The NANOGrav 11yr Data Set: Limits on Supermassive Black Hole Binaries in Galaxies within 500Mpc
Creators: name: Arzoumanian, Zaven
name: Baker, Paul T.
name: Brazier, Adam
name: Brook, Paul R.
name: Burke-Spolaor, Sarah
name: Becsy, Bence
name: Charisi, Maria
name: Chatterjee, Shami
name: Cordes, James M.
name: Cornish, Neil J.
name: Crawford, Fronefield
name: Cromartie, H. Thankful
name: DeCesar, Megan E.
name: Demorest, Paul B.
name: Dolch, Timothy
name: Elliott, Rodney D.
name: Ellis, Justin A.
name: Ferrara, Elizabeth C.
name: Fonseca, Emmanuel
name: Garver-Daniels, Nathan
name: Gentile, Peter A.
name: Good, Deborah C.
name: Hazboun, Jeffrey S.
name: Islo, Kristina
name: Jennings, Ross J.
name: Jones, Megan L.
name: Kaiser, Andrew R.
name: Kaplan, David L.
name: Kelley, Luke Z.
name: Key, Joey Shapiro
name: Lam, Michael T.
name: Lazio, T. Joseph W.
name: Luo, Jing
name: Lynch, Ryan S.
name: Ma, Chung-Pei
name: Madison, Dustin R.
name: McLaughlin, Maura A.
name: Mingarelli, Chiara M. F.
name: Ng, Cherry
name: Nice, David J.
name: Pennucci, Timothy T.
name: Pol, Nihan S.
name: Ransom, Scott M.
name: Ray, Paul S.
name: Shapiro-Albert, Brent J.
name: Siemens, Xavier
name: Simon, Joseph
name: Spiewak, Renee
name: Stairs, Ingrid H.
name: Stinebring, Daniel R.
name: Stovall, Kevin
name: Swiggum, Joseph K.
name: Taylor, Stephen R.
name: Vallisneri, Michele
name: Vigeland, Sarah J.
name: Witt, Caitlin A.
name: Collaboration, The NANOGrav
Publisher: name: arXiv
Year: 2021
Subjects: subject: Astrophysics of Galaxies (astro-ph.GA)
subject: High Energy Astrophysical Phenomena (astro-ph.HE)
subject: FOS: Physical sciences
subject: FOS: Physical sciences

description: Supermassive black hole binaries (SMBHBs) should form frequently in galactic nuclei as a result of galaxy mergers. At sub-parsec separations, binaries become strong sources of low-frequency gravitational waves (GWs), targeted by Pulsar Timing Arrays (PTAs). We used recent upper limits on continuous GWs from the North American Nanohertz Observatory for Gravitational Waves (NANOGrav) 11yr dataset to place constraints on putative SMBHBs in nearby massive galaxies. We compiled a comprehensive catalog of ~44,000 galaxies in the local universe (up to redshift ~0.05) and populated them with hypothetical binaries, assuming that the total mass of the binary is equal to the SMBH mass derived from global scaling relations. Assuming circular equal-mass binaries emitting at NANOGrav's most sensitive frequency of 8nHz, we found that 216 galaxies are within NANOGrav's sensitivity volume. We ranked the potential SMBHBs based on GW detectability by calculating the total signal-to-noise ratio (S/N) such binaries would induce within the NANOGrav array. We placed constraints on the chirp mass and mass ratio of the 216 hypothetical binaries. For 19 galaxies, only very unequal-mass binaries are allowed, with the mass of the secondary less than 10 percent that of the primary, roughly comparable to constraints on a SMBHB in the Milky Way. Additionally, we were able to exclude binaries delivered by major mergers (mass ratio of at least 1/4) for several of these galaxies. We also derived the first limit on the density of binaries delivered by major mergers purely based on GW data.
description: Submitted to ApJ. Send comments to Maria Charisi (maria.charisi@nanograv.org)