My research area is relatively broad but primarily focuses on neutron stars, radio transients, supernova remnants, pulsar wind nebulae, and instrumentation. Please see the word cloud below, which I generated automatically from my publications using NASA ADS.

In the sections below, I briefly describe my main research topics, where I added links to some of my publications as footnotes for further details.

Neutron Stars, Pulsars, and Magnetars

Sufficiently massive stars of at least 8 solar masses end their lives in supernova explosions, mainly by core collapse. The resulting compact objects are called neutron stars and were first discovered in 1967 as pulsars. These dead stars are extreme objects in many ways and act as laboratories for us to study physics under extreme conditions, much beyond what is possible on Earth.

Despite intensive research efforts since their discovery, many aspects of neutron stars and pulsars remain poorly understood to this day. Firstly, the mechanism by which they shine is only vaguely known, and even their spectra are not well measured. Broadband observations of large samples of pulsars¹ can therefore help elucidate the emission physics at play.

Aside from their emission properties, the rotation of pulsars tells us about their astrometric, binary and neutron-star intrinsic properties. Large-scale pulsar timing projects² are therefore the staple of neutron star astronomy. Some young to middle-aged (and even some millisecond) pulsars exhibit sudden spin-up events in their otherwise reasonably stable rotation history, which are called pulsar glitches. Measuring glitches and their recovery is one of the few ways to probe the properties of the neutron star interior. A related question is whether glitches affect any of the pulsar emission properties³.

Many pulsars are high-velocity objects and are often colloquially compared with rotating cannonballs flying through space as a result of supposed asymmetries in their birth supernovae. Measurements of pulsar proper motions and their inferred transverse velocities² are a vital ingredient to understanding supernova kinematics and refining theoretical blast models.

While most pulsars have periods between 0.5 to 1 seconds, the fastest known radio pulsar spins with a 1.4 millisecond period, and the slowest completes a rotation every 23.5 seconds. The slowest-spinning pulsars are interesting because they spin close to the limits where their emission is expected to cease, thereby probing emission theories⁴.

Neutron stars with magnetic fields even higher than those of regular pulsars are known as magnetars, whose emission is believed to be powered not by rotational energy but by energy stored in their magnetic fields. They show peculiar and somewhat erratic behaviour in their rotation, pulse profiles, and radio spectra⁵.

Radio Transients or Fast Radio Bursts

Fast radio bursts (FRBs) are enigmatic bursts of roughly millisecond duration that seem to come from cosmological distances and are detected at radio frequencies around 1 to multiple GHz. Discovered in 2007, they are one of the most intriguing puzzles in astronomy. Despite their substantial all-sky occurrence rate, only about a few hundred or so have been discovered so far.

Initially, most FRBs were discovered with the Parkes radio telescope⁷ or the refurbished Molonglo telescope⁶ in Australia. More recently, the field became dominated by large field-of-view instruments like the CHIME experiment in Canada, which had the highest FRB detection rate per unit time so far, or the ASKAP project in Australia, which managed to localise many of their FRB detections to host galaxies. Upcoming facilities such as the MeerKAT telescope array provide the perfect opportunities to study the faint end of the FRB flux density distribution due to their sheer sensitivity and allow burst localisations down to the arcsecond level and over large bandwidths⁸.

While the majority of the one-off FRBs appear as single-peaked pulses at millisecond time resolution, some bursts exhibited spectacular morphologies at microsecond time scales⁹, as well as spectral and polarimetric properties.

Supernova Remnants

The gaseous remains expelled at high velocities during a supernova explosion are known as supernova remnants (SNRs). As the blast wave sweeps up the ambient matter, the travelling shock wave can accelerate charged particles to high energies, which in turn radiate energy away in various frequency bands. Many SNRs are visible in the radio, X-ray, and gamma-ray wavebands.

SNRs are one of the prime candidate sources thought to be responsible for the observed flux of cosmic rays (at least up to a certain energy threshold), i.e. charged particles that are continuously impinging on the Earth’s atmosphere. For example, the Galactic SNR W51C¹⁰ appears to be a powerful particle accelerator, either mainly of leptons (electrons and positrons), hadrons (protons and heavier nuclei), or a mixture of the two. Several other SNRs have been observed in the very high-energy waveband, too, especially those that seem to interact with molecular cloud complexes.

Instrumentation

I have been part of the recommissioning team at the Molonglo Synthesis Radio Telescope near Canberra, Australia, and I am currently involved with commissioning the MeerTRAP real-time detection system for the MeerKAT telescope array in South Africa. My work included the design and implementation of reliable communication and control systems¹¹ and the design of efficient telescope scheduling algorithms² to increase the number of observed targets per day and the time on them while reducing stress on the telescope structure¹².