"That would be the most extreme general relativistic effect detected so far," he added.
X-raying Black Holes While the Event Horizon Telescope is observing black holes in radio wavelengths, the other frontier of black hole astronomy is in the X-ray regime.
The gas falling into black holes emits light across the electromagnetic spectrum, but the hottest, most energetic gas, which is swirling closest to a black hole's event horizon, can be seen in X-ray light.
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This light is only visible beyond the atmosphere of Earth, to space telescopes such as NASA's Chandra observatory and NuSTAR telescope, Europe's XMM Newton observatory, and Japan's Suzaku telescope. These observations aren't directly imaging the environs of black holes, like the Event Horizon Telescope, but are breaking up X-ray light into its constituent colors, or wavelengths, to search for clues about what's happening to the gas in those extreme environments.
For example, astronomer Chris Reynolds of the University of Maryland, College Park, uses X-ray observations to study the spins of black holes. "Because the physics is so extreme, when a black hole spins, it actually twists up the space-time around it and we can see the effect it has on gas orbiting the black hole," Reynolds said.