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

Abstract

We determine the atomic hydrogen (HI) to halo mass relation (HIHM) using Arecibo Legacy Fast ALFA survey HI data at the location of optically selected groups from the Galaxy and Mass Assembly (GAMA) survey. We make direct HI detections for 37 GAMA groups. Using HI group spectral stacking of 345 groups, we study the group HI content as function of halo mass across a halo mass range of $10^{11} - 10^{14.7}\text{ M}_\odot$. We also correct our results for Eddington bias. We find that the group HI 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 HI-stacking studies. Our results are also consistent with mock observations from SHARK and IllustrisTNG.