Post-Newtonian Binary Dynamics in Effective Field Theory of Horndeski Gravity

TL;DR

This paper develops a post-Newtonian effective field theory for Horndeski gravity, analyzing binary system dynamics and constraining model parameters using pulsar data, thus extending gravitational theory analysis beyond general relativity.

Contribution

It formulates the first post-Newtonian effective field theory for Horndeski gravity and applies it to real binary systems to constrain model parameters.

Findings

Derived the effective Lagrangian for binary systems in Horndeski gravity.

Calculated the periastron advance for specific pulsar binaries.

Constrained Horndeski model parameters using observational data.

Abstract

General relativity has been very successful since its proposal more a century ago. However, various cosmological observations and theoretical consistency still motivate us to explore extended gravity theories. Horndeski gravity stands out as one attractive theory by introducing only one scalar field. Here we formulate the post-Newtonian effective field theory of Horndeski gravity and investigate the conservative dynamics of the inspiral compact binary systems. We calculate the leading effective Lagrangian for a compact binary and obtain the periastron advance per period. In particular, we apply our analytical calculation to two binary systems, PSR B 1534+12 and PSR J0737-3039, and constrain the relevant model parameters. The theoretical framework can also be extended to higher order systematically.