Galaxy And Mass Assembly (GAMA): The group H i mass as a function of halo mass.

We determine the atomic hydrogen (H  i) to halo mass relation (HIHM) using Arecibo Legacy Fast ALFA survey H  i data at the location of optically selected groups from the Galaxy And Mass Assembly (GAMA) survey. We make direct H  i detections for 37 GAMA groups. Using H  i group spectral stacking of 345 groups, we study the group H  i content as a function of halo mass across a halo mass range of 10¹¹–10^14.7 M_⊙. We also correct our results for Eddington bias. We find that the group H  i mass generally rises as a function of halo mass from 1.3% of the halo mass at |$10^{11.6} \, \text{M}_\odot$| to 0.4% at |$10^{13.7} \, \text{M}_\odot$| with some indication of flattening towards the high-mass end. Despite the differences in optical survey limits, group catalogues, and halo mass estimation methods, our results are consistent with previous group H  i -stacking studies. Our results are also consistent with mock observations from shark and IllustrisTNG. [ABSTRACT FROM AUTHOR]