The Detection of Hot Cores and Complex Organic Molecules in the Large Magellanic Cloud

TL;DR

This study reports the first extragalactic detection of complex organic molecules in the Large Magellanic Cloud, revealing hot core chemistry and comparable abundances to Galactic hot cores, with implications for high-redshift organic chemistry.

Contribution

First detection of COMs in the LMC, demonstrating hot core chemistry in a low-metallicity extragalactic environment using ALMA.

Findings

Detected dimethyl ether and methyl formate in the LMC

COM abundances scaled for metallicity are similar to Galactic hot cores

Sources exhibit properties of hot cores with associated maser emissions

Abstract

We report the first extragalactic detection of the complex organic molecules (COMs) dimethyl ether (CH$_3$OCH$_3$) and methyl formate (CH$_3$OCHO) with the Atacama Large Millimeter/submillimeter Array (ALMA). These COMs together with their parent species methanol (CH$_3$OH), were detected toward two 1.3 mm continuum sources in the N 113 star-forming region in the low-metallicity Large Magellanic Cloud (LMC). Rotational temperatures ($T_{\rm rot}\sim130$ K) and total column densities ($N_{\rm rot}\sim10^{16}$ cm$^{-2}$) have been calculated for each source based on multiple transitions of CH$_3$OH. We present the ALMA molecular emission maps for COMs and measured abundances for all detected species. The physical and chemical properties of two sources with COMs detection, and the association with H$_2$O and OH maser emission indicate that they are hot cores. The fractional abundances of COMs scaled by a factor of 2.5 to account for the lower metallicity in the LMC are comparable to those found at the lower end of the range in Galactic hot cores. Our results have important implications for studies of organic chemistry at higher redshift.