The photon ring: a black hole ready for its close-up

Blackhole jet (infographic Waterloo) - Scientists have discerned a sharp ring of light created by photons whipping around the back of a supermassive black hole in a vivid confirmation of theoretical prediction When scientists unveiled humanity's historic first image of a black hole in 2019 - depicting a dark core encircled by a fiery aura of material falling toward it - they believed even richer imagery and insights were waiting to be teased out of the data. Simulations predicted that, hidden behind the glare of the diffuse orange glow, there should be a thin, bright ring of light created by photons flung around the back of the black hole by its intense gravity. A team of researchers led by astrophysicist Avery Broderick used sophisticated imaging algorithms to essentially "remaster" the original imagery of the supermassive black hole at the centre of the M87 galaxy. "We turned off the searchlight to see the fireflies," said Broderick, an associate faculty member at Perimeter Institute and the University of Waterloo. "We have been able to do something profound - to resolve a fundamental signature of gravity around a black hole." By essentially "peeling off" elements of the imagery, says co-author Hung-Yi Pu, an assistant professor at National Taiwan Normal University, "the environment around the black hole can then be clearly revealed." To accomplish this, the team employed a new imaging algorithm within the Event Horizon Telescope (EHT) analysis framework THEMIS to isolate and extract the distinct ring feature from the original observations of the M87 black hole - as well as detect the telltale footprint of a powerful jet blasting outward from the black hole.