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Optimal strategies for continuous wave detection in pulsar timing arrays: Realistic pulsar noise and a gravitational wave background

Shashwat C. Sardesai1,2, Gabriel E. Freedman1, Sarah J. Vigeland1, and Caitlin A. Witt3

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Phys. Rev. D 113, 084067 – Published 30 April, 2026

DOI: https://doi.org/10.1103/174h-7xf1

Abstract

Pulsar timing arrays are sensitive to low-frequency gravitational waves (GWs), such as those produced by supermassive binary black holes at subparsec separations. The incoherent superposition of GWs emitted by a cosmological population of these sources produces a gravitational wave background (GWB), while some individual sources may be resolvable as deterministic signals with slowly varying GW frequencies, which are often referred to as “continuous waves” (CWs). The Fp-statistic is a frequentist method of detecting these CWs. In this paper, we study how the presence of pulsar red noise and a GWB affect the Fp-statistic. We compare results when marginalizing over the red noise and using the maximum-likelihood values of the red noise, and find little difference between the two. We also present results of using the Fp-statistic to analyze the NANOGrav 12.5-year dataset, where we find no evidence for CWs in agreement with the previously published Bayesian results.

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Phys. Rev. D 113, 084067– Published 30 April, 2026
  • Received 1 November 2025
  • Accepted 7 April 2026
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