Independent analysis confirms M87 black hole image ring shape
An independent group has reanalysed data from the Event Horizon Telescope (EHT) and produced the same ring-like image of the black hole at the centre of the M87 galaxy, corroborating the original findings first published in 2019. The new results were published on 11 November in Nature.
The EHT collaboration released the first picture ever taken of a black hole’s shadow in 2019. The international collaboration stitches together data collected simultaneously from an array of ground-based radio telescopes that stretches across several continents. The reconstruction is extremely challenging, but in principle the result is an image with the same level of detail, or resolution, that would be achieved with a single radio dish as wide as Earth.
The image of the supermassive black hole at the centre of the M87 galaxy was consistent with astrophysical models based on Albert Einstein’s general theory of relativity, which first predicted the existence of black holes. The image had a bright ring of roughly the correct radius, given what was known about the size of the black hole, with a darker disk at the centre.
Some researchers were unconvinced by the original image, arguing that the circular shape was an artefact of the team’s image-reconstruction techniques. Starting in 2022, Junichiro Makino, an astrophysicist at Kobe University in Japan, and his collaborators questioned those conclusions. By applying one of the data-analysis techniques the EHT collaboration had used, but with slightly different assumptions, Makino’s team obtained a different result. Their image shows a glob of radio emissions rather than a ring.
The new independent analysis used an algorithm to combine telescope measurements of the black hole in a different way to the original analysis. Its results, including new images of the black hole, largely corroborate the original findings.
The research paper behind the new analysis is by Lai, S., Thyagarajan, N., Wong, O. I. & Diakogiannis, F., published in Nature with the doi: (2026). The earlier work questioning the original image is by Miyoshi, M., Kato, Y. & Makino, J., published in Astrophys. J. 933, 36 (2022).
