Effective two-body approach to the hierarchical three-body problem: quadrupole to 1PN

Understand

Many binary systems of interest for gravitational-wave astronomy are orbited by a third distant body, which can considerably alter their relativistic dynamics.

• Precision computations are needed to understand the interplay between relativistic corrections and three-body interactions.
• We use an effective field theory approach to derive the effective action describing the long time-scale dynamics of hierarchical three-body systems up to 1PN quadrupole order.
• At this level of approximation, computations are complicated by the backreaction of small oscillations on orbital time-scales as well as deviations from the adiabatic approximation.