An isolated supermassive black hole binary (SMBHB) produces an identical cross-correlation pattern of pulsar timings as an isotropic stochastic background gravitational waves (GWs) generated possibly by inflation. Can there remain the identical cross-correlation pattern in the presence of a secondary SMBHB? To address this issue, the present paper focuses on GWs with similar amplitudes but slightly different frequencies f1 and f2 coming from two different directions. Beats between the two GWs can modify angular correlation patterns. The beat-induced correlation patterns are not stationary but modulated with a beat frequency fbeat≡∣f1−f2∣. We obtain an analytic solution that allows us to infer fbeat from the modulated angular correlations.
@article{arxiv.2501.13450,
title = {Can we hear beats with pulsar timing arrays?},
author = {Shun Yamamoto and Hideki Asada},
journal= {arXiv preprint arXiv:2501.13450},
year = {2025}
}
Comments
12 pages, 4 figures, discussions on two GW sources over the stochastic background and validity of the monochromatic assumption added, Figure 4 caption corrected, accepted for JCAP