2025ApJ...993..149Z

Using the data from Mapping Nearby Galaxies at Apache Point Observatory (MaNGA) and H I-MaNGA surveys, we build a sample of 37 gas-star misaligned galaxies with robust H I detections, which are believed to have undergone external gas accretion processes. Both star-forming (SF) and quiescent (QS) misaligned galaxies exhibit narrower H I line widths compared to their gas-star aligned controls. The H I profiles of SF misaligned galaxies tend to be single-peaked, displaying a slightly higher fraction of single-peaked shape compared to their aligned controls. The QS misaligned galaxies exhibit prominently single-peaked H I profiles, while their aligned controls show distinct double-horned profiles. The shape of H I profiles is expected to change with the H I surface density radial gradients through external gas accretion-the interaction between the accreted gas and the pre-existing gas leads to the redistribution of angular momentum and induces gas inflow. This suggests that the progenitors of SF misaligned galaxies are central H I enriched; in this case, the shapes of the H I profiles are insensitive to further increases in central H I surface density. The progenitors of QS misaligned galaxies are central H I deficient, hence the transition from central H I deficient to H I enriched surface density leads to significantly more single-peaked H I profiles.