What happens to a black hole when it runs into another black hole? This new model shows you exactly.

The question of just what happens when two black holes meet is one that we've been fascinated with for awhile. But, even though we know a little about how the whole process might go down theoretically as the two merge, what we haven't known is how it would look.

A new working paper posted on ArXiv by a group of researchers led by Cornell University's Andy Bohn takes on just that question. While other attempts at visualizing the process have done a good job , they haven't taken into account how the movement of light across spacetime and the physics of vision, would come together to create the visual. Explains the paper:

In this paper, we focus on the question of what an observer in the vicinity of a BBH would actually see as the black holes orbit, spiral inward, and merge, with an example shown in figure 1. This is in contrast to most BBH visualizations, in which the positions or horizons of the two black holes are simply shown as a function of time in some coordinate system. We instead compute the paths of light rays that enter the observer's eye or camera to find what would actually be seen. Furthermore, this path must be computed in the fully time-dependent spacetime, as the orbital velocities for a black-hole binary are typically large enough that the system cannot be approximated as time-independent during the time taken by the photons to travel across it.


After generating a model that better accounts for the effects of gravitational lensing on the eye of the viewer, the team generated the image above of two black holes meeting, situated near our own Milky Way.

You can check out the whole paper right here.