Exploring Molecular Complexity in the Age of ALMA

Li-Hong Xu (University of New Brunswick)

February 04, 2016

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Abstract: Over the past five decades, radio astronomy has shown that molecular complexity is a natural outcome of interstellar chemistry, in particular in star-forming regions. However, the pathways that lead to the formation of complex molecules are by no means fully understood and the remarkable depth of chemical complexity is still continuing to be revealed. One feature of particular interest to us at present is the sulphur chemistry in the dense interstellar medium, which is not well understood.
The Atacama Large Millimeter Array (ALMA), a high-resolution ground-based telescope array in Chile, was recently used by our astronomical colleagues for a spectral line survey of the famous Sagittarius B2(N) molecular cloud between 84 – 114.4 GHz. Our laboratory high resolution spectroscopic studies played a pivotal role in the detection and analysis of several species in the complex spectra observed. For the first time, a number of large Alkanols and Alkanethiol molecules were observed along with their associated isotopologues. With the assumption of local thermodynamic equilibrium (LTE), these have allowed deduction of the column densities and isotopic ratios in the Sgr B2(N) environment for each molecule. Our team’s observations are supplemented by astrochemical modeling, using a new network that, for the first time, includes reaction pathways for alkanethiols.