Probing circular polarization in stochastic gravitational wave background with pulsar timing arrays

TL;DR

This paper investigates the potential to detect circular polarization in a stochastic gravitational wave background using pulsar timing arrays, focusing on anisotropic backgrounds and methods to distinguish polarized signals.

Contribution

It introduces generalized overlap reduction functions for circular polarization and demonstrates the conditions under which polarization can be detected or separated.

Findings

Circular polarization detection is unlikely for isotropic backgrounds.

Anisotropic backgrounds offer a chance to observe circular polarization.

Methods to distinguish polarized from unpolarized gravitational waves are proposed.

Abstract

We study the detectability of circular polarization in a stochastic gravitational wave background from various sources such as supermassive black hole binaries, cosmic strings, and inflation in the early universe with pulsar timing arrays. We calculate generalized overlap reduction functions for the circularly polarized stochastic gravitational wave background. We find that the circular polarization can not be detected for an isotropic background. However, there is a chance to observe the circular polarization for an anisotropic gravitational wave background. We also show how to separate polarized gravitational waves from unpolarized gravitational waves.