Modelling the Impact of Stellar Feedback on Astrochemistry in Molecular Clouds

University Of Massachusetts Amherst, Amherst MA

Investigators

Abstract

Stars form within regions of cold, dense molecular gas. Many outstanding problems in star formation, including the origin of star masses and the rate of star formation, rely on first, accurately determining how much molecular gas there is and, second, how energetic that gas is. However, there is no single perfect tracer for all gas densities and temperatures. The most abundant molecule within molecular clouds, molecular hydrogen (H2), is virtually invisible. Consequently, obtaining fundamental information requires understanding the relation between H2 and the emission of other less abundant species, which are all complex functions of the local environment. This research will provide a basis for understanding chemical distributions in different star-forming environments and will focus on the relationship between H2 and easily observable molecules, such as carbon monoxide (CO) and hydrogen cyanide (HCN). The goal of this research project is to investigate the evolution of chemical abundances and line emission in star-forming molecular clouds as a function of star formation activity. The investigator will perform numerical simulations of turbulent, star-forming clouds that include magneto-hydrodynamics, radiative transfer, gravity and feedback from stars. This project will use full chemical networks coupled with multi-physics molecular cloud simulations to study the relationship between observations and underlying physical quantities. The investigator will quantitatively explore three fundamental questions: How does the relation between atomic carbon, CO, and HCN emission and H2 density evolve as a function of star formation activity? How well do tracers, such as CO and HCN, probe the gas energetics and correlate with total star formation? What is the impact of kinematic feedback due to proto-stellar outflows on astrochemistry? This work has implications for estimating the total molecular gas mass, star formation efficiency, and the correspondence between molecular cloud properties (temperature, mass, velocity dispersion) and the star formation rate. They plan to archive and share the abundance and emission maps with the astronomy community through the website "Dataverse". This will allow comparison with observations, including Atacama Large Millimeter Array (ALMA) data, for a wide range of species, cloud conditions, and physical scales. New numerical methods developed under the auspices of this funding will also be publicly released.