Thursday astronomers presented an image of the black hole " M87 *" ("M87 *"), "clearer" than that shown by a network of telescopes in 2019, but a scientist who participated in reaching the first image called for reservations about it because of the use of simulation methods to obtain it. .

A team of American researchers led by Leah Medeiros, from the Institute for Advanced Studies, presented a "new version" of this image that roamed the world when it was released, according to a study whose results were published in the "Astrophysical Journal Letters" magazine.

And the international collaboration team "Event Horizon Telescope" (EHT) produced an image of a small dark circle in the center of a glowing orange halo, which is the shape known as the giant black hole located at the heart of the galaxy "M87" (Messier 87), 55 million light-years away. about the ground.

The Institute for Advanced Study indicated that the new image is "more clear", and it shows a much finer orange ring, caused by matter that reached huge temperatures before being absorbed by the black hole, and its central circle is only the "shadow".

A black hole is so dense that nothing, not even light, can escape its gravitational pull.

The first image was obtained at the end of an observational campaign of the Event Horizon Telescope's radio telescope network conducted in 2017.

The new image was produced by passing the data collected by AHT through a machine-learning algorithm filter, called PRIMO, which analyzed about thirty thousand images of black holes obtained through simulations.

However, astrophysics professor Heino Valcke of the Netherlands' Radboud University (in Nijmegen) called this approach "interesting, but very risky".

The EHT team, which he co-founded, avoided such an approach because it "introduces a very strong bias in image reconstruction," Valcke told AFP.

In fact, this simulation is based on theoretical models, "because we do not know what the black hole looks like exactly and we still need to test the laws of physics near it," according to Valcke, who pointed out that the interpretation of the image reached by observing "M87 * using simulations, stemming from the belief that the models used are correct.

One of the authors of the study, which was supervised by Lea Medeiros, described the Primo method as "a golden opportunity for our collective work to understand the physics of black holes," according to a statement issued by the Institute for Advanced Studies.

But for Heino Valcke, the result obtained is "not an image, but an informed assumption".