Jessica L. Evans

Morphological properties of z 0.5 absorption-selected galaxies: the role of galaxy inclination

We have used Galaxy IMage 2D (GIM2D) to quantify the morphological properties of 40 intermediate-redshift Mg ii absorption-selected galaxies [0.03 ≤ W_r(2796) ≤ 2.9 A], imaged with WFPC-2/Hubble Space Telescope (HST), and compared them to the halo gas properties measured from HIRES/Keck and UVES/VLT quasar spectra. We find that as the quasar–galaxy separation, D, increases the Mg ii equivalent decreases with large scatter, implying that D  is not the only physical parameter affecting the distribution and quantity of halo gas. Our main result shows that inclination correlates with Mg ii absorption properties after normalizing out the relationship (and scatter) between the absorption properties and D. We find a 4.3σ correlation between W_r(2796) and galaxy inclination, normalized by impact parameter, i/D. Other measures of absorption optical depth also correlate with i/D at greater than 3.2σ significance. Overall, this result suggests that Mg ii gas has a co-planer geometry, not necessarily disc-like, that is coupled to the galaxy inclination. It is plausible that the absorbing gas arises from tidal streams, satellites, filaments, etc., which tend to have somewhat co-planer distributions. This result does not support a picture in which Mg ii absorbers with W_r(2796) ≲ 1 A are predominantly produced by star formation driven winds. We further find that: (1) Mg ii host galaxies have quantitatively similar bulge and disc scalelength distribution to field galaxies at similar redshifts and have a mean disc and bulge scalelength of 3.8 and 2.5 kpc, respectively; (2) Galaxy colour and luminosity do not correlate strongly with absorption properties, implying a lack of a connection between host galaxy star formation rates and absorption strength; and (3) parameters such as scalelengths and bulge-to-total ratios do not significantly correlate with the absorption parameters, suggesting that the absorption is independent of galaxy size or mass.

A correlation between galaxy morphology and Mg II halo absorption strength

We compared the quantified morphological properties of 37 in termediate redshift (0.3 ≤ z ≤ 1) Mg II absorption selected galaxies to the properties of the absorbi ng halo gas [0.03 ≤ Wr(2796) ≤ 2.90 A], observed in the spectra of background quasars. The galaxy morphologies were measured using GIM2D modeling of Hubble Space TelescopeWFPC‐2 images and the absorbing gas properties were obtained from HIRES/Keck and UVES/VLT quasar spectra. We found a 3.1 � correlation between galaxy morphological asymmetries normalized by the quasar‐galaxy projected separations, A/D, and the Mg II rest‐frame equivalent widths. Saturation effects cause increased scatter in the relationshi p with increasing Wr(2796). We defined a subsample for which the fraction of saturated pixels in the absorption profiles is fsat < 0.5. This criterion resulted in a subsample of 28 systems with Wr(2796) ≤ 1.39 A. The correlation strengthened to 3.3 �. We also find a paucity of small morphological asymmetries for galaxies selected by Mg II absorption as compared to those of the general population of field galaxies, as measured in the M edium Deep Survey. The K‐S probability that the two samples are drawn from the same galaxy population is ruled out at a 99.8% confidence level. Based upon four different measures of galaxy asymmetry, it is evident that the morphological perturbations of galaxies selected by Mg II absorption are “minor” and centrally concentrated. The A/D‐Wr(2796) correlation suggests a connection between the processes that perturb galaxies and the quantity of gas in their halos, normalized by the impact parameter. Since the perturbations are minor, it is clear that dramatic processes or events are not required for a galaxy to have an extended halo; the galaxies appear “normal”. We suggest that common, more mild processes that populate halos with gas, such as satelli te galaxy merging, accretion of the local cosmic web, and longer‐range galaxy‐galaxy interactions, consequently also induce the observed minor perturbations in the galaxies. Subject headings:quasars: absorption lines—galaxies: halos—galaxies: interactions

MAGiiCAT V. ORIENTATION OF OUTFLOWS AND ACCRETION DETERMINE THE KINEMATICS AND COLUMN DENSITIES OF THE CIRCUMGALACTIC MEDIUM

We investigate the dependence of gas kinematics and column densities in the MgII-absorbing circumgalactic medium on galaxy color, azimuthal angle, and inclination to trace baryon cycle processes. Our sample of 30 foreground isolated galaxies at

MAGiiCAT IV. kinematics of the circumgalactic medium and evidence for quiescent evolution around Red Galaxies

0.3<z_{\rm gal}<1.0

THE REDSHIFT DISTRIBUTION OF INTERVENING WEAK Mg II QUASAR ABSORBERS AND A CURIOUS DEPENDENCE ON QUASAR LUMINOSITY

, imaged with the Hubble Space Telescope, are probed by background quasars within a projected distance of

Gas kinematics in the multiphase circumgalactic medium

20<D<110

On the Heterogeneity of Metal-Line and Lyα Absorption in Galaxy “Halos” at z ~ 0.7

kpc. From the high-resolution (

Resolution Effects on Quasar Absorption Line Studies of LambdaCDM Simulations

\Delta v\simeq 6.6

Constraints on Galactic Wind Physics in Cosmological Simulations using Absorption Profiles

km s

Resolution effects on quasar absorption line studies of lambda CDM

^{-1}