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Targeted search for an individual SMBHB in NANOGrav 15-year and EPTA DR2 data sets

Li-Wen Tian, Yan-Chen Bi, Yu-Mei Wu, Qing-Guo Huang

TL;DR

This study tests whether the SMBHB candidate 3C 66B emits continuous gravitational waves detectable by pulsar timing arrays. It employs a targeted Bayesian search in the NG15 and EPTA DR2full data sets, modeling the GWB as a common red noise and incorporating an eccentric, inspiraling SMBHB signal via a generalized quasi-Keplerian framework up to 3PN. No evidence of a 3C 66B GW signal is found; the authors derive 95% upper limits on the signal amplitude $S_0$ and chirp mass $M_c$, and use likelihood reweighting to assess Hellings–Downs correlations, which reaffirm non-detection. The results, consistent with prior NG analyses, provide tighter constraints on 3C 66B and demonstrate how EM priors and HD considerations can be integrated in PTA searches for individual SMBHBs, informing SMBHB demographics and the SMBHB contribution to the stochastic background.

Abstract

While pulsar timing array (PTA) collaborations have reported evidence for a stochastic gravitational wave background (GWB), the detection of continuous gravitational waves (GWs) from a confirmed supermassive black hole binary (SMBHB) would provide strong support for the SMBHB origin of GWB. In this study, we analyze continuous GWs from the SMBHB candidate 3C 66B, modeling the GWB as a common uncorrelated red noise. Using Bayesian methods, we perform targeted searches across two PTA data sets: Nanohertz Observatory for Gravitational Waves 15 years data set and the European Pulsar Timing Array DR2 full data set. We find no evidence of such signal in both data sets and then place upper limits on the amplitude of the signal and the chirp mass of the source. Additionally, we evaluate the case of a GWB characterized by Hellings-Downs correlations using a likelihood reweighting method, which consistently reconfirms the conclusion of non-detection.

Targeted search for an individual SMBHB in NANOGrav 15-year and EPTA DR2 data sets

TL;DR

This study tests whether the SMBHB candidate 3C 66B emits continuous gravitational waves detectable by pulsar timing arrays. It employs a targeted Bayesian search in the NG15 and EPTA DR2full data sets, modeling the GWB as a common red noise and incorporating an eccentric, inspiraling SMBHB signal via a generalized quasi-Keplerian framework up to 3PN. No evidence of a 3C 66B GW signal is found; the authors derive 95% upper limits on the signal amplitude and chirp mass , and use likelihood reweighting to assess Hellings–Downs correlations, which reaffirm non-detection. The results, consistent with prior NG analyses, provide tighter constraints on 3C 66B and demonstrate how EM priors and HD considerations can be integrated in PTA searches for individual SMBHBs, informing SMBHB demographics and the SMBHB contribution to the stochastic background.

Abstract

While pulsar timing array (PTA) collaborations have reported evidence for a stochastic gravitational wave background (GWB), the detection of continuous gravitational waves (GWs) from a confirmed supermassive black hole binary (SMBHB) would provide strong support for the SMBHB origin of GWB. In this study, we analyze continuous GWs from the SMBHB candidate 3C 66B, modeling the GWB as a common uncorrelated red noise. Using Bayesian methods, we perform targeted searches across two PTA data sets: Nanohertz Observatory for Gravitational Waves 15 years data set and the European Pulsar Timing Array DR2 full data set. We find no evidence of such signal in both data sets and then place upper limits on the amplitude of the signal and the chirp mass of the source. Additionally, we evaluate the case of a GWB characterized by Hellings-Downs correlations using a likelihood reweighting method, which consistently reconfirms the conclusion of non-detection.

Paper Structure

This paper contains 7 sections, 16 equations, 1 figure, 3 tables.

Table of Contents

  1. Introduction
  2. Source Model
  3. Data Analysis
  4. Timing Residual Model
  5. Model Comparison
  6. Result
  7. Conclusion and Discussion

Figures (1)

  • Figure 1: Marginalized posteriors of $e_0$, $\eta$, and $\log_{10} S_0$ from the targeted search modeling the GWB as a CURN in the NG15 and DR2full data sets: (a) NG15 Earth term search; (b) NG15 Earth+Pulsar term search; (c) DR2full Earth term search; (d) DR2full Earth+Pulsar term search.