TY - JOUR
T1 - The NANOGrav 15 yr Data Set
T2 - Constraints on Supermassive Black Hole Binaries from the Gravitational-wave Background
AU - The NANOGrav Collaboration
AU - Agazie, Gabriella
AU - Anumarlapudi, Akash
AU - Archibald, Anne M.
AU - Baker, Paul T.
AU - Bécsy, Bence
AU - Blecha, Laura
AU - Bonilla, Alexander
AU - Brazier, Adam
AU - Brook, Paul R.
AU - Burke-Spolaor, Sarah
AU - Burnette, Rand
AU - Case, Robin
AU - Casey-Clyde, J. Andrew
AU - Charisi, Maria
AU - Chatterjee, Shami
AU - Chatziioannou, Katerina
AU - Cheeseboro, Belinda D.
AU - Chen, Siyuan
AU - Cohen, Tyler
AU - Cordes, James M.
AU - Cornish, Neil J.
AU - Crawford, Fronefield
AU - Cromartie, H. Thankful
AU - Crowter, Kathryn
AU - Cutler, Curt J.
AU - D’Orazio, Daniel J.
AU - DeCesar, Megan E.
AU - DeGan, Dallas
AU - Demorest, Paul B.
AU - Deng, Heling
AU - Dolch, Timothy
AU - Drachler, Brendan
AU - Ferrara, Elizabeth C.
AU - Fiore, William
AU - Fonseca, Emmanuel
AU - Freedman, Gabriel E.
AU - Gardiner, Emiko
AU - Garver-Daniels, Nate
AU - Gentile, Peter A.
AU - Gersbach, Kyle A.
AU - Glaser, Joseph
AU - Good, Deborah C.
AU - Gültekin, Kayhan
AU - Hazboun, Jeffrey S.
AU - Hourihane, Sophie
AU - Islo, Kristina
AU - Jennings, Ross J.
AU - Johnson, Aaron
AU - Jones, Megan L.
AU - Unal, Caner
N1 - Publisher Copyright:
© 2023. The Author(s). Published by the American Astronomical Society.
PY - 2023/8/1
Y1 - 2023/8/1
N2 - 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 producing realistic GWB spectra. Additionally, while reasonable parameters are able to reproduce the 15 yr observations, the implied GWB amplitude necessitates either a large number of parameters to be at the edges of expected values or a small number of parameters to be notably different from standard expectations. While we are not yet able to definitively establish the origin of the inferred GWB signal, the consistency of the signal with astrophysical expectations offers a tantalizing prospect for confirming that SMBH binaries are able to form, reach subparsec separations, and eventually coalesce. As the significance grows over time, higher-order features of the GWB spectrum will definitively determine the nature of the GWB and allow for novel constraints on SMBH populations.
AB - 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 producing realistic GWB spectra. Additionally, while reasonable parameters are able to reproduce the 15 yr observations, the implied GWB amplitude necessitates either a large number of parameters to be at the edges of expected values or a small number of parameters to be notably different from standard expectations. While we are not yet able to definitively establish the origin of the inferred GWB signal, the consistency of the signal with astrophysical expectations offers a tantalizing prospect for confirming that SMBH binaries are able to form, reach subparsec separations, and eventually coalesce. As the significance grows over time, higher-order features of the GWB spectrum will definitively determine the nature of the GWB and allow for novel constraints on SMBH populations.
UR - http://www.scopus.com/inward/record.url?scp=85167712194&partnerID=8YFLogxK
U2 - 10.3847/2041-8213/ace18b
DO - 10.3847/2041-8213/ace18b
M3 - Article
AN - SCOPUS:85167712194
SN - 2041-8205
VL - 952
JO - Astrophysical Journal Letters
JF - Astrophysical Journal Letters
IS - 2
M1 - L37
ER -