Constraining gravitational wave propagation using pulsar timing array correlations

Abstract

Pulsar timing arrays (PTA) are a promising probe to the cosmologically novel nanohertz gravitational wave (GW) regime through the stochastic GW background. In this work, we consider subluminal GW modes as a possible source of correlations in a PTA, utilizing the public code ptafast and the 12.5 years correlations data by NANOGrav, which we hypothesize are sourced by GWs. Our results show no evidence in support of tensor- or vector-induced GW correlations in the data, and that vector correlations are disfavored. This places an upper bound to the graviton mass, ${m}_{\mathrm{g}}\ensuremath{\lesssim}{10}^{\ensuremath{-}22}\text{ }\text{ }\mathrm{eV}$, characteristic of the PTA GW energy scale.

Topics & Concepts