NASA visualizes how binary black holes bend light

Shane McGlaun - Apr 16, 2021, 8:02am CDT
NASA visualizes how binary black holes bend light

NASA has released a new visualization that shows what the light-bending action of a pair of orbiting black holes would look like. The movie, which can be seen below, shows how a distant pair of black holes would distort and redirect light coming from the hot gas of the accretion disks surrounding them. When viewed from the orbital plane, each of the black hole’s accretion disks would take on a double-hump characteristic.

When one of the discs passes in front of the other, gravity in the foreground blackhole transforms its partner’s disk into a rapidly changing sequence of arcs. NASA scientists say that the visualization shows two supermassive black holes with a larger one of 200 million solar masses and a smaller companion weighing about half as much.

NASA believes black holes of these types could maintain an accretion disk for millions of years. The discs have different colors, including reds and blues, to make it easier to track the light sources. Scientists say the colors also reflect that hotter gas would give off light closer to the blue end of the spectrum, noting that material orbiting smaller black holes experience stronger gravitational effects resulting in higher temperatures.

For supermassive black holes of the size, both accretion discs would emit most of their light in the UV spectrum. Notable in the video is that the accretion discs look noticeably brighter on one side. Gravitational distortion alters the path of the light coming from different parts of the disc producing a warped image. Rapid motion of the gas near the black hole changes the disc luminosity through a phenomenon known as Doppler boosting, which brightens the side rotating toward the viewer and dims the side spinning away.

Also seen in the visualization is a phenomenon known as relativistic aberration. This causes the black holes to appear smaller as they approach the viewer and larger as they move away. All of those effects would disappear if viewing the scene from above.

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