Black holes are so dense that their gravity pulls in everything around them, even light. But that doesn’t mean that they are invisible to view. They collect clouds of dust and gas which form a structure around the black hole called an accretion disk, from which matter is pulled into the black hole over time. These accretion disks give off light and form the distinctive humped appearance made famous by movies like Interstellar.
Now, NASA has created a visualization, shared in the video above, showing what happens when two of these black holes pass one another, demonstrating how the gravity of each warps the accretion disk of the other. The larger black hole, equivalent to 200 times the mass of the sun, is shown in orange, and the smaller black hole is shown in blue. The effect of the extreme gravitational forces creates unexpected and twisted warping of the disks.
In reality, most of the light emitted in this situation would be in the ultraviolet range, rather than the visible light range. But it is accurate that material orbiting a smaller black hole would experience more intense gravitational forces, which would make it hotter. And hotter material gives off light which is shifted toward the blue end of the spectrum.
The visualization isn’t just for fun though. Simulations like this one are used to investigate what features astronomers could expect to see when observing real black holes.
“We’re seeing two supermassive black holes, a larger one with 200 million solar masses and a smaller companion weighing half as much,” said Jeremy Schnittman, an astrophysicist at NASA’s Goddard Space Flight Center in Greenbelt, Maryland, who created the visualization, in a statement. “These are the kinds of black hole binary systems where we think both members could maintain accretion disks lasting millions of years.”
This visualization shows a phenomenon called gravitational lensing, in which a massive body distorts the image of a body behind it. A similar method can be used to investigate distant stars and to identify exoplanets.
“A striking aspect of this new visualization is the self-similar nature of the images produced by gravitational lensing,” Schnittman explained. “Zooming into each black hole reveals multiple, increasingly distorted images of its partner.”