Researchers have suspected this for a long time, but they couldn’t get any direct confirmation. Now we know for a fact – there is a supermassive black hole at the center of the Milky Way. The proof being the image presented by the participants of the Event Horizon Telescope project. Maciej Wielgus, PhD Eng., from the Max Planck Institute for Radio Astronomy in Bonn, a graduate of the Faculty of Mechatronics at WUT, made his contribution to this unique discovery.

So far, the strongest evidence about the existence of a black hole at the center of our galaxy has been provided by observations of the motion of stars near the center (Sagittarius A*, abbreviated to Sgr A*), indicating the presence of a mass four million times greater than the mass of the Sun. The image presented on 12 May 2022 is a visual confirmation of many years of researchers' assumptions. You can see there the shadow of a black hole and a bright ring right next to the event horizon of a black hole. The size of the black hole's shadow is approximately 52 microseconds of arc across the sky.

Our man in the world of great discoveries

The image was produced by a global research team called the Event Horizon Telescope (EHT) Collaboration, using observations from a worldwide network of radio telescopes. A team of over 300 researchers from 80 institutes around the world took part in the work.

One of these research units is the Max Planck Institute for Radio Astronomy in Bonn, where Dr. Maciej Wielgus has been working since 2021. In the project, he dealt mainly with the calibration and processing of data and studies of temporal variability of the source. He is also the first author of one of the 10 publications on the analysis of Sgr A* light change curve. The articles are published in the "The Astrophysical Journal Letters".

EHT results allow us to study the environment of the black hole at the center of our galaxy in a way that has not yet been achieved. To the surprise of the researchers, Sgr A* seems to rotate in a plane perpendicular to the plane of the galaxy. Observations also suggest the presence of a strong magnetic field and a large temperature difference between electrons and protons. The observed ring diameter allowed the EHT team to perform a general relativity test , which the Einstein's theory passed correctly.

New image after three years

The picture shown is not the first image of a black hole in history. In 2019, the results of the observation of the shadow of a black hole from the Messier 87 galaxy (object M87*) were announced. Dr. Wielgus, then working at the Black Hole Initiative – an interdisciplinary center at Harvard University, was also involved in the observations.

Both black holes are supermassive. But M87* is about 1,600 times more massive than Sgr A*, 55 million light-years away, while Sgr A* is 27,000 light-years away from us. Despite these differences, they both have a similar angular size in the sky. Observations of "our" black hole were, however, much more difficult than in the M87 galaxy due to much faster variability around the black hole.

Maciej Wielgus, PhD Eng. is a graduate of master's studies in automation and robotics at the Faculty of Mechatronics of the Warsaw University of Technology. In 2016, at the Institute of Micromechanics and Photonics, Faculty of Mechatronics, WUT - he defended his doctoral thesis. The dissertation entitled "Adaptive decomposition algorithms and the concept of the analytical signal in the analysis of striated images," which was prepared under the supervision of Prof. Krzysztof Patorski, PhD Eng. In 2017, he received the award of the Prime Minister for that.

The text was created on the basis of information from Maciej Wielgus, PhD Eng., and the article naukawpolsce.pl