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Regularizing the pulsar timing array likelihood: A path toward Fourier space

Serena Valtolina* and Rutger van Haasteren†

  • *Contact author: serena.valtolina@aei.mpg.de
  • †Contact author: rutger@vhaasteren.com
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Phys. Rev. D 112, 043046 – Published 29 August, 2025

DOI: https://doi.org/10.1103/s3gy-km61

Abstract

The recent announcement of evidence for a stochastic background of gravitational waves (GWB) in pulsar timing array (PTA) data has piqued interest across the scientific community. A combined analysis of all currently available data holds the promise of confirming the announced evidence as a solid detection of a GWB. However, the complexity of individual pulsar noise models and the variety of modeling tools used for different types of pulsars present significant challenges for a truly unified analysis. In this work we propose a novel approach to the analysis of PTA data: first a posterior distribution over Fourier modes is produced for each pulsar individually. Then, in a global analysis of all pulsars, these posterior distributions can be reused for a GWB search, which retains all information regarding the signals of interest without the added complexity of the underlying noise models or implementation differences. This approach facilitates combining radio and gamma-ray pulsar data, while reducing the complexity of the model and of its implementations when carrying out a GWB search with PTA data.

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Phys. Rev. D 112, 043046– Published 29 August, 2025
  • Received 20 December 2024
  • Revised 8 April 2025
  • Accepted 23 June 2025
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Published by the American Physical Society under the terms of the Creative Commons Attribution 4.0 International license. Further distribution of this work must maintain attribution to the author(s) and the published article’s title, journal citation, and DOI. Open access publication funded by the Max Planck Society.

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