How Gas Accretion Feeds Galactic Disks

Numerous observations indicate that galaxies need a continuous gas supply to fuel star formation and explain the star formation history. However, direct observational evidence of gas accretion remains rare. Using the EAGLE cosmological hydrodynamic simulation suite, we study cold gas accretion onto...

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Bibliographic Details
Published in:The Astrophysical journal 2019-04, Vol.875 (1), p.54
Main Authors: Ho, Stephanie H., Martin, Crystal L., Turner, Monica L.
Format: Article
Language:English
Subjects:
Accretion disks
Astrophysics
Cold
Cold gas
Galaxies
galaxies: evolution
galaxies: formation
galaxies: halos
Inflow
Kinematics
Optical disks
Physicists
Quasars
quasars: absorption lines
Star & galaxy formation
Star formation
Stars
Stars & galaxies
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Summary:Numerous observations indicate that galaxies need a continuous gas supply to fuel star formation and explain the star formation history. However, direct observational evidence of gas accretion remains rare. Using the EAGLE cosmological hydrodynamic simulation suite, we study cold gas accretion onto galaxies and the observational signatures of the cold gas kinematics. For EAGLE galaxies at z = 0.27, we find that cold gas accretes onto galaxies anisotropically with typical inflow speeds between 20 and 60 km s−1. Most of these galaxies have comparable mass inflow rates and star formation rates, implying that the cold inflowing gas plausibly accounts for sustaining the star-forming activities of the galaxies. As motivation for future work to compare the cold gas kinematics with measurements from quasar sightline observations, we select an EAGLE galaxy with an extended cold gas disk, and we probe the cold gas using mock quasar sightlines. We demonstrate that by viewing the disk edge on, sightlines at azimuthal angles below 10° and impact parameters out to 60 pkpc can detect cold gas that corotates with the galaxy disk. This example suggests that cold gas disks extending beyond the optical disks possibly explain the sightline observations that detect corotating cold gas near galaxy major axes.
ISSN:0004-637X
1538-4357
DOI:10.3847/1538-4357/ab0ec2