MIGHTEE-Hi: Evolution of Hi Scaling Relations of Star-forming Galaxies at z < 0.5*

We present the first measurements of H i galaxy scaling relations from a blind survey at z > 0.15. We perform spectral stacking of 9023 spectra of star-forming galaxies undetected in H i at 0.23 < z < 0.49, extracted from MIGHTEE-H i Early Science data cubes, acquired with the MeerKAT radio telescope. We stack galaxies in bins of galaxy properties (stellar mass M *, star formation rateSFR, and specific star formation rate sSFR, with sSFR ≡ M */SFR), obtaining ≳5σ detections in most cases, the strongest H i-stacking detections to date in this redshift range. With these detections, we are able to measure scaling relations in the probed redshift interval, finding evidence for a moderate evolution from the median redshift of our sample z med ∼ 0.37 to z ∼ 0. In particular, low-M * galaxies ( log 10 ( M * / M ⊙ ) ∼ 9 ) experience a strong H i depletion (∼0.5 dex in log 10 ( M H I / M ⊙ ) ), while massive galaxies ( log 10 ( M * / M ⊙ ) ∼ 11 ) keep their H i mass nearly unchanged. When looki...