On the Kinematics of Cold, Metal-enriched Galactic Fountain Flows in Nearby Star-forming Galaxies.

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]