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Rights statement: This is a pre-copy-editing, author-produced PDF of an article accepted for publication in Monthly Notices of the Royal Astronomical Society following peer review. The definitive publisher-authenticated version C M Baugh, Violeta Gonzalez-Perez, Claudia D P Lagos, Cedric G Lacey, John C Helly, Adrian Jenkins, Carlos S Frenk, Andrew J Benson, Richard G Bower, Shaun Cole, Galaxy formation in the Planck Millennium: the atomic hydrogen content of dark matter haloes, Monthly Notices of the Royal Astronomical Society, Volume 483, Issue 4, March 2019, Pages 4922–4937 is available online at: https://academic.oup.com/mnras/article/483/4/4922/5251995

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## Galaxy formation in the Planck Millennium: the atomic hydrogen content of dark matter halos

Research output: Contribution to journalJournal article

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• C. M. Baugh
• Violeta Gonzalez-Perez
• Claudia D. P. Lagos
• Cedric G. Lacey
• John Helly
• Carlos S. Frenk
• Andrew Benson
• Richard Bower
• Shaun Cole
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Journal publication date 1/03/2019 Monthly Notices of the Royal Astronomical Society 4 483 16 4922–4937 Published 18/12/18 English

### Abstract

We present recalibrations of the GALFORM semi-analytical model of galaxy formation in a new N-body simulation with the Planck cosmology. The Planck Millennium simulation uses more than 128 billion particles to resolve the matter distribution in a cube of $800$ Mpc on a side, which contains more than 77 million dark matter haloes with mass greater than $2.12 \times 10^{9} h^{-1} {\rm M_{\odot}}$ at the present day. Only minor changes to a very small number of model parameters are required in the recalibration. We present predictions for the atomic hydrogen content (HI) of dark matter halos, which is a key input into the calculation of the HI intensity mapping signal expected from the large-scale structure of the Universe. We find that the HI mass $-$ halo mass relation displays a clear break at the halo mass above which AGN heating suppresses gas cooling, $\approx 3 \times 10^{11} h^{-1} M_{\rm \odot}$. Below this halo mass, the HI content of haloes is dominated by the central galaxy; above this mass it is the combined HI content of satellites that prevails. We find that the HI mass - halo mass relation changes little with redshift up to $z=3$. The bias of HI sources shows a scale dependence that gets more pronounced with increasing redshift.

### Bibliographic note

This is a pre-copy-editing, author-produced PDF of an article accepted for publication in Monthly Notices of the Royal Astronomical Society following peer review. The definitive publisher-authenticated version C M Baugh, Violeta Gonzalez-Perez, Claudia D P Lagos, Cedric G Lacey, John C Helly, Adrian Jenkins, Carlos S Frenk, Andrew J Benson, Richard G Bower, Shaun Cole, Galaxy formation in the Planck Millennium: the atomic hydrogen content of dark matter haloes, Monthly Notices of the Royal Astronomical Society, Volume 483, Issue 4, March 2019, Pages 4922–4937 is available online at: https://academic.oup.com/mnras/article/483/4/4922/5251995