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The distribution of neutral hydrogen around high-redshift galaxies and quasars in the EAGLE simulation

Rahmati, A and Schaye, J and Crain, RA and Bower, RG and Furlong, M and Schaller, M and Theuns, T (2015) The distribution of neutral hydrogen around high-redshift galaxies and quasars in the EAGLE simulation. Monthly Notices of the Royal Astronomical Society, 452 (2). pp. 2034-2056. ISSN 0035-8711

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Abstract

The observed high covering fractions of neutral hydrogen (H I) with column densities above ~10<sup>17</sup> cm<sup>-2</sup> around Lyman-Break Galaxies (LBGs) and bright quasars at redshifts z ~ 2-3 has been identified as a challenge for simulations of galaxy formation. We use the Evolution and Assembly of Galaxies and their Environment (EAGLE) cosmological, hydrodynamical simulation, which has been shown to reproduce a wide range of galaxy properties and for which the subgrid feedback was calibrated without considering gas properties, to study the distribution of HI around high-redshift galaxies.We predict the covering fractions of strong HI absorbers (N<inf>HI</inf> ≳ 10<sup>17</sup> cm<sup>-2</sup>) inside haloes to increase rapidly with redshift but to depend only weakly on halo mass. For massive (M<inf>200</inf> ≳ 10<sup>12</sup>M⊙) haloes, the covering fraction profiles are nearly scale-invariant and we provide fitting functions that reproduce the simulation results. While efficient feedback is required to increase the HI covering fractions to the high observed values, the distribution of strong absorbers in and around haloes of a fixed mass is insensitive to factor of 2 variations in the strength of the stellar feedback. In contrast, at fixed stellar mass the predicted HI distribution is highly sensitive to the feedback efficiency. The fiducial EAGLE simulation reproduces both the observed global column density distribution function of HI and the observed radial covering fraction profiles of strong HI absorbers around LBGs and bright quasars.

Item Type: Article
Additional Information: This is a pre-copyedited, author-produced PDF of an article accepted for publication in Monthly Notices of the Royal Astronomical Society following peer review. The version of record MNRAS (September 11, 2015) 452 (2): 2034-2056. is available online at: http://dx.doi.org/10.1093/mnras/stv1414
Uncontrolled Keywords: 0201 Astronomical And Space Sciences
Subjects: Q Science > QB Astronomy
Divisions: Astrophysics Research Institute
Publisher: Oxford University Press
Date Deposited: 11 Sep 2015 14:02
Last Modified: 07 Sep 2017 13:07
DOI or Identification number: 10.1093/mnras/stv1414
URI: http://researchonline.ljmu.ac.uk/id/eprint/1982

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