The NANOGrav 15-year Data Set: Bayesian Limits on Gravitational Waves from Individual Supermassive Black Hole Binaries
Creators: name: Agazie, Gabriella
name: Anumarlapudi, Akash
name: Archibald, Anne M.
name: Arzoumanian, Zaven
name: Baker, Paul T.
name: Bécsy, Bence
name: Blecha, Laura
name: Brazier, Adam
name: Brook, Paul R.
name: Burke-Spolaor, Sarah
name: Case, Robin
name: Casey-Clyde, J. Andrew
name: Charisi, Maria
name: Chatterjee, Shami
name: Cohen, Tyler
name: Cordes, James M.
name: Cornish, Neil
name: Crawford, Fronefield
name: Cromartie, H. Thankful
name: Crowter, Kathryn
name: DeCesar, Megan
name: Demorest, Paul B.
name: Digman, Matthew C.
name: Dolch, Timothy
name: Drachler, Brendan
name: Ferrara, Elizabeth C.
name: Fiore, William
name: Fonseca, Emmanuel
name: Freedman, Gabriel
name: Garver-Daniels, Nathaniel
name: Gentile, Peter
name: Glaser, Joseph
name: Good, Deborah
name: Gültekin, Kayhan
name: Hazboun, Jeffrey
name: Hourihane, Sophie
name: Jennings, Ross
name: Johnson, Aaron D.
name: Jones, Megan
name: Kaiser, Andrew R.
name: Kaplan, David
name: Kelley, Luke Zoltan
name: Kerr, Matthew
name: Key, Joey
name: Laal, Nima
name: Lam, Michael
name: Lamb, William G.
name: Lazio, T. Joseph W.
name: Lewandowska, Natalia
name: Liu, Tingting
name: Lorimer, Duncan R.
name: Luo, Jing Santiago
name: Lynch, Ryan S.
name: Ma, Chung-Pei
name: Madison, Dustin
name: McEwen, Alexander
name: McKee, James W.
name: McLaughlin, Maura
name: McMann, Natasha
name: Meyers, Bradley W.
name: Meyers, Patrick M.
name: Mingarelli, Chiara M. F.
name: mitridate, andrea
name: natarajan, priya
name: Ng, Cherry
name: Nice, David
name: Ocker, Stella Koch
name: Olum, Ken
name: Pennucci, Timothy T.
name: Perera, Benetge
name: Petrov, Polina
name: Pol, Nihan
name: Radovan, Henri A.
name: Ransom, Scott
name: Ray, Paul S.
name: Romano, Joseph
name: Sardesai, Shashwat C.
name: Schmiedekamp, Ann
name: Schmiedekamp, Carl
name: Schmitz, Kai
name: Shapiro-Albert, Brent J.
name: Siemens, Xavier
name: Simon, Joseph
name: Siwek, Magdalena
name: Stairs, Ingrid
name: Stinebring, Dan
name: Stovall, Kevin
name: Susobhanan, Abhimanyu
name: Swiggum, Joseph
name: Taylor, Jacob
name: Taylor, Stephen
name: Turner, Jacob E.
name: Unal, Caner
name: Vallisneri, Michele
name: van Haasteren, Rutger
name: Vigeland, Sarah J.
name: Wahl, Haley M.
name: Witt, Caitlin
name: Young, Olivia
Publisher: name: arXiv
Year: 2023
Subjects: subject: High Energy Astrophysical Phenomena (astro-ph.HE)
subject: General Relativity and Quantum Cosmology (gr-qc)
subject: FOS: Physical sciences
subject: FOS: Physical sciences

description: Evidence for a low-frequency stochastic gravitational wave background has recently been reported based on analyses of pulsar timing array data. The most likely source of such a background is a population of supermassive black hole binaries, the loudest of which may be individually detected in these datasets. Here we present the search for individual supermassive black hole binaries in the NANOGrav 15-year dataset. We introduce several new techniques, which enhance the efficiency and modeling accuracy of the analysis. The search uncovered weak evidence for two candidate signals, one with a gravitational-wave frequency of $\sim$4 nHz, and another at $\sim$170 nHz. The significance of the low-frequency candidate was greatly diminished when Hellings-Downs correlations were included in the background model. The high-frequency candidate was discounted due to the lack of a plausible host galaxy, the unlikely astrophysical prior odds of finding such a source, and since most of its support comes from a single pulsar with a commensurate binary period. Finding no compelling evidence for signals from individual binary systems, we place upper limits on the strain amplitude of gravitational waves emitted by such systems.
description: 23 pages, 13 figures, 2 tables. Accepted for publication 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