Understanding the evolution of the universe

Dr Bradley Frank is a Radio Astronomer and Associate Director of the South African Radio Astronomical Observatory. He is also a Lecturer in the Department of Astronomy at the University of Cape Town. Brad's research aims to answer fundamental questions about how our universe, the galaxies within our universe and the stars and planets within these galaxies were formed.

Brad is Co-Chair of a working group in the MeerKAT International GHz Tiered Extragalactic Exploration (MIGHTEE survey). The MIGHTEE survey is an international collaboration of researchers using the MeerKAT telescope to create deep images of the extragalactic sky to explore the cosmic evolution of galaxies.

Built and operated by the South African Radio Astronomical Observatory (SARAO), MeerKAT is one of the most powerful radio telescopes in the world. It can collect high-quality data from galaxies that are 200 mega parsecs (more than 600,000,000 light-years) away from the Earth. Prof Matt Jarvis leads the MIGHTEE survey from the University of Oxford's Department of Physics. Brad is the Co-Chair of the working group that studies the detection of neutral hydrogen gas in galaxies in the universe.

Hydrogen is considered to be the building block of galaxies. Brad is studying how observations of neutral hydrogen can help us understand the evolution and environments of galaxies as a function of cosmic time.

Brad visited Oxford in 2019 via the AfOx Visiting Fellows Program to collaborate with Matt Jarvis from the Department of Physics to analyse some of this data.

"Brad being here has helped accelerate our research. He has the technical ability to transform the data that the MeerKAT telescope produces. All of us in the Physics department- students and other researchers have benefitted from Brad's visit. Thanks to his visit, colleagues here in Oxford will be able to co-produce papers with our counterparts in South Africa, and it will happen in a much quicker timeline."

Prof Matt Jarvis

Picture Credit: South African Radio Astronomy Observatory (SARAO)

Brad's role in the MIGHTEE survey is to process and analyse the raw data when it comes off the telescope. The MeerKAT telescope will produce one terabyte (1000GB) of data every hour. Brad and his team have to process and analyse tens of terabytes of data to start to create radio images of galaxies. Astronomy students around the world study this data. A Master's student supervised by Brad has recently submitted a Master's thesis based on this data and is starting a PhD at the Anton Pannekoek Institute for Astronomy in Amsterdam.

The MeerKAT telescope is located in the Karoo region of South Africa, away from man-made electronics or machines that emit radio emissions that can interfere with the faint radio signals coming from objects in the distant universe. Before the raw data can be analysed, it needs to be transported from the Karoo and stored in an archive facility in Cape Town, which is about 1500km away. Transporting and analysing the data involves using innovative fibre-optic links, cloud computing and high-performance computing frameworks, and a network of national and international researchers and institutions primarily focused on collaborations with SARAO and MeerKAT researchers.

Once the data is transported and securely stored, the data processing takes a significant amount of time. A few hours' worths of MeerKAT observations can take days to calibrate, image and analyse. Analysing the science images provides an excellent opportunity to do quality assurance for the telescope and continuously use the high-performance/high-throughput systems needed to handle MeerKAT data.

"The computational challenges are enormous. However, it is hugely satisfying to transform the raw data from the telescope into high-quality images that showcase the capability of the telescope and the complexity of galaxies and their environments. We are studying some systems in detail that has never been done before."

Dr Bradley Frank

Picture Credit: South African Radio Astronomy Observatory (SARAO)

Brad used his time in Oxford to analyse the MeerKAT data for the MIGHTEE survey. The team has prototyped a workflow that transforms raw data into science images; and has provided this to the core group of researchers for source finding and validation. Brad has collaborated with other researchers from Oxford's Physics department, who have worked on simulations and the statistical analysis of the science images to test and verify the robustness of the data.

"I must emphasise that our work's scale and challenges are unprecedented. We are dealing with data rates and complexity that is extremely challenging. However, this visit has allowed us to understand the data in a very deep and robust way. Our processes will benefit other surveys, the observatory and the community, so our research will have a much greater impact than just the MIGHTEE collaboration."

Dr Bradley Frank