Constraining Post_Newtonian Parameters With Gravitational Waves

TL;DR

This paper demonstrates that gravitational wave observations, specifically with LISA, can significantly constrain higher-order post-Newtonian parameters, improving tests of gravity beyond solar system limits even at low signal-to-noise ratios.

Contribution

It provides a method to re-express gravitational wave data in terms of post-Newtonian parameters and estimates the potential constraints achievable with LISA on these parameters.

Findings

LISA can constrain a higher-order post-Newtonian parameter at 10% level.

Constraints are possible even at low signal-to-noise ratios.

Significant improvements over solar system tests are achievable.

Abstract

We re-express gravitational wave results in terms of post-Newtonian parameters. Using these expressions, and some simplifying assumptions, we compute that in a favorable case, i.e. a ten solar-mass black hole spiraling in to a 10^6 solar-mass black hole, LISA observations will be able to constrain at the 10% level or better a single combination of post-post-Newtonian parameters one order higher than those already constrained by solar system evidence. This significant constraint will be possible even if the signal-to-noise level is so low that the signal can only be found by matched filtering, and hence only deviations between alternate signal interpretations of order one half cycle or more can be detected.