Pulsar timing array source ensembles

Abstract

The stochastic gravitational wave background for pulsar timing arrays is often modeled by a Gaussian ensemble which is isotropic and unpolarized. However, the Universe has a discrete set of polarized gravitational wave sources at specific sky locations. Can we trust that the Gaussian ensemble is an accurate description? To investigate this, we explicitly construct an ensemble containing $N$ individual binary sources with circular orbits. The orbital inclination angles are randomly distributed, hence the individual sources are elliptically polarized. We then compute the first two moments of the Hellings and Downs correlation, as well as the pulsar-averaged correlation mean and (cosmic) variance. The first moments are the same as for a previously studied ensemble of circularly polarized sources. However, the second moments, and hence the variances, are different for the two ensembles. While neither discrete source model is exactly described by a Gaussian ensemble, we show that in the limit of large $N$, the differences are small.

arXiv commentFinal published version

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Cited by in corpus (11)

• Answers to frequently asked questions about the pulsar timing array Hellings and Downs curve
• Spectral Variance in a Stochastic Gravitational-Wave Background From a Binary Population
• Source anisotropies and pulsar timing arrays
• Pulsar Timing Array Harmonic Analysis and Source Angular Correlations
• Charting the Nanohertz Gravitational Wave Sky with Pulsar Timing Arrays
• Optimal reconstruction of the Hellings and Downs correlation
• The impact of large-scale galaxy clustering on the variance of the Hellings-Downs correlation: theoretical framework
• Toward a test of Gaussianity of a gravitational wave background
• Mitigating cosmic variance in the Hellings-Downs curve: a Cosmic Microwave Background analogy
• The impact of large-scale galaxy clustering on the variance of the Hellings-Downs correlation: numerical results
• Finite Populations & Finite Time: The Non-Gaussianity of a Gravitational Wave Background