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Title: 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 Caiiλλ3934, 3969 and Naiλλ5891, 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 ≤ logM*/M≤ 10.6. The quasar–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 densitiesN(Caii) > 1012.5cm−2(N(Nai) > 1012.0cm−2) occur with an incidencefC(Caii) = 0.63+0.10−0.11(fC(Nai) = 0.57+0.10−0.11). We find no evidence for a dependence offCor the rest-frame equivalent widthsWr(CaiiK) orWr(Nai5891) onRorM*. Instead,Wr(CaiiK) is correlated with local SFR at >3σsignificance, suggesting that Caiitraces star formation-driven outflows. While most of the absorbers have velocities within ±50 km s−1of the host redshift, their velocity widths (characterized by Δv90) are universally 30–177 km s−1larger 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 atR> 5 kpc. Finally, we assess the relationship between dust reddening andWr(CaiiK) (Wr(Nai5891)), finding that 33% (24%) of the absorbers are inconsistent with the best-fit Milky WayE(B−V)-Wrrelations at >3σsignificance.

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Award ID(s):
1715630 2009417 2044303
Author(s) / Creator(s):
; ; ; ; ; ; ; ; ;
Publisher / Repository:
DOI PREFIX: 10.3847
Date Published:
Journal Name:
The Astrophysical Journal
Medium: X Size: Article No. 171
["Article No. 171"]
Sponsoring Org:
National Science Foundation
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