The black hole in the center of the Milky Way is made visible for the first time by a large research team – a sensational achievement.
Garching – In the center of the Milky Way there is a black hole. Researchers have known this for several years German researcher Reinhard Genzel received the 2020 Nobel Prize in Physics for this discovery. So far, however, the black hole called Sagittarius A* (Sgr A*) has only been observed indirectly: researchers have been able to observe its effects on the environment and derive its mass from it, for example. Now astronomers have made the black hole in the center of our galaxy visible for the first time – a difficult undertaking, because a black hole swallows light and can therefore not actually be seen or photographed.
The Event Horizon Telescope (EHT) was used to visually detect the object for the first time In 2019, the first image ever of a black hole was taken had. The EHT is an association of several radio telescopes around the world that simultaneously target an object and collect data. But even radio telescopes cannot make the black hole itself visible, so the researchers resorted to a trick they had already used in 2019: They concentrated on the glowing gas that orbits the black hole and were able to discover a telltale signature there: a dark central one Region called shadow surrounded by bright, ring-shaped structure. The black hole that affected the matter that surrounds it.
Event Horizon Telescope (EHT) reveals black hole at center of Milky Way
“We were amazed at how well the size of the ring matched the predictions of Einstein’s general theory of relativity,” says EHT project scientist Geoffrey Bower. “These unprecedented observations have greatly enhanced our understanding of what is happening at the center of our galaxy and offer new insights into how these giant black holes are connected to their surroundings.”
supermassive black hole |
center of the Milky Way |
4.3 million solar masses |
about 27,000 light years |
The black hole Sagittarius A* is about 27,000 light-years from Earth and appears in the sky about the size of a donut on the moon. But the EHT — eight radio telescopes linked together to form an Earth-sized virtual telescope — was able to image the black hole. Over several nights in 2017, the telescopes collected hours of data, which were then evaluated by supercomputers.
Black hole in the center of the Milky Way: Sagittarius A* photographed for the first time
The newly released image resembles the black hole in the galaxy Messier 87 (M87*) captured by the EHT back in 2019 – although Sagittarius A* is significantly smaller and less massive. “We have two completely different types of galaxies and two very different masses of black holes, but near the rims of these black holes they look strikingly similar,” says Sera Markoff, co-chair of the EHT Science Council. “This tells us that general relativity dominates at close range for these objects, and any differences we see further away must be due to variations in the material surrounding the black holes.”
More than 300 researchers from 80 institutions around the world were involved in the new image of the black hole – the EHT Collaboration. For five years, this team worked on the image of the center of the Milky Way. And the work continues: In March 2022, the Event Horizon Telescope conducted another observing campaign – with more telescopes than ever before. According to a statement, more images and films of black holes will be presented in the future. (Tanya Banner)
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