MIGHTEE-H I: the H I size–mass relation over the last billion years

Journal article

We present the observed H I size–mass relation of 204 galaxies from the MIGHTEE Survey Early Science data. The high sensitivity of MeerKAT allows us to detect galaxies spanning more than 4 orders of magnitude in H I mass, ranging from dwarf galaxies to massive spirals, and including all morphological types. This is the first time the relation has been explored on a blind homogeneous data set that extends over a previously unexplored redshift range of 0 < z < 0.084, i.e. a period of around one billion years in cosmic time. The sample follows the same tight logarithmic relation derived from previous work, between the diameter (⁠DHI⁠) and the mass (⁠MHI⁠) of H I discs. We measure a slope of 0.501 ± 0.008, an intercept of −3.252+0.073−0.074⁠, and an observed scatter of 0.057 dex. For the first time, we quantify the intrinsic scatter of 0.054 ± 0.003 dex (⁠∼10 per cent⁠), which provides a constraint for cosmological simulations of galaxy formation and evolution. We derive the relation as a function of galaxy type and find that their intrinsic scatters and slopes are consistent within the errors. We also calculate the DHI−MHI relation for two redshift bins and do not find any evidence for evolution with redshift. These results suggest that over a period of one billion years in look-back time, galaxy discs have not undergone significant evolution in their gas distribution and mean surface mass density, indicating a lack of dependence on both morphological type and redshift.

Authors: Rajohnson, SHA; Frank, BS; Ponomareva, AA; Maddox, N; Kraan-Korteweg, RC

• Publication status: Published
• Peer review status: Peer reviewed
• Publisher: Oxford University Press
• Journal: Monthly Notices of the Royal Astronomical Society
• Volume: 512
• Issue: 2
• Pages: 2697-2706
• Publication date: 2022-03-14
• Acceptance date: 2022-03-09
• DOI: 10.1093/mnras/stac693
• EISSN: 1365-2966
• ISSN: 0035-8711
• Language: English
• Keywords: surveys; galaxies: kinematics and dynamics; radio lines: galaxies; galaxies: evolution; FFR