Scylla. VI. Parsec-scale Dust Extinction Maps in the SMC and LMC

Abstract We present a novel methodology for mapping dust extinction in nearby galaxies at parsec-scale resolution. We apply it to 68 Hubble Space Telescope (HST) fields within the Small and Large Magellanic Clouds (23 fields in the SMC and 45 fields in the LMC) using multiband HST photometry from the Scylla and Metal Evolution Transport and Abundance in the LMC surveys. Our technique leverages kriging , a geostatistical interpolation method built on the principles of Gaussian process regression, combined with Gaussian mixture modeling to statistically isolate background stellar sources and account for line-of-sight depth effects. Three-dimensional dust simulations demonstrate the method’s capability to recover column densities to an accuracy of A V ≈ 0.1 mag in fields with at least 1000 sources. The resulting 4″ resolution (∼1 pc) dust maps reveal detailed structure and strong spatial correlation with ancillary interstellar medium (ISM) tracers, especially in star-forming regions like 30 Doradus. Global extinction of total column densities follows log-normal profiles in both galaxies, with the SMC exhibiting slightly higher mean extinction ( e μ = 0.47 mag) than the broader LMC ( e μ = 0.43 mag), likely due to significant line-of-sight depths. We find systematic offsets between dust mass surface densities (Σ D ) derived from extinction versus far-IR emission in both galaxies, with Σ D , FIR / Σ D , A V ratios ranging from 0.6–1.8. This work provides the highest-resolution dust extinction maps in SMC and LMC to date, which offer a vital independent benchmark for constraining dust emissivity, CO-dark gas fractions, and the multiscale structure of the ISM in low-metallicity environments.