But where gas takes days to weeks to orbit the larger M87*, in the much smaller Sgr A* it completes an orbit in mere minutes. EHT scientist Chi-kwan (‘CK’) Chan, from Steward Observatory and Department of Astronomy and the Data Science Institute of the University of Arizona, USA, explains: “The gas in the vicinity of the black holes moves at the same speed - nearly as fast as light - around both Sgr A* and M87*. This achievement was considerably more difficult than for M87*, even though Sgr A* is much closer to us. 'We have two completely different types of galaxies and two very different black hole masses, but close to the edge of these black holes they look amazingly similar,” says Sera Markoff, Co-Chair of the EHT Science Council and a professor of theoretical astrophysics at the University of Amsterdam, the Netherlands. 'This tells us that General Relativity governs these objects up close, and any differences we see further away must be due to differences in the material that surrounds the black holes.” The two black holes look remarkably similar, even though our galaxy’s black hole is more than a thousand times smaller and less massive than M87*. The EHT achievement follows the collaboration’s 2019 release of the first image of a black hole, called M87*, at the centre of the more distant Messier 87 galaxy. Similar to the image, despite very different black holes Onsala Space Observatory and Chalmers have been involved in the ALMA project since its inception, and Chalmers has delivered receivers for both telescopes.

At Chalmers and Onsala Space Observatory, we are proud to have delivered instruments and expertise to the APEX and ALMA telescopes, without which this image would not have been possible', says John Conway.ĪPEX is a collaborative project between Onsala Space Observatory, ESO (European Southern Observatory) and the Max Planck Institute for Radio Astronomy. 'We can study this wonderful image thanks to long-term investments in science infrastructure in Sweden and around the world. In addition to other facilities, the EHT network of radio observatories includes the Atacama Large Millimeter/submillimeter Array (ALMA) and the Atacama Pathfinder EXperiment (APEX) in the Atacama Desert in Chile, two telescopes that Chalmers and Onsala Space Observatory have been a part of for a long time.

The EHT observed Sgr A* on multiple nights in 2017, collecting data for many hours in a row, similar to using a long exposure time on a camera. To image it, the team created the powerful EHT, which linked together eight existing radio observatories across the planet to form a single “Earth-sized” virtual telescope. 'These unprecedented observations have greatly improved our understanding of what happens at the very centre of our galaxy, and offer new insights on how these giant black holes interact with their surroundings.' The EHT team's results are being published today in a special issue of The Astrophysical Journal Letters.īecause the black hole is about 27 000 light-years away from Earth, it appears to us to have about the same size in the sky as a doughnut on the Moon. “We were stunned by how well the size of the ring agreed with predictions from Einstein’s Theory of General Relativity,' said EHT Project Scientist Geoffrey Bower from the Institute of Astronomy and Astrophysics, Academia Sinica, Taipei. The new view captures light bent by the powerful gravity of the black hole, which is four million times more massive than our Sun. Four million times more massive than the sunĪlthough we cannot see the black hole itself, because it is completely dark, glowing gas around it reveals a telltale signature: a dark central region (called a shadow) surrounded by a bright ring-like structure. This strongly suggested that this object - known as Sagittarius A* (Sgr A*, pronounced 'sadge-ay-star') - is a black hole, and today’s image provides the first direct visual evidence of it. Scientists had previously seen stars orbiting around something invisible, compact, and very massive at the centre of the Milky Way.

The image is a long-anticipated look at the massive object that sits at the very centre of our galaxy. It’s an exciting time to be working in science, says Michael Lindqvist. This image is putting theories about the nature of space and time to the test. We also know more about it than any other black hole. That’s much closer to us than its counterpart in M 87, which we were able to see in the first image from the Event Horizon Telescope in 2019. 'Now for the first time we can see the black hole at the centre of the Milky Way. The science team includes three astronomers from Chalmers’ Department of Space, Earth and Environment: John Conway and Michael Lindqvist, both at Onsala Space Observatory, and Chiara Ceccobello, working in Astronomy and Plasma Physics at the time of the research.

First black hole image