Image credits, left to right: [1] Art: Measuring mistakes by Ulrike Kuchner. Lapel pin: CepheidStudio. [2] EROJ003707+0909.5, aka the space-invader. [3] Mapping dark matter with gravitational lensing. [4] Searching for gravitationally lensed gravitational waves.
Research: fundamental physics with big telescopes
I use gravitational lensing as a tool to explore big questions about how the universe works, including the nature of dark matter and dark energy, and the formation of compact objects and galaxies through cosmic time. My research currently focuses on multi-messenger gravitational lensing, including gravitationally lensed gravitational waves and preparing for exciting discoveries with Rubin's Legacy Survey of Space and Time. In recent years, my research has been funded by The Royal Society, the Leverhulme Trust, and the Science and Technology Facilities Council.
Previously, as a Royal Society University Research Fellow, I created and led the Local Cluster Substructure Survey (LoCuSS), a collaboration of 30 colleagues from a dozen countries. Our goals included using gravitational lensing to calibrate galaxy clusters as a cosmological probe and constraining the physics of galaxy transformation in clusters. We built a unique dataset including data from our observations with Chandra, XMM-Newton, GALEX, HST, Keck, Subaru, Gemini, UKIRT, Spitzer, Herschel, and CARMA. Many of our key results were led by students and postdocs; more information about their achievements is available from this curated list of LoCuSS publications.
As a Postdoc at Caltech I lead the first measurement of the galaxy morphology-density relation at high redshift, and pioneered gravitational lensing as a tool for measuring the relationship between the mass of galaxy clusters and their observable properties. Today these relationships are central to using galaxy clusters to explore dark energy, and were a major focus within LoCuSS. I received the Royal Astronomical Society's Fowler Award for this work in 2007. While I was a postdoc my observing experience grew to include the Keck, Hale, and Magellan telescopes.
As a PhD student at Durham University I was among the first to use radial arcs to explore the nature of dark matter, and combined near-infrared observations with gravitational lensing to test theories of galaxy formation. I also discovered the gravitationally lensed galaxy that was later re-christened the space invader. During my PhD I used data from the Hubble Space Telescope (HST), and observed with UKIRT, CFHT, WHT and the AAT.
