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We present the KODIAQ-Z survey aimed to characterize the cool, photoionized gas at 2.2 ≲ z ≲ 3.6 in 202 H i -selected absorbers with 14.6 ≤ log N H I < 20 that probe the interface between galaxies and the intergalactic medium (IGM). We find that gas with 14.6 ≤ log N H I < 20 at 2.2 ≲ z ≲ 3.6 can be metal-rich (âˆ'1.6 ≲ [X/H] ≲ âˆ' 0.2) as seen in damped Ly α absorbers (DLAs); it can also be very metal-poor ([X/H] < âˆ' 2.4) or even pristine ([X/H] < âˆ' 3.8), which is not observed in DLAs but is common in the IGM. For 16 < log N H I < 20 absorbers, the frequency of pristine absorbers is about 1%â€"10%, while for 14.6 ≤ log N H I ≤ 16 absorbers it is 10%â€"20%, similar to the diffuse IGM. Supersolar gas is extremely rare (<1%) at these redshifts. The factor of several thousand spread from the lowest to highest metallicities and large metallicity variations (a factor of a few to >100) between absorbers separated by less than Î" v < 500 km sâˆ'1 imply that the metals are poorly mixed in 14.6 ≤ log N H I < 20 gas. We show that these photoionized absorbers contribute to about 14% of the cosmic baryons and 45% of the cosmic metals at 2.2 ≲ z ≲ 3.6. We find that the mean metallicity increases with N H i , consistent with what is found in z < 1 gas. The metallicity of gas in this column density regime has increased by a factor ∼8 from 2.2 ≲ z ≲ 3.6 to z < 1, but the contribution of the 14.6 ≤ log N H I < 19 absorbers to the total metal budget of the universe at z < 1 is a quarter of that at 2.2 ≲ z ≲ 3.6. We show that FOGGIE cosmological zoom-in simulations have a similar evolution of [X/H] with N H i , which is not observed in lower-resolution simulations. In these simulations, very metal-poor absorbers with [X/H] < âˆ' 2.4 at z ∼ 2â€"3 are tracers of inflows, while higher-metallicity absorbers are a mixture of inflows and outflows. [ABSTRACT FROM AUTHOR]

We use medium-resolution Keck/Echellette Spectrograph and Imager spectroscopy of bright quasars to study cool gas traced by Ca ii λλ 3934, 3969 and Na i λλ 5891, 5897 absorption in the interstellar/circumgalactic media of 21 foreground star-forming galaxies at redshifts 0.03 < z < 0.20 with stellar masses 7.4 ≤ log M */ M ⊙ ≤ 10.6. The quasarâ€"galaxy pairs were drawn from a unique sample of Sloan Digital Sky Survey quasar spectra with intervening nebular emission, and thus have exceptionally close impact parameters (R ⊥ < 13 kpc). The strength of this line emission implies that the galaxies’ star formation rates (SFRs) span a broad range, with several lying well above the star-forming sequence. We use Voigt profile modeling to derive column densities and component velocities for each absorber, finding that column densities N (Ca ii) > 1012.5 cmâˆ'2 (N (Na i) > 1012.0 cmâˆ'2) occur with an incidence f C(Ca ii) = 0.63+0.10âˆ'0.11 (f C(Na i) = 0.57+0.10âˆ'0.11). We find no evidence for a dependence of f C or the rest-frame equivalent widths W r (Ca ii K) or W r (Na i 5891) on R ⊥ or M *. Instead, W r (Ca ii K) is correlated with local SFR at >3 σ significance, suggesting that Ca ii traces star formation-driven outflows. While most of the absorbers have velocities within ±50 km sâˆ'1 of the host redshift, their velocity widths (characterized by Î" v 90) are universally 30â€"177 km sâˆ'1 larger than that implied by tilted-ring modeling of the velocities of interstellar material. These kinematics must trace galactic fountain flows and demonstrate that they persist at R ⊥ > 5 kpc. Finally, we assess the relationship between dust reddening and W r (Ca ii K) (W r (Na i 5891)), finding that 33% (24%) of the absorbers are inconsistent with the best-fit Milky Way E (B âˆ'V)- W r relations at >3 σ significance. [ABSTRACT FROM AUTHOR]

We combine 126 new galaxy-O vi absorber pairs from the CGM2 survey with 123 pairs drawn from the literature to examine the simultaneous dependence of the column density of O vi absorbers (N O VI) on galaxy stellar mass, star-formation rate, and impact parameter. The combined sample consists of 249 galaxy-O vi absorber pairs covering z = 0â€"0.6, with host galaxy stellar masses M * = 107.8â€"1011.2 M ⊙ and galaxy-absorber impact parameters R ⊥ = 0â€"400 proper kiloparsecs. In this work, we focus on the variation of N O VI with galaxy mass and impact parameter among the star-forming galaxies in the sample. We find that the average N O VI within one virial radius of a star-forming galaxy is greatest for star-forming galaxies with M * = 109.2â€"1010 M ⊙. Star-forming galaxies with M * between 108 and 1011.2 M ⊙ can explain most O vi systems with column densities greater than 1013.5 cmâˆ'2. Sixty percent of the O vi mass associated with a star-forming galaxy is found within one virial radius, and 35% is found between one and two virial radii. In general, we find that some departure from hydrostatic equilibrium in the CGM is necessary to reproduce the observed O vi amount, galaxy mass dependence, and extent. Our measurements serve as a test set for CGM models over a broad range of host galaxy masses. [ABSTRACT FROM AUTHOR]