An ALMA archival study of the clump mass function in the Large Magellanic Cloud

Abstract

We present 1.3 and 3.2 mm continuum maps of three star forming regions in the Large Magellanic Cloud (LMC) observed with the Atacama Large Millimeter/Submillimeter Array (ALMA). The data were taken as part of two projects retrieved from the ALMA public archive plus one project observed specifically for this work. We develop a technique to combine maps at these wavelengths to estimate dust-only emission corrected for free-free emission contamination. From these observations we identify 32 molecular clumps in the LMC and estimate their total mass from their dust emission to range from 205 to 5740 M$_{\odot}$. We derive a cumulative clump mass function ($N(\geq M) \propto M^{\alpha + 1}$) and fit it with a double power law to find $\alpha_{\mathrm{low}} = -1.76^{+0.04}_{-0.05}$, $\alpha_{\mathrm{high}} = -3.3 \pm 0.2$, and a break mass of 2500$^{+300}_{-200}$ M$_{\odot}$. A comparison to the 30 Doradus-10 mass function derived previously from CO (2-1) data reveals a consistent range of clump masses and good agreement between the fitted slopes. We also find that the low mass index of the LMC mass function agrees well with the high mass index for core and clump mass functions from several star forming regions in the Milky Way. This agreement may indicate an extension of the Milky Way power law to higher masses than previously observed.