Zooming in on feedback in active galaxies: the first high-resolution radio survey

A super-massive black hole exists at the centre of almost every massive galaxy, but what role do they play in galaxy evolution? In about 10 percent of all galaxies, we observe energetic phenomena like outflows and jets of plasma that are powered by these black holes. When a galaxy shows these characteristics we call it an active galaxy, and refer to the black hole and its energetic ouput as an active galactic nucleus (AGN). We know from both observations and cosmological simulations that feedback between an AGN and its host galaxy can have a significant impact on that galaxy's evolution. What we do not know are the details of how this AGN feedback works.

Current AGN feedback studies rely on indirect evidence and focus on individual objects or small samples. It can be extremely difficult to tell the difference between star formation, which is how galaxies normally grow, and AGN activity. High resolution imaging can help, and at radio wavelengths this alone is enough to clearly distinguish between AGN activity and star formation. Traditionally radio telescopes with high enough resolution to do this have tiny fields of view which limits studies to small numbers of galaxies.

The advent of next-generation of low-frequency radio telescopes offers a new and exciting way to overcome this challenge. This relies on combining both wide-field and high-resolution capabilities of the LOw Frequency ARray (LOFAR), using techniques I have developed. LOFAR is a Square Kilometre Array (SKA) pathfinder with antennas spread all across Europe. Default operations use only the antennas centred in the Netherlands, but I have developed a high-resolution imaging data pipeline to combine signals from all the antennas in the array, providing a larger effective 'lens' and 20 times improved resolution.

My high-resolution work is opening a new regime for radio surveys, and I hold the record for the highest resolution image ever made below 100 MHz (just below the FM radio band). My ambitious and exciting UKRI FLF project is to conduct the first high-resolution survey across the entire Northern sky, which will allow me to study the physical processes by which AGN produce radio emission, what properties govern these processes across large samples of galaxies, and how these processes impact the typical growth of galaxies through star formation. This survey will build from smaller datasets on interesting areas of sky with exquisite coverage across radio, infrared, optical, and X-ray wavelengths, and eventually cover the entire Northern sky.

I will drive forward major advances in AGN feedback studies with my UKRI-FLF project, and push the field to new and exciting territory in answering fundamental astrophysical questions. Dealing with such large data volumes will feed into the general trend for developing tools and techniques to deal with Big Data. I will exploit opportunities for interdisciplinary science, including working with computer scientists to develop new algorithms for identifying and classifying the radio emission from AGN in large surveys. In the next few years, my work will lay the foundation for future scientific surveys with the SKA, in which the UK has already invested £119 million. I will build international collaborations with SKA pathfinder teams in South Africa, the Netherlands, and place Durham and the UK at the forefront of this exciting new revolution in science.

The key impact goals of this research are:
(1) To increase our fundamental knowledge of how the Universe was shaped by super-massive black holes
(2) To employ new data processing methods which push the boundaries of national/international facilities
(3) To retain skills and knowledge in the UK which will contribute to the nation's scientific and economic competitiveness
(4) To provide high-profile innovative research and broaden the public perception of who can be a scientist

The stakeholders who will most directly benefit from (1) and (2) are the academic and public sectors. This includes the general public, through outreach activities, media attention, and citizen science projects during this fellowship project. The results will be presented in a format suitable for the public on the project website long after the fellowship ends. The academic sector will benefit directly from the scientific advancements of this study, both during the fellowship and building on its successes in the future.

Both direct and indirect impact for a wide range of sectors will come from (2) and (3) in terms of preparing for the Square Kilometre Array (SKA), which is a global organisation with headquarters at Jodrell Bank in the UK. The methodology and technical skills I have developed in my research will help shape how the SKA data processing infrastructure is built and used, which will have direct and indirect impacts across the commercial / private sector, and for the policy makers at an international level. By performing SKA-type science before the SKA, I have a unique opportunity to impact the decision making process by understanding exactly what challenges we will face with the SKA and how to best overcome them. In addition to guiding concrete logistical decisions, this will help foster an excellent global collaboration within the SKA, and specifically promote the UK contribution.

Finally, by establishing myself as a scientific leader in the UK, I will indirectly impact the UK public with (3) and (4). In particular, I will help shape the scientific landscape in the UK with my cutting edge research. My non-standard background includes a previous career in the military, and my unique science-related sewing is featured online and has been displayed in a scientific art exhibition. When coupled with my successful, innovative science, I aim to challenge the public perception of what it takes to be a scientist and help break down barriers for underrepresented minorities, particularly women, in Science, Technology, Engineering, and Mathematics (STEM) career fields.