Research

I study theoretical cosmology, including the cosmic microwave background, the early universe, and connections to high energy and particle physics.

You can see my publications on inSpire.

Cosmic Microwave Background

Since the discovery of the cosmic microwave background (CMB) in 1964, measurements of the CMB have completely transformed our understanding of the history and contents of the universe. Ongoing and future observations of the CMB will continue to play a primary role in the development of modern cosmology. I am a member of the Simons Observatory, CCAT-Prime, and CMB-S4 collaborations, three future ground-based experiments, and the PICO collaboration, a proposed CMB satellite mission, which will survey the CMB with unprecedented sensitivity.

Light Relics

One of the key observational targets of the next generation of cosmological surveys is a measurement of the light relic energy density. The term ‘light relics’ refers to the collection of relativistic low-mass particles which were produced abundantly in the early universe. During the early phase of the current hot Big Bang expansion, the universe was filled with an extremeley dense thermal plasma which was so hot that even very weakly interacting particles were in thermal equilibrium. This includes, for example, the three species of neutrinos of the Standard Model of particle physics. The neutrinos fell out of equilibrium after about one second of expansion, however they remain extremely numerous today, making up the cosmic neutrino background. The gravitational influence of light relics has left observable signatures in the CMB and large scale structure, allowing cosmological observations to serve as a probe of neutrino physics and very weakly interacting particles beyond the Standard Model. Some of my research is devoted to developing the tools necessary to exploit cosmological observations to constrain particle physics, using the early universe as the ultimate high luminosity experiment.

Inflation

An extremely rapid, nearly exponential expansion of space, known as cosmic inflation, is thought to have occurred in the very early universe. Quantum fluctuations in the fields that drove this expansion provided the seeds for the cosmological structure observed in the universe today. The next generation of cosmological surveys seek to find signatures of cosmic inflation and to determine the physics responsible for generating this phase of expansion in the early universe. Part of my research focuses on determining how to best utilize observations to inform our understanding of the early universe.