The NANOGrav 12.5 yr Data Set: A Computationally Efficient Eccentric Binary Search Pipeline and Constraints on an Eccentric Supermassive Binary Candidate in 3C 66B

Creators: Agazie, Gabriella; Arzoumanian, Zaven; Baker, Paul T.; Bécsy, Bence; Blecha, Laura; Blumer, Harsha; Brazier, Adam; Brook, Paul R.; Burke-Spolaor, Sarah; Casey-Clyde, J. Andrew; Charisi, Maria; Chatterjee, Shami; Cheeseboro, Belinda D.; Cohen, Tyler; Cordes, James M.; Cornish, Neil J.; Crawford, Fronefield; Cromartie, H. Thankful; DeCesar, Megan E.; Demorest, Paul B.; Dey, Lankeswar; Dolch, Timothy; Ellis, Justin A.; Ferdman, Robert D.; Ferrara, Elizabeth C.; Fiore, William; Fonseca, Emmanuel; Freedman, Gabriel E.; Garver-Daniels, Nate; Gentile, Peter A.; Glaser, Joseph; Good, Deborah C.; Gopakumar, Achamveedu; Gültekin, Kayhan; Hazboun, Jeffrey S.; Jennings, Ross J.; Johnson, Aaron D.; Jones, Megan L.; Kaiser, Andrew R.; Kaplan, David L.; Kelley, Luke Zoltan; Key, Joey S.; Laal, Nima; Lam, Michael T.; Lamb, William G.; Lazio, T. Joseph W.; Lewandowska, Natalia; Liu, Tingting; Lorimer, Duncan R.; Luo, Jing; Lynch, Ryan S.; Ma, Chung-Pei; Madison, Dustin R.; McEwen, Alexander; McKee, James W.; McLaughlin, Maura A.; Meyers, Patrick M.; Mingarelli, Chiara M. F.; Mitridate, Andrea; Ng, Cherry; Nice, David J.; Ocker, Stella Koch; Olum, Ken D.; Pennucci, Timothy T.; Pol, Nihan S.; Radovan, Henri A.; Ransom, Scott M.; Ray, Paul S.; Romano, Joseph D.; Sardesai, Shashwat C.; Schmitz, Kai; Siemens, Xavier; Simon, Joseph; Siwek, Magdalena S.; Sosa Fiscella, Sophia V.; Spiewak, Renée; Stairs, Ingrid H.; Stinebring, Daniel R.; Stovall, Kevin; Susobhanan, Abhimanyu; Swiggum, Joseph K.; Taylor, Stephen R.; Turner, Jacob E.; Unal, Caner; Vallisneri, Michele¹; Vigeland, Sarah J.; Witt, Caitlin A.; Young, Olivia

1. California Institute of Technology

Abstract

The radio galaxy 3C 66B has been hypothesized to host a supermassive black hole binary (SMBHB) at its center based on electromagnetic observations. Its apparent 1.05 yr period and low redshift (∼0.02) make it an interesting testbed to search for low-frequency gravitational waves (GWs) using pulsar timing array (PTA) experiments. This source has been subjected to multiple searches for continuous GWs from a circular SMBHB, resulting in progressively more stringent constraints on its GW amplitude and chirp mass. In this paper, we develop a pipeline for performing Bayesian targeted searches for eccentric SMBHBs in PTA data sets, and test its efficacy by applying it to simulated data sets with varying injected signal strengths. We also search for a realistic eccentric SMBHB source in 3C 66B using the NANOGrav 12.5 yr data set employing PTA signal models containing Earth term-only as well as Earth+pulsar term contributions using this pipeline. Due to limitations in our PTA signal model, we get meaningful results only when the initial eccentricity e₀ < 0.5 and the symmetric mass ratio η > 0.1. We find no evidence for an eccentric SMBHB signal in our data, and therefore place 95% upper limits on the PTA signal amplitude of 88.1 ± 3.7 ns for the Earth term-only and 81.74 ± 0.86 ns for the Earth+pulsar term searches for e₀ < 0.5 and η > 0.1. Similar 95% upper limits on the chirp mass are (1.98 ± 0.05) × 10⁹and (1.81 ± 0.01) × 10⁹M_☉. These upper limits, while less stringent than those calculated from a circular binary search in the NANOGrav 12.5 yr data set, are consistent with the SMBHB model of 3C 66B developed from electromagnetic observations.

