“The image of a black hole actually contains a series of nested rings,” explains Michael Johnson of the Harvard and Smithsonian Center for Astrophysics (CfA).
“Each successive ring is approximately the same diameter, but it gets sharper and sharper because its light orbits the black hole more times before reaching the observer.”
With the current EHT (Event Horizon Telescope) image, we have glimpsed all the complexity that should arise in the image of any black hole,” the researcher revealed.
Because black holes trap photons that cross their event horizon, they cast a shadow over their surrounding bright emission of the hot, falling gas.
A “ring of photons” surrounds this shadow, produced by light that is concentrated by strong gravity near the black hole.
This photon ring bears the fingerprint of the black hole: its size and shape encode the mass and rotation or “spin” of the black hole.
With EHT imaging, black hole researchers have a new tool to study these extraordinary objects.
“This is an extremely exciting time to think about the physics of black holes,” says Daniel Kapec of the Institute for Advanced Studies.
Einstein’s theory of general relativity makes a series of surprising predictions for the kinds of observations that are finally within reach, and researchers say we can expect many advances in the years to come.
“As a theorist, I find that the rapid convergence between theory and The experiment is especially gratifying, and I hope that we can continue to isolate and observe more universal predictions of general relativity as these experiments become more sensible,” Kapec explained.
George Wong, a graduate student in physics at the University of Illinois at Urbana-Champaign revealed that “bringing together experts from different fields allowed us to really connect a theoretical understanding of the photon ring with what’s possible with observation.”
Wong was the scientist who developed software to produce simulated images of black holes at higher resolutions than previously calculated and decompose them into the predicted series of sub-images.
“What started as classic pencil-and-paper calculations prompted us to push our simulations to new limits,” Wong revealed.
The researchers also found that the black hole imaging substructure creates new possibilities for observing black holes.
What really surprised researchers was that while the nested rings are almost imperceptible to the naked eye in images, even perfect images, they are strong and clear signals for sets of telescopes called interferometers-
“While capturing black hole images normally requires many distributed telescopes, the subrings are perfect to study using only two telescopes that are very far apart. Adding one space telescope to the EHT would be enough.”