Local measurement of {\Lambda} using pulsar timing arrays

TL;DR

This paper explores how a non-zero cosmological constant affects gravitational wave detection via pulsar timing arrays, proposing a new method to measure mbda locally through angular dependence of timing residuals.

Contribution

It introduces the impact of mbda on gravitational wave signals in PTA, suggesting a novel local measurement technique based on angular residual patterns.

Findings

Timing residuals show a distinctive angular dependence influenced by mbda.

A peak in residuals occurs at a specific angle, serving as a gauge for mbda.

The effect could aid in the first direct detection of gravitational waves and measure mbda locally.

Abstract

We have considered the propagation of gravitational waves (GW) in de Sitter space time and how a non-zero value of the cosmological constant might affect their detection in pulsar timing arrays (PTA). If {\Lambda} is different from zero waves are non-linear in Friedmann-Robertson-Walker coordinates and although the amount of non-linearity is very small it gives noticeable effects for GW originating in extragalactic sources such as spiraling black hole binaries. The results indicate that the timing residuals induced by gravitational waves from such sources in PTA would show a peculiar angular dependence with a marked enhancement around a particular value of the angle subtended by the source and the pulsars, depending mainly on the actual value of the cosmological constant and the distance to the source. The position of the peak could represent a gauge of the value of \Lambda. The enhancement that the new effect brings about could facilitate the first direct detection of gravitational waves while representing a local measurement of \Lambda.