MIGHTEE-H i: the M H i - M * relation of massive galaxies and the H i mass function at 0.25 < z < 0.5

Journal article

The relationship between the already formed stellar mass in a galaxy and the gas reservoir of neutral atomic hydrogen, is a key element in our understanding of how gas is turned into stars in galaxy haloes. In this paper, we measure the relation based on a stellar-mass selected sample at and the MeerKAT International GHz Tiered Extragalactic Exploration-H i Data Release 1 spectral data. Using a powerful Bayesian stacking technique, for the first time we are also able to measure the underlying bivariate distribution of H i mass and stellar mass of galaxies with M, finding that an asymmetric underlying H i distribution is strongly preferred by our complete samples. We define the concepts of the average of the logarithmic H i mass, , and the logarithmic average of the H i mass, , and find that the difference between and can be as large as 0.5 dex for the preferred asymmetric H i distribution. We observe shallow slopes in the underlying scaling relations, suggesting the presence of an upper H i mass limit beyond which a galaxy can no longer retain further H i gas. From our bivariate distribution we also infer the H i mass function at this redshift and find tentative evidence for a decrease of 2–10 times in the comoving space density of the most H i massive galaxies up to .

Authors: Pan, H; Jarvis, MJ; Heywood, I; Yasin, T; Maddox, N

• Publication status: Published
• Peer review status: Peer reviewed
• Publisher: Oxford University Press
• Journal: Monthly Notices of the Royal Astronomical Society
• Volume: 544
• Issue: 2
• Pages: 1710-1731
• Publication date: 2025-10-29
• Acceptance date: 2025-10-24
• DOI: 10.1093/mnras/staf1857
• EISSN: 1365-2966
• ISSN: 0035-8711
• Language: English
• Keywords: radio lines: galaxies; galaxies: fundamental parameters; methods: statistical