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Lookup NU author(s): Dr Anne ArchibaldORCiD
This work is licensed under a Creative Commons Attribution 4.0 International License (CC BY 4.0).
© 2023. The Author(s). Published by the American Astronomical Society.We report multiple lines of evidence for a stochastic signal that is correlated among 67 pulsars from the 15 yr pulsar timing data set collected by the North American Nanohertz Observatory for Gravitational Waves. The correlations follow the Hellings-Downs pattern expected for a stochastic gravitational-wave background. The presence of such a gravitational-wave background with a power-law spectrum is favored over a model with only independent pulsar noises with a Bayes factor in excess of 1014, and this same model is favored over an uncorrelated common power-law spectrum model with Bayes factors of 200-1000, depending on spectral modeling choices. We have built a statistical background distribution for the latter Bayes factors using a method that removes interpulsar correlations from our data set, finding p = 10−3 (≈3σ) for the observed Bayes factors in the null no-correlation scenario. A frequentist test statistic built directly as a weighted sum of interpulsar correlations yields p = 5 × 10−5 to 1.9 × 10−4 (≈3.5σ-4σ). Assuming a fiducial f −2/3 characteristic strain spectrum, as appropriate for an ensemble of binary supermassive black hole inspirals, the strain amplitude is 2.4 − 0.6 + 0.7 × 10 − 15 (median + 90% credible interval) at a reference frequency of 1 yr−1. The inferred gravitational-wave background amplitude and spectrum are consistent with astrophysical expectations for a signal from a population of supermassive black hole binaries, although more exotic cosmological and astrophysical sources cannot be excluded. The observation of Hellings-Downs correlations points to the gravitational-wave origin of this signal.
Author(s): Agazie G, Anumarlapudi A, Archibald AM, Arzoumanian Z, Baker PT, Becsy B, Blecha L, Brazier A, Brook PR, Burke-Spolaor S, Burnette R, Case R, Charisi M, Chatterjee S, Chatziioannou K, Cheeseboro BD, Chen S, Cohen T, Cordes JM, Cornish NJ, Crawford F, Cromartie HT, Crowter K, Cutler CJ, DeCesar ME, DeGan D, Demorest PB, Deng H, Dolch T, Drachler B, Ellis JA, Ferrara EC, Fiore W, Fonseca E, Freedman GE, Garver-Daniels N, Gentile PA, Gersbach KA, Glaser J, Good DC, Gultekin K, Hazboun JS, Hourihane S, Islo K, Jennings RJ, Johnson AD, Jones ML, Kaiser AR, Kaplan DL, Kelley LZ, Kerr M, Key JS, Klein TC, Laal N, Lam MT, Lamb WG, Lazio TJW, Lewandowska N, Littenberg TB, Liu T, Lommen A, Lorimer DR, Luo J, Lynch RS, Ma C-P, Madison DR, Mattson MA, McEwen A, McKee JW, McLaughlin MA, McMann N, Meyers BW, Meyers PM, Mingarelli CMF, Mitridate A, Natarajan P, Ng C, Nice DJ, Ocker SK, Olum KD, Pennucci TT, Perera BBP, Petrov P, Pol NS, Radovan HA, Ransom SM, Ray PS, Romano JD, Sardesai SC, Schmiedekamp A, Schmiedekamp C, Schmitz K, Schult L, Shapiro-Albert BJ, Siemens X, Simon J, Siwek MS, Stairs IH, Stinebring DR, Stovall K, Sun JP, Susobhanan A, Swiggum JK, Taylor J, Taylor SR, Turner JE, Unal C, Vallisneri M, van Haasteren R, Vigeland SJ, Wahl HM, Wang Q, Witt CA, Young O
Publication type: Article
Publication status: Published
Journal: Astrophysical Journal Letters
Year: 2023
Volume: 951
Issue: 1
Print publication date: 01/07/2023
Online publication date: 29/06/2023
Acceptance date: 01/06/2023
Date deposited: 01/08/2023
ISSN (print): 2041-8205
ISSN (electronic): 2041-8213
Publisher: American Astronomical Society
URL: https://doi.org/10.3847/2041-8213/acdac6
DOI: 10.3847/2041-8213/acdac6
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