Radboud University

The first image of a black hole

First picture of a black hole

For the first time, astronomers have managed to take a photo of a supermassive black hole and its shadow. They used the Event Horizon Telescope (EHT), a worldwide network of eight radio telescopes, that together form a virtual telescope the size of the earth. The news was presented on 10 April 2019 in six press conferences around the world simultaneously. Astrophysicists of Radboud University played an important role in this project.

The photo shows the black hole at the centre of Messier 87, a massive galaxy in the nearby Virgo galaxy cluster. This black hole is 55 million light-years from earth and is 6.5 billion times the mass of the Sun. Interlinking the eight telescopes has resulted in unprecedented sensitivity and resolution. Time after time, independent observations with the EHT, using different imaging techniques, have revealed a circular-type structure, with a dark area in the middle, a shadow of the black hole in M87.

Global cooperation

“Scientists from all over the world have worked together”, says Prof. Anton Zensus of MPIfR in Bonn, chair of the EHT management. The director of the EHT Project, Sheperd S. Doeleman of the American Harvard/Smithsonian Center for Astrophysics, speaks of “a milestone in astronomy, achieved with a team of over 200 researchers from 18 countries”.

“All astrophysicists fantasise about what it would be like to see a real black hole”, Falcke says, “but many accept that it will not happen. They are so small and so far away. Twenty years ago, not every astrophysicist was convinced that black holes really existed. And now we can really see them. It has been a whirlwind!”

In november 2018 all EHT researchers were together on a congress in Nijmegen, At that occasion, this picture was made:

Sterrenkunde congres Groep-DvA-158825

Star roles for Radboud astronomers

In order to distill an image of the shadow of the black hole in M87 from the sea of ​​astronomical data, the signals from all telescopes had to be compared and combined. The Event Horizon Telescope team spent countless computer hours on this, with star roles for the astronomers of Radboud University.

Zwarte gat team Radboud Universiteit

At the start: Heino Falcke

Heino Falcke, Professor of Astroparticle Physics and Radio Astronomy at Radboud University, is the chair of the EHT Science Council and was there when the idea to photograph a black hole using a network of telescopes was first proposed.

In the nineties, Falcke was already fascinated by black holes during his PhD: “It was during my PhD that I understood that we do not fully comprehend gravity yet. In reality, its workings and how this ties in with the Standard Model of particle physics is a big mystery.” Black holes are the most extreme case of gravity imaginable. “Theories can only be truly tested with black holes.”


Exotic objects

Black holes are exotic cosmic objects which have enormous mass, but are small in size. A black hole exerts extreme influence on its environment. It curves spacetime and heats surrounding matter to super-high temperatures. “The size of the shadow is related to the mass of a black hole and we managed to actually measure the enormous mass of the black hole in M87”, says Sera Markoff, Professor of Astrophysics in Amsterdam, who is a member of the EHT Science Council and coordinator of the Multiwavelength Working Group.

“We know that black holes exert an enormous influence over their surroundings, at scales hundreds of millions times bigger than those of its event horizon. Using the EHT, we have been able to observe the origin of this process for the first time”, adds Markoff.


Would you like to know more about astronomy at Radboud University? Go to www.ru.nl/astrophysics There you will find more information about our training, research and activities.