Galaxies With Accretion Signatures at z < 1
Physics Graduate Student, University of Notre Dame
The circumgalactic medium (CGM) acts as a gas reservoir, housing material that could be used for future star formation. How a galaxy accretes this material depends strongly on its mass, morphology, and orientation. Here I present two projects which observationally test these galaxy model predictions at z < 1. To test the predictions of morphology and orientation, I am using a blindly-selected sample of 35 HI absorbers (partial and Lyman limit systems with 16.0 ≤ logN_HI < 19.0 [cm^-2]) to identify and characterize the host galaxies. Half of these absorbers exhibit properties strongly suggesting an intergalactic medium origin. I will present results from the IFU observations focused on the low-metallicity absorbers. Galaxy models also predict that high-mass halos should house little cool gas due to the presence of accretion shocks. Using two samples of massive luminous red galaxies (21 galaxies with QSO sightlines probing the outer CGM out to ~R_vir and 50 galaxies with QSO sightlines probing the inner CGM to ~0.3 R_vir), I will present the HI covering factor in these halos. When comparing the amount of cool gas in galaxy halos over the range 9 ≤ logM_star ≤ 12 M_sun, there is little difference. The metallicity distributions of the gas are also indistinguishable, with some of the lowest-metallicity gas seen in high-mass halos.
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