We search for an isotropic stochastic gravitational-wave background (GWB) in the 12.5.yr pulsar-timing data set collected by the North American Nanohertz Observatory for Gravitational Waves. Our analysis finds strong evidence of a stochastic process, modeled as a power law, with common amplitude and spectral slope across pulsars. Under our fiducial model, the Bayesian posterior of the amplitude for an f(-2/3) power-law spectrum, expressed as the characteristic GW strain, has median 1.92x10(-15) and 5%-95% quantiles of 1.37-2.67x10(-15) at a reference frequency of f(yr) = 1 yr(-1); the Bayes factor in favor of the common-spectrum process versus independent red-noise processes in each pulsar exceeds 10,000. However, we find no statistically significant evidence that this process has quadrupolar spatial correlations, which we would consider necessary to claim a GWB detection consistent with general relativity. We find that the process has neither monopolar nor dipolar correlations, which may arise from, for example, reference clock or solar system ephemeris systematics, respectively. The amplitude posterior has significant support above previously reported upper limits; we explain this in terms of the Bayesian priors assumed for intrinsic pulsar red noise. We examine potential implications for the supermassive black hole binary population under the hypothesis that the signal is indeed astrophysical in nature.
- The NANOGrav 12.5 yr Data Set: Search for an Isotropic Stochastic Gravitational-wave Background
- Zaven Arzoumanian - Goddard Space Flight CenterPaul T Baker - Widener UniversityHarsha Blumer - West Virginia UniversityBence Becsy - Montana State UniversityAdam Brazier - Cornell UniversityPaul R Brook - West Virginia UniversitySarah Burke-Spolaor - West Virginia UniversityShami Chatterjee - Cornell UniversitySiyuan Chen - University of OrléansJames M Cordes - Cornell UniversityNeil J Cornish - Montana State UniversityFronefield Crawford - Franklin & Marshall CollegeH. Thankful Cromartie - University of VirginiaMegan E DeCesar - Lafayette CollegePaul B Demorest - National Radio Astronomy ObservatoryTimothy Dolch - Hillsdale CollegeJustin A Ellis - Durham UniversityElizabeth C Ferrara - Goddard Space Flight CenterWilliam Fiore - West Virginia UniversityEmmanuel Fonseca - McGill UniversityNathan Garver-Daniels - West Virginia UniversityPeter A Gentile - West Virginia UniversityDeborah C Good - University of British ColumbiaJeffrey S Hazboun - University of WashingtonA. Miguel Holgado - Carnegie Mellon UniversityKristina Islo - University of Wisconsin–MilwaukeeRoss J Jennings - Cornell UniversityMegan L Jones - University of Wisconsin–MilwaukeeAndrew R Kaiser - West Virginia UniversityDavid L Kaplan - University of Wisconsin–MilwaukeeLuke Zoltan Kelley - Northwestern UniversityJoey Shapiro Key - University of WashingtonNima Laal - Oregon State UniversityMichael F Lam - Rochester Inst Technol, Sch Phys & Astron, Rochester, NY 14623 USAT. Joseph W Lazio - California Institute of TechnologyDuncan R Lorimer - West Virginia UniversityJing Luo - University of TorontoRyan S Lynch - First Green BankDustin R Madison - West Virginia UniversityNlaura A McLaughlin - West Virginia Univ, Dept Phys & Astron, POB 6315, Morgantown, WV 26506 USAChiara M. F Mingarelli - University of ConnecticutCherry Ng - University of TorontoDavid J Nice - Lafayette CollegeTimothy T Pennucci - Eötvös Loránd UniversityNihan S Pol - West Virginia UniversityScott M Ransom - National Radio Astronomy ObservatoryPaul S Ray - United States Naval Research LaboratoryBrent J Shapiro-Albert - West Virginia UniversityXavier Siemens - University of Wisconsin–MilwaukeeJoseph Simon - California Institute of TechnologyRenee Spiewak - Swinburne University of TechnologyIngrid H Stairs - University of British ColumbiaDaniel R Stinebring - Oberlin CollegeKevin Stovall - National Radio Astronomy ObservatoryJerry P Sun - Oregon State UniversityJoseph K Swiggum - Lafayette CollegeStephen R Taylor - Vanderbilt UniversityJacob E Turner - West Virginia UniversityMichele Vallisneri - California Institute of TechnologySarah J Vigeland - University of Wisconsin–MilwaukeeCaitlin A Witt - West Virginia UniversityNANOGrav Collaboration
- Astrophysical journal. Letters, Vol.905(2), p.L34
- IOP PUBLISHING LTD
- 18
- 1430284 / National Science Foundation (NSF) Physics Frontiers Center; National Science Foundation (NSF) Simons Foundation state of West Virginia (WVEPSCoR via the Higher Education Policy Commission) AST-1744119 / University of Central Florida (UCF) 1003907 / National Science Foundation EPSCoR Research Infrastructure Improvement Cooperative Agreement; National Science Foundation (NSF) Universidad Ana G. Mendez (UAGM) National Aeronautics and Space Administration; National Aeronautics & Space Administration (NASA) Canadian Institute for Advanced Research; Canadian Institute for Advanced Research (CIFAR) JPL RTD program Yang Enterprises (YEI), Inc. WVU 0923409; 1458952; 1815664 / NSF; National Science Foundation (NSF) MTA-ELTE Extragalactic Astrophysics Research Group - Hungarian Academy of Sciences (Magyar Tudomanyos Akademia) NSERC Discovery Grant; Natural Sciences and Engineering Research Council of Canada (NSERC)
- 991019295362407081
- Physics
- English
- Journal article