Spatial variations of dust abundances across the Large Magellanic Cloud

TL;DR

This study analyzes how dust composition and abundance vary across the Large Magellanic Cloud using infrared data, revealing links between dust components, star formation, and stellar evolution.

Contribution

It provides the first detailed mapping of dust component variations across the LMC, highlighting different origins and evolution pathways for dust grains.

Findings

VSG abundance correlates with star formation activity.

PAH abundance increases near molecular clouds and the stellar bar.

Dust components have distinct origins and evolutionary processes.

Abstract

Using the data obtained with the Spitzer Space telescope as part of the Surveying the Agents of a Galaxy's Evolution (SAGE) legacy survey, we have studied the variations of the dust composition and abundance across the Large Magellanic Cloud (LMC). Such variations are expected, as the explosive events which have lead to the formation of the many HI shells observed should have affected the dust properties. Using a model and comparing with a reference spectral energy distribution from our Galaxy, we deduce the relative abundance variations of small dust grains across the LMC. We examined the infrared color ratios as well as the relative abundances of very small grains (VSGs) and polycyclic aromatic hydrocarbons (PAHs) relative to the big grain (BG) abundance. Results show that each dust component could have different origins or evolution in the interstellar medium (ISM). The VSG abundance traces the star formation activity and could result from shattering of larger grains, whereas the PAH abundance increases around molecular clouds as well as in the stellar bar, where they could have been injected into the ISM during mass loss from old stars.