In 2017, astronomers from the Event Horizon Telescope (EHT) Collaboration captured the first image of a black hole by coordinating radio dishes around the world to act as a single, planet-sized telescope. The synchronized network focused in on M87*, the black hole at the center of Messier 87, a giant elliptical galaxy located some 53 million light-years away in the constellation of Virgo. The telescope’s laser-focused resolution revealed a very thin glowing ring around a dark center, representing the first visual of a black hole’s shadow. Astronomers have now refocused their view to capture a new layer of M87*. The team has harnessed another global web of observatories — the Global millimeter VLBI Array (GMVA) — to capture a more zoomed-out view of the black hole.
In this artist’s conception, M87*’s massive jet is seen rising up from the center of the black hole. Image credit: S. Dagnello, NRAO, AUI & NSF.
Most galaxies harbor a supermassive black hole at their center.
While black holes are known for engulfing matter in their immediate vicinity, they can also launch powerful jets of matter that extend beyond the galaxies that they live in.
Understanding how black holes create such enormous jets has been a long standing problem in astronomy.
“We know that jets are ejected from the region surrounding black holes, but we still do not fully understand how this actually happens,” said Dr. Ru-Sen Lu, an astronomer at the Shanghai Astronomical Observatory.
“To study this directly we need to observe the origin of the jet as close as possible to the black hole.”
The new image of M87* shows precisely this for the first time: how the base of a jet connects with the matter swirling around a supermassive black hole.
Previous observations had managed to separately image the region close to the black hole and the jet, but this is the first time both features have been observed together.
“This new image completes the picture by showing the region around the black hole and the jet at the same time,” said Dr. Jae-Young Kim, an astronomer at the Kyungpook National University and the Max Planck Institute for Radio Astronomy.
This image shows the jet and shadow of the black hole at the center of Messier 87. Image credit: R.-S. Lu, SHAO / E. Ros, MPIfR / S. Dagnello, NRAO, AUI& NSF.
The new image shows the jet emerging near M87*, as well as what scientists call the shadow of the black hole.
As matter orbits the black hole, it heats up and emits light. The black hole bends and captures some of this light, creating a ring-like structure around the black hole as seen from Earth.
The darkness at the center of the ring is the black hole shadow, which was first imaged by the EHT in 2017.
Both this new image and the EHT one combine data taken with several radio-telescopes worldwide, but the image released today shows radio light emitted at a longer wavelength than the EHT one: 3.5 mm instead of 1.3 mm.
“At this wavelength, we can see how the jet emerges from the ring of emission around the central supermassive black hole,” said Dr. Thomas Krichbaum, an astronomer at the Max Planck Institute for Radio Astronomy.
The size of the ring observed by the GMVA network is roughly 50% larger in comparison to the original EHT image.
“To understand the physical origin of the bigger and thicker ring, we had to use computer simulations to test different scenarios,” said Dr. Keiichi Asada, an astronomer at the Academia Sinica.
“The results suggest the new image reveals more of the material that is falling towards the black hole than what could be observed with the EHT.”
This research is described in a paper in the journal Nature.
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R.-S. Lu et al. 2023. A ring-like accretion structure in M87 connecting its black hole and jet. Nature 616, 686-690; doi: 10.1038/s41586-023-05843-w
