In April 2019, the Event Horizon Telescope (EHT) Collaboration released stunning images of M87*, a supermassive black hole in the center of Messier 87, an elliptical galaxy some 53 million light-years away in the constellation of Virgo. Now, astrophysicists have combined theoretical predictions and sophisticated imaging algorithms to remaster the original images of M87*. Their findings are consistent with theoretical predictions and offer new ways to explore these mysterious objects.
The M87* image the EHT scientists unveiled in 2019 was a landmark, but Dr. Avery Broderick, an astrophysicist with Perimeter Institute and the University of Waterloo, and colleagues felt they could sharpen the image and glean new insights by working smarter, not harder.
They applied new software techniques to reconstruct the original 2017 data in search of phenomena that theories and models predicted were lurking beneath the surface.
The new, resulting image depicts the photon ring, comprised of a series of increasingly sharp sub-rings, which the they then stacked to get the full image.
“We turned off the searchlight to see the fireflies,” Dr. Broderick said.
“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, the environment around the black hole can then be clearly revealed,” said Dr. Hung-Yi Pu, an astrophysicist at National Taiwan Normal University.
To accomplish this, the researchers employed a new imaging algorithm within the EHT analysis framework THEMIS to isolate and extract the distinct ring feature from the original observations of M87* as well as detect the telltale footprint of a powerful jet blasting outward from the black hole.
Their findings both confirm theoretical predictions and offer new ways to explore these mysterious objects, which are believed to reside at the heart of most galaxies.
“The approach we took involved leveraging our theoretical understanding of how these black holes look to build a customized model for the EHT data,” said Dr. Dominic Pesce, an astrophysicist at the Harvard & Smithsonian’s Center for Astrophysics.
“This model decomposes the reconstructed image into the two pieces that we care most about, so we can study both pieces individually rather than blended together.”
“The result was possible because the EHT is a computational instrument at its heart,” Dr. Broderick said.
“It is as dependent on algorithms as it is upon steel. Cutting-edge algorithmic developments have allowed us to probe key features of the image while rendering the remainder in the EHT’s native resolution.”
“As we continue to add more telescopes and build out the next-generation EHT, the increased quality and quantity of data will allow us to place more definitive constraints on these signatures that we’re only now getting our first glimpses of,” said Dr. Paul Tiede, an astrophysicist at the Harvard & Smithsonian’s Center for Astrophysics and Harvard University’s Black Hole Initiative.
The findings appear in the Astrophysical Journal.
Avery E. Broderick et al. 2022. The Photon Ring in M87*. ApJ 935, 61; doi: 10.3847/1538-4357/ac7c1d
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