NBIA Gravity Seminar: Ira Rothstein (Carnegie Mellon University)

Speaker: Ira Rothstein

Title:Environmental Effects on Binary Inspirals

Abstract: The problem of predicting the gravitational wave signal from a binary inspirals involves solving a complicated set of non-linear differential equations. There has been great progress made in making such  predictions analytically in Post-Newtonian limit (small relative velocities) using techniques originally developed for quantum field theory. In this talk I will discuss how one can extend these ideas to include the effects of  an inviscid  fluid environment by utilizing field theoretic techniques developed to study non-equilibtrium systems.  I will begin by building  a point particle  action for a compact object moving in an perfect  fluid. By doing so we effectively trade a set of boundary conditions for a coefficient in the action, which greatly simplifies the problem. I will then demonstrate how this approximation can reproduce the full answer at distances large compared to the radius of the object. This will lead naturally to a discussion of ``Dalamberts’ paradox'' which states that an object moving at constant velocity through fluid with no viscosity feels no drag force. I will then show how to introduce viscosity using the closed-time path integral formulation of field theory.  By covariantizing this theory I will show how one can systematically include Post-Newtonian corrections to the action for the purpose of making precision gravitational wave predictions which are sensitive to environmental conditions.