The distribution of neutral hydrogen around high-redshift galaxies and quasars in the EAGLE simulation
Abstract
The observed high covering fractions of neutral hydrogen (H I) with column densities above ∼1017 cm-2 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 H I around high-redshift galaxies. We predict the covering fractions of strong H I absorbers (N_{H I}≳ 10^{17} cm^{-2}) inside haloes to increase rapidly with redshift but to depend only weakly on halo mass. For massive (M200 ≳ 1012M⊙) 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 H I 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 H I distribution is highly sensitive to the feedback efficiency. The fiducial EAGLE simulation reproduces both the observed global column density distribution function of H I and the observed radial covering fraction profiles of strong H I absorbers around LBGs and bright quasars.
- Publication:
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Monthly Notices of the Royal Astronomical Society
- Pub Date:
- September 2015
- DOI:
- 10.1093/mnras/stv1414
- arXiv:
- arXiv:1503.05553
- Bibcode:
- 2015MNRAS.452.2034R
- Keywords:
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- methods: numerical;
- galaxies: formation;
- galaxies: high-redshift;
- intergalactic medium;
- quasars: absorption lines;
- Astrophysics - Cosmology and Nongalactic Astrophysics;
- Astrophysics - Astrophysics of Galaxies
- E-Print:
- Accepted for publication in MNRAS. V2: Very minor changes