MIGHTEE-H I: H I galaxy properties in the large-scale structure environment at z ∼ 0.37 from a stacking experiment

We present the first measurement of H I mass of star-forming galaxies in different large scale structure environments from a blind survey at z ∼ 0.37. In particular, we carry out a spectral line stacking analysis considering 2875 spectra of colour-selected star-forming galaxies undetected in H I at 0.23 < z < 0.49 in the COSMOS field, extracted from the MIGHTEE-H I Early Science data cubes, acquired with the MeerKAT radio telescope. We stack galaxies belonging to different subsamples depending on three different definitions of large-scale structure environment: local galaxy overdensity, position inside the host dark matter halo (central, satellite, or isolated), and cosmic web type (field, filament, or knot). We first stack the full star-forming galaxy sample and find a robust H I detection yielding an average galaxy H I mass of MH I = (8.12 ± 0.75) × 109 M⊙ at ∼11.8σ. Next, we investigate the different subsamples finding a negligible difference in MH I as a function of the galaxy...