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Title: 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-timescale temporal correlations (“red noise”) in the pulse times of arrival (TOAs) 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 search yields strong evidence (natural log Bayes factor of 9.634 ± 0.016) for red noise in PSR J1824−2452A, but the search 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 data sets 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 yr mission with a TOA error of 2μs and an observing cadence of 20 observations per month compared to the 5μs 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 time-correlated red noise commensurate with an injected stochastic gravitational-wave background having an more » amplitude ofAGWB= 2 × 10−15and spectral index of timing residuals ofγGWB= 13/3 can be detected in a pulsar with similar TOA precision to PSR B1937+21. This is with no additional red noise in a 10 yr mission that observes the pulsar 15 times per month and has an average TOA error of 1μs.

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Authors:
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Award ID(s):
2020265
Publication Date:
NSF-PAR ID:
10366914
Journal Name:
The Astrophysical Journal
Volume:
928
Issue:
1
Page Range or eLocation-ID:
Article No. 67
ISSN:
0004-637X
Publisher:
DOI PREFIX: 10.3847
Sponsoring Org:
National Science Foundation
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