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Properties of HI discs in the Auriga cosmological simulations

Marinacci, F.; Grand, R.J.J.; Pakmor, R.; Springel, V.; Gómez, F.A.; Frenk, C.S.; White, S.D.M.

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F. Marinacci

R.J.J. Grand

R. Pakmor

V. Springel

F.A. Gómez

S.D.M. White


We analyse the properties of the H i gas distribution in the Auriga project, a set of magnetohydrodynamic cosmological simulations performed with the moving-mesh code arepo and a physics model for galaxy formation that succeeds in forming realistic late-type galaxies in the 30 Milky Way-sized haloes simulated in this project. We use a simple approach to estimate the neutral hydrogen fraction in our simulation set, which treats low-density and star-forming gas separately, and we explore two different prescriptions to subtract the contribution of molecular hydrogen from the total H i content. The H i gas in the vast majority of the systems forms extended discs although more disturbed morphologies are present. Notwithstanding the general good agreement with observed H i properties – such as radial profiles and the mass–diameter relation – the Auriga galaxies are systematically larger and more gas-rich than typical nearby galaxies. Interestingly, the amount of H i gas outside the disc plane correlates with the star formation rate, consistent with a picture where most of this extra-planar H i gas originates from a fountain-like flow. Our findings are robust with respect to the different assumptions adopted for computing the molecular hydrogen fraction and do not vary significantly over a wide range of numerical resolution. The H i modelling introduced in this paper can be used in future work to build artificial interferometric H i data cubes, allowing an even closer comparison of the gas dynamics in simulated galaxies with observations.


Marinacci, F., Grand, R., Pakmor, R., Springel, V., Gómez, F., Frenk, C., & White, S. (2017). Properties of HI discs in the Auriga cosmological simulations. Monthly Notices of the Royal Astronomical Society, 466(4), 3859-3875.

Journal Article Type Article
Acceptance Date Dec 22, 2016
Online Publication Date Jan 18, 2017
Publication Date May 1, 2017
Deposit Date Feb 27, 2017
Publicly Available Date Mar 2, 2017
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 466
Issue 4
Pages 3859-3875


Accepted Journal Article (6.3 Mb)

Copyright Statement
This article has been accepted for publication in Monthly Notices of the Royal Astronomical Society ©: 2017 The Authors. Published by Oxford University Press on behalf of the Royal Astronomical Society. All rights reserved.

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