Astronomers release first image of supermassive black hole at centre of Milky Way

Astronomers have unveiled the first images of the closest black hole to Earth, located at the centre of the Milky Way galaxy, from which they hope to glean new information about the mysterious celestial bodies.

The supermassive black hole, named Sagittarius A*, is 25,000 light years from Earth. The image is the product of pooling data from the Event Horizon Telescope, a global network of eight radio observatories, over the course of several years.

Black holes are collapsed stars that produce such extreme gravity that not even light or electromagnetic radiation can escape their pull. As a result, it is impossible to see inside a black hole. Instead, the picture of Sagittarius A* captures a bright ring of light particles beyond the black hole’s outer edge, known as the event horizon.

The findings were released on Thursday during six simultaneous press conferences held in the German town of Garching, as well as in Washington, DC and other locations worldwide.

“Through literally years of exhaustive tests we are now confident to have captured the first image of the black hole in our galactic centre,” said José L Gómez, an astrophysicist at the Institute of Astrophysics of Andalucía who worked on the project.

The picture was produced by stitching together 6,000 terabytes of data from a network of eight Earth-based telescopes using a process called “very-long baseline interferometry”. There are now a total of 11 different telescopes used as part of the project.

In 2019, the same team of researchers produced the first ever picture of a black hole at the centre of the Messier 87 galaxy, which is 53mn light years away and 6bn times larger than the sun.

Heino Falcke, professor of astroparticle physics and radio astronomy at Radboud University in the Netherlands and one of the project’s leaders, told the Financial Times the image of Sagittarius A* was “scientifically and emotionally more important in many ways” than the team’s previous work.

“We can now look inside the throat of this beast at the centre of our own Milky Way for the first time,” he said. Sagittarius A* is one-thousandth of the size of the black hole pictured in 2019, but it is 1,000 times closer.

Due to the proximity of Sagittarius A* to Earth, Falcke said astronomers could “measure its surroundings, see how it’s fed by cosmic gas and dust and know its mass more precisely”. The information enables them to better understand how black holes work, more than a century after physicist Albert Einstein first predicted their existence as part of his theory of relativity.

“As our nearest supermassive black hole [Sagittarius A*] can be studied in ways that are not possible for other sources, making it a new unique laboratory for exploring the physics of black holes and testing the prediction of Einstein’s general relativity,” said Mariafelicia de Laurentis, professor of astrophysics at the University of Naples Federico II.

In 2020, the Nobel Prize in physics was awarded to astronomers Andrea Ghez and Reinhard Genzel for their work in studying Sagittarius A* over the past three decades. Their research team never pictured the black hole but tracked the movement of stars using the telescope at the European Southern Observatory, which offered evidence of its existence.

The Event Horizon Telescope project is estimated to cost around $40mn, receiving funding from the EU’s European Research Council, the US National Science Foundation and Asian science agencies.

“We’ll never get closer to a supermassive black hole than this one. We can measure the entire symphony of colours that the black hole generates and then we can use this to improve our understanding,” said Falcke.