The Square Kilometre Array (SKA)

Research group

Research theme

Sub department

About

Related research groups

Slow and steady: long-term evolution of the 76-second pulsar J0901−4046

Monthly Notices of the Royal Astronomical Society Oxford University Press (OUP) (2025)

Authors:

MC Bezuidenhout, NDR Bhat, M Caleb, LN Driessen, F Jankowski, M Kramer, V Morello, I Pastor-Marazuela, K Rajwade, J Roy, BW Stappers, M Surnis, J Tian

Abstract:

Abstract PSR J0901−4046, a likely radio-loud neutron star with a period of 75.88 seconds, challenges conventional models of neutron star radio emission. Here, we showcase results from 46 hours of follow-up observations of PSR J0901−4046 using the MeerKAT, Murriyang, GMRT, and MWA radio telescopes. We demonstrate the intriguing stability of the source’s timing solution over more than three years, leading to an RMS arrival-time uncertainty of just ∼10−4 of the rotation period. Furthermore, non-detection below 500 MHz may indicate a low-frequency turnover in the source’s spectrum, while no secular decline in the flux density of the source over time, as was apparent from previous observations, has been observed. Using high time-resolution MeerKAT data, we demonstrate two distinct quasi-periodic oscillation modes present in single pulses, with characteristic time scales of 73 ms and 21 ms. We also observe a statistically significant change in the relative prevalence of distinct pulse morphologies compared to previous observations, possibly indicating a shift in the magnetospheric composition over time. Finally, we show that the W50 pulse width is nearly constant from 544–4032 MHz, consistent with zero radius-to-frequency mapping. The very short duty cycle (∼1.4○) is more similar to radio pulsars with periods >5 seconds than to radio-loud magnetars. This, along with the lack of magnetar-like outbursts or timing glitches, complicates the identification of the source with ultra-long period magnetar models.
More details from the publisher

A Coherent Radio Burst from an X-Ray Neutron Star in the Carina Nebula

The Astrophysical Journal Letters American Astronomical Society 985:1 (2025) L3-L3

Authors:

KM Rajwade, J Tian, G Younes, B Posselt, B Stappers, Z Wadiasingh, ED Barr, MC Bezuidenhout, M Caleb, F Jankowski, M Kramer, I Pastor-Marazuela, M Surnis

Abstract:

Abstract The neutron star zoo comprises several subpopulations that range from energetic magnetars and thermally emitting X-ray neutron stars to radio-emitting pulsars. Despite studies over the last five decades, it has been challenging to obtain a clear physical link between the various populations of neutron stars, vital to constrain their formation and evolutionary pathways. Here we report the detection of a burst of coherent radio emission from a known radio-quiet, thermally emitting neutron star 2XMM J104608.7−594306 in the Carina Nebula. The burst has a distinctive sharp rise followed by a decay made up of multiple components, which is unlike anything seen from other radio-emitting neutron stars. It suggests an episodic event from the neutron star surface, akin to transient radio emission seen from magnetars. The radio burst confirms that the X-ray source is a neutron star and suggests a new link between these apparently radio-quiet X-ray-emitting sources and other transient or persistent radio-emitting neutron stars. It also suggests that a common physical mechanism for emission might operate over a range of magnetic field strengths and neutron star ages. We propose that 2XMM J104608.7−594306 straddles the boundary between young, energetic neutron stars and their evolved radio-emitting cousins and may bridge these two populations. The detection of such a radio burst also shows that other radio-quiet neutron stars may also emit such sporadic radio emission that has been missed by previous radio surveys and highlights the need for regular monitoring of this unique subpopulation of neutron stars.
More details from the publisher
More details

Relativistic ejecta from stellar mass black holes: insights from simulations and synthetic radio images

Monthly Notices of the Royal Astronomical Society Oxford University Press (OUP) 540:1 (2025) 1084-1106

Authors:

Katie Savard, James H Matthews, Rob Fender, Ian Heywood
More details from the publisher

MeerKAT discovery of a hyperactive repeating fast radio burst source

Monthly Notices of the Royal Astronomical Society Oxford University Press (OUP) (2025)

Authors:

J Tian, I Pastor-Marazuela, KM Rajwade, BW Stappers, K Shaji, KY Hanmer, M Caleb, MC Bezuidenhout, F Jankowski, R Breton, ED Barr, M Kramer, PJ Groot, S Bloemen, P Vreeswijk, D Pieterse, PA Woudt, RP Fender, RAD Wijnands, DAH Buckley

Abstract:

Abstract We present the discovery and localisation of a repeating fast radio burst (FRB) source from the MeerTRAP project, a commensal fast radio transient search programme using the MeerKAT telescope. FRB 20240619D was first discovered on 2024 June 19 with three bursts being detected within two minutes in the MeerKAT L-band (856–1712 MHz). We conducted follow-up observations of FRB 20240619D with MeerKAT using the Ultra-High Frequency (UHF; 544–1088 MHz), L-band and S-band (1968–2843 MHz) receivers one week after its discovery, and recorded a total of 249 bursts. The MeerKAT-detected bursts exhibit band-limited emission with an average fractional bandwidth of 0.31, 0.34 and 0.48 in the UHF, L-band and S-band, respectively. We find our observations are complete down to a fluence limit of ∼1 Jy ms, above which the cumulative burst rate follows a power law R( > F)∝(F/1 Jy ms)γ with γ = −1.6 ± 0.1 and −1.7 ± 0.1 in the UHF and L-band, respectively. The near-simultaneous L-band, UHF and S-band observations reveal a frequency dependent burst rate with 3 × more bursts being detected in the L-band than in the UHF and S-band, suggesting a spectral turnover in the burst energy distribution of FRB 20240619D. Our polarimetric analysis demonstrates that most of the bursts have ∼100% linear polarisation fractions and ∼10%–20% circular polarisation fractions. We find no optical counterpart of FRB 20240619D in the MeerLICHT optical observations simultaneous to the radio observations and set a fluence upper limit in MeerLICHT’s q-band of 0.76 Jy ms and an optical-to-radio fluence ratio limit of 0.034 for a 15 s exposure.
More details from the publisher

The Ejection of Transient Jets in Swift J1727.8−1613 Revealed by Time-dependent Visibility Modeling

The Astrophysical Journal Letters American Astronomical Society 984:2 (2025) l53

Authors:

Callan M Wood, James CA Miller-Jones, Arash Bahramian, Steven J Tingay, He-Xin Liu, Diego Altamirano, Rob Fender, Elmar Körding, Dipankar Maitra, Sera Markoff, David M Russell, Thomas D Russell, Craig L Sarazin, Gregory R Sivakoff, Roberto Soria, Alexandra J Tetarenko, Valeriu Tudose
More details from the publisher