We use the 21-cm emission-line data from the Deep Investigation of Neutral Gas Origin-Very Large Array (DINGO-VLA) project to study the atomic hydrogen gas H I of the Universe at redshifts z < 0.1. Results are obtained using a stacking analysis, combining the H I signals from 3622 galaxies extracted from 267 VLA pointings in the G09 field of the Galaxy and Mass Assembly Survey (GAMA). Rather than using a traditional one-dimensional spectral stacking method, a three-dimensional cubelet stacking method is used to enable deconvolution and the accurate recovery of average galaxy fluxes from this high-resolution interferometric data set. By probing down to galactic scales, this experiment also overcomes confusion corrections that have been necessary to include in previous single-dish studies. After stacking and deconvolution, we obtain a 30σ H I mass measurement from the stacked spectrum, indicating an average H I mass of MH I = (1.67 ± 0.18) × 109 M⊙. The corresponding cosmic density of neutral atomic hydrogen is ΩH I = (0.38 ± 0.04) × 10−3 at redshift of z = 0.051. These values are in good agreement with earlier results, implying there is no significant evolution of ΩH I at lower redshifts.
Bibliographical noteThis article has been accepted for publication in Monthly Notices of the Royal Astronomical Society, Volume 508, Issue 2, December 2021, Pages 2758–2770, https://doi.org/10.1093/mnras/stab2810. Copyright 2021 The Author(s). Published by Oxford University Press on behalf of the Royal Astronomical Society. All rights reserved.
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