The NANOGrav 15 yr Data Set: Constraints on Supermassive Black Hole Binaries from the Gravitational-wave Background

Abstract The NANOGrav 15 yr data set shows evidence for the presence of a low-frequency gravitational-wave background (GWB). While many physical processes can source such low-frequency gravitational waves, here we analyze the signal as coming from a population of supermassive black hole (SMBH) binaries distributed throughout the Universe. We show that astrophysically motivated models of SMBH binary populations are able to reproduce both the amplitude and shape of the observed low-frequency gravitational-wave spectrum. While multiple model variations are able to reproduce the GWB spectrum at our current measurement precision, our results highlight the importance of accurately modeling binary evolution for…

• NS
  National Science Foundation

  Awards: 1430284, AST-1744119, AST-1909933, 1815664, 2114721, 2011772, 1744119, PHY-2011772, 2009468, 2007993, 2020265, 1909933, NSF AST-2007993
• NA
  National Aeronautics and Space Administration

  Awards: S-15633Y, 80GSFC21M0002, HST-HF2-51453.001, NAS5-26555
• SF
  Simons Foundation

  Award: 80GSFC21M0002
• GA
  Gordon and Betty Moore Foundation

  Award: 2114721
• RC
  Research Corporation for Science Advancement

  Award: 27553
• VU
  Vanderbilt University
• CI
  California Institute of Technology
• CI
  Canadian Institute for Advanced Research
• UO
  University of Central Florida

  Award: AST-1744119
• ST
  Space Telescope Science Institute

  Awards: NAS5-26555, HST-HF2-51453.001, 26555
• AU
  Associated Universities
• FH
  Flatiron Health
• JP
  Jet Propulsion Laboratory

  Award: 80GSFC21M0002
• GS
  Goddard Space Flight Center

  Awards: NAS5-26555, 80GSFC21M0002
• NS
  Natural Sciences and Engineering Research Council of Canada
• SA
  Science and Technology Facilities Council

  Awards: ST/W000946/1, ST/W000946/1
• OO
  Office of Naval Research
• UN
  U.S. Naval Research Laboratory

  Awards: NAS5-26555, S-15633Y