On the Evidence for a Common-spectrum Process in the Search for the Nanohertz Gravitational-wave Background with the Parkes Pulsar Timing Array

By B. Goncharov, R. Shannon, D. Reardon, G. Hobbs, A. Zic, M. Bailes, M. Curyło, S. Dai, M. Kerr, M. Lower and 19 more. 2021

277 citations recorded by the source corpus.

A nanohertz-frequency stochastic gravitational-wave background can potentially be detected through the precise timing of an array of millisecond pulsars. This background produces low-frequency noise in the pulse arrival times that would have a characteristic spectrum common to all pulsars and a well-defined spatial correlation. Recently the North American Nanohertz Observatory for Gravitational Waves collaboration (NANOGrav) found evidence for the common-spectrum component in their 12.5 yr data set. Here we report on a search for the background using the second data release of the Parkes Pulsar Timing Array. If we are forced to choose between the two NANOGrav models—one with a common-spectrum process and one without—we find strong support for the common-spectrum process. However, in this paper, we consider the possibility that the analysis suffers from model misspecification. In particular, we present simulated data sets that contain noise with distinctive spectra but show strong evidence for a common-spectrum process under the standard assumptions. The Parkes data show no significant evidence for, or against, the spatially correlated Hellings–Downs signature of the gravitational-wave background. Assuming we did observe the process underlying the spatially uncorrelated component of the background, we infer its amplitude to be A=2.2−0.3+0.4×10−15 in units of gravitational-wave strain at a frequency of 1 yr−1. Extensions and combinations of existing and new data sets will improve the prospects of identifying spatial correlations that are necessary to claim a detection of the gravitational-wave background.

Subfields: Astronomy and Astrophysics, Statistical and Nonlinear Physics

View Paper: https://www.semanticscholar.org/paper/837b690ffc28ea2411ab865c0d7079a0ef6a163c

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Citations in the corpus

Searching for the Nano-Hertz Stochastic Gravitational Wave Background with the Chinese Pulsar Timing Array Data Release I (2023, methodology): “Our GWB amplitude seems to be compatible with that of the common red signal of other PTAs (Arzoumanian et al. 2020; Chen et al. 2021; Goncharov et al. 2021; Antoniadis et al. 2022), although the median of posterior distribution seems to be 0.4–0.5 dex higher.”
Search for an Isotropic Gravitational-wave Background with the Parkes Pulsar Timing Array (2023, methodology): “This may be due to high-fluctuationfrequency processes present in the data set, such as unmodeled pulse-shape variations (Shannon et al. 2016; Arzoumanian et al. 2020; Goncharov et al. 2021b).”
The second data release from the European Pulsar Timing Array (2023, background): “…observation of a common signal with excess power in the nanohertz frequency ranges (i.e. a common red signal, as defined in Arzoumanian et al. 2020; Goncharov et al. 2021; Chen et al. 2021) in pulsar timing array (PTA) datasets, with emerging evidence for quadrupolar correlations 1 opens a new era…”
The NANOGrav 15 yr Data Set: Constraints on Supermassive Black Hole Binaries from the Gravitational-wave Background (2023, background): “…of this work must maintain attribution to the author(s) and the title of the work, journal citation and DOI. the Parkes Pulsar Timing Array (PPTA; Goncharov et al. 2021), the European Pulsar Timing Array (Chen et al. 2021), and the International Pulsar Timing Array (IPTA; Antoniadis et al. 2022).”
The NANOGrav 15 yr Data Set: Evidence for a Gravitational-wave Background (2023, methodology): “Subsequent independent analyses by the PPTA and EPTA collaborations reported results consistent with ours (Goncharov et al. 2021a; Chen et al. 2021), as did the search of a combined data set (Antoniadis et al. 2022)—a syzygy of tantalizing discoveries that portend the rise of low-frequency GW…”
The second data release from the European Pulsar Timing Array. III. Search for gravitational wave signals (2023, methodology): “This CRS is consistent with the ﬁndings of the NANOGrav 12.5-yr data set (Arzoumanian et al. 2020), PPTA DR2 (Goncharov et al. 2021b), and IPTA DR2 (Antoniadis et al. 2022).”