Speaker
Description
Pulsar timing array datasets are used to detect a stochastic gravitational wave background (SGWB) through angular cross-correlations between timing residuals measured from different pulsars. Analytically, these cross-correlations are computed through the overlap reduction function (ORF), which expresses the GW signal strength’s dependence on the angular separation of the pulsars. Since a GW’s characteristics are strongly model-dependent, the ORF takes different forms in modified models of gravity beyond general relativity. In our study, we focus on viable massive gravity (MG) in which the graviton has a tiny, non-zero mass. Such a theory of MG implies a modified dispersion relation and additional polarization modes for GWs. Accounting for these modifications of the SGWB, we compare the theoretically predicted ORFs with currently available observational data. In particular, we utilize the European Pulsar Timing Array Data Release 2 (EPTA DR2) to perform Bayesian analysis on the SGWB to determine if there is an observational preference for MG models.