Caitlin Casey

I’m an observational astronomer with expertise in high-redshift galaxies. I use the most massive and unusual galaxies at early times to test fundamental properties of galaxy assembly (including their gas, stars, and dust) within a ΛCDM cosmological framework.

Research: I am an observational astronomer who studies the assembly of the most massive galaxies in the Universe. New observations from cutting-edge observatories like the James Webb Space Telescope (JWST), the Atacama Large Millimeter Array (ALMA), and Keck Observatory have taught us that the earliest times after the Big Bang were far more active than expected from our cosmological models — galaxies had more gas, formed more stars, and built supermassive black holes in the blink of an eye. By finding the most extreme galaxies formed at the earliest times, I test fundamental laws of physics within our cosmological framework. I lead the COSMOS survey which is a two square degree extragalactic deep field dedicated to finding the most rare, extreme galaxies and mapping them within their large-scale environments. COSMOS-Web, a sub-project within COSMOS, earned the largest allocation of public observing time on JWST in its first year and has mapped an area three times larger than all other JWST deep fields combined. Beyond early galaxy evolution, I am also interested in observational measurements of galaxy clusters in formation, weak gravitational lensing out to high redshifts, and the detection of high-redshift transient phenomena. I also have significant background in radio and submillimeter astronomy and their application to the high-redshift Universe, particularly in taking census of cold gas and dust at early times, which are not as well understood as galaxies’ stellar content.

Biography: Caitlin Casey completed her PhD in 2010 at the Institute of Astronomy, University of Cambridge as a Gates Cambridge Scholar funded through the Bill & Melinda Gates Foundation. From 2010 - 2013, she held a NASA Hubble Postdoctoral Fellowship at the University of Hawai’i at Mānoa’s Institute for Astronomy. From 2013 - 2015, Casey held the McCue Postdoctoral Fellowship of Cosmology at the University of California, Irvine. She was faculty in the Department of Astronomy at the University of Texas at Austin from 2015-2024 before joining UCSB Physics in 2025. Casey was awarded the 2018 Newton Lacy Pierce Prize for outstanding early career achievements in observational astronomical work by the American Astronomical Society. Other notable awards include a 2019 Cottrell Scholar Award granted by the Research Corporation for Science Advancement (RCSA) and the 2025 Edith and Peter O’Donnell Award for the Physical Sciences granted by the Texas Academy of Medicine, Engineering, Science & Technology.