On the H i Content of MaNGA Major Merger Pairs

The role of H i content in galaxy interactions is still under debate. To study the H i content of galaxy pairs at different merging stages, we compile a sample of 66 major-merger galaxy pairs and 433 control galaxies from the Sloan Digital Sky Survey IV (SDSS-IV) MaNGA IFU survey. In this study, we adopt kinematic asymmetry as a new effective indicator to describe the merging stage of galaxy pairs. 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 (f (H I)), star formation rate (SFR), and H i star formation efficiency (SFEH I) between the pair and control samples. Our results suggest that the H i gas fraction of major-merger pairs on average is marginally decreased by similar to 15% relative to isolated galaxies, implying mild H i depletion during galaxy interactions. Compared to isolated galaxies, pre-passage paired galaxies have similar f (H I), SFR, and SFEH I, while pairs during the pericentric passage have weakly decreased f (H I) (-0.10 +/- 0.05 dex), significantly enhanced SFR (0.42 +/- 0.11 dex), and SFEH I (0.48 +/- 0.12 dex). When approaching the apocenter, paired galaxies show marginally decreased f (H I) (-0.05 +/- 0.04 dex), comparable SFR (0.04 +/- 0.06 dex), and SFEH I (0.08 +/- 0.08 dex). We propose that the marginally detected H i depletion may originate from the gas consumption in fueling the enhanced H-2 reservoir of galaxy pairs. In addition, new FAST observations also reveal a H i absorber (N (H I) similar to 4.7 x 10(21) cm(-2)), which may suggest gas infalling and the triggering of active galactic nuclei activity.