ESA Science & Technology - Artist's impression of material around a black hole

Artist's concept of the relativistic flow of matter around a fast rotating black hole in the centre on an accretion disk (orange). In the immediate vicinity of the black hole, the characteristic spectral fingerprint of iron atoms is smeared out by relativistic effects. The light from those atoms, that move towards the observer appears shifted to shorter wavelengths (blue) and much brighter than that on the receding side of the disk (red). In addition, the image of the disk in the vicinity of the black hole appears warped by the strong curvature of spacetime.