Searching for pulsars and fast transients with the MeerKAT telescope

Abstract

Pulsars are fascinating and extreme objects of nature. These rapidly spinning, highly magnetised neutron stars are visible to us as pulsed sources of electromagnetic radiation. The MeerKAT radio telescope has, since its inauguration in 2018, been the most sensitive radio telescope in the Southern Hemisphere and an exemplary instrument for pulsar searches. The main body of work of this thesis presents the TRAPUM survey for young pulsars in supernova remnants (SNRs) and pulsar wind nebulae (PWNe). The motivations for the searches are many: new young pulsars place constraints on the birth rates and properties of neutron stars and also the energy budgets of PWNe. A total of 134 targets were searched for pulsars with a mean sensitivity of ∼52 µJy, yielding two new pulsars. One of the discoveries is PSR J1831−0941, an adolescent pulsar powering the PWN G22.0+0.0 and located within a faint SNR shell. The other, PSR J1818−1502 is an old, faint pulsar serendipitously discovered in the foreground of SNR G15.9+0.2. The target list included a handful of TeV sources that could potentially be PWNe, and also ten central compact objects (CCOs). In order to understand the detection rate, I have synthesised 100 Galactic young pulsar populations and find evidence that, after beaming effects, luminosity followed closely by scattering-dominated smearing are the most significant selection effects against new detections on the Galactic plane. This motivates future surveys, such as those with the SKAO, to observe at higher frequencies to maximise young pulsar discoveries. I also present some further work: a study of the emission and rotational properties of 26 new Galactic radio sources discovered by the MeerTRAP real-time single pulses searches. Many of the new objects are members of a class of pulsar known as rotating radio transients (RRATs), with spin periods of a few seconds. One discovery has a period of 17.5 s, pointing to an understudied population of very slow pulsars. Such objects challenge views of radio emission mechanisms from pulsars, and may also provide clues about possible evolutionary connections between manifestations of neutron stars. Using arrival times calculated for single pulses and aided by localisations of arcsecond precision enabled by MeerTRAP’s transient buffer system, timing solutions for five of the RRATs were derived. This work further demonstrates the utility of running single pulse searches commensally to traditional periodicity searches, and the important role of rapid precise localisation for following up discoveries.

Date of Award	9 Jun 2025
Original language	English
Awarding Institution	The University of Manchester
Supervisor	Benjamin Stappers (Main Supervisor) & Rene Breton (Co Supervisor)