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arXiv · 2304.02640

A Test of Gravity with Pulsar Timing Arrays

Qiuyue Liang·Meng-Xiang Lin·Mark Trodden
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Abstract

A successful measurement of the Stochastic Gravitational Wave Background (SGWB) in Pulsar Timing Arrays (PTAs) would open up a new window through which to test the predictions of General Relativity (GR). We consider how these measurements might reveal deviations from GR by studying the overlap reduction function -- the quantity that in GR is approximated by the Hellings-Downs curve -- in some sample modifications of gravity, focusing on the generic prediction of a modified dispersion relation for gravitational waves. We find a distinct signature of such modifications to GR -- a shift in the minimum angle of the angular distribution -- and demonstrate that this shift is quantitatively sensitive to any change in the phase velocity. In a given modification of gravity, this result can be used, in some regions of parameter space, to distinguish the effect of a modified dispersion relation from that due to the presence of extra polarization modes.

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Qiuyue Liang, Meng-Xiang Lin, Mark Trodden. 2023-04-05. A Test of Gravity with Pulsar Timing Arrays. https://doi.org/10.1088/1475-7516%2F2023%2F11%2F042

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