DINGO / GAMA / WAVES: HI - halo mass relation

Abstract We investigate the relation between neutral atomic hydrogen (H i) and dark matter halo mass (HIHM) using observations from the Deep Investigation of Neutral Gas Origins (DINGO) pilot survey 100h data, combined with spectroscopic data from the Galaxy and Mass Assembly (GAMA) survey and photometric data from the Wide Area VISTA Extragalactic Survey (WAVES) photometric catalog. We employ a combination of direct detections and spectral stacking to probe the H i content of halos across a wide mass range (1010.5 ≲ Mh/M⊙ ≲ 1014.5). By incorporating WAVES photometric members on top of the existing GAMA group catalog, we present a novel approach of extending stacking analyses beyond spectroscopic completeness limits, enabling recovery of satellite H i content otherwise missed. We find that the HIHM relation exhibits a double power-law form, with a turnover near Mh ∼ 1011.2M⊙. Central galaxies dominate the halo H i budget below Mh ∼ 6 × 1012M⊙, while satellites dominate at higher halo masses. Including photometric members increases the measured H i content in halos above 1013M⊙ by a factor of 1.5-3, highlighting the importance of gas-rich satellites in the group and cluster regime. Comparison with previous group-stacking studies shows that low-surface brightness galaxies, and intra-group H i structures contribute only a minor fraction to the total H i mass in group and cluster halos, as the summed galaxy H i masses are consistent with the total halo H i content.