Characterizing Continuous Gravitational Waves from Supermassive Black Hole Binaries in Realistic Pulsar Timing Array Data
Pulsar timing arrays recently found evidence for a gravitational-wave background (GWB), likely the stochastic overlap of gravitational waves from many supermassive black hole binaries. Anticipating a continuous gravitational-wave (CW) detection from a single binary soon to follow, we examine how wel...
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2025-01-01
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| Online Access: | https://doi.org/10.3847/1538-4357/ade4c2 |
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| author | Emiko C. Gardiner Bence Bécsy Luke Zoltan Kelley Neil J. Cornish |
| author_facet | Emiko C. Gardiner Bence Bécsy Luke Zoltan Kelley Neil J. Cornish |
| author_sort | Emiko C. Gardiner |
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| description | Pulsar timing arrays recently found evidence for a gravitational-wave background (GWB), likely the stochastic overlap of gravitational waves from many supermassive black hole binaries. Anticipating a continuous gravitational-wave (CW) detection from a single binary soon to follow, we examine how well current Bayesian methods can detect CWs and characterize their binary properties by modeling the response of the NANOGrav 15 yr pulsar timing array to simulated binary populations. We run Markov Chain Monte Carlo searches for CWs in these data sets and compare them to quicker detection statistics including the optimal signal-to-noise ratio (S/N), matched filter detection statistic, and reduced log-likelihood ratio between the signal and noise models calculated at the injected parameters. The latter is the best proxy for Bayesian detection fractions, corresponding to a 50% detection fraction (by Bayes factors >10 favoring a CW detection over noise-only model) at an S/N = 4.6. Source confusion between the GWB and a CW, or between multiple CWs, can cause false detections and unexpected dismissals. Fifty-three percent of realistic binary populations consistent with the recently observed GWB have successful CW detections. Additionally, 82% of these CWs are in the fourth or fifth frequency bin of the 16.03 yr data set (6.9 and 10.8 nHz), with 95th percentile regions spanning 4–12 nHz frequencies, 0.7–20 × 10 ^9 M _⊙ chirp masses, 60 Mpc–8 Gpc luminosity distances, and 18–13,000 deg ^2 68% confidence localization areas. These successful detections often poorly recover the chirp mass, with only 29% identifying the chirp mass accurately to within 1 dex with a 68% posterior width also narrower than 1 dex. |
| format | Article |
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| institution | Kabale University |
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| language | English |
| publishDate | 2025-01-01 |
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| record_format | Article |
| series | The Astrophysical Journal |
| spelling | doaj-art-16cfabd5927343dcbdafd800cbe8d3372025-08-20T03:56:41ZengIOP PublishingThe Astrophysical Journal1538-43572025-01-01988222210.3847/1538-4357/ade4c2Characterizing Continuous Gravitational Waves from Supermassive Black Hole Binaries in Realistic Pulsar Timing Array DataEmiko C. Gardiner0https://orcid.org/0000-0002-8857-613XBence Bécsy1https://orcid.org/0000-0003-0909-5563Luke Zoltan Kelley2https://orcid.org/0000-0002-6625-6450Neil J. Cornish3https://orcid.org/0000-0002-7435-0869Department of Astronomy, University of California , Berkeley 501 Campbell Hall #3411 Berkeley, CA 94720, USADepartment of Physics, Oregon State University , Corvallis, OR 97331, USA; Institute for Gravitational Wave Astronomy and School of Physics and Astronomy, University of Birmingham , Edgbaston, Birmingham B15 2TT, UKDepartment of Astronomy, University of California , Berkeley 501 Campbell Hall #3411 Berkeley, CA 94720, USADepartment of Physics, Montana State University , Bozeman, MT 59717, USAPulsar timing arrays recently found evidence for a gravitational-wave background (GWB), likely the stochastic overlap of gravitational waves from many supermassive black hole binaries. Anticipating a continuous gravitational-wave (CW) detection from a single binary soon to follow, we examine how well current Bayesian methods can detect CWs and characterize their binary properties by modeling the response of the NANOGrav 15 yr pulsar timing array to simulated binary populations. We run Markov Chain Monte Carlo searches for CWs in these data sets and compare them to quicker detection statistics including the optimal signal-to-noise ratio (S/N), matched filter detection statistic, and reduced log-likelihood ratio between the signal and noise models calculated at the injected parameters. The latter is the best proxy for Bayesian detection fractions, corresponding to a 50% detection fraction (by Bayes factors >10 favoring a CW detection over noise-only model) at an S/N = 4.6. Source confusion between the GWB and a CW, or between multiple CWs, can cause false detections and unexpected dismissals. Fifty-three percent of realistic binary populations consistent with the recently observed GWB have successful CW detections. Additionally, 82% of these CWs are in the fourth or fifth frequency bin of the 16.03 yr data set (6.9 and 10.8 nHz), with 95th percentile regions spanning 4–12 nHz frequencies, 0.7–20 × 10 ^9 M _⊙ chirp masses, 60 Mpc–8 Gpc luminosity distances, and 18–13,000 deg ^2 68% confidence localization areas. These successful detections often poorly recover the chirp mass, with only 29% identifying the chirp mass accurately to within 1 dex with a 68% posterior width also narrower than 1 dex.https://doi.org/10.3847/1538-4357/ade4c2Gravitational wavesSupermassive black holesGravitational wave sourcesGravitational wave astronomyMarkov chain Monte Carlo |
| spellingShingle | Emiko C. Gardiner Bence Bécsy Luke Zoltan Kelley Neil J. Cornish Characterizing Continuous Gravitational Waves from Supermassive Black Hole Binaries in Realistic Pulsar Timing Array Data The Astrophysical Journal Gravitational waves Supermassive black holes Gravitational wave sources Gravitational wave astronomy Markov chain Monte Carlo |
| title | Characterizing Continuous Gravitational Waves from Supermassive Black Hole Binaries in Realistic Pulsar Timing Array Data |
| title_full | Characterizing Continuous Gravitational Waves from Supermassive Black Hole Binaries in Realistic Pulsar Timing Array Data |
| title_fullStr | Characterizing Continuous Gravitational Waves from Supermassive Black Hole Binaries in Realistic Pulsar Timing Array Data |
| title_full_unstemmed | Characterizing Continuous Gravitational Waves from Supermassive Black Hole Binaries in Realistic Pulsar Timing Array Data |
| title_short | Characterizing Continuous Gravitational Waves from Supermassive Black Hole Binaries in Realistic Pulsar Timing Array Data |
| title_sort | characterizing continuous gravitational waves from supermassive black hole binaries in realistic pulsar timing array data |
| topic | Gravitational waves Supermassive black holes Gravitational wave sources Gravitational wave astronomy Markov chain Monte Carlo |
| url | https://doi.org/10.3847/1538-4357/ade4c2 |
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