Three years after the release of the first ever image of a black hole, scientists from the event horizon telescope shared an image of Sagittarius A*, the supermassive specimen sitting at the center of our universe.
Heino Falcke, an astronomer at the University of the Netherlands, said it was a dream that came true after decades of work.
The black holes in the images are vastly different. The center of M87 is an enormous elliptical galaxy that is more massive than our own. The jet is powered by intense magnetic fields.
Sagittarius A* is less massive than M87's black hole, making it much harder to see. Roger Blandford said that Sagittarius A* has a very low mass supply.
The two images look similar, despite the differences. When you get to the edge of a black hole, gravity takes over.
The researchers had to face unique observational challenges in order to take an image of Sagittarius A*. Sagittarius A* is small, just 30 times larger than our sun, and 27,000 light-years away. Sagittarius A* is a relatively small black hole, which makes it more likely to have activity such as the motion of superheated plasma that surrounds it.
The results of the M87 were published two years after the observations.
The new images were taken in April of last year, during the same window in which the EHT took the now-famous image of M87's black hole. Over the course of 10 nights, eight telescopes gathered views of Sagittarius A*. The amount of information collected was enormous. The files were too large to be uploaded to the internet. More than 1,000 hard drives were transported back to the two processing facilities, one at the Haystack Observatory near Boston and the other at the Max Planck Institute for Radio Astronomy in Bonn, Germany.
The EHT uses a technique called very-long-baseline interferometry to produce its images, turning Earth into a giant virtual telescope by combining the views of multiple observatories from the South Pole to Spain. Spreading out the telescopes allows for sharper images, just as a larger mirror on an optical telescope affords better views, except in this case the observations were performed at a wavelength of 1.3 millimeters rather than the wavelength of visible light. Astronomers were able to peer through the hot gas surrounding the black hole, but they were also able to see the shadow from the event horizon.
The end result of decades of observations that began with our first glimpse of Sagittarius A* in 1918, is now known as Imaging Sagittarius A*. Einstein's general theory of relativity predicts that a black hole is most likely to be a massive yet compact object.
The idea of tracking the motions of stars was one of the reasons why the 2020 Nobel Prize in physics was awarded. Luciano Rezzolla said that one star in particular, named S2, has a beautiful trajectory and has a clear view of the black hole.
Scientists will compare this black hole to its larger sibling inside M87 after seeing it for the first time.
The results of both observations are beautiful and affirm the scientific process. Sagittarius A* is an object that has fascinated us for a long time and now, right before our eyes, it dazzles us with its dance. This is our home.
The story is being developed. Throughout the day, this article will be updated.
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