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@ARTICLE{Agazie:593120,
      author       = {Agazie, Gabriella and Anumarlapudi, Akash and Archibald,
                      Anne M. and Arzoumanian, Zaven and Baker, Paul T. and
                      Bécsy, Bence and Blecha, Laura and Brazier, Adam and Brook,
                      Paul R. and Burke-Spolaor, Sarah and Burnette, Rand and
                      Case, Robin and Charisi, Maria and Chatterjee, Shami and
                      Chatziioannou, Katerina and Cheeseboro, Belinda D. and Chen,
                      Siyuan and Cohen, Tyler and Cordes, James M. and Cornish,
                      Neil J. and Crawford, Fronefield and Cromartie, H. Thankful
                      and Crowter, Kathryn and Cutler, Curt J. and DeCesar, Megan
                      E. and DeGan, Dallas and Demorest, Paul B. and Deng, Heling
                      and Dolch, Timothy and Drachler, Brendan and Ellis, Justin
                      A. and Ferrara, Elizabeth C. and Fiore, William and Fonseca,
                      Emmanuel and Freedman, Gabriel E. and Garver-Daniels, Nate
                      and Gentile, Peter A. and Gersbach, Kyle A. and Glaser,
                      Joseph and Good, Deborah C. and Gültekin, Kayhan and
                      Hazboun, Jeffrey S. and Hourihane, Sophie and Islo, Kristina
                      and Jennings, Ross J. and Johnson, Aaron D. and Jones, Megan
                      L. and Kaiser, Andrew R. and Kaplan, David L. and Kelley,
                      Luke Zoltan and Kerr, Matthew and Key, Joey S. and Klein,
                      Tonia C. and Laal, Nima and Lam, Michael T. and Lamb,
                      William G. and W. Lazio, T. Joseph and Lewandowska, Natalia
                      and Littenberg, Tyson B. and Liu, Tingting and Lommen,
                      Andrea and Lorimer, Duncan R. and Luo, Jing and Lynch, Ryan
                      S. and Ma, Chung-Pei and Madison, Dustin R. and Mattson,
                      Margaret A. and McEwen, Alexander and McKee, James W. and
                      McLaughlin, Maura A. and McMann, Natasha and Meyers, Bradley
                      W. and Meyers, Patrick M. and Mingarelli, Chiara M. F. and
                      Mitridate, Andrea and Natarajan, Priyamvada and Ng, Cherry
                      and Nice, David J. and Ocker, Stella Koch and Olum, Ken D.
                      and Pennucci, Timothy T. and Perera, Benetge B. P. and
                      Petrov, Polina and Pol, Nihan S. and Radovan, Henri A. and
                      Ransom, Scott M. and Ray, Paul S. and Romano, Joseph D. and
                      Sardesai, Shashwat C. and Schmiedekamp, Ann and
                      Schmiedekamp, Carl and Schmitz, Kai and Schult, Levi and
                      Shapiro-Albert, Brent J. and Siemens, Xavier and Simon,
                      Joseph and Siwek, Magdalena S. and Stairs, Ingrid H. and
                      Stinebring, Daniel R. and Stovall, Kevin and Sun, Jerry P.
                      and Susobhanan, Abhimanyu and Swiggum, Joseph K. and Taylor,
                      Jacob and Taylor, Stephen R. and Turner, Jacob E. and Unal,
                      Caner and Vallisneri, Michele and van Haasteren, Rutger and
                      Vigeland, Sarah J. and Wahl, Haley M. and Wang, Qiaohong and
                      Witt, Caitlin A. and Young, Olivia},
      title        = {{T}he {NANOG}rav 15-year {D}ata {S}et: {E}vidence for a
                      {G}ravitational-{W}ave {B}ackground},
      issn         = {2041-8213},
      address      = {London},
      publisher    = {Institute of Physics Publ.},
      reportid     = {PUBDB-2023-05304, arXiv:2306.16213. arXiv:2306.16213},
      year         = {2023},
      note         = {30 pages, 18 figures. Published in Astrophysical Journal
                      Letters as part of Focus on NANOGrav's 15-year Data Set and
                      the Gravitational Wave Background. For questions or
                      comments, please email comments@nanograv.org},
      abstract     = {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 10$^{14}$,
                      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 (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.},
      cin          = {T},
      ddc          = {520},
      cid          = {I:(DE-H253)T-20120731},
      pnm          = {611 - Fundamental Particles and Forces (POF4-611) / DFG
                      project G:(GEPRIS)390833306 - EXC 2121: Quantum Universe
                      (390833306) / GRK 2149 - GRK 2149: Starke und schwache
                      Wechselwirkung - von Hadronen zu Dunkler Materie
                      (269952272)},
      pid          = {G:(DE-HGF)POF4-611 / G:(GEPRIS)390833306 /
                      G:(GEPRIS)269952272},
      experiment   = {EXP:(DE-MLZ)NOSPEC-20140101},
      typ          = {PUB:(DE-HGF)25},
      eprint       = {2306.16213},
      howpublished = {arXiv:2306.16213},
      archivePrefix = {arXiv},
      SLACcitation = {$\%\%CITATION$ = $arXiv:2306.16213;\%\%$},
      doi          = {10.3204/PUBDB-2023-05304},
      url          = {https://bib-pubdb1.desy.de/record/593120},
}