Dependence of Merger-driven Star Formation and Gas-phase Metallicity Evolution on Merger Type and Stellar Mass

Galaxy mergers play a fundamental role in driving gas inflows, altering star formation, and redistributing metals, yet how these processes depend on merger type, merger stage, and progenitor galaxy properties remains incompletely understood. In this work, we investigate the resolved impact of mergers on star formation rate (SFR) and gas-phase metallicity using MaNGA integral-field spectroscopy and the MaNGA Galaxy Merger Catalog of Comerford et al. (2024). By comparing merger galaxies to matched controls, we quantify local offsets in SFR and metallicity as functions of merger type, merger stage, stellar mass, and galactocentric radius. We find that major mergers generally exhibit stronger SFR enhancement and greater metallicity dilution than minor mergers. In major mergers, SFR enhancement is often spatially extended, whereas in minor mergers it is weaker and more centrally concentrated. The SFR response in major mergers varies non-monotonically with merger stage, with stronger enhancement in the early (first-passage) and post-coalescence stages and weaker enhancement in the late (between-passage) stage. Metallicity dilution is generally strongest in early-stage major mergers and weaker at later stages, although this stage dependence is not monotonic across all stellar-mass bins. We also find stellar-mass dependence that lower-mass systems show stronger metallicity dilution in both major and minor mergers, while the strongest SFR enhancement occurs in intermediate- and high-mass major mergers. These results show that the resolved star formation and metallicity responses depend jointly on merger type, merger stage, and stellar mass and exhibit different behaviors across the merger sequence.