Copyright and License

© 2024. The Author(s). Published by the American Astronomical Society. Original content from this work may be used under the terms of the Creative Commons Attribution 4.0 licence. Any further distribution of this work must maintain attribution to the author(s) and the title of the work, journal citation and DOI.

Acknowledgement

This work has been carried out by the NANOGrav Collaboration, which receives support from the National Science Foundation (NSF) Physics Frontiers Center award numbers 1430284 and 2020265. The Arecibo Observatory is a facility of the NSF operated under a cooperative agreement (No. AST-1744119) by the University of Central Florida (UCF) in alliance with Universidad Ana G. Méndez (UAGM) and Yang Enterprises (YEI), Inc. The Green Bank Observatory is a facility of the NSF operated under a cooperative agreement by Associated Universities, Inc. The National Radio Astronomy Observatory is a facility of the NSF operated under a cooperative agreement by Associated Universities, Inc. We thank the IPTA steering committee for their valuable input on the manuscript. L.D. and A.S. thank Subhajit Dandapat for the useful discussions. L.D. acknowledges the use of the Thorny Flat Supercomputing System at West Virginia University, which is partly funded by the NSF Major Research Instrumentation Program (MRI) Award #1726534. L.B. acknowledges support from the NSF under award No. AST-1909933 and from the Research Corporation for Science Advancement under Cottrell Scholar Award No. 27553. P.R.B. is supported by the Science and Technology Facilities Council, grant No. ST/W000946/1. S.B. gratefully acknowledges the support of a Sloan Fellowship, and the support of NSF under award #1815664. M.C. and S.R.T. acknowledge support from NSF AST-2007993. M.C. and N.S.P. were supported by the Vanderbilt Initiative in Data Intensive Astrophysics (VIDA) Fellowship. Support for this work was provided by the NSF through the Grote Reber Fellowship Program administered by Associated Universities, Inc./National Radio Astronomy Observatory. Support for H.T.C. is provided by NASA through the NASA Hubble Fellowship Program grant No. HST-HF2-51453.001 awarded by the Space Telescope Science Institute, which is operated by the Association of Universities for Research in Astronomy, Inc., for NASA, under contract NAS5-26555. M.E.D. acknowledges support from the Naval Research Laboratory by NASA under contract S-15633Y. T.D. and M.T.L. are supported by an NSF Astronomy and Astrophysics Grant (AAG) award number 2009468. E.C.F. is supported by NASA under award No. 80GSFC21M0002. G.E.F., S.C.S., and S.J.V. are supported by NSF award PHY-2011772. The Flatiron Institute is supported by the Simons Foundation. A.D.J. and M.V. acknowledge support from the Caltech and Jet Propulsion Laboratory President's and Director's Research and Development Fund. A.D.J. acknowledges support from the Sloan Foundation. The work of N.La. and X.S. is partly supported by the George and Hannah Bolinger Memorial Fund in the College of Science at Oregon State University. N.La. acknowledges the support from Larry W. Martin and Joyce B. O'Neill Endowed Fellowship in the College of Science at Oregon State University. Part of this research was carried out at the Jet Propulsion Laboratory, California Institute of Technology, under a contract with the National Aeronautics and Space Administration (80NM0018D0004). D.R.L. and M.A.M. are supported by NSF #1458952. M.A.M. is supported by NSF #2009425. C.M.F.M. was supported in part by the National Science Foundation under grants Nos. NSF PHY-1748958 and AST-2106552. A.Mi. is supported by the Deutsche Forschungsgemeinschaft under Germany's Excellence Strategy—EXC 2121 Quantum Universe—390833306. The Dunlap Institute is funded by an endowment established by the David Dunlap family and the University of Toronto. K.D.O. was supported in part by NSF grant No. 2207267. T.T.P. acknowledges support from the Extragalactic Astrophysics Research Group at Eötvös Lorönd University, funded by the Eötvös Lorönd Research Network (ELKH), which was used during the development of this research. S.M.R. and I.H.S. are CIFAR Fellows. Portions of this work performed at NRL were supported by ONR 6.1 basic research funding. J.D.R. also acknowledges support from start-up funds from Texas Tech University. J.S. is supported by an NSF Astronomy and Astrophysics Postdoctoral Fellowship under award No. AST-2202388, and acknowledges previous support by the NSF under award No. 1847938. Pulsar research at UBC is supported by an NSERC Discovery Grant and by CIFAR. S.R.T. acknowledges support from an NSF CAREER award #2146016. C.U. acknowledges support from BGU (Kreitman fellowship), and the Council for Higher Education and Israel Academy of Sciences and Humanities (Excellence fellowship). C.A.W. acknowledges support from CIERA, the Adler Planetarium, and the Brinson Foundation through a CIERA-Adler postdoctoral fellowship. O.Y. is supported by the National Science Foundation Graduate Research Fellowship under grant No. DGE-2139292. A.G. acknowledges the support of the Department of Atomic Energy, Government of India, under project identification No. RTI 4002. We thank the anonymous referee for their comments and suggestions.

