Radio interferometry: Prof. Deller is an expert in and passionate about driving advances in signal processing used for radio telescope arrays. Modern radio interferometers produce many Tb/s of data, making real-time processing a necessity - yet advances in calibration techniques demand a flexible and adaptable signal processing solution. Graphical Processing Units (GPUs) are widely used to implement flexible yet highly performant radio astronomy signal processing operations in real time.

Neutron stars: These dead stars are incredibly massive and compact - heavier than the Sun yet only 20km in diameter. Because of this, their spin is highly stable and predictable. Some neutron stars - radio pulsars - emit beams of radio emission from their magnetic poles, which sweep across the sky due to their rotation. With radio telescopes, we can "time" the arrival of these pulses, and use them like clocks to study the effects of gravitational interactions and the presence of ionised gas in the galaxy. Prof. Deller uses very high angular resolution radio interferometers to pinpoint radio pulsars in three dimensions, as well as studying the fiery aftermath that results from the merger of two neutron stars.

Fast Radio Bursts: These millisecond-duration flashes of radio energy are sufficiently intense to be seen from distances exceeding one billion light years! Just like radio pulsars, they are powerful laboratories for extreme physics in their own right, but also like pulsars, they can be used as test signals that uncover the effects of ionised gas. Most of the matter in the Universe is found in a very tenuous state in the vast regions between galaxies, and this matter is very difficult (in fact, largely impossible) to observe directly. Fast Radio Bursts, however, reveal its presence due to the effect it has on the speed of the radio pulse, causing the low-frequency radio waves to arrive slightly later (milliseconds to seconds) than the high frequency radio waves. Making use of this, we can employ Fast Radio Bursts to map the previously unseen yet dominant contribution to matter in the Universe.

Space domain awareness: The radio signals used by spacecraft to communicate with the Earth (or even just generated unintentionally by on-board electronics) are an increasing challenge for astrophysical observations - just like reflections from satellites are a problem for optical astronomy observations. However, they also offer an opportunity, since radio interferometers can be used to make ultra-precise tracking observations of spacecraft from low Earth orbit (LEO) up to geostationary orbits, cis-lunar orbits, or even in deep space.