Skip to main content

Research Repository

Advanced Search

The spatial distribution of neutral hydrogen as traced by low H i mass galaxies

Kim, H.-S.; Wyithe, J.S.B.; Baugh, C.M.; Lagos, C. d. P.; Power, C.; Park, J.

The spatial distribution of neutral hydrogen as traced by low H i mass galaxies Thumbnail


H.-S. Kim

J.S.B. Wyithe

C. d. P. Lagos

C. Power

J. Park


The formation and evolution of galaxies with low neutral atomic hydrogen (HI) masses, MHI<108h−2M⊙, are affected by host dark matter halo mass and photoionisation feedback from the UV background after the end of reionization. We study how the physical processes governing the formation of galaxies with low HI mass are imprinted on the distribution of neutral hydrogen in the Universe using the hierarchical galaxy formation model, GALFORM. We calculate the effect on the correlation function of changing the HI mass detection threshold at redshifts 0≤z≤0.5. We parameterize the clustering as ξ(r)=(r/r0)−γ and we find that including galaxies with MHI<108h−2M⊙ increases the clustering amplitude r0 and slope γ compared to samples of higher HI masses. This is due to these galaxies with low HI masses typically being hosted by haloes with masses greater than 1012h−1M⊙, and is in contrast to optically selected surveys for which the inclusion of faint, blue galaxies lowers the clustering amplitude. We show the HI mass function for different host dark matter halo masses and galaxy types (central or satellite) to interpret the values of r0 and γ of the clustering of HI-selected galaxies. We also predict the contribution of low HI mass galaxies to the 21cm intensity mapping signal. We calculate that a dark matter halo mass resolution better than ∼1010h−1M⊙ at redshifts higher than 0.5 is required in order to predict converged 21cm brightness temperature fluctuations.


Kim, H., Wyithe, J., Baugh, C., Lagos, C. D. P., Power, C., & Park, J. (2017). The spatial distribution of neutral hydrogen as traced by low H i mass galaxies. Monthly Notices of the Royal Astronomical Society, 465(1), 111-122.

Journal Article Type Article
Acceptance Date Oct 25, 2016
Online Publication Date Oct 30, 2016
Publication Date Feb 11, 2017
Deposit Date Mar 13, 2017
Publicly Available Date Mar 17, 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 465
Issue 1
Pages 111-122


Published Journal Article (739 Kb)

Copyright Statement
This article has been accepted for publication in Monthly notices of the Royal Astronomical Society ©: 2016 The Authors Published by Oxford University Press on behalf of the Royal Astronomical Society. All rights reserved.

You might also like

Downloadable Citations