A novel probe of graviton dispersion relations at nano-Hertz frequencies

TL;DR

This paper extends a theorem to include modified graviton dispersion relations, predicting distinctive signatures in nano-Hertz gravitational wave backgrounds detectable by pulsar timing arrays, aiding tests of fundamental physics.

Contribution

It introduces a generalized framework for probing graviton dispersion modifications using pulsar timing array data, focusing on the inspiral phase of binary sources.

Findings

Modified dispersion relations produce localized spectral distortions.

Future pulsar timing arrays can constrain graviton dispersion parameters.

Predictions do not depend on non-linear merger effects.

Abstract

We generalise Phinney's 'practical theorem' to account for modified graviton dispersion relations motivated by certain cosmological scenarios. Focusing on specific examples, we show how such modifications can induce characteristic localised distortions, bumps, in the frequency profile of the stochastic gravitational wave background emitted from distant binary sources. We concentrate on gravitational waves at nano-Hertz frequencies probed by pulsar timing arrays, and we forecast the capabilities of future experiments to accurately probe parameters controlling modified dispersion relations. Our predictions are based on properties of gravitational waves emitted in the first inspiral phase of the binary process, and do not rely on assumptions of non-linear effects occurring during the binary merging phase