# PhD Defense: Brian Pardo

## Post-Newtonian Gravitational Dynamics from Effective Field Theory

Abstract: Gravitational wave astronomy is rapidly maturing into a standard tool to study astrophysics,astronomy, and cosmology. Understanding the evolution and mergers of compactobject binaries, an important source of gravitational waves, is essential tointerpreting signals from modern gravitational wave observatories such as LIGO.In this thesis, we present progress towards computing the dynamics of binarysystems during the early stages of binary mergers known as the inspiralphase. During this stage of a binary merger, there is a separation of scalesbetween the compact object size, the orbital separation, and the radiationwavelength that lends itself to an effective field theory description, known asnonrelativistic general relativity. In this approach, we use velocity as thepower-counting parameter of a post-Newtonian expansion to study these objectsin a systematic way. In particular, we first study subleading spineffects in the equations of motion, the adiabatically conserved quantities ofthe system, and the radiative flux-balance equations to ultimately compute theaccumulated orbital phase observable. We then compute the state-of-the-artnext-to-next-to-leading order radiation reaction equations of motion from firstprinciples. We perform important consistency checks for our results, andcompare when possible, with the literature.

Research Advisor: Dr. Adam Leibovich

### Location and Address

321 Allen Hall & Zoom

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