The Astrophysical Journal (Jan 2024)

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

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

DOI
https://doi.org/10.3847/1538-4357/ad1f61
Journal volume & issue
Vol. 963, no. 2
p. 144

Abstract

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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 e _0 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 e _0 0.1. Similar 95% upper limits on the chirp mass are (1.98 ± 0.05) × 10 ^9 and (1.81 ± 0.01) × 10 ^9 M _☉ . 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.

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