On the H I Content of MaNGA Major Merger Pairs

To study the role of H I content in galaxy interactions, we select galaxy pairs and control galaxies from the SDSS-IV MaNGA IFU survey, adopting kinematic asymmetry as a new effective indicator to describe the merger stage. With archival data from the HI-MaNGA survey and new observations from the Five-hundred-meter Aperture Spherical radio Telescope (FAST), we investigate the differences in H I gas fraction (fH I), star formation rate (SFR), and H I star formation efficiency (SFEH I) between pairs and controls. Our results suggest that on average the H I gas fraction of major-merger pairs is marginally decreased by ∼ 15% relative to isolated galaxies, and paired galaxies during pericentric passage show weakly decreased fH I (−0.10 ± 0.05 dex), significantly enhanced SFR (0.42 ± 0.11 dex), and SFEH I (0.48 ± 0.12 dex). We propose the marginally detected H I depletion may originate from the gas consumption in fueling the enhanced H₂ reservoir of galaxy pairs.