Low-Redshift Lyman Limit Systems as Diagnostics of Cosmological Inflows and Outflows

We use cosmological hydrodynamic simulations with stellar feedback from the FIRE project to study the physical nature of Lyman limit systems (LLSs) at z~2) tend to have higher metallicities ([X/H] ~ -0.5) while very low metallicity ([X/H] < -2) LLSs are typically associated with gas infalling fro...

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Bibliographic Details
Published in:arXiv.org 2017-05
Main Authors: Hafen, Z, C -A Faucher-Giguere, Angles-Alcazar, D, Keres, D, Feldmann, R, Chan, T K, Quataert, E, Murray, N, Hopkins, P F
Format: Article
Language:English
Subjects:
Columns (structural)
Dark matter
Density distribution
Galactic winds
Galaxies
Galaxy distribution
Halos
Inflow
Intergalactic media
Kinematics
Metallicity
Outflow
Radial velocity
Red shift
Simulation
Velocity
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Summary:We use cosmological hydrodynamic simulations with stellar feedback from the FIRE project to study the physical nature of Lyman limit systems (LLSs) at z~2) tend to have higher metallicities ([X/H] ~ -0.5) while very low metallicity ([X/H] < -2) LLSs are typically associated with gas infalling from the intergalactic medium. However, most LLSs occupy an intermediate region in metallicity-radial velocity space, for which there is no clear trend between metallicity and radial kinematics. Metal-enriched inflows arise in the FIRE simulations as a result of galactic winds that fall back onto galaxies at low redshift. The overall simulated LLS metallicity distribution has a mean (standard deviation) [X/H] = -0.9 (0.4) and does not show significant evidence for bimodality, in contrast to recent observational studies but consistent with LLSs arising from halos with a broad range of masses and metallicities.
ISSN:2331-8422
DOI:10.48550/arxiv.1608.05712