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Dust in the Wind: Composition and Kinematics of Galaxy Outflows at the Peak Epoch of Star Formation

Jones, T; Stark, DP; Ellis, RS; (2018) Dust in the Wind: Composition and Kinematics of Galaxy Outflows at the Peak Epoch of Star Formation. The Astrophysical Journal , 863 (2) 10.3847/1538-4357/aad37f. Green open access

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Abstract

Galactic-scale outflows regulate the stellar mass growth and chemical enrichment of galaxies, yet key outflow properties such as the chemical composition and mass-loss rate remain largely unknown. We address these properties with Keck/ESI echellete spectra of nine gravitationally lensed z sime 2–3 star-forming galaxies, probing a range of absorption transitions. Interstellar absorption in our sample is dominated by outflowing material with typical velocities of ~−150 $\mathrm{km}\,{{\rm{s}}}^{-1}$. Approximately 80% of the total column density is associated with a net outflow. Mass-loss rates in the low-ionization phase are comparable to or in excess of the star formation rate, with total outflow rates likely higher when accounting for ionized gas. On the order of half of the heavy element yield from star formation is ejected in the low-ionization phase, confirming that outflows play a critical role in regulating galaxy chemical evolution. Covering fractions vary and are in general non-uniform, with most galaxies having incomplete covering by the low ions across all velocities. Low-ion abundance patterns show remarkably little scatter, revealing a distinct "chemical fingerprint" of outflows. Gas-phase Si/Fe abundances are significantly supersolar ([Si/Fe] gsim 0.4), indicating a combination of α-enhancement and dust depletion. The derived properties are comparable to the most kinematically broad, metal-rich, and depleted intergalactic absorption systems at similar redshifts, suggesting that these extreme systems are associated with galactic outflows at impact parameters conservatively within a few tens of kiloparsecs. We discuss implications of the abundance patterns in z sime 2–3 galaxies and the role of outflows at this epoch.

Type: Article
Title: Dust in the Wind: Composition and Kinematics of Galaxy Outflows at the Peak Epoch of Star Formation
Open access status: An open access version is available from UCL Discovery
DOI: 10.3847/1538-4357/aad37f
Publisher version: http://dx.doi.org/10.3847/1538-4357/aad37f
Language: English
Additional information: This version is the version of record. For information on re-use, please refer to the publisher’s terms and conditions.
Keywords: Science & Technology, Physical Sciences, Astronomy & Astrophysics, galaxies: evolution, galaxies: ISM, LYMAN-ALPHA SYSTEMS, MASS-METALLICITY RELATION, RESONANCE-ABSORPTION LINES, GRAVITATIONALLY LENSED GALAXY, APPROXIMATE-TO 2.4, DIGITAL SKY SURVEY, FORMING GALAXIES, CIRCUMGALACTIC MEDIUM, WAVELENGTHS LONGWARD, INTERSTELLAR-MEDIUM
UCL classification: UCL
UCL > Provost and Vice Provost Offices > UCL BEAMS
UCL > Provost and Vice Provost Offices > UCL BEAMS > Faculty of Maths and Physical Sciences
UCL > Provost and Vice Provost Offices > UCL BEAMS > Faculty of Maths and Physical Sciences > Dept of Physics and Astronomy
URI: https://discovery.ucl.ac.uk/id/eprint/10057582
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