Halo Gas and Galaxy Disk Kinematics Derived from Observations and ΛCDM Simulations of Mg II Absorption-selected Galaxies at Intermediate Redshift
Abstract
We obtained ESI/Keck rotation curves of 10 Mg II absorption-selected galaxies (0.3 ≤ z ≤ 1.0) for which we have WFPC-2/HST images and high-resolution HIRES/Keck and UVES/VLT quasar spectra of the Mg II absorption profiles. We perform a kinematic comparison of these galaxies and their associated halo Mg II absorption. For all 10 galaxies, the majority of the absorption velocities lie in the range of the observed galaxy rotation velocities. In 7/10 cases, the absorption velocities reside fully to one side of the galaxy systemic velocity and usually align with one arm of the rotation curve. In all cases, a constant rotating thick-disk model poorly reproduces the full spread of observed Mg II absorption velocities when reasonably realistic parameters are employed. In 2/10 cases, the galaxy kinematics, star formation surface densities, and absorption kinematics have a resemblance to those of high-redshift galaxies showing strong outflows. We find that Mg II absorption velocity spread and optical depth distribution may be dependent on galaxy inclination. To further aid in the spatial-kinematic relationships of the data, we apply quasar absorption-line techniques to a galaxy (v_c = 180 km s^(–1)) embedded in ΛCDM simulations. In the simulations, Mg II absorption selects metal-enriched "halo" gas out to ~100 kpc from the galaxy, tidal streams, filaments, and small satellite galaxies. Within the limitations inherent in the simulations, the majority of the simulated Mg II absorption arises in the filaments and tidal streams and is infalling toward the galaxy with velocities between –200 km s^(-1) ≤ v_r ≤ –180 km s^(–1). The Mg II absorption velocity offset distribution (relative to the simulated galaxy) spans ~200 km s^(–1) with the lowest frequency of detecting Mg II at the galaxy systematic velocity.
Additional Information
© 2010 The American Astronomical Society. Issue 2 (2010 March 10); received 2008 July 7, accepted for publication 2009 December 17; published 2010 February 16. We thank Greg Wirth for his help and advice with ESI/Keck. We are grateful to A. Kravtsov for providing the hydro code. We are in debt to N. Gnedin creating the graphics package IFRIT. We thank Aneta Siemiginowska for her discussion regarding the X-ray data of Q127−145. We express our gratitude to the anonymous referee for a careful reading and for insightful comments that lead to an improved manuscript. C.W.C and G.G.K were funded by the NSF grant AST 0708210. G.G.K was partially funded by the NMSU Graduate Research Enhancement Grant. M.T.M thanks the Australian Research Council for a QEII Research Fellowship (DP0877998). Most of the data presented herein were obtained at the W. M. Keck Observatory, which is operated as a scientific partnership among the California Institute of Technology, the University of California and the National Aeronautics and Space Administration. The Observatory was made possible by the generous financial support of the W. M. Keck Foundation. Some observations were made with the NASA/ESA Hubble Space Telescope, obtained from the Data Archive at the Space Telescope Science Institute, which is operated by the Association of Universities for Research in Astronomy, Inc., under NASA contract NAS 5–26555. Some of this research was based on observations made with ESO Telescopes at the Paranal Observatories under program IDs listed in Table 1. The computer simulations presented in this paper were performed at the National Energy Research Scientific Computing Center (NERSC) of the Lawrence Berkeley National Laboratory.Attached Files
Published - Kacprzak2010p7261Astrophys_J.pdf
Files
| Name | Size | Download all |
|---|---|---|
|
md5:09d2f7f08998df86df7b8323db8a46e6
|
2.7 MB | Preview Download |
Additional details
- Eprint ID
- 17766
- Resolver ID
- CaltechAUTHORS:20100317-113658511
- AST-0708210
- NSF
- New Mexico State University
- DP0877998
- Australian Research Council
- W. M. Keck Foundation
- NAS 5–26555
- NASA
- Created
-
2010-03-17Created from EPrint's datestamp field
- Updated
-
2021-11-08Created from EPrint's last_modified field