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Dr. Jeff Cooke

I am interested in the formation and evolution of galaxies over cosmic time via external and internal processes. I am currently leading research in three main areas: high-redshift supernova detection and study, high redshift galaxy spectroscopic properties and large- and small-scale environments, and absorption-line system investigations.

Supernovae have a direct influence on the formation and evolution of galaxies by such means as inducing and arresting star formation, enriching galaxies chemically, and contributing to the ionization and expulsion of gas. I pioneered a technique to detect supernovae in high redshift galaxies and at distances far greater than has been previously achieved. I am using these supernovae to measure the form of the stellar initial mass function and to constrain galaxy processes. This research has also discovered super-luminous supernovae in the early Universe, some of which, may be observational examples of a long-theorized third supernova explosion process termed pair-instability supernovae. Our most distant discoveries occurred when the universe was only about 10% its current age. Because many of the first generation of stars (Population III stars) are believed to result in pair-instability supernovae, we now have the capability and may be detecting the deaths of the very first stars!

The dark matter mass, spatial distribution, and merger histories of galaxies are powerful means to track and study the formation and evolution of galaxies. I conduct large, deep imaging and spectroscopic surveys at high redshift and analyze the results against high-resolution cosmological simulation predictions. This work has uncovered a surprising relationship between both the spectral features and kinematics of galaxies and their large-scale environment (whether or not they reside in dense groups, on group outskirts, or in the field in filaments). These surveys have also revealed that galaxy mergers and interactions affect the strength and/or presence of spectroscopic features.

Absorption-line systems provide the necessary gas to fuel initial and ongoing star formation in galaxies. However, discerning sightlines through coalescing proto-galaxy populations from sightlines through inflowing gas from the IGM or galaxy halo outflows is far from straightforward. I am involved in several projects aimed to characterize absorption systems illuminated by a background quasar or galaxy. Understanding gas consumption and expulsion and identifying fundamental absorber properties and their host galaxies is essential for a complete picture of galaxy formation and evolution.

Email  
Phone   +61 3 9214 5392
Fax   +61 3 9214 8797
Office   AR 315
Personal Webpage   http://www.astro.caltech.edu/~cooke