Mining the time axis with TRON – III. Discovery of a nulling pulsar towards the SMC with MeerKAT
Year: 2026
Type: article
Abstract: ABSTRACT We report on the discovery of a nulling pulsar, PSR J0052–7551, in archival MeerKAT L-band observations of the Small Magellanic Cloud (SMC). The discovery was made using the image-plane transient detection pipeline, TRON, which creates a residual image for each time sample and uses a heuristic pruning strategy to identify promising candidates in the resulting temporal image cube. The TRON pipeline was triggered on the approximately minute-time-scale variability associated with the nulling behaviour of a canonical pulsar. Follow-up MeerKAT UHF-band beamformer observations revealed a pulsar with a spin period of 0.55 s and a measured period derivative of 6.1(6) $\times 10^{-17}$ s s$^{-1}$. The source is seen in projection towards the periphery of the SMC, and has a dispersion measure value of 29.24(2) pc cm$^{-3}$, which is on the order of the expected Milky Way contribution along the line of sight. We use a Gaussian Mixture Model to fit the nulling behaviour, which yielded a nulling fraction of $\sim 32$%. We find that the null lengths are consistent with an exponential distribution, indicating a stochastic process. Additionally, power spectra of the UHF visibility data reveal an unexplained quasi-periodic feature at $\sim$5–7 s that cannot be attributed to the source itself, radio frequency interference, or standard instrumental effects. Following on from previous image-plane detections of pulsars by the TRON approach, which relied on either scintillation or eclipsing behaviour, this is the first detection triggered by nulling. This discovery confirms TRON’s sensitivity to a wide range of astrophysical phenomena of medium time-scale duration.
Institutions: Rhodes University, South African Radio Astronomy Observatory, University of Cape Town, University of Oxford, Istituto di Radioastronomia di Bologna, National Institute for Astrophysics, University of Warwick, Centre National de la Recherche Scientifique, Université Paris Sciences et Lettres, Observatoire de Paris, Galaxies, Etoiles, Physique et Instrumentation, Instituto de Astrofísica de Canarias, University of Sheffield
Language: English
Subfield: Astronomy and Astrophysics
Field: Physics and Astronomy
Domain: Physical Sciences
Open Access status: gold
Estimated APC paid: $3,046
Funders: Breakthrough Prize Foundation, Australian Government, Royal Society, Commonwealth Scientific and Industrial Research Organisation, National Research Foundation, University of Pretoria, University of the Western Cape, Universiteit Stellenbosch, Cape Peninsula University of Technology, University of Cape Town, Science and Technology Facilities Council
OpenAlex ID: W7212002508
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