Probing Parity Violation in the Stochastic Gravitational Wave Background with Astrometry

TL;DR

This paper explores how astrometry can detect parity-violating signals in the stochastic gravitational wave background by analyzing specific correlation functions, offering a complementary approach to pulsar timing methods.

Contribution

It introduces a method to identify parity violation in the SGWB through astrometric measurements by defining and quantifying the $EB$ correlation function.

Findings

Feasibility of detecting parity violation using astrometry.

Definition and quantification of the $EB$ correlation function.

Assessment of detectability of parity-violating signals.

Abstract

Astrometry holds the potential for testing fundamental physics through the effects of the Stochastic Gravitational Wave Background (SGWB) in the $\sim 1-100$ nHz frequency band on precision measurements of stellar positions. Such measurements are complementary to tests made possible by the detection of the SGWB using Pulsar Timing Arrays. Here, the feasibility of using astrometry for the identification of parity-violating signals within the SGWB is investigated. This is achieved by defining and quantifying a non-vanishing $EB$ correlation function within astrometric correlation functions, and investigating how one might estimate the detectability of such signals.