In 2019, the first image of a black hole was taken using the Event Horizon Telescope (EHT). Messier 87 (M87) Located at the center of the galaxy, the black hole was seen with gas swirling around it and other features. Astronomers have predicted theoretically. Although the photo was hailed as historic, it was too blurry and did not reveal the intricate details of the black hole. Now, astronomers have reconstructed the image to reveal the black hole’s photon ring that was previously unseen.
The black hole in the galaxy M87 receives light from nearby gas, including radio light. When a light beam passes a black hole, its direction changes due to the distortion of spacetime. This bending of light has been observed with stars and galaxies but, in the case of black holes, the bending of light is more significant.
While light passes by the black hole in all directions, only the light focused on us is visible. Astronomers have observed that black holes can act as a strong lens and focus light towards us. According to this theory, when light is directed towards us, we should see a thin circle of light known as a photo ring.
However, this photon ring was not visible in the landmark photo. This may be due to material obstructing the light path. When light passes through a region of cold gas, it is scattered and this results in a gray image.
In the new study, the team noticed that the EHT data actually contained two photos. One is the photon ring and the other is the dim glow of the surrounding region. They used an algorithm to peel back the layers of the image and revealed the photon ring.
The new observations are published in a paper in Astrophysical Journal,