The team of American researchers led by Lia Medeiros, of the Institute for Advanced Study (IAS), presents a "new reconstruction" of this image that had then gone around the world, according to the study published in Astrophysical Journal Letters.
The international collaboration EHT (Event Horizon Telescope) had produced the image of a small dark circle in the middle of a flamboyant orange halo, signature of the gigantic black hole housed in the heart of the galaxy Messier 87 (M87), 55 million light-years from Earth.
The new image is "sharper," according to a statement from the IAS. It has a much thinner orange ring, produced by matter brought to gigantic temperatures before being absorbed by the black hole, and whose central circle is only "the shadow". A black hole is of such density that nothing can escape its gravitational force, not even light.
The first image was obtained following an observation campaign of the EHT radio telescope network conducted in 2017. The new image was produced by passing the data collected by the EHT through the filter of a machine learning algorithm, called PRIMO, which analyzed about 30,000 images of black holes from simulations.
An approach described as "interesting, but also very dangerous" by astrophysics professor Heino Falcke, of the Dutch Radboud University (Nijmegen). Who explains that the EHT collaboration, of which he is one of the founders, had excluded such an approach because "it introduces a very strong bias in the reconstruction of the image," he told AFP.
Indeed, these simulations are based on theoretical models, "because we do not know what exactly a black hole looks like and we still need to test the laws of physics in its vicinity". Using simulations, interpreting the image obtained by observing M87* is therefore "believing that your models are correct," he adds.
One of the authors of the study signed by Dr. Medeiros calls the PRIMO method "a golden opportunity for our collective work to understand the physics of black holes," according to the IAS statement.
For Prof. Heino Falcke, however, the result obtained is "not an image, but a +enlightened+ assumption".
© 2023 AFP