Effective field theory and astrophysics

Abstract:  I review the effective field theory (EFT) approach focusing on progress and problems in gravitational wave astrophysics. EFT is a powerful framework allowing one to account for features of extended objects, including tidal deformation, spin angular momentum, and intrinsic structure, within a convenient point particle language. Investigations in the inspirals of compact binaries have led to two important developments: 1) generalizing Lagrangian/Hamiltonian mechanics to dissipative problems in a generic way, and 2) numerically solving for retarded Green's functions for wave propagation in black hole spacetimes. Being based on Lagrangian mechanics (which is applicable for energy conserving problems), EFT was initially unable to properly describe the dissipative evolution of compact binary inspirals. I discuss how recent work generalizing Lagrangian mechanics to dissipative systems is used in EFT to tackle important physical problems entailing irreversible processes. EFT calculations also require knowing the relevant Green's function in order to obtain quantitative predictions. I will discuss progress on numerical investigations of the retarded Green's functions for wave propagation in black hole spacetimes that, combined with dissipative mechanics, provides EFT with a uniquely powerful set of tools to give quantitative predictions for gravitational wave sources and other interesting astrophysical problems.