Black Hole with Accretion Disk Visualization

This visualization shows the strange ways that light is gravitationally warped in the region around a black hole surrounded by a rapidly-rotating disk of gas and dust. The distortions seen in this image are due to the physics of general relativity, which informs us how the path of light is deflected in the presence of a gravitational field.

The material forming a black hole has been compressed to densities so high that it is hidden within an “event horizon,” beyond which the gravitational field is so strong that nothing, not even light, can escape. Outside of this event horizon light paths will bend sharply, and even loop around the black hole, under the influence of the intense gravitational fields.

The speed at which material, in what is known as an accretion disk, orbits the black hole increases with proximity. The orbital speed of material closest to the event horizon approaches the speed of light. This produces an effect known as “relativistic doppler beaming” which enhances the brightness of material moving towards us along our line of sight, and correspondingly dims the brightness of material moving away.

The gravitational warping of the light from background stars is strong, creating the effect of a powerful lens. Light from the region directly behind the black hole forms an “Einstein Ring” that encircles the event horizon. Inside this ring we find an inverted view of the entire sky, which is increasingly distorted. The inner black disk is known as the black hole’s “shadow” which appears slightly larger than the actual location of the event horizon due to the distortion of the light paths.

The light from the orbiting material is likewise distorted, making the flat accretion disk appear to bend completely around the black hole’s shadow and have the disk behind the black hole appear to be both above and below it. Yet despite these strange visual distortions that change with viewing angle, the accretion disk itself physically remains flat.

These illustrations depict what is known as a “Schwarzschild” black hole, made from material that had no overall rotation. A black hole created from rapidly spinning material retains a sense of this rotation and displays additional asymmetries not pictured here; this is known as a “Kerr” black hole.

The appearance of a black hole like this is “scale invariant,” meaning that the way light warps around it will appear the same, regardless of the mass of the object. The only thing that changes is the overall size of the distortions and shadow. Thus a black hole ten times as massive as the one shown here, viewed from ten times further away, would look exactly the same.

These animations show qualitatively correct depictions of light distortion around a black hole that use a simplified optical model for the effect, rather than full general relativistic ray-tracing code.