1. On the Kinematics of Cold, Metal-enriched Galactic Fountain Flows in Nearby Star-forming Galaxies.
- Author
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Rubin, Kate H. R., Juarez, Christian, Cooksey, Kathy L., Werk, Jessica K., Prochaska, J. Xavier, O’Meara, John M., Burchett, Joseph N., Rickards Vaught, Ryan J., Kulkarni, Varsha P., and Straka, Lorrie A.
- Subjects
KINEMATICS ,GALAXIES ,MILKY Way ,FOUNTAINS ,STELLAR mass - Abstract
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 cmâ'2 (N (Na i) > 1012.0 cmâ'2 ) occur with an incidence fC (Ca ii) = 0.63+0.10 â'0.11 (fC (Na i) = 0.57+0.10 â'0.11 ). We find no evidence for a dependence of fC or the rest-frame equivalent widths Wr (Ca ii K) or Wr (Na i 5891) on R⊥ or M* . Instead, Wr (Ca ii K) is correlated with local SFR at >3 Ď significance, suggesting that Ca ii traces star formation-driven outflows. While most of the absorbers have velocities within ±50 km sâ'1 of the host redshift, their velocity widths (characterized by Î" v90 ) are universally 30â€"177 km sâ'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 Wr (Ca ii K) (Wr (Na i 5891)), finding that 33% (24%) of the absorbers are inconsistent with the best-fit Milky Way E (B â'V)- Wr relations at >3 Ď significance. [ABSTRACT FROM AUTHOR]- Published
- 2022
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