Cold dust clumps in dynamically hot gas

TL;DR

This study catalogs and analyzes cold dust clumps in the Large Magellanic Cloud using Herschel data, revealing a power-law mass distribution similar to HI clouds, and compares dust and gas properties.

Contribution

It introduces an automated method for identifying dust clouds in the LMC and characterizes their physical and statistical properties, including mass distribution.

Findings

Dust cloud mass spectrum follows a power law with exponent -1.8.

Dust and HI mass distributions are similar.

Cold dust masses are derived from spectral energy distribution fits.

Abstract

We present clumps of dust emission from Herschel observations of the Large Magellanic Cloud (LMC) and their physical and statistical properties. We catalog cloud features seen in the dust emission from Herschel observations of the LMC, the Magellanic type irregular galaxy closest to the Milky Way, and compare these features with HI catalogs from the ATCA+Parkes HI survey. Using an automated cloud-finding algorithm, we identify clouds and clumps of dust emission and examine the cumulative mass distribution of the detected dust clouds. The mass of cold dust is determined from physical parameters that we derive by performing spectral energy distribution fits to 250, 350, and 500 micronm emission from SPIRE observations using DUSTY and GRASIL radiative transfer calculation with dust grain size distributions for graphite/silicate in low-metallicity extragalactic environments. The dust cloud mass spectrum follows a power law distribution with an exponent of gamma=-1.8 for clumps larger than 400 solar mass and is similar to the HI mass distribution. This is expected from the theory of ISM structure in the vicinity of star formation.