Rotational and radio emission properties of PSR J0738−4042 over half a century

ABSTRACT We present a comprehensive study of the rotational and emission properties of PSR J0738−4042 using a combination of observations taken by the Deep Space Network, Hartebeesthoek, Parkes (Murriyang) and Molonglo observatories between 1972 and 2023. Our timing of the pulsar is motivated by pre...

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Published in:Monthly notices of the Royal Astronomical Society 2023-10, Vol.524 (4), p.5904-5917
Main Authors: Lower, M E, Johnston, S, Karastergiou, A, Brook, P R, Bailes, M, Buchner, S, Deller, A T, Dunn, L, Flynn, C, Kerr, M, Manchester, R N, Mandlik, A, Oswald, L S, Parthasarathy, A, Shannon, R M, Sobey, C, Weltevrede, P
Format: Article
Language:English
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Summary:ABSTRACT We present a comprehensive study of the rotational and emission properties of PSR J0738−4042 using a combination of observations taken by the Deep Space Network, Hartebeesthoek, Parkes (Murriyang) and Molonglo observatories between 1972 and 2023. Our timing of the pulsar is motivated by previously reported profile/spin-down events that occurred in 2005 September and 2015 December, which result in an anomalously large braking index of n = 23 300 ± 1800. Using a Gaussian process regression framework, we develop continuous models for the evolution of the pulsar spin-down rate ($\dot{\nu }$) and profile shape. We find that the pulse profile variations are similar regardless of radio observing frequency and polarization. Small-scale differences can be ascribed to changes in the interstellar medium along the line of sight and frequency-dependent changes in magnetospheric radio emission height. No new correlated spin-down or profile events were identified in our extended data set. However, we found that the disappearance of a bright emission component in the leading edge of archival profiles between 1981 and 1988 was not associated with a substantial change in $\dot{\nu }$. This marks a notable departure from the previous profile/spin-down events in this pulsar. We discuss the challenges these observations pose for physical models and conclude that interactions between the pulsar and in-falling asteroids or a form of magnetospheric state-switching with a long periodicity are plausible explanations.
ISSN:0035-8711
1365-2966
DOI:10.1093/mnras/stad2243