A Detection of Red Noise in PSR J1824$-$2452A and Projections for PSR B1937+21 using NICER X-ray Timing Data

Abstract

We have used X-ray data from the Neutron Star Interior Composition Explorer (NICER) to search for long time-scale, correlated variations ("red noise") in the pulse times of arrival from the millisecond pulsars PSR J1824$-$2452A and PSR B1937+21. These data more closely track intrinsic noise because X-rays are unaffected by the radio-frequency dependent propagation effects of the interstellar medium. Our Bayesian search methodology yields strong evidence (natural log Bayes factor of $9.634\pm 0.016$) for red noise in PSR J1824$-$2452A, but is inconclusive for PSR B1937+21. In the interest of future X-ray missions, we devise and implement a method to simulate longer and higher precision X-ray datasets to determine the timing baseline necessary to detect red noise. We find that the red noise in PSR B1937+21 can be reliably detected in a 5-year mission with a time-of-arrival (TOA) error of 2 microseconds and an observing cadence of 20 observations per month compared to the 5 microsecond TOA error and 11 observations per month that NICER currently achieves in PSR B1937+21. We investigate detecting red noise in PSR B1937+21 with other combinations of observing cadences and TOA errors. We also find that an injected stochastic gravitational wave background (GWB) with an amplitude of $A_{\mathrm{GWB}}=2\times 10^{-15}$ and spectral index of ${\gamma }_{\mathrm{GWB}}=13/3$ can be detected in a pulsar with similar TOA precision to PSR B1937+21, but with no additional red noise, in a 10-year mission that observes the pulsar 15 times per month and has an average TOA error of 1 microsecond.

21 pages, 13 figures

References in corpus (17)

• TEMPO2, a new pulsar timing package. I: Overview
• Switched magnetospheric regulation of pulsar spin-down
• On the evidence for a common-spectrum process in the search for the nanohertz gravitational-wave background with the Parkes Pulsar Timing Array
• The International Pulsar Timing Array: Second data release
• PINT: A Modern Software Package for Pulsar Timing
• NANOGrav Limits on Gravitational Waves from Individual Supermassive Black Hole Binaries in Circular Orbits
• The NANOGrav 12.5-year Data Set: Wideband Timing of 47 Millisecond Pulsars
• Identifying and mitigating noise sources in precision pulsar timing data sets
• Time-domain Implementation of the Optimal Cross-Correlation Statistic for Stochastic Gravitational-Wave Background Searches in Pulsar Timing Data
• The NANOGrav Nine-Year Data Set: Excess Noise in Millisecond Pulsar Arrival Times
• Realistic sensitivity curves for pulsar timing arrays
• Low-rank approximations for large stationary covariance matrices, as used in the Bayesian and generalized-least-squares analysis of pulsar-timing data
• Modelling and mitigating refractive propagation effects in precision pulsar timing observations
• The NANOGrav 11-Year Data Set: Evolution of Gravitational Wave Background Statistics
• High-Precision X-ray Timing of Three Millisecond Pulsars with NICER: Stability Estimates and Comparison with Radio
• Bayesian estimation of non-Gaussianity in pulsar timing analysis
• OH Evolution in Molecular Clouds

Cited by in corpus (1)

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