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One of the key unsolved problems in astronomy is to understand how galaxies evolve and transform over cosmic time. Over the last 10 billion years the demographics of the galaxy population has changed, with the number of star-forming galaxies staying roughly constant and quiescent galaxies increasing. To explain the bimodal galaxy population there must be processes that both disrupt the supply of gas that is fueling star formation and transforms the galaxies’ morphologies. Reproducing these trends is a key test for galaxy evolution models. There is much debate regarding the exact physical mechanisms and timescales involved in galaxy transformation. The general consensus until recently was that star formation stops because cold gas is consumed by star formation, or heated or removed by large-scale outflows driven by either supernovae or supermassive black holes. Recent discoveries of large amounts of gas in transitioning galaxies in the local Universe challenge this traditional picture. Over the past decade, while large-area galaxy surveys have revolutionized our knowledge of the demographics of the quiescent galaxy population and its build-up over cosmic time, the mechanisms that lead to the disruption of the gas supply and hence the shut-down of star formation are still poorly understood. This project seeks to understand the processes which trigger the shutdown in star formation and answer this major open question in astronomy.
Project summary
There are several projects that can be undertaken by a graduate student on topics related to galaxy evolution, quenching and AGN at redshifts 0.5<z<3. These are part of a larger collaborative project to understand the processes which drive the shutdown of star formation in galaxies, using the wealth of photometric and spectroscopic data from ground-based and space-based observatories (e.g. HST, SOFIA, Chandra, JWST, Herschel, Spitzer, UKIRT, VLT) in deep extragalactic fields. The first part of the student-led project is to apply existing photometric selection techniques to deep fields to find the largest sample of high-redshift quenching galaxies to date. If expansion to a thesis project is desired, later parts of the project involve investigating the star-formation histories, morphologies, dust content, environment and AGN activity in the high redshift post-starburst galaxies.
These projects will be undertaken within the highly supportive and collaborative post-starburst galaxy group at STScI/JHU, and with collaborators in the UK. There are plenty of opportunities for travel to collaborators and conferences. All of the projects should result in a student-led refereed paper and presentations at conferences.
Student work
Planned work as part of photometry project:
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