The intrinsic reddening of the Magellanic Clouds as traced by background galaxies -- III. The Large Magellanic Cloud

TL;DR

This study creates a detailed map of intrinsic reddening across the Large Magellanic Cloud using optical and near-infrared data from background galaxies, revealing dust distribution and star-forming regions.

Contribution

It provides one of the first large-scale extragalactic reddening maps of the LMC based on background galaxy SED fitting, improving understanding of dust and star formation.

Findings

Reddening map aligns with dust emission and star-forming regions.

Smaller reddening in the molecular ridge than previously reported.

Map is consistent with other stellar-based reddening maps.

Abstract

We present a map of the total intrinsic reddening across ~90 deg$^{2}$ of the Large Magellanic Cloud (LMC) derived using optical (ugriz) and near-infrared (IR; YJKs) spectral energy distributions (SEDs) of background galaxies. The reddening map is created from a sample of 222,752 early-type galaxies based on the LEPHARE $\chi^{2}$ minimisation SED-fitting routine. We find excellent agreement between the regions of enhanced intrinsic reddening across the central (4x4 deg$^2$) region of the LMC and the morphology of the low-level pervasive dust emission as traced by far-IR emission. In addition, we are able to distinguish smaller, isolated enhancements that are coincident with known star-forming regions and the clustering of young stars observed in morphology maps. The level of reddening associated with the molecular ridge south of 30 Doradus is, however, smaller than in the literature reddening maps. The reduced number of galaxies detected in this region, due to high extinction and crowding, may bias our results towards lower reddening values. Our map is consistent with maps derived from red clump stars and from the analysis of the star formation history across the LMC. This study represents one of the first large-scale categorisations of extragalactic sources behind the LMC and as such we provide the LEPHARE outputs for our full sample of ~2.5 million sources.