TY - JOUR
T1 - Consistency of the Parkes Pulsar Timing Array signal with a nanohertz gravitational-wave background
AU - Goncharov, Boris
AU - Thrane, Eric
AU - Shannon, Ryan M.
AU - Harms, Jan
AU - Bhat, N. D. Ramesh
AU - Hobbs, George
AU - Kerr, Matthew
AU - Manchester, Richard N.
AU - Reardon, Daniel J.
AU - Russell, Christopher J.
AU - Zhu, Xing Jiang
AU - Zic, Andrew
N1 - Copyright © 2022. The Author(s). Published by the American Astronomical Society. Version archived for private and non-commercial use with the permission of the author/s and according to publisher conditions. For further rights please contact the publisher.
PY - 2022/6/1
Y1 - 2022/6/1
N2 - Pulsar timing array experiments have recently reported strong evidence for a common-spectrum stochastic process with a strain spectral index consistent with that expected of a nanohertz-frequency gravitational-wave background, but with negligible yet non-zero evidence for spatial correlations required for a definitive detection. However, it was pointed out by the Parkes Pulsar Timing Array (PPTA) collaboration that the same models used in recent analyses resulted in strong evidence for a common-spectrum process in simulations where none is present. In this work, we introduce a methodology to distinguish pulsar power spectra with the same amplitude from noise power spectra of similar but distinct amplitudes. The former is the signature of a spatially uncorrelated pulsar term of a nanohertz gravitational-wave background, whereas the latter could represent ensemble pulsar noise properties. We test the methodology on simulated data sets. We find that the reported common process in PPTA pulsars is indeed consistent with the spectral feature of a pulsar term. We recommend this methodology as one of the validity tests that the real astrophysical and cosmological backgrounds should pass, as well as for inferences about the spatially uncorrelated component of the background.
AB - Pulsar timing array experiments have recently reported strong evidence for a common-spectrum stochastic process with a strain spectral index consistent with that expected of a nanohertz-frequency gravitational-wave background, but with negligible yet non-zero evidence for spatial correlations required for a definitive detection. However, it was pointed out by the Parkes Pulsar Timing Array (PPTA) collaboration that the same models used in recent analyses resulted in strong evidence for a common-spectrum process in simulations where none is present. In this work, we introduce a methodology to distinguish pulsar power spectra with the same amplitude from noise power spectra of similar but distinct amplitudes. The former is the signature of a spatially uncorrelated pulsar term of a nanohertz gravitational-wave background, whereas the latter could represent ensemble pulsar noise properties. We test the methodology on simulated data sets. We find that the reported common process in PPTA pulsars is indeed consistent with the spectral feature of a pulsar term. We recommend this methodology as one of the validity tests that the real astrophysical and cosmological backgrounds should pass, as well as for inferences about the spatially uncorrelated component of the background.
UR - http://www.scopus.com/inward/record.url?scp=85132903727&partnerID=8YFLogxK
U2 - 10.3847/2041-8213/ac76bb
DO - 10.3847/2041-8213/ac76bb
M3 - Article
AN - SCOPUS:85132903727
SN - 2041-8205
VL - 932
SP - 1
EP - 7
JO - Astrophysical Journal Letters
JF - Astrophysical Journal Letters
IS - 2
M1 - L22
ER -