Cosmic Shimmering: the Gravitational Wave Signal of Time-Resolved Cosmic Shear Observations

TL;DR

This paper proposes a new method to detect gravitational waves by analyzing their time-dependent effects on the shapes of resolved astronomical objects, complementing existing detection techniques.

Contribution

It introduces a formalism for gravitational wave-induced shape distortions and explores their angular correlations, opening new avenues for gravitational wave detection via cosmic shear observations.

Findings

Sensitivity to low-frequency gravitational waves

Distinct angular correlation signatures identified

Potential for future high-resolution surveys

Abstract

We introduce a novel approach for detecting gravitational waves through their influence on the shape of resolved astronomical objects. This method, complementary to pulsar timing arrays and astrometric techniques, explores the time-dependent distortions caused by gravitational waves on the shapes of celestial bodies, such as galaxies or any resolved extended object. By developing a formalism based on that adopted in the analysis of weak lensing effects, we derive the response functions for gravitational wave-induced distortions and compute their angular correlation functions. Our results highlight the sensitivity of these distortions to the lowest frequencies of the gravitational wave spectrum and demonstrate how they produce distinct angular correlation signatures, including null and polarisation-sensitive correlations. These findings pave the way for future high-resolution surveys to exploit this novel observable, potentially offering new insights into the stochastic gravitational wave background and cosmological models.