SIMBAD references

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 (SFE_H 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 ∼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 SFE_H 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 SFE_H 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 SFE_H 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 H₂ reservoir of galaxy pairs. In addition, new FAST observations also reveal a H I absorber (N_H I_ ∼ 4.7 × 10²¹ cm^–2), which may suggest gas infalling and the triggering of active galactic nuclei activity.