These black holes are formed in the cataclysmic merger of galaxies. My research is shedding new light on the properties, environments, and histories of massive black hole mergers. Observing these needs a gravitational-wave detector in space (LISA, the Laser Interferometer Space Antenna, circa 2034), or (for the truly supermassive ones) a network of pulsars spread throughout the Milky Way that can be timed to extraordinary precision (a PTA, Pulsar Timing Array, online now!).
Some pulsars spin as fast as a kitchen blender, whipping beams of radiation into our line of sight to be detected in our radio telescopes as a "pulse". These cosmic lighthouses are incredibly stable. By tracking timing deviations, we haved searched, and found evidence for, the fingerprint of nanohertz gravitational waves that distort spacetime between the pulsar and the Earth. These timing deviations are correlated across all pulsars in the Milky Way, allowing us to sit at the center of a vast detector web. I chaired NANOGrav's gravitational-wave detection working group for several years. More recently, I co-led the analysis campaign that found first evidence for nanohertz-frequency gravitational waves. At the beginning of 2023, I was elected as Chair of NANOGrav, and made the announcement of our evidence alongside several colleagues, as well as Kip Thorne and Jocelyn Bell-Burnell.
MPhys Physics [1st Class] (2010)
Jesus College, University of Oxford
PhD Astronomy (2014)
Institute of Astronomy, University of Cambridge
NASA Jet Propulsion Laboratory (2014-2017)
California Institute of Technology (2017-2019)
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Co-Lead, NANOGrav's GW Evidence Paper