A Gaussian process framework for testing general relativity with gravitational waves

TL;DR

This paper introduces a Gaussian process framework to detect deviations from general relativity in gravitational-wave signals, focusing on minimal assumptions and localized deviations near merger events.

Contribution

The authors develop a novel Gaussian process method with a specialized kernel to search for localized deviations in gravitational-wave data, applied to real and simulated signals.

Findings

No evidence found for deviations from general relativity in analyzed events.

The method constrains fractional deviations to as low as 7% of GW190701_203306 strain.

Demonstrates the effectiveness of Gaussian processes in testing fundamental physics with gravitational waves.

Abstract

Gravitational-wave astronomy provides a promising avenue for the discovery of new physics beyond general relativity as it probes extreme curvature and ultra-relativistic dynamics. However, in the absence of a compelling alternative to general relativity, it is difficult to carry out an analysis that allows for a wide range of deviations. To that end, we introduce a Gaussian process framework to search for deviations from general relativity in gravitational-wave signals from binary black hole mergers with minimal assumptions. We employ a kernel that enforces our prior beliefs that - if gravitational waveforms deviate from the predictions of general relativity - the deviation is likely to be localised in time near the merger with some characteristic frequency. We demonstrate this formalism with simulated data and apply it to events from Gravitational-Wave Transient Catalog 3. We find no evidence for a deviation from general relativity. We limit the fractional deviation in gravitational-wave strain to as low as 7% (90% credibility) of the strain of GW190701_203306.