Connecting the Galactic and Extragalactic with MUSE: a comparison of integrated and resolved stellar populations

Galaxies grow through a combination of in situ star formation and mergers with other galaxies. For nearby galaxies this complex evolution can be traced directly by studying the spectrophotometric properties of individual stars, allowing us to dissect a galaxy like the Milky Way into its various chemical and kinematic components. At larger distances, outside the Local Group, observational limitations dictate that stellar population properties be derived using integrated rather than resolved measurements, and we typically rely upon the predictions of stellar population synthesis (SPS) models to interpret these data in terms of, e.g., star-formation history and chemical composition. Understanding the relationship between resolved (individual star) and integrated measurements is critical in order to connect detailed observations of objects in the nearby Universe with our picture of galaxy evolution over cosmic time.

The aim of this project is to compare properties of individual stars to the elemental abundances and star-formation histories that can be derived from integrated light measurements using observational data from the Multi Unit Spectroscopic Explorer (MUSE) and Hubble Space Telescope (HST). The figure above shows an example of MUSE data for the nearby galaxy NGC 6822; every pixel in the right-hand panel has a spectrum associated with it, and can be used to extract spectral measurements for ~150 individual stars as well as an integrated spectrum for the whole region.

As part of this project you will: 1) work with observational data to extract stellar and integrated light spectra, 2) derive properties for resolved stars based on a comparison with state-of-the-art stellar models, 3) learn to model integrated spectra using stellar population synthesis techniques, 4) conduct a comparison of integrated and resolved measurements to establish  baseline for extending integrated light studies to more distant galaxies.

We have entered an exciting era of instrumentation that allows us to resolve other galaxies and put their stars into the context of the Milky Way. This project would put you on the path for becoming an expert in the rapidly developing interdisciplinary field of resolved galaxy evolution, as well as provide valuable experience working with modern astronomical data.

For more information about this research, or to discuss any related research area, please contact the supervisors.