Constraining the evolutionary history of Newton's constant with gravitational wave observations

TL;DR

This paper explores how space-based gravitational wave detectors can constrain the time variation of Newton's constant by analyzing black hole merger signals, providing a new method to test fundamental physics.

Contribution

It introduces a novel approach to constrain the first time-derivative of Newton's constant using gravitational wave observations from space-based detectors.

Findings

Space-based detectors can map constraints on ot;G/G as a function of sky position and redshift.

A three-year LISA observation of a 10^5 solar mass binary can measure ot;G/G to better than 10^{-11}/yr.

The method provides a new way to test the constancy of fundamental physical constants over cosmic time.

Abstract

Space-borne gravitational wave detectors, such as the proposed Laser Interferometer Space Antenna, are expected to observe black hole coalescences to high redshift and with large signal-to-noise ratios, rendering their gravitational waves ideal probes of fundamental physics. The promotion of Newton's constant to a time-function introduces modifications to the binary's binding energy and the gravitational wave luminosity, leading to corrections in the chirping frequency. Such corrections propagate into the response function and, given a gravitational wave observation, they allow for constraints on the first time-derivative of Newton's constant at the time of merger. We find that space-borne detectors could indeed place interesting constraints on this quantity as a function of sky position and redshift, providing a {\emph{constraint map}} over the entire range of redshifts where binary black hole mergers are expected to occur. A LISA observation of an equal-mass inspiral event with total redshifted mass of 10^5 solar masses for three years should be able to measure $\dot{G}/G$ at the time of merger to better than 10^(-11)/yr.