Pulsar timing array analysis in a Legendre polynomial basis

Fuente: arXiv
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Autori principali: Allen, Bruce, von Blanckenburg, Arian L., Olum, Ken D.
Natura: Preprint
Pubblicazione: 2025
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author Allen, Bruce
von Blanckenburg, Arian L.
Olum, Ken D.
author_facet Allen, Bruce
von Blanckenburg, Arian L.
Olum, Ken D.
contents We use Legendre polynomials, previously employed in this context by Lee et al., van Haasteren and Levin, and Pitrou and Cusin, to model signals in pulsar timing arrays. These replace the (Fourier mode) basis of trigonometric functions normally used for data analysis. The Legendre basis makes it simpler to incorporate pulsar modeling effects, which remove constant-, linear-, and quadratic-in-time terms from pulsar timing residuals. In the Legendre basis, this zeroes the amplitudes of the the first three Legendre polynomials. We use this basis to construct an optimal quadratic cross-correlation estimator $\widehatμ$ of the Hellings and Downs (HD) correlation and compute its variance $σ^2_{\widehatμ}$ in the way described by Allen and Romano. Remarkably, if the gravitational-wave background (GWB) and pulsar noise power spectra are (sums of) power laws in frequency, then in this basis one obtains analytic closed forms for many quantities of interest.
format Preprint
id arxiv_https___arxiv_org_abs_2510_05913
institution arXiv
publishDate 2025
record_format arxiv
spellingShingle Pulsar timing array analysis in a Legendre polynomial basis
Allen, Bruce
von Blanckenburg, Arian L.
Olum, Ken D.
General Relativity and Quantum Cosmology
Cosmology and Nongalactic Astrophysics
Instrumentation and Methods for Astrophysics
85A40 (Primary) 62M15, 42C10 (Secondary)
J.2; G.3; G.1.5; I.6.4
We use Legendre polynomials, previously employed in this context by Lee et al., van Haasteren and Levin, and Pitrou and Cusin, to model signals in pulsar timing arrays. These replace the (Fourier mode) basis of trigonometric functions normally used for data analysis. The Legendre basis makes it simpler to incorporate pulsar modeling effects, which remove constant-, linear-, and quadratic-in-time terms from pulsar timing residuals. In the Legendre basis, this zeroes the amplitudes of the the first three Legendre polynomials. We use this basis to construct an optimal quadratic cross-correlation estimator $\widehatμ$ of the Hellings and Downs (HD) correlation and compute its variance $σ^2_{\widehatμ}$ in the way described by Allen and Romano. Remarkably, if the gravitational-wave background (GWB) and pulsar noise power spectra are (sums of) power laws in frequency, then in this basis one obtains analytic closed forms for many quantities of interest.
title Pulsar timing array analysis in a Legendre polynomial basis
topic General Relativity and Quantum Cosmology
Cosmology and Nongalactic Astrophysics
Instrumentation and Methods for Astrophysics
85A40 (Primary) 62M15, 42C10 (Secondary)
J.2; G.3; G.1.5; I.6.4
url https://arxiv.org/abs/2510.05913