How Gas Accretion Feeds Galactic Disks

Abstract

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 km s${}^{-1}$ 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${}^{\circ }$ and impact parameters out to 60 pkpc can detect cold gas that corotates with the galaxy disk. This example suggests cold gas disks that extend beyond the optical disks possibly explain the sightline observations that detect corotating cold gas near galaxy major axes.

24 pages, 16 figures; accepted by ApJ

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Cited by in corpus (12)

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• Kinematics of Circumgalactic Gas: Feeding Galaxies and Feedback
• Disk Growth and Quenching
• The Angular Momentum of the Circumgalactic Medium in the TNG100 Simulation
• MusE GAs FLOw and Wind (MEGAFLOW) IV: A two sightline tomography of a galactic wind
• The spatially-resolved gas and dust connection in neutral inflows and outflows in nearby AGN
• Evidence for a Rotational Component in the Circumgalactic Medium of Nearby Galaxies
• Properties of galaxies with ring structures
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• Discovery of a Low-Redshift Damped Ly$\alpha$ System in a Foreground Extended Disk Using a Starburst Galaxy Background Illuminator
• A Bayesian chemical evolution model of the DustPedia Galaxy M74