Scientists capture the first image of a supermassive black hole at the heart of the Milky Way

The world has received the second picture ever taken of a supermassive black hole, and this time, it’s a black hole that’s relatively close to home. Today, scientists collaborating on the massive Event Horizon Telescope (EHT) project released an image of Sagittarius A*, the gigantic black hole spinning at the center of our own Milky Way galaxy.

This heavenly gift comes from the same project that caused quite a stir in 2019 when they released the first image ever taken of a black hole. That now iconic fuzzy orange photo showed a supermassive black hole at the heart of a gigantic galaxy called Messier 87, or M87, which is 55 million light-years from Earth. The groundbreaking result helped scientists verify the circular shape of these objects, as well as further confirm Albert Einstein’s theory of general relativity, which predicted the existence of black holes.

Now the team is back with another photo of a black hole, this one right in our own backyard. Located approximately 26,000 light-years from Earth, Sagittarius A*, or Sgr A*, is believed to be about 4 million times the mass of our Sun. Scientists have inferred its existence in the center of our galaxy for decades based on how objects move around the black hole. But this is the first time we have a direct image of its shadow, further proof of the life of our cosmic neighborhood nexus.

With each new supermassive black hole image we get, scientists learn a little more about these enigmatic objects. “These supermassive black holes, we really don’t know how they formed or got so big,” says Meredith Clark Powell, a black hole researcher at Stanford University. the edge. “So it’s a very active area of ​​research.”

Truth be told, you can’t capture an image of a black hole directly. Black holes, by their very nature, cannot be “seen”, as these objects are so massive that nothing can escape their gravitational pull, including light. Instead, we can capture the silhouette of a black hole. If a supermassive black hole is surrounded by a spinning disk of gas and dust, that material will glow brightly as the gas and dust are accelerated and heated by the powerful gravitational pull of the nearby hole. What the EHT is really capturing is the shadow of the black hole against the backdrop of that glowing gas and dust.

However, taking pictures of these black hole shadows is not an easy task. To capture an image like this of Sagittarius A*, a single telescope would have to be the size of planet Earth to do the job, according to the Event Horizon Telescope group. Since building such a device isn’t exactly realistic, scientists came up with a solution. The EHT is a wide range of radio dishes spread over five different continents. All the radio telescopes work together to observe the same object, behaving like a giant telescope the size of a planet. Then it’s up to EHT scientists to piece together the data the telescopes collected to create a single image.

EHT used the same technique to capture M87; eight EHT radio antennas spent a week observing that black hole in April 2017, resulting in months and months of work compiling the data in the image that was eventually released. At the same time, EHT also observed Sagittarius A*, but creating its image proved to be much more challenging and time-consuming.

Although it is closer to Earth than the black hole in M87, Sgr A* is smaller and less active, and the material surrounding the object is much fainter, making it difficult to observe. In addition to that, the material does surround Sgr A* exhibits a strange flare when particles surrounding the black hole are accelerated to much higher energies. While it’s an interesting light show, it changes the black hole’s composition every few hours, making it difficult to observe over time.

On top of all that, Sgr A* is in our own galaxy, which makes it more difficult to see from Earth. Observing this black hole means looking through the galactic plane of the Milky Way and all the gaseous material between us and the black hole. That provides a lot of interference that scientists had to work around.

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