Pulsar timing array source ensembles

authored by: Bruce Allen, Serena Valtolina
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.
Organisation(s): Institute of Gravitation Physics
External Organisation(s): Max Planck Institute for Gravitational Physics (Albert Einstein Institute)
Type: Article
Journal: Physical Review D
Volume: 109
No. of pages: 17
ISSN: 2470-0010
Publication date: 30.04.2024
Publication status: Published
Peer reviewed: Yes
ASJC Scopus subject areas: Nuclear and High Energy Physics
Electronic version(s): https://doi.org/10.1103/PhysRevD.109.083038 (Access: Open)

BibTeX

@article{635791fca54346a7bbab9202c37bec32,
title = "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.",
author = "Bruce Allen and Serena Valtolina",
note = "Publisher Copyright: {\textcopyright} 2024 authors. Published by the American Physical Society. ",
year = "2024",
month = apr,
day = "30",
doi = "10.1103/PhysRevD.109.083038",
language = "English",
volume = "109",
journal = "Physical Review D",
issn = "2470-0010",
publisher = "American Institute of Physics",
number = "8",
}