First picture published – astronomical sensation

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Created: 05/13/2022 04:54 am

Of: Tanya Banner

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At the center of the Milky Way lurks the supermassive black hole Sagittarius A*. The Event Horizon Telescope presents the first photo of it – a sensation.

• The Event Horizon Telescope took the first photo of a black hole in 2019 – an astronomical sensation at the time.
• The researchers have now followed suit and the first image from black hole in the center of the Milky Way – Sagittarius A*.
• Sgr A* is about 26,000 light-years from Earth – eight telescopes had to work together to image the black hole.

+++ 4.30 p.m.: Now the cat is out of the bag, for the first time the black hole at the center of our Milky Way can be seen with your own eyes. A more detailed article on that Image of the black hole Sagittarius A* at the center of the Milky Way released by the Event Horizon Telescope can be found here.

+++ 3.40 p.m.: The black hole in the center of the Milky Way was much more difficult for the researchers to photograph than the more distant black hole M87*. EHT scientist Chi-kwan Chan explains why: “The gas near the black holes moves at the same speed – almost as fast as light – around both Sgr A* and M87*. But while the gas takes days to weeks to orbit the larger M87*, it completes an orbit around the much smaller Sgr A* in just a few minutes. That means the brightness and pattern of the gas around Sgr A* changed rapidly as the EHT Collaboration observed it — a bit like trying to get a clear picture of a puppy quickly chasing its tail.”

Black hole at the center of the Milky Way: Sagittarius A* photographed

+++ 3.30 p.m.: The newly released image resembles the black hole in the galaxy Messier 87 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.”

+++ 3.15 p.m.: Sagittarius A* is the black hole at the center of our Milky Way. The image of this black hole is very similar to the 2019 EHT image of the black hole at the center of galaxy M87. This also surprised the researchers, according to the press conference.

But what is actually shown in the picture? A black hole absorbs light, so it can’t actually be photographed. But the gas that orbits the black hole glows brightly and betrays the black hole: A central dark region can be seen in this gas – the shadow of the black hole.

Event Horizon Telescope reveals black hole at center of Milky Way

+++ 3:07 p.m.: Huib van Langefeld (EHT Project Director) now presents the results. More than 300 people were involved in the work, explains van Langefeld.

+++ 3.05 p.m.: It is indeed the black hole at the center of our Milky Way that the Event Horizon Telescope (EHT) – a coalition of telescopes around the world – captured. Sagittarius A* is located at the center of our Milky Way, about 26,000 light-years from Earth.

“We will see something very new, exciting and exciting at the center of our Milky Way,” said the press conference in Garching. The black hole at the center of the Milky Way was detected years ago – and now there is the first visual evidence that numerous telescopes around the world have now brought together.

+++ 2.55 p.m.: In April 2019 it was a sensation: the first image that visually proves a black hole. Has the Event Horizon Telescope (EHT) captured the black hole at the center of our galaxy, the Milky Way, this time? The result will be presented in a few minutes. This ticker keeps you up to date on what is being presented and attempts to categorize the scientific results.

Black hole photographed in the center of the Milky Way? Event Horizon Telescope presents results

+++ 2.25 p.m.: The press conference on the discovery of the Event Horizon Telescope in the Milky Way begins at 3 p.m. There are several synchronous press conferences worldwide that present the “groundbreaking” discovery at the same time.

Update from Thursday, May 12, 1:00 p.m.: Today, the Event Horizon Telescope (EHT) collaboration will present “groundbreaking results for the Milky Way” at a press conference. It is not yet known what exactly it is about. Experts assume that the first images of the black hole in the center of the Milky Way (Sagittarius A*) will be presented. The press conference starts at 3 p.m. – then you will see what it is really about.

Event Horizon Telescope (EHT): First photo of the black hole presented

First report from Wednesday, May 11th: Garching – When the Event Horizon Telescope (EHT) Collaboration held a press conference in April 2019, the researchers involved presented a groundbreaking scientific achievement: they had for the first time photographed the shadow of a black hole and thus visible evidence of a supermassive one black hole rendered. The picture went around the world and suddenly caused a great deal of interest in black holes. Now there is another one Invitation to a press conference of the EHT, at which “groundbreaking results for the Milky Way” will be presented. Just like in 2019, there will be multiple press conferences around the world at the same time. Much more is not known so far.

But in the scientific community there is a guess as to what the EHT should present this time: Is it the first recording or even a movie of Sagittarius A*, the supermassive black hole at the center of the Milky Way? It is possible – experts had already suspected in 2019 that an image of Sagittarius A* would be presented. However, the researchers then presented an image of the black hole at the center of the Messier 87 galaxy.

Event Horizon Telescope: Did it capture the black hole at the center of the Milky Way?

But how is it even possible for the Event Horizon Telescope to photograph a black hole? Supermassive black holes are found at the center of most galaxies and are characterized by one thing: they devour everything that gets too close. Matter, once it has crossed the event horizon, falls into the black hole from which nothing comes out – not even light. Something that itself swallows light is actually impossible to photograph. What’s more, black holes are far away – the black hole captured in 2019 is about 55 million light-years from Earth, the black hole at the center of the Milky Way is at a distance of about 26,000 light-years.

In order to still be able to photograph black holes, the EHT uses a special technique: Very Long Baseline Interferometry (VLBI). Several radio telescopes distributed all over the world are synchronized and used simultaneously to observe a selected object. When the first photo of a black hole was published, the researchers involved explained that they could read a newspaper in New York with the resulting resolution of their huge, earth-spanning telescope from Paris.

Event Horizon Telescope (EHT): How do you photograph a black hole that swallows light?

But that still doesn’t explain how the researchers can photograph an object that swallows light. You have to know that supermassive black holes are mostly surrounded by what is known as an accretion disk are. This consists of matter that has been attracted to the black hole but has not yet crossed the event horizon. This accretion disk surrounds the black hole, the gas inside it is hot and glows – which the researchers used for their purposes in 2019. Heino Falcke from the EHT explained it this way in 2019: “When a black hole plunges into a bright region like a disk of glowing gas, we expect it to produce a dark region resembling a shadow.”

And indeed: The Event Horizon Telescope was able to photograph the ring-like structure with a dark center – the shadow of the black hole. Eight telescopes were involved in the observation at the time – they were in Hawaii, Mexico, Arizona and the Sierra Nevada, in the Chilean Atacama Desert and even in Antarctica. The observations resulted in petabytes of raw data that were processed by supercomputers, including those at the Max Planck Institute for Radio Astronomy in Bonn.

Photographing a black hole was considered impossible a generation ago

“We have achieved something that was thought impossible a generation ago,” said EHT researcher Sheperd S. Doeleman in a 2019 press release. “Breakthroughs in technology, connections between the world’s best radio observatories, and innovative algorithms have opened up a whole new window for us on black holes and the event horizon.”

“We have achieved what was thought impossible just a generation ago.”

Will the Event Horizon Telescope provide a view of the black hole at the center of the Milky Way this time? It’s possible – but it’s also possible that the Event Horizon Telescope Collaboration has a completely different surprise in store for observers. (tab)