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Lookup NU author(s): Dr Anne ArchibaldORCiD
This work is licensed under a Creative Commons Attribution 4.0 International License (CC BY 4.0).
© 2025. The Author(s). Published by the American Astronomical Society.Pulse profile stability is a central assumption of standard pulsar timing methods. Thus, it is important for pulsar timing array experiments such as the North American Nanohertz Observatory for Gravitational Waves (NANOGrav) to account for any pulse profile variability present in their data sets. We show that in the NANOGrav 15 yr data set, the integrated pulse profile of PSR J1022+1001 as seen by the Arecibo radio telescope at 430, 1380, and 2030 MHz varies considerably in its shape from observation to observation. We investigate the possibility that this is due to the “ideal feed assumption” (IFA), on which NANOGrav’s routine polarization calibration procedure relies. PSR J1022+1001 is ∼90% polarized in one pulse profile component, and also has significant levels of circular polarization. Time-dependent deviations in the feed’s polarimetric response (PR) could cause mixing between the intensity I and the other Stokes parameters, leading to the observed variability. We calibrate the PR using a mixture of measurement equation modeling and measurement equation template matching techniques. The resulting profiles are no less variable than those calibrated using the IFA method, nor do they provide an improvement in the timing quality of this pulsar. We observe the pulse shape in 25 MHz bandwidths to vary consistently across the band, which cannot be explained by interstellar scintillation in combination with profile evolution with frequency. Instead, we favor phenomena intrinsic to the pulsar as the cause.
Author(s): Fiore W, McLaughlin MA, Agazie G, Anumarlapudi A, Archibald AM, Arzoumanian Z, Baker PT, Brook PR, Cromartie HT, Crowter K, DeCesar ME, Demorest PB, Dey L, Dolch T, Ferrara EC, Fonseca E, Freedman GE, Garver-Daniels N, Gentile PA, Glaser J, Good DC, Hazboun JS, Jennings RJ, Jones ML, Kaplan DL, Kerr M, Lam MT, Lorimer DR, Luo J, Lynch RS, McEwen A, McMann N, Meyers BW, Ng C, Nice DJ, Pennucci TT, Perera BBP, Pol NS, Radovan HA, Ransom SM, Ray PS, Schmiedekamp A, Schmiedekamp C, Shapiro-Albert BJ, Stairs IH, Stovall K, Susobhanan A, Swiggum JK, Wahl HM
Publication type: Article
Publication status: Published
Journal: Astrophysical Journal
Year: 2025
Volume: 984
Issue: 2
Print publication date: 06/05/2025
Online publication date: 17/03/2025
Acceptance date: 16/03/2025
Date deposited: 09/06/2025
ISSN (print): 0004-637X
ISSN (electronic): 1538-4357
Publisher: Institute of Physics
URL: https://doi.org/10.3847/1538-4357/adc255
DOI: 10.3847/1538-4357/adc255
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