Sarah Leslie

Sarah Leslie (Australia)

personal webpage

leslie @

Evolution of the cosmic star formation rate 

Observations have led to an evolutionary picture of how galaxies evolve: young galaxies are disk shaped, actively forming stars and are blue in color, but will evolve to become massive galaxies that are red in colour, having no appreciable star formation and elliptical morphologies. This evolution is thought to be driven by the accretion of gas, episodes of intense star formation and supermassive black hole growth and activity. However the relative importance of these events is not well understood. To properly investigate these open issues, we need observations of representative samples of galaxies in their different evolutionary states.

The international panchromatic Cosmic Evolution Survey (COSMOS), is the only survey large enough to study the coupled evolution of the large scale structure of the Universe, galaxies, star formation, and active galactic nuclei (supermassive black holes) across cosmic time. The area of sky covered by COSMOS has the most extensive set of multi-wavelength observations for any deep field, spanning the entire electromagnetic spectrum from X-ray, UV, optical, infrared. COSMOS has detected around 2 million galaxies.

For my PhD, I will be working with a new large radio survey of the COSMOS field using the Janksy Very Large Array (JVLA),  unmatched by any radio dataset to date. My project will be to combine this new JVLA data with the multiwavelength catalogues from the COSMOS project to quantify the importance of stellar mass, environment and galaxy type on the evolution of galaxies. This radio data will provide important, independent measurements of the dust conditions of the early universe, and will allow us to constrain star formation rates of galaxies formed when the Universe was just one tenth of its current age. With the large COSMOS data set, we will be able to dissect the relative importances of galaxy mass, morphology, supermassive black hole activity, and the large scale structure of the Universe on the evolution of galaxies. 
I will also be working with wide field surveys of the local Universe, such as the Sloan Digital Sky Survey and the Wide-field Infrared Survey Explorer to anchor our understanding of galaxy evolution to the conditions of the present day.  This work will illuminate the pathways via which galaxies evolve.

Supervisor: Eva Schinnerer  (MPIA)

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