"The result provides overwhelming evidence that the object at the heart of our galaxy is indeed a black hole and yields valuable clues about the workings of such giants, which are thought to reside at the center of most galaxies," the Center for Astrophysics explained on its website. "The image was produced by a global research team called the Event Horizon Telescope (EHT) — which includes scientists from the Center for Astrophysics | Harvard & Smithsonian (CfA) — using observations from a worldwide network of radio telescopes."
"The image, described today in a special issue of The Astrophysical Journal Letters, is a long-anticipated look at the massive object that sits at the very center of the Milky Way," the institution added. "Scientists had previously seen stars orbiting around something invisible, compact and very massive in our galaxy’s core. This strongly suggested that the object — known as Sagittarius A*, or Sgr A* — was a black hole; today’s image provides the first direct visual evidence of it."
Black holes are hyperdense objects with gravity wells too strong for light to escape. Smaller ones are formed by the core collapse of massive stars; the much larger ones at the center of most galaxies are more mysterious in origin.
This is not the first time a black hole has been imaged. In 2019, a groundbreaking image was revealed of the black hole at the heart of M87, a distant elliptical galaxy. That black hole is 1,500 times larger than the one at the center of the Milky Way, which is itself estimated to be four million times the mass of our Sun.
Despite this, the images look remarkably similar.
"The researchers had to develop sophisticated new tools that accounted for the gas movement around Sgr A*," noted the report. "While M87* was an easier, steadier target, with nearly all images looking the same, that was not the case for Sgr A*. Because of this, today's image of the Sgr A* black hole is an average of the different images the team extracted, finally revealing the giant lurking at the center of the Milky Way galaxy."