The supermassive black hole that scientists suspect is at the center of our Milky Way galaxy has been imaged by a global team of scientists.
The image of the object, called Sagittarius A, was captured by the Event Horizon Telescope (EHT), a global network of astronomers and telescopes that includes Trinity College Dublin.
The black hole itself is completely dark as anything that gets too close, including light, is engulfed by tremendous gravitational forces. But the glowing gas and bright ring structure and shadow around the hole reveal its telltale signature, scientists say.
Albert Einstein predicted that black holes have tremendous gravitational pull and will consume anything – gas, dust, light – that passes too close to an “event horizon” from which there is no return.
Scientists now plan to compare images of the two black holes and test ideas about how they contributed to the formation of galaxies.
“As a theorist, I can only admit that Einstein was right again,” says Dr. Luciano Rezolla, Andrews Professor of Astronomy at TCD, in relation to Einstein’s General Theory of Relativity (published in 1916). “The mass and distance of the object were known very precisely before our observations,” says Rezolla.
“We therefore used these strict limitations on the size of the shadow to exclude other compact objects such as boson stars or wormholes.”
“What we’re seeing definitely looks like a black hole,” says Rezolla.
In 2019, scientists captured an image of a black hole at the center of the M87 galaxy, 55 million light-years from Earth, which scientists estimate has 6.5 billion times the mass of our Sun.
The black hole at the center of our galaxy is closer, 27,000 light-years away and lighter – four million times the mass of the Sun.
The discovery solves the mystery of what created radio waves emanating from the center of the Milky Way.
At the press conference, held simultaneously in locations around the world, scientists zoomed in on the image of the black hole on a 45-second visual journey from Earth to the center of the Milky Way.
For the image of Sagittarius A, astronomers connected eight radio observatories around the world into a single virtual telescope.
The radio waves emitted by the black hole are generated by telltale hot gases surrounding the structure, scientists say.
The experience of imaging the M87 black hole helped astronomers this time, but it still proved a major technical challenge.
“Despite all the experience with M87, Sgr A was not child’s play,” says Rezzolla. “The rapid variability of the emission and a very lively environment in the center of the galaxy have forced us to develop new techniques for the analysis of the data and the numerical simulations.
“The end result is that we now have much more confidence in black hole behavior and can discard a number of theoretical models that don’t fit observations.”
The images of the two black holes look similar, although the black hole at the center of the Milky Way is 1,000 times smaller.
This is important because it confirms Einstein’s theories about how matter behaved near black holes more than a century ago.
https://www.independent.ie/news/einstein-was-right-again-scientists-produce-first-image-of-supermassive-black-hole-at-the-centre-of-our-milky-way-galaxy-41643614.html “Einstein was right again” – Scientists create the first image of a supermassive black hole at the center of our Milky Way