A pair of black holes orbiting millions of times the mass of the Sun take a hypnotic pas de deux in a new NASA visualization. The film traces how black holes distort and redirect the light emanating from the maelstrom of hot gas – called the accretion disk – that surrounds each of them.
Seen from close to the orbital plane, each accretion disc takes on a characteristic double-humped appearance. But as one passes the other, the gravity of the foreground black hole transforms its partner into a sequence of rapidly evolving arcs. These distortions play out as the light from the two discs navigates the tangled fabric of space and time near the black holes.
“We are 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 visualization. “These are the types of black hole binary systems where we believe both members could maintain accretion disks for millions of years.
The accretion discs have different colors, red and blue, to make it easier to track light sources, but the choice also reflects reality. Hotter gas emits light closer to the blue end of the spectrum, and material orbiting small black holes experiences stronger gravitational effects that produce higher temperatures. For these masses, the two accretion disks would actually emit most of their UV light, with the blue disk reaching a slightly higher temperature.
Visualizations like this help scientists imagine the fascinating consequences of the extreme gravity funhouse mirror. The new video duplicates a previous one produced by Schnittman, showing a lonely black hole from different angles.
Seen almost in the direction of the edges, the accretion discs appear noticeably brighter on one side. Gravitational distortion alters the paths of light coming from different parts of the discs, producing a distorted image. The rapid movement of gas near the black hole changes the brightness of the disk through a phenomenon called Doppler amplification – an effect of Einstein’s theory of relativity that lights up the side turning towards the viewer and darkening the side that is spinning.
The visualization also shows a more subtle phenomenon called relativistic aberration. Black holes appear smaller as they approach the viewer and larger as they move away.
These effects disappear when viewing the system from above, but new features emerge. The two black holes produce small images of their partners surrounding them in each orbit. Upon closer inspection, it is clear that these images are in fact edge views. To produce them, light from black holes has to be redirected 90 degrees, which means we are looking at black holes from two different angles – face up and edge up – at the same time.
“A striking aspect of this new visualization is the self-similar nature of the images produced by the gravitational lens,” Schnittman explained. “Zooming in on each black hole reveals multiple, increasingly distorted images of its partner.”
Schnittman created the visualization by calculating the path light rays take from the accretion disks as they weave their way through warped spacetime around black holes. On a modern desktop computer, the calculations required to create the video images would have taken about a decade. So Schnittman teamed up with Goddard data scientist Brian P. Powell to use the Discover supercomputer at NASA’s Climate Simulation Center. Using just 2% of Discover’s 129,000 processors, these calculations took about a day.
Astronomers expect that in the not too distant future they will be able to detect gravitational waves – ripples in space-time – produced when two supermassive black holes in a system much like the one Schnittman has shown spiraling together and merging. .
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Material provided by NASA / Goddard Space Flight Center. Original written by Francis Reddy. Note: Content can be changed for style and length.