Effects of waveform model systematics on the interpretation of GW150914
산업수학기반연구부

B.P. Abbott, R. Abbott, ....J.J.Oh, S.H.Oh, E.J.Son, Whansun Kim...

Classical and Quantum Gravity
34
(2017)
Parameter estimates of GW150914 were obtained using Bayesian inference, based on three semianalytic waveform models for binary black hole coalescences. These waveform models differ from each other in their treatment of black hole spins, and all three models make some simplifying assumptions, notably to neglect subdominant waveform harmonic modes and orbital eccentricity. Furthermore, while the models are calibrated to agree with waveforms obtained by full numerical solutions of Einstein's equations, any such calibration is accurate only to some nonzero tolerance and is limited by the accuracy of the underlying phenomenology, availability, quality, and parameterspace coverage of numerical simulations. This paper complements the original analyses of GW150914 with an investigation of the effects of possible systematic errors in the waveform models on estimates of its source parameters. To test for systematic errors we repeat the original Bayesian analysis on mock signals from numerical simulations of a series of binary configurations with parameters similar to those found for GW150914. Overall, we find no evidence for a systematic bias relative to the statistical error of the original parameter recovery of GW150914 due to modeling approximations or modeling inaccuracies. However, parameter biases are found to occur for some configurations disfavored by the data of GW150914: for binaries inclined edgeon to the detector over a small range of choices of polarization angles, and also for eccentricities greater than ~0.05. For signals with higher signaltonoise ratio than GW150914, or in other regions of the binary parameter space (lower masses, larger mass ratios, or higher spins), we expect that systematic errors in current waveform models may impact gravitationalwave measurements, making more accurate models desirable for future observations.
 초록
Parameter estimates of GW150914 were obtained using Bayesian inference, based on three semianalytic waveform models for binary black hole coalescences. These waveform models differ from each other in their treatment of black hole spins, and all three models make some simplifying assumptions, notably to neglect subdominant waveform harmonic modes and orbital eccentricity. Furthermore, while the models are calibrated to agree with waveforms obtained by full numerical solutions of Einstein's equations, any such calibration is accurate only to some nonzero tolerance and is limited by the accuracy of the underlying phenomenology, availability, quality, and parameterspace coverage of numerical simulations. This paper complements the original analyses of GW150914 with an investigation of the effects of possible systematic errors in the waveform models on estimates of its source parameters. To test for systematic errors we repeat the original Bayesian analysis on mock signals from numerical simulations of a series of binary configurations with parameters similar to those found for GW150914. Overall, we find no evidence for a systematic bias relative to the statistical error of the original parameter recovery of GW150914 due to modeling approximations or modeling inaccuracies. However, parameter biases are found to occur for some configurations disfavored by the data of GW150914: for binaries inclined edgeon to the detector over a small range of choices of polarization angles, and also for eccentricities greater than ~0.05. For signals with higher signaltonoise ratio than GW150914, or in other regions of the binary parameter space (lower masses, larger mass ratios, or higher spins), we expect that systematic errors in current waveform models may impact gravitationalwave measurements, making more accurate models desirable for future observations.
 초록
Parameter estimates of GW150914 were obtained using Bayesian inference, based on three semianalytic waveform models for binary black hole coalescences. These waveform models differ from each other in their treatment of black hole spins, and all three models make some simplifying assumptions, notably to neglect subdominant waveform harmonic modes and orbital eccentricity. Furthermore, while the models are calibrated to agree with waveforms obtained by full numerical solutions of Einstein's equations, any such calibration is accurate only to some nonzero tolerance and is limited by the accuracy of the underlying phenomenology, availability, quality, and parameterspace coverage of numerical simulations. This paper complements the original analyses of GW150914 with an investigation of the effects of possible systematic errors in the waveform models on estimates of its source parameters. To test for systematic errors we repeat the original Bayesian analysis on mock signals from numerical simulations of a series of binary configurations with parameters similar to those found for GW150914. Overall, we find no evidence for a systematic bias relative to the statistical error of the original parameter recovery of GW150914 due to modeling approximations or modeling inaccuracies. However, parameter biases are found to occur for some configurations disfavored by the data of GW150914: for binaries inclined edgeon to the detector over a small range of choices of polarization angles, and also for eccentricities greater than ~0.05. For signals with higher signaltonoise ratio than GW150914, or in other regions of the binary parameter space (lower masses, larger mass ratios, or higher spins), we expect that systematic errors in current waveform models may impact gravitationalwave measurements, making more accurate models desirable for future observations.
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