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The distribution of atomic hydrogen in EAGLE galaxies: morphologies, profiles, and H I holes

Bahé, Y.M.; Crain, R.A.; Kauffmann, G.; Bower, R.G.; Schaye, J.; Furlong, M.; Lagos, C.; Schaller, M.; Trayford, J.W.; Dalla Vecchia, C.; Theuns, T.

The distribution of atomic hydrogen in EAGLE galaxies: morphologies, profiles, and H I holes Thumbnail


Authors

Y.M. Bahé

R.A. Crain

G. Kauffmann

R.G. Bower

J. Schaye

M. Furlong

C. Lagos

M. Schaller

J.W. Trayford

C. Dalla Vecchia



Abstract

We compare the mass and internal distribution of atomic hydrogen (H I) in 2200 present-day central galaxies with Mstar > 1010  M⊙ from the 100 Mpc EAGLE ‘Reference’ simulation to observational data. Atomic hydrogen fractions are corrected for self-shielding using a fitting formula from radiative transfer simulations and for the presence of molecular hydrogen using an empirical or a theoretical prescription from the literature. The resulting neutral hydrogen fractions, , agree with observations to better than 0.1 dex for galaxies with Mstar between 1010 and 1011  M⊙. Our fiducial, empirical H2 model based on gas pressure results in galactic H I mass fractions, [Math Processing Error], that agree with observations from the GASS survey to better than 0.3 dex, but the alternative theoretical H2 formula from high-resolution simulations leads to a negative offset in [Math Processing Error] of up to 0.5 dex. Visual inspection of mock H I images reveals that most H I discs in simulated H I-rich galaxies are vertically disturbed, plausibly due to recent accretion events. Many galaxies (up to 80 per cent) contain spuriously large H I holes, which are likely formed as a consequence of the feedback implementation in EAGLE. The H I mass–size relation of all simulated galaxies is close to (but 16 per cent steeper than) observed, and when only galaxies without large holes in the H I disc are considered, the agreement becomes excellent (better than 0.1 dex). The presence of large H I holes also makes the radial H I surface density profiles somewhat too low in the centre, at [Math Processing Error] (by a factor of ≲ 2 compared to data from the Bluedisk survey). In the outer region ([Math Processing Error]), the simulated profiles agree quantitatively with observations. Scaled by H I size, the simulated profiles of H I-rich ([Math Processing Error]) and control galaxies ([Math Processing Error]) follow each other closely, as observed.

Citation

Bahé, Y., Crain, R., Kauffmann, G., Bower, R., Schaye, J., Furlong, M., …Theuns, T. (2016). The distribution of atomic hydrogen in EAGLE galaxies: morphologies, profiles, and H I holes. Monthly Notices of the Royal Astronomical Society, 456(1), 1115-1136. https://doi.org/10.1093/mnras/stv2674

Journal Article Type Article
Acceptance Date Nov 12, 2015
Online Publication Date Dec 19, 2015
Publication Date Feb 11, 2016
Deposit Date Apr 5, 2016
Publicly Available Date Mar 29, 2024
Journal Monthly Notices of the Royal Astronomical Society
Print ISSN 0035-8711
Electronic ISSN 1365-2966
Publisher Royal Astronomical Society
Peer Reviewed Peer Reviewed
Volume 456
Issue 1
Pages 1115-1136
DOI https://doi.org/10.1093/mnras/stv2674

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Copyright Statement
This article has been accepted for publication in Monthly Notices of the Royal Astronomical Society ©: 2015 The Authors Published by Oxford University Press on behalf of the Royal Astronomical Society. All rights reserved.





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