Pulsar timing array sensitivity to anisotropies in the gravitational wave background

2024/07/19 by Paul Frederik Depta, Valerie Domcke, Depta, Paul Frederik +5 · 5 citations
Earth and Planetary Sciences · Physics and Astronomy · #Cosmology and Nongalactic Astrophysics (astro-ph.CO) #FOS: Physical sciences #General Relativity and Quantum Cosmology (gr-qc) #Geophysics and Gravity Measurements #High Energy Astrophysical Phenomena (astro-ph.HE) #Pulsars and Gravitational Waves Research #Radio Astronomy Observations and Technology

paper · pdf · doi:10.48550/arxiv.2407.14460

openalex publication_date 2024/07/19 · openalex created_date 2025/10/10 · openalex updated_date 2026/07/28

Abstract

Pulsar Timing Array (PTA) observations have recently gathered substantial evidence for the existence of a gravitational wave background in the nHz frequency band. Searching for anisotropies in this signal is key to determining its origin, and in particular to distinguish possible astrophysical from cosmological sources. In this work, we assess the sensitivity of current and future pulsar timing arrays to such anisotropies using the full covariance matrix of pulsar timing delays. While current day pulsar timing arrays can only set mildly informative constraints on the dipole and quadrupole, we show that percent level accuracy for several low multipoles can be achieved in the near future. Moreover, we demonstrate that anisotropies in the gravitational wave background and the Hellings-Downs angular correlation, indicating the presence of GWs, are approximately uncorrelated, and can hence be reconstructed independently. These results can be reproduced with \hrefhttps://github.com/Mauropieroni/fastPTAfastPTA, a publicly available Python code to forecast the constraining power of PTA configurations.

Cited by

• Prospects and Limitations of PTAs Anisotropy Searches -- The Frequentist Case
• Cosmic Variance in Anisotropy Searches at Pulsar Timing Arrays
• Simulating a Gaussian stochastic gravitational wave background signal in pulsar timing arrays
• From new physics to a running power law and back again: Minimal refitting techniques for the reconstruction of the gravitational-wave background signal in pulsar timing array data
• Beyond diagonal approximations: improved covariance modeling for pulsar timing array data analysis

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• Measuring kinematic anisotropies with pulsar timing arrays
• Prospects and Limitations of PTAs Anisotropy Searches -- The Frequentist Case
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