Astronomers at the University of the Western Cape (UWC) are members of an international team responsible for the remarkable discovery of two giant radio galaxies. These galaxies were spotted in new radio maps of the sky created by the MeerKAT International Gigahertz Tiered Extragalactic Exploration (MIGHTEE) survey. It is one of the largest survey projects underway with South Africa's impressive MeerKAT radio telescope and serves as a precursor to the Square Kilometre Array (SKA) due to become fully operational in the mid-2020s.
Harriet Box caught up with Dr Matthew Prescott, a Research Fellow at the University of the Western Cape and co-author of the work.
What makes this discovery so remarkable?
If you look up into the night sky on a clear night... that faint band of stars you see is our galaxy, the Milky Way. It is vast. Now imagine these two radio galaxies 60 times the size of our Milky Way. These radio galaxies are scarce (there are only 850 known out of hundreds of billions) and are among the largest single objects in the Universe. From end to end, they are around 6 million light years across, which means even if you could travel at the speed of light (somehow?) it would still take you 6-million years to get from one side to the other. This is why they’re dubbed 'giant radio galaxies' or referred to as cosmic beasts.
What exactly are you working on?
We’re working on a project called the MIGHTEE survey. It stands for The MeerKAT International GHz Tiered Extragalactic Exploration Survey, and is a project to observe and measure the radio properties of ~100,000 galaxies, using the newly built MeerKAT telescope. This is so we can learn how galaxies have evolved throughout the universe, from around 2-billion years after the Big Bang to the present day.
What leaves you in awe about the work you’re involved in?
MIGHTEE is an exciting project to be involved in, it’s pretty amazing - we live in a time when we have instruments and the computational power to be able to measure the properties of thousands of galaxies. We’re able to determine how massive galaxies are, how many stars are forming in them and what the supermassive black holes at their centres are doing, all from collecting the light they emit using telescopes. Here in South Africa we are fortunate to get to play with the MeerKAT telescope - the end product of engineers’ laborious efforts. It’s an excellent instrument and without a doubt there will be many new discoveries made with it.
Which part of your work do you enjoy the most?
As an astronomer I am fortunate to work on interesting problems (in my case on galaxies), and meet lots of different people. You're always learning something new. Most days are spent in front of a computer screen crunching numbers or writing up results (it’s nice to get results!). As a bonus (in normal times), you usually get to travel to lots of places to either go observing or attend conferences. It’s also a great honour to work alongside other local and international universities.
Why did you join UWC?
It was all a bit of an accident. I applied for a postdoc job after completing my PhD back in Liverpool and got it. I was meant to come to SA for a couple years but I've thoroughly enjoyed it and hung around.
At which stage of your life did you get the opportunity to work with this world-class technology such as MeerKAT?
So it's only in the last two years that MeerKAT has come to fruition as an instrument and surveys such as MIGHTEE have begun. Before that, we've been working on smaller sky surveys, all building up to the work that MIGHTEE is now doing.
Was it ever a dream of yours to become involved in such a huge international project?
It's a bit of a step up from looking at the planets in my backyard with a small 3'' telescope. I don't think I ever expected to be working on a large international project back then.
Are you excited that Meerkat is based on the African continent?
MeerKAT is a fantastic opportunity for South Africa and Africa on the whole. It's shown to the world that large engineering projects can be successfully done here and it'll continue to show the way when more dishes are added to the array to form the Square Kilometre Array, over the next few years.
What’s the toughest challenge you’ve ever faced to date?
MIGHTEE was the toughest by far. It is made up of around 30 people (with around a third of them affiliated to UWC). On this team there are dedicated radio astronomers who take the raw data from the MeerKAT telescope and reduce it to make the pretty images (I think these people are genuinely wizards). There's also dedicated optical astronomers who have measured the galaxies' distances using conventional telescopes (in this case one in Hawaii called Subaru). Radio data however on it's own is pretty much useless (that's not controversial!) and it's been my job to combine the radio and optical datasets. By eyeballing and sifting through thousands of combined images we're able to spot interesting objects like the Giant Radio Galaxies we have found here.
Working with what's probably the best radio telescope built so far is pretty exciting.
What is it about this field that excites you? What new developments in your field do you find the most interesting?
South Africa is currently THE place to be for radio astronomers. MeerKAT is currently the best and most sensitive radio telescope built so far and the data that it is producing is of very good quality.
Along with the SKA, MeerKAT will allow us to probe very faint objects, at higher resolution and sensitivity than ever before. Complementing these there's lots of new optical telescopes that are currently being built. From this we'll get a much more detailed picture of how galaxies have formed and evolved over the course of cosmic time.
There's lots of other developments happening currently in the field of astronomy too. Gravitational waves were finally discovered in the last few years after being predicted by Einstein in 1916. Radio telescopes around the world are also being combined to image the black holes at the centres of galaxies.
What’s one interesting thing you learned about your job?
In Astronomy you spend lots of time reading papers from journals, so you're pretty much constantly learning new things.
Can you tell me a bit about your background?
My mum, Brenda, was a secretary and my dad was a plasterer. My brother was an engineer and way more hands on or practical than I ever could be.
I'm from a small town in North West England called Westhoughton, not too far from Manchester. Nothing particular has ever happened there. People from there are called 'Kaew Yeds' (cow heads). According to legend, a cow in the town got its head stuck in a gate, and it's farmer owner armed with a saw, valued his gate more than the cow.
Who would you like to acknowledge for their support over the years?
Support-wise I'd have to acknowledge my mum, my dad Tom and brother Chris for all of their support over the years. Thank you!
Why did you decide to enter your particular field?
I've always enjoyed maths, physics and geology as a kid. One Christmas my auntie and uncle bought me a telescope and my interest in astronomy started there, looking at the planets and stars on cold nights in the backyard.
Do astronomers ever relax? Where would you be found on a random weekend?
I used to play squash a lot but my knees can't handle it anymore. I can still manage to get up hills though so on a random weekend I'll probably be found up Table Mountain or somewhere down the peninsula. During lockdown that's not been happening but online 'pub quizzes' have taken off, so I have either been competing in those or running those for the department.
Any advice for young academics just starting their studies?
Astronomy can be hard head work and most of it nowadays consists of sitting in front of a computer screen. I think getting an early grasp of how to make computer programmes is essential these days. This skill will be used more and more in the future, not just in astronomy.