Mapping Dust Attenuation at Kiloparsec Scales. III. The 2175 Bump

We combine the SwiM v4.2 Swift/UVOT+MaNGA catalog with 2MASS K s imaging to map the 2175 attenuation bump at kiloparsec scales in nearby galaxies. We use two complementary estimators: an ultraviolet-to-near-infrared attenuation-curve method, yielding A bump UOIR and B for 2487 high-continuum-S/N spaxels, and the NUV-only method of Battisti et al. (2025), yielding A bump NUV and k bump for 7934 spaxels. The two absolute bump estimates agree well where they overlap. We compare bump strength with local stellar-population, emission-line, attenuation-curve, and geometric diagnostics after separating star-forming (SF) and non-SF regions. The strongest bumps occur at low specific H alpha surface brightness, H alpha/, especially in non-SF regions, where this ratio traces ionized-gas emission per unit stellar mass rather than sSFR. The bump also weakens with EW(H alpha) and strengthens with D n4000 and stellar age. In contrast, metallicity, inclination, galactocentric radius, A V, and optical attenuation-curve slope are secondary predictors. The absolute strength A bump NUV increases with H alpha and, while the relative strengths k bump and B do not, indicating that absolute bump amplitude partly follows dust column whereas normalized strengths better trace effective bump prominence. These results support local radiation-field processing of the 2175 carriers.