Scientists extract the sharpest image of a black hole yet
The brightest spot in the outer disc shifted to the right, showing off the object's chaotic nature.
Black holes are one of the most powerful forces in the universe, but we had never seen one until the Event Horizon Telescope (EHT) team released the first image back in 2019. Now, the EHT Collaboration has released the most detailed image yet of the same M87 black hole, created with the aid of an additional telescope and independent data from 2018, that better displays the insane physics behind these supermassive objects.
The first image was captured in 2017 (it takes a long time to process the data) using eight high-altitude telescopes from locations including Chile and Antarctica. The complex technique required the synchronization of atomic clocks, use of the Earth's rotation and processing of petabytes of RAW telescope data. The result was slightly fuzzy, but clearly showed the expected "donut" with the black hole at the center and accretion disk made of matter inhaled from nearby stars.
However, the EHT collaboration captured another image a year later using an additional telescope in Greenland. That "significantly" improved the image fidelity, particularly in the north-south direction, according to the EHT. One of the original platforms, The Large Millimeter Telescope, also gained sensitivity by using its full 50 meter surface for the first time. The teams also introduced new data analysis techniques that boosted accuracy.
The result is a sharper and brighter image that also clearly shows the Doppler/Einstein effects that cause a black hole to appear to be brighter on one side. That bright spot actually shifted to the right between the capture of the two images.
"The biggest change, that the brightness peak shifted around the ring, is actually something we predicted when we published the first results in 2019," said Dr. Britt Jeter from Taiwan's ASIAA. "While general relativity says the ring size should stay pretty fixed, the emission from the turbulent, messy accretion disk around the black hole will cause the brightest part of the ring to wobble around a common center. The amount of wobble we see over time is something we can use to test our theories for the magnetic field and plasma environment around the black hole."
The new image also shows that the science behind the image technique is sound and reproduceable. "Confirmation of the ring in a completely new data set is a huge milestone for our collaboration and a strong indication that we are looking at a black hole shadow and the material orbiting around it," said Dr. Keiichi Asada from ASIAA.
The EHT Collaboration will continue to advance the science with new observations set for the first half of 2024. At that time, scientists hope to capture multiple images to create the first "video" of a black hole to show its chaotic movements. As before, it could take several years (and the participation of many scientists) to get the final result.
