The NANOGrav 15 yr dataset: Posterior predictive checks for gravitational-wave detection with pulsar timing arrays

Date

2025-02-01

Author

Agazie, Gabriella
Anumarlapudi, Akash
Archibald, Anne M.
Arzoumanian, Zaven
Baier, Jeremy George
Baker, Paul T.
Becsy, Bence
Blecha, Laura
Brazier, Adam
Brook, Paul R.
Burke-Spolaor, Sarah
Casey-Clyde, J. Andrew
Charisi, Maria
Chatterjee, Shami
Chatziioannou, Katerina
Cohen, Tyler
Cordes, James M.
Cornish, Neil J.
Crawford, Fronefield
Cromartie, H. Thankful
Crowter, Kathryn
Decesar, Megan E.
Demorest, Paul B.
Deng, Heling
Dey, Lankeswar
Dolch, Timothy
Ferrara, Elizabeth C.
Fiore, William
Fonseca, Emmanuel
Freedman, Gabriel E.
Gardiner, Emiko C.
Garver-Daniels, Nate
Gentile, Peter A.
Gersbach, Kyle A.
Glaser, Joseph
Good, Deborah C.
Gultekin, Kayhan
Hazboun, Jeffrey S.
Jennings, Ross J.
Johnson, Aaron D.
Jones, Megan L.
Kaiser, Andrew R.
Kaplan, David L.
Kelley, Luke Zoltan
Kerr, Matthew
Key, Joey S.
Laal, Nima
Lam, Michael T.
Lamb, William G.
Larsen, Bjorn
Joseph, T.
Lazio, W.
Lewandowska, Natalia
Liu, Tingting
Lorimer, Duncan R.
Luo, Jing
Lynch, Ryan S.
Ma, Chung-Pei
Madison, Dustin R.
Mcewen, Alexander
Mckee, James W.
Mclaughlin, Maura A.
Mcmann, Natasha
Meyers, Bradley W.
Meyers, Patrick M.
Mingarelli, Chiara M. F.
Mitridate, Andrea
Ng, Cherry
Nice, David J.
Ocker, Stella Koch
Olum, Ken D.
Pennucci, Timothy T.
Perera, Benetge B. P.
Pol, Nihan S.
Radovan, Henri A.
Ransom, Scott M.
Ray, Paul S.
Romano, Joseph D.
Runnoe, Jessie C.
Saffer, Alexander
Sardesai, Shashwat C.
Schmiedekamp, Ann
Schmiedekamp, Carl
Schmitz, Kai
Shapiro-Albert, Brent J.
Siemens, Xavier
Simon, Joseph
Siwek, Magdalena S.
Fiscella, Sophia V. Sosa
Stairs, Ingrid H.
Stinebring, Daniel R.
Stovall, Kevin
Susobhanan, Abhimanyu
Swiggum, Joseph K.
Taylor, Stephen R.
Turner, Jacob E.
Ünal, Caner
Vallisneri, Michele
Vigeland, Sarah J.
Wahl, Haley M.
Witt, Caitlin A.
Wright, David
Young, Olivia

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Pulsar timing array experiments have reported evidence for a stochastic background of nanohertz gravitational waves consistent with the signal expected from a population of supermassive black hole binaries. Their analyses assume power-law spectra for intrinsic pulsar noise and for the background, as well as a Hellings-Downs cross-correlation pattern among the gravitational-wave- induced residuals across pulsars. These assumptions may not be realized in actuality. We test them in the NANOGrav 15 yr dataset using Bayesian posterior predictive checks. After fitting our fiducial model to real data, we generate a population of simulated dataset replications. We use the replications to assess whether the optimal statistic significance, interpulsar correlations, and spectral coefficients are extreme. We recover Hellings-Downs correlations in simulated datasets at significance levels consistent with the correlations measured in the NANOGrav 15 yr dataset. A similar test on spectral coefficients shows that their values in real data are not extreme compared to their distributions across replications. We also evaluate the evidence for the stochastic background using posterior predictive versions of the frequentist optimal statistic and of Bayesian model comparison and find comparable significance (3.26 and 36 respectively) to what was previously reported for the standard statistics. We conclude with novel visualizations of the reconstructed gravitational waveforms that enter the residuals for each pulsar. Our analysis strengthens confidence in the identification and characterization of the gravitational-wave background.

URI

https://hdl.handle.net/11511/115723

Collections

Department of Physics, Article