(ORDO NEWS) — Scientists at the University of Arizona have revealed why images of black holes in the galaxy M87 and the Milky Way are very similar, despite the huge differences in the mass of both objects. The astronomers’ explanation is given in a press release posted on the Phys.org website.
The M87 galaxy, located 53.5 million light-years from Earth, hosts a supermassive black hole, Powehi (or M87*), with a mass of about 3.5 billion solar masses, which corresponds to a size larger than the size of the solar system.
It was considered the largest object of its kind until supermassive black holes with masses of 9.7 and 27 billion solar masses were discovered. In 2019, an image of Powehi was first released showing a glowing ring around a dark space known as the black hole’s “shadow”.
On May 12, 2022, the Event Horizon Telescope (EHT) collaboration published an image of the second supermassive black hole, Sgr A*, which is at the center of the Milky Way and is 1,500 times smaller than Powehi, which is comparable to the size of Mercury’s orbit.
Despite the fact that the masses of both black holes are very different, the image of Sgr A* almost does not differ in shape from the image of the black hole in M87. According to the researchers, this confirms a fundamental prediction of Einstein’s theory of gravity, according to which the size of a black hole depends only on its mass.
Because M87 is 2,000 times further away than Sgr A*, both objects appear to be identical in appearance, despite significant differences in size.
According to Dimitrios Psaltis, professor of astronomy and physics at the University of Arizona, if scientists could get an image of a black hole with a mass of only about ten times the mass of the Sun (in reality, this is impossible due to low resolution), then it would be very similar to an image of M87.
The luminous ring surrounding the shadow of a black hole is formed by photons and photon-emitting particles moving in circular orbits in curved space-time, as predicted by Einstein’s equations. That is why, in all cases, black holes should look like luminous donuts, the scientist says.
In 2000 and 2001, M87* and Sgr A* were identified by scientists as the only possible targets for the Earth-sized Event Horizon Virtual Telescope, as they are in a suitable environment that makes them sufficiently distinguishable for observations.
However, analyzing and validating the final image of Sgr A* required petabytes of data, sophisticated algorithms and years of research, including the development of models that should help determine the physical properties of the black hole and its surroundings.
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