Journal article
Apparent dispersion in pulsar braking index measurements caused by timing noise
AF Vargas, A Melatos
Monthly Notices of the Royal Astronomical Society | Published : 2023
Abstract
Stochastic temporal wandering of the spin frequency ν of a rotation-powered pulsar (i.e. the achromatic component of timing noise unrelated to interstellar propagation) affects the accuracy with which the secular braking torque can be measured. Observational studies confirm that pulsars with anomalous braking indices |n| = |νν̈/ν'2| ≫ 1 exhibit elevated levels of timing noise, where an overdot symbolizes a derivative with respect to time. Here it is shown, through analytic calculations and Monte Carlo simulations involving synthetic data and modern Bayesian timing techniques, that the variance 〈n2〉 of the measured n scales with the square of the timing noise amplitude σν̈. The anomalous regi..
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Grants
Awarded by Australian Research Council
Funding Acknowledgements
The authors thank Patrick Meyers, for discussing the Brownian model and making the baboo package freely available, and Liam Dunn, for guidance in the use of the TEMPONEST and TEMPO2 software infrastructure and advice that allowed the Brownian model to qualitatively emulate the phase residuals of PSR J0942-5552 in Fig. 1 . Additionally, we thank Patrick Meyers, Liam Dunn, Nicholas O'Neill, and Joe O'Leary for useful discussions regarding Section 4 , which led ultimately to an understanding of local and non-local n measurements. We thank the anonymous referee for helpful suggestions which improved the manuscript. This research was supported by the Australian Research Council Centre of Excellence for Gravitational Wave Discovery (OzGrav), grant number CE170100004. AFV is supported by a Melbourne Research Scholarship and by the N. D. Goldsworthy Scholarship for Physics. The numerical calculations were performed on the OzSTAR supercomputer facility at Swinburne University of Technology. The OzSTAR program receives funding in part from the Astronomy National Collaborative Research Infrastructure Strategy (NCRIS) allocation provided by the Australian Government.