Sensitivity of Weak Lensing Surveys to Gravitational Waves from Inspiraling Supermassive Black Hole Binaries

TL;DR

This paper assesses the potential of weak lensing surveys to detect gravitational waves from supermassive black hole binaries, highlighting current limitations and future possibilities.

Contribution

It develops a formalism and framework to evaluate the sensitivity of weak lensing surveys to low-frequency gravitational waves, bridging observational gaps.

Findings

Current surveys are limited by angular resolution and noise.

An ideal cosmic-variance-limited survey could detect these gravitational waves.

Sensitivity requires capabilities far beyond existing or planned facilities.

Abstract

We explore the sensitivity of weak lensing surveys to gravitational waves (GWs) emitted by inspiraling supermassive black hole binaries (SMBHBs) in the nanohertz to microhertz frequency band, bridging the gap between pulsar timing arrays and space-based interferometers. Building on the formalism for GW-induced shear distortions, we develop a signal-to-noise framework that incorporates survey characteristics such as cadence, angular resolution, and depth. We model the effective galaxy population to evaluate the noise power spectral density and derive characteristic strain sensitivity curves. Applying this framework to both LSST-like and idealized survey configurations, we show that current surveys are limited by angular resolution and measurement noise, while an idealized, cosmic-variance-limited survey could in principle probe this frequency range. We emphasize that such sensitivity requires observational capabilities far beyond those of existing or planned facilities, and our results should be interpreted as an ultimate limit on the information accessible through weak lensing measurements.