Data Availability

The NANOGrav 12.5 yr data set is available at https://nanograv.org/science/data/125-year-pulsar-timing-array-data-release, and the MCMC chains from the NANOGrav 12.5 yr GWB search are available at https://nanograv.org/science/data/125-year-stochastic-gravitational-wave-background-search.

Software References

ENTERPRISE (Ellis et al. 2019; Johnson et al. 2023), enterprise_extensions (Taylor et al. 2021; Johnson et al. 2023), PTMCMCSampler (Ellis & van Haasteren 2017; Johnson et al. 2023), GWecc.jl (Susobhanan 2023), libstempo (Vallisneri 2020), NumPy (Harris et al. 2020), pandas (McKinney 2010), wquantiles (Sabater 2015), tensiometer (Raveri & Doux 2021), matplotlib (Hunter 2007), corner (Foreman-Mackey 2016)

Contributions

This paper uses an alphabetical order author list to recognize that a large, decade-timescale project such as NANOGrav is necessarily the result of the work of many people. All authors contributed to the activities of the NANOGrav Collaboration leading to the work presented here and reviewed the manuscript, text, and figures before the paper's submission. Additional specific contributions to this paper are as follows. The NANOGrav 12.5 yr targeted search for an eccentric SMBHB source in 3C 66B was led by L.D. with crucial inputs from A.S. and S.B.S. B.D.C. led this project during its initial exploratory stages with inputs from C.A.W., S.B.S., L.D., A.S., and A.G. The theoretical aspects of this project were investigated by L.D. and A.S. The data analysis and visualization scripts used in this project were developed by L.D., A.S., and B.D.C. with inputs from C.A.W. The GWecc.jl package is developed and maintained by A.S. This manuscript was prepared by A.S. and L.D. with input from S.B.S., A.G., D.L.K., M.A.M., S.J.V., C.A.W., B.B., M.C., and T.D. Z.A, H.B., P.R.B., H.T.C., M.E.D., P.B.D., T.D., J.A.E., R.D.F., E.C.F., E.F., N.G.-D., P.A.G., D.C.G., M.L.J., M.T.L., D.R.L., R.S.L., J.L., M.A.M., C.N., D.J.N., T.T.P., N.S.P., S.M.R., K.S., I.H.S., R.S., J.K.S., R.S., and S.J.V. developed the 12.5 yr data set through a combination of observations, arrival time calculations, data checks, and refinements, and timing model development and analysis; additional specific contributions to the data set are summarized in Alam et al. (2020).

Files

Agazie_2024_ApJ_963_144.pdf

Files (9.9 MB)

Name	Size	Download all
Agazie_2024_ApJ_963_144.pdf md5:5cd01c18a5a5ab10c7b2df0d3868554a	9.9 MB	Preview Download

	All versions	This version
Views	0	0
Downloads	1	1
Data volume	9.9 MB	9.9 MB