The international collaboration of EHT astronomers proved Thursday in image the existence of a supermassive black hole in the heart of our galaxy, Sagittarius A *, three years following the first photo of a black hole located in a distant galaxy.
The ‘silhouette’ of the black hole silhouetted once morest a glowing disc of matter is reminiscent of the black hole in the distant galaxy M87, which is much larger than our own. Scientists see it as proof that the same mechanisms of physics are at work at the heart of two systems of very different sizes.
‘I can show you the image of the black hole Sgr A* at the center of the galaxy,’ announced to applause Huib Jan Van Langevelde, director of the EHT project, at a press conference in Garching, Germany.
‘Invisible’ black hole
Technically, you can’t see a black hole, because the object is so dense and its gravitational force so powerful that not even light can escape from it. But we can observe the material that circulates around, before being swallowed.
‘We have direct proof that this object is a black hole,’ explained Sara Issaoun, of the Harvard Center for Astrophysics, describing ‘the cloud of gas (around the black hole) which emits radio waves and which we have observed’.
Black holes are said to be stellar when they have the mass of a few suns, or supermassive when they have a mass of millions or even billions of suns.
Sagittarius A* (Sgr A*), which owes its name to its detection in the direction of the constellation of Sagittarius, has a mass of approximately four million suns and is 27,000 light years from Earth. Its existence has been assumed since 1974, with the detection of an unusual radio source at the center of the galaxy.
The EHT, an international network of eight radio-astronomical observatories, had brought in 2019 the historic image of M87 *, a supermassive black hole of six billion solar masses in its galaxy, Messier 87, located at 55 million years. light. With its four million solar mass, Sgr A* is a featherweight in the bestiary of supermassive black holes.
/ATS