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

Islo, K.; Hazboun, J. S.; Crowter, K.; Jones, M. L.; Chatziioannou, K.; Burnette, R.; Sun, J. P.; Runnoe, J. C.; Siwek, M. S.; Cromartie, H. T.; Anumarlapudi, A.; Shapiro-Albert, B. J.; Johnson, A.; DeGan, D.; Glaser, J.; Young, O.; Mingarelli, C. M. F.; Key, J. S.; Gültekin, K.; Schmitz, K.; Ocker, S. K.; Fonseca, E.; Gardiner, E.; Charisi, M.; Stinebring, D. R.; Freedman, G. E.; Taylor, S. R.; Turner, J. E.; Schult, L.; McLaughlin, M. A.; D'Orazio, D. J.; Cornish, N. J.; Littenberg, T. B.; Vallisneri, M.; Lamb, W. G.; Luo, J.; Gersbach, K. A.; Pennucci, T.; Agazie, G.; Ransom, S. M.; Swiggum, J. K.; Bonilla, A.; Crawford, F.; Hourihane, S.; Radovan, H. A.; Susobhanan, A.; Burke-Spolaor, S.; Baker, P. T.; Olum, K. D.; Meyers, P. M.; Fiore, W.; McKee, J. W.; Cohen, T.; Chatterjee, S.; Sardesai, S. C.; Cordes, J. M.; Simon, J.; Taylor, J.; Gentile, P. A.; Perera, B. B. P.; Dolch, T.; Kaiser, A. R.; Siemens, X.; Case, R.; McEwen, A.; Nice, David J.; Wang, Q.; Ng, C.; Kaplan, D. L.; Kelley, L. Z.; Wright, D.; Demorest, P. B.; Garver-Daniels, N.; Blecha, L.; Brazier, A.; Madison, D. R.; Wachter, J. M.; Schmiedekamp, C.; Cutler, C. J.; DeCesar, M. E.; McMann, N.; Unal, C.; Ferrara, E. C.; Good, D. C.; Meyers, B. W.; Pol, N. S.; Lewandowska, N.; Schmiedekamp, A.; Lynch, R. S.; Petrov, P.; Stairs, I. H.; Lam, M. T.; Bésy, B.; Chen, S.; Witt, C. A.; Ray, P. S.; Casey-Clyde, J. A.; Kerr, M.; Stovall, K.; Laal, N.; Cheeseboro, B. D.; Natarajan, P.; Vigeland, S. J.; Ma, C. P.; Wahl, H. M.; Liu, T.; Jennings, R. J.; Brook, P. R.; Romano, J. D.; Deng, H.; Drachler, B.; Archibald, A. M.; Mitridate, A.

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 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.

Title	The NANOGrav 15 yr Data Set: Constraints on Supermassive Black Hole Binaries from the Gravitational-wave Background
Creator	Islo, K.
	Hazboun, J. S.
	Crowter, K.
	Jones, M. L.
	Chatziioannou, K.
	Burnette, R.
	Sun, J. P.
	Runnoe, J. C.
	Siwek, M. S.
	Cromartie, H. T.
	Anumarlapudi, A.
	Shapiro-Albert, B. J.
	Johnson, A.
	DeGan, D.
	Glaser, J.
	Young, O.
	Mingarelli, C. M. F.
	Key, J. S.
	Gültekin, K.
	Schmitz, K.
	Ocker, S. K.
	Fonseca, E.
	Gardiner, E.
	Charisi, M.
	Stinebring, D. R.
	Freedman, G. E.
	Taylor, S. R.
	Turner, J. E.
	Schult, L.
	McLaughlin, M. A.
	D'Orazio, D. J.
	Cornish, N. J.
	Littenberg, T. B.
	Vallisneri, M.
	Lamb, W. G.
	Luo, J.
	Gersbach, K. A.
	Pennucci, T.
	Agazie, G.
	Ransom, S. M.
	Swiggum, J. K.
	Bonilla, A.
	Crawford, F.
	Hourihane, S.
	Radovan, H. A.
	Susobhanan, A.
	Burke-Spolaor, S.
	Baker, P. T.
	Olum, K. D.
	Meyers, P. M.
	Fiore, W.
	McKee, J. W.
	Cohen, T.
	Chatterjee, S.
	Sardesai, S. C.
	Cordes, J. M.
	Simon, J.
	Taylor, J.
	Gentile, P. A.
	Perera, B. B. P.
	Dolch, T.
	Kaiser, A. R.
	Siemens, X.
	Case, R.
McEwen, A.
Nice, David J.
Wang, Q.
Ng, C.
Kaplan, D. L.
Kelley, L. Z.
Wright, D.
Demorest, P. B.
Garver-Daniels, N.
Blecha, L.
Brazier, A.
Madison, D. R.
Wachter, J. M.
Schmiedekamp, C.
Cutler, C. J.
DeCesar, M. E.
McMann, N.
Unal, C.
Ferrara, E. C.
Good, D. C.
Meyers, B. W.
Pol, N. S.
Lewandowska, N.
Schmiedekamp, A.
Lynch, R. S.
Petrov, P.
Stairs, I. H.
Lam, M. T.
Bésy, B.
Chen, S.
Witt, C. A.
Ray, P. S.
Casey-Clyde, J. A.
Kerr, M.
Stovall, K.
Laal, N.
Cheeseboro, B. D.
Natarajan, P.
Vigeland, S. J.
Ma, C. P.
Wahl, H. M.
Liu, T.
Jennings, R. J.
Brook, P. R.
Romano, J. D.
Deng, H.
Drachler, B.
Archibald, A. M.
Mitridate, A.
Publisher	Astrophysical Journal Letters
Academic Department	Physics
Division	Natural Sciences
Organization	Lafayette College
Date Issued	August 1, 2023
Date Available	2023-12-20
Type	Article
Language	English
Keyword	Galaxy evolution
	Gravitational waves
	Supermassive black holes
Bibliographic Citation	Agazie, G., et al. (2023 Aug 1) "The NANOGrav 15 yr Data Set: Constraints on Supermassive Black Hole Binaries from the Gravitational-wave Background." Astrophysical Journal Letters 952 (2): L37.
Standard Identifier	Handle 10385/wd375z115
Standard Identifier	DOI 10.3847/2041-8213/ace18b
Permalink	http://hdl.handle.net/10385/wd375z115
Rights Statement	Creative Commons - Attribution
Rights Holders	The Authors