Down-to-earth UP astrophysicist sheds light on black hole

Posted on April 12, 2019

A team of over 200 scientists from five continents used a virtual earth-sized telescope to make humanity’s first image of a black hole.UP astrophysicist, Prof Roger Deane played a role in the Event Horizon Telescope (EHT) project. He spoke to Primarashni Gower.

PG: What are the implications of the first images of the black hole for humankind?

RD: Humanity just made its first image of a black hole. What was previously believed in the minds of astronomers, is now in hand for the whole world to see.  The image revealed is a ring of light that is bent around the black hole due to its extreme gravity. This provides the first visual proof that black holes exist. Going forward, if we improve the image with an improved global telescope, we can test Einstein’s General Theory of Relativity by comparing the measured shadow size and shape with theoretical predictions

PG: What was your role?

RG: UP’s role was to create a highly realistic simulation of this Earth-sized instrument, understand its limits, and the extent to which we can make inferences about the shadow of a black hole. We are also working on the expansion of the array into Africa.

PG: How do you feel about the results?

RD: I'm still blown away by the image. It hasn't really worn off yet. I’m just proud and honoured to play my small part in this amazing international team.

PG: What is your sub-group on the Event Horizon Telescope working on now?

RD: We are applying our simulations to other instruments, current and future, like the African African Very Long Baseline Interferometry (VLBI) Network – which will provide the sharp images required to complement the MeerKAT surveys. As part of these efforts and a service to the community, we released a public version of our software on the same day as the EHT results release, a collaboration with Radboud University.

UP's Prof Roger Deane with a simulated image of a black hole. Background image: T. Bronzwaer, J. Davelaar, M. Moscibrodzka, H. Falcke/BlackHoleCam

PG: What role does South Africa have to play?

RD: In the drive towards MeerKAT and the Square Kilometre Array, South Africa, through the Department of Science and Technology/National Research Foundation and the SA Radio Astronomy Observatory, has invested in developing skills in young scientists. I myself, and my students and postdocs, have been beneficiaries of that. Converting those skills into internationally sought-after expertise is the crucial next step and requires sustained funding of these young people.

Our involvement in the EHT Consortium is one example of how that conversion of skills to expertise can put South African scientists on the global stage and part of major scientific breakthroughs such as this.  We hope to see many such examples in the MeerKAT and SKA spheres.

PG: What are you doing at UP?

RD: UP is growing a brand new astronomy group focused on MeerKAT, the Square Kilometre Array, and the technique of creating virtual Earth-sized telescopes like the Event Horizon Telescope and African VLBI Network. This was a very deliberate and strategic plan formulated in discussions with Vice-Principal and Mathematician Prof Anton Ströh. The astronomy group has a strong, data-driven interest in understanding the nature of black holes, how they influence their host galaxies, and how often they come in pairs. Our science-driven approach is coupled with the realisation that this new era of complex, big data telescopes requires technical expertise and new algorithmic approaches. Astronomy is a key contributor and beneficiary to the Fourth Industrial Revolution - UP needs to ensure is at the forefront of that.

PG: What sparked your interest in astronomy and physics?

RD: Growing up in Welkom, the Free State we were spoilt with excellent skies and of course the Milky Way – we South Africans take that for granted. Many of my Northern Hemisphere colleagues are quite jealous. My father Brian was insistent about a subscription to National Geographic and my brother Tim, who is eight years older than me, would always pick out the interesting astronomy articles. So, I had some exposure beyond just the sky, which I think is key and is not always easily accessible in countries with less emphasis on science.”

PG: Do you believe in life on other planets and why? 

RD: Yes, it seems very likely to me. I think humans are simultaneously special and not special. I also think we sometimes forget those two points a little too frequently in our day-to-day life.  

PG: Does your wife also have a physics background? 

RD: She is a clinical psychologist, so thankfully the conversation broadens at dinner time. We often joke that we explore the inner and outer universes, which can lead to divergent philosophical opinions.

PG: What would happen if a person fell into a black hole?

RD: There are two classes of black holes - “stellar mass” black holes are ones that are a little more massive than the Sun and form when a star much larger than the Sun runs out of its hydrogen fuel and explodes. The second class are about 1 million to 1 billion times more massive and creatively named supermassive black holes. They are found at the centre of galaxies and are the types we target with the EHT.

If you fell into a stellar mass black hole, you get “spaghettified”. If you fell into a supermassive, the effects may not be as “noticeable” – it depends on a few things.

PG: Where is the nearest black hole? 

RD: The nearest stellar mass black hole could be just a few light years away (but dormant so not detectable). We are pretty confident that the nearest supermassive black hole is at the centre of our Milky Way galaxy, about 30,000 light years away. In contrast, the black hole shadow reported in the EHT results are from a black hole that lies at the centre of another galaxy over 50 million light years away (which is still very close in astronomy terms!)


- Author Primarashni Gower

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