TY - JOUR
T1 - NANOGrav 15-year gravitational-wave background methods
AU - (NANOGrav Collaboration)
AU - Johnson, Aaron D.
AU - Meyers, Patrick M.
AU - Baker, Paul T.
AU - Cornish, Neil J.
AU - Hazboun, Jeffrey S.
AU - Littenberg, Tyson B.
AU - Romano, Joseph D.
AU - Taylor, Stephen R.
AU - Vallisneri, Michele
AU - Vigeland, Sarah J.
AU - Olum, Ken D.
AU - Siemens, Xavier
AU - Ellis, Justin A.
AU - Van Haasteren, Rutger
AU - Hourihane, Sophie
AU - Agazie, Gabriella
AU - Anumarlapudi, Akash
AU - Archibald, Anne M.
AU - Arzoumanian, Zaven
AU - Blecha, Laura
AU - Brazier, Adam
AU - Brook, Paul R.
AU - Burke-Spolaor, Sarah
AU - Bécsy, Bence
AU - Casey-Clyde, J. Andrew
AU - Charisi, Maria
AU - Chatterjee, Shami
AU - Chatziioannou, Katerina
AU - Cohen, Tyler
AU - Cordes, James M.
AU - Crawford, Fronefield
AU - Cromartie, H. Thankful
AU - Crowter, Kathryn
AU - Decesar, Megan E.
AU - Demorest, Paul B.
AU - Dolch, Timothy
AU - Drachler, Brendan
AU - Ferrara, Elizabeth C.
AU - Fiore, William
AU - Fonseca, Emmanuel
AU - Freedman, Gabriel E.
AU - Garver-Daniels, Nate
AU - Gentile, Peter A.
AU - Glaser, Joseph
AU - Good, Deborah C.
AU - Gültekin, Kayhan
AU - Jennings, Ross J.
AU - Jones, Megan L.
AU - Kaiser, Andrew R.
AU - Schmiedekamp, Ann
N1 - Publisher Copyright:
© 2024 American Physical Society. American Physical Society.
PY - 2024/5/15
Y1 - 2024/5/15
N2 - Pulsar timing arrays (PTAs) use an array of millisecond pulsars to search for gravitational waves in the nanohertz regime in pulse time of arrival data. This paper presents rigorous tests of PTA methods, examining their consistency across the relevant parameter space. We discuss updates to the 15-year isotropic gravitational-wave background analyses and their corresponding code representations. Descriptions of the internal structure of the flagship algorithms enterprise and ptmcmcsampler are given to facilitate understanding of the PTA likelihood structure, how models are built, and what methods are currently used in sampling the high-dimensional PTA parameter space. We introduce a novel version of the PTA likelihood that uses a two-step marginalization procedure that performs much faster in gravitational wave searches, reducing the required resources facilitating the computation of Bayes factors via thermodynamic integration and sampling a large number of realizations for computing Bayesian false-alarm probabilities. We perform stringent tests of consistency and correctness of the Bayesian and frequentist analysis methods. For the Bayesian analysis, we test prior recovery, simulation recovery, and Bayes factors. For the frequentist analysis, we test that the optimal statistic, when modified to account for a non-negligible gravitational-wave background, accurately recovers the amplitude of the background. We also summarize recent advances and tests performed on the optimal statistic in the literature from both gravitational wave background detection and parameter estimation perspectives. The tests presented here validate current analyses of PTA data.
AB - Pulsar timing arrays (PTAs) use an array of millisecond pulsars to search for gravitational waves in the nanohertz regime in pulse time of arrival data. This paper presents rigorous tests of PTA methods, examining their consistency across the relevant parameter space. We discuss updates to the 15-year isotropic gravitational-wave background analyses and their corresponding code representations. Descriptions of the internal structure of the flagship algorithms enterprise and ptmcmcsampler are given to facilitate understanding of the PTA likelihood structure, how models are built, and what methods are currently used in sampling the high-dimensional PTA parameter space. We introduce a novel version of the PTA likelihood that uses a two-step marginalization procedure that performs much faster in gravitational wave searches, reducing the required resources facilitating the computation of Bayes factors via thermodynamic integration and sampling a large number of realizations for computing Bayesian false-alarm probabilities. We perform stringent tests of consistency and correctness of the Bayesian and frequentist analysis methods. For the Bayesian analysis, we test prior recovery, simulation recovery, and Bayes factors. For the frequentist analysis, we test that the optimal statistic, when modified to account for a non-negligible gravitational-wave background, accurately recovers the amplitude of the background. We also summarize recent advances and tests performed on the optimal statistic in the literature from both gravitational wave background detection and parameter estimation perspectives. The tests presented here validate current analyses of PTA data.
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U2 - 10.1103/PhysRevD.109.103012
DO - 10.1103/PhysRevD.109.103012
M3 - Article
AN - SCOPUS:85192766068
SN - 2470-0010
VL - 109
JO - Physical Review D
JF - Physical Review D
IS - 10
M1 - 103012
ER -