Investigating the Physics and Environment of Lyman Limit Systems in Cosmological Simulations
Monthly Notices of the Royal Astronomical Society
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Erkal, D. (2015). Investigating the Physics and Environment of Lyman Limit Systems in Cosmological Simulations. Monthly Notices of the Royal Astronomical Society, 451 904-916. https://doi.org/10.1093/mnras/stv980
In this work, I investigate the properties of Lyman limit systems (LLSs) using state-of-the-art zoom-in cosmological galaxy formation simulations with on the fly radiative transfer, which includes both the cosmic UV background (UVB) and local stellar sources. I compare the simulation results to observations of the incidence frequency of LLSs and the H i column density distribution function over the redshift range z = 2–5 and find good agreement. I explore the connection between LLSs and their host haloes and find that LLSs reside in haloes with a wide range of halo masses with a nearly constant covering fraction within a virial radius. Over the range z = 2–5, I find that more than half of the LLSs reside in haloes with M < 10^10 h^−1 M⊙, indicating that absorption line studies of LLSs can probe these low-mass galaxies which H2-based star formation models predict to have very little star formation. I study the physical state of individual LLSs and test a simple model which encapsulates many of their properties. I confirm that LLSs have a characteristic absorption length given by the Jeans length and that they are in photoionization equilibrium at low column densities. Finally, I investigate the self-shielding of LLSs to the UVB and explore how the non-sphericity of LLSs affects the photoionization rate at a given N_HI. I find that at z ≈ 3, LLSs have an optical depth of unity at a column density of ∼10^18 cm^−2 and that this is the column density which characterizes the onset of self-shielding.
galaxies: formation, galaxies: high-redshift, methods: numerical, quasars: absorption lines
This work was supported in part by the NSF grant AST-0908063, and by the NASA grant NNX- 09AJ54G. The simulations used in this work have been performed on the Joint Fermilab - KICP Supercomputing Cluster, supported by grants from Fermilab, Kavli Institute for Cosmological Physics, and the University of Chicago.
External DOI: https://doi.org/10.1093/mnras/stv980
This record's URL: https://www.repository.cam.ac.uk/handle/1810/249026