample suggests that rotating "halo" gas is a common feature of intermediate-redshift spiral galaxies and that the kinematic signature of rotation dominates over radial infall or outflow even for gas well away from the galactic plane. We discuss possible explanations for this behavior and compare our observations with possible local analogs.

Subfields: Astronomy and Astrophysics, Instrumentation

View Paper: https://www.semanticscholar.org/paper/3537a6d18c4155af2afd73b09451d30b7d11c68f

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In Astronomy and Astrophysics

1. L. Hernquist
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In Instrumentation

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7. A. Shapley
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Citations in the corpus

• First results from the TNG50 simulation: galactic outflows driven by supernovae and black hole feedback (2019, background): “Outflows are usually observed through the Doppler shift of specific gas tracers, either through blueshifted features in absorption (e.g. Steidel et al. 2002), or through broad line components in emission (e.g. Heckman et al. 1990).”
• THE COS-HALOS SURVEY: AN EMPIRICAL DESCRIPTION OF METAL-LINE ABSORPTION IN THE LOW-REDSHIFT CIRCUMGALACTIC MEDIUM (2012, background): “This appears to contrast with previous work on Mg ii kinematics, where the profiles have tended to lie on only one side of systemic (Steidel et al. 2002; Kacprzak et al. 2010).”
• Mg II Absorption Systems in Sloan Digital Sky Survey QSO Spectra (2005, background): “Disks certainly contribute at least partially to the absorber population, as suggested by Charlton & Churchill (1998) and confirmed for specific cases by Steidel et al. (2002).”
• Four phases of angular-momentum buildup in high-z galaxies: from cosmic-web streams through an extended ring to disc and bulge (2014, background): “…lines at large radii in intermediate-redshift galaxies (z < 1) indicate velocities consistent with rotation in terms of magnitude and in terms of residing in one side of the galaxy systemic velocity, typically aligned with one arm of the rotation curve (Steidel et al. 2002; Kacprzak et al. 2010).”
• TRACING OUTFLOWS AND ACCRETION: A BIMODAL AZIMUTHAL DEPENDENCE OF Mg ii ABSORPTION (2012, unknown): “…al. 2010; Bordoloi et al. 2011; Coil et al. 2011; Rubin et al. 2010; Ménard & Fukugita 2012; Martin et al. 2012) and accretion onto host galaxies (Steidel et al. 2002; Chen et al. 2010a; Chen et al. 2010b; Kacprzak et al. 2010a, 2011b; Stewart et al. 2011; Ribaudo et al. 2011; Kacprzak et al.…”
• AN EMPIRICAL CHARACTERIZATION OF EXTENDED COOL GAS AROUND GALAXIES USING Mg ii ABSORPTION FEATURES (2010, methodology): “…velocity dispersion between the galaxy–MgII absorber pair sample is comparable to the velocity dispersion seen in a Milky-Way size galaxy (see also Steidel et al. 2002; Chen et al. 2005; Kacprzak et al. 2010 for rotation curve comparisons of galaxies and strong absorbers at intermediate…”
• Gemini Near-Infrared Spectroscopy of Luminous z ∼ 6 Quasars: Chemical Abundances, Black Hole Masses, and Mg II Absorption (2007, background): “Strong Mg ii absorption systems are usually directly associated with galaxy halos or disks (e.g., Charlton&Churchill 1998; Churchill et al. 2000; Steidel et al. 2002).”
• THE STRUCTURE AND KINEMATICS OF THE CIRCUMGALACTIC MEDIUM FROM FAR-ULTRAVIOLET SPECTRA OF z ≃ 2–3 GALAXIES (2010, methodology): “…the QSO is compared with galaxies with known redshifts and projected separations (e.g., Bergeron & Boissé 1991; Steidel et al. 1994; Chen et al. 2001; Steidel et al. 2002; Lanzetta et al. 1995; Danforth & Shull 2008; Bowen et al. 1995; Bouché et al. 2007; Kacprzak et al. 2009); most of this work…”