There’s a new addition to astronomers’ portrait gallery of black holes
Astronomers announced May 12 that they have finally assembled an image of the supermassive black hole at the center of our galaxy
“This image shows a bright ring surrounding the darkness, the telltale sign of the shadow of the black hole,” an astrophysicist of the University of Arizona in Tucson said at a news conference announcing the result
The black hole, known as Sagittarius A*, appears as a faint silhouette amidst the glowing material that surrounds it The image reveals the turbulent, twisting region immediately surrounding the black hole in new detail The findings also were published May 12 in 6 studies in the Astrophysical Journal Letters
A planet-spanning network of radio telescopes, known as the Event Horizon Telescope, worked together to create this much-anticipated look at the Milky Way’s giant Three years ago, the same team released the first-ever image of a supermassive black hole (SN: 4/10/19) That object sits at the center of the galaxy M87, about 55 million light-years from Earth
But Sagittarius A*, or SGR A* for short, is “humanity’s black hole,” says astrophysicist of the University of Amsterdam, and a member of the collaboration
At 27,000 light-years away, the behemoth is the closest giant black hole to Earth That proximity means that SGR A* is the most-studied supermassive black hole in the universe Yet SGR A* and others like it remain some of the most mysterious objects ever found,
That’s because, like all black holes, SGR A* is an object so dense that its gravitational pull won’t let light escape Black holes are “natural keepers of their own secrets,” says physicist of the Institute for Advanced Study in Princeton, N J, who is not part of the collab team Their gravity traps light that falls within a border called the event horizon Collaboration images of SGR A* and the M87 black hole skirt up to that inescapable edge,
SGR A* feeds on hot material pushed off of massive stars at the galactic center That gas, drawn toward SGR A* by its gravitational pull, flows into a surrounding disk of glowing material, called an accretion disk The disk, the stars and an outer bubble of X-ray light “are like an ecosystem,” says astrophysicist Daryl Haggard of McGill University in Montreal and a member of the collaboration “They’re completely tied together”
That accretion disk is where the action is — as the gas moves within immensely strong magnetic fields — so astronomers want to know more about how the disk works
In fact, the accretion disk around SGR A* seems to constantly flicker and simmer This variability, the constant flickering, is like a froth on top of ocean waves, Mark off says “And so we’re seeing this froth that is coming up from all this activity, and we’re trying to understand the waves underneath the froth”
The big question, she adds, has been if astronomers would be able to see something changing in those waves within the new work, they’ve seen hints of those changes below the froth, but the full analysis is still ongoing.
By combining about 3:5 petabytes of data, or the equivalent of about 100 million TikTok videos, captured in April 2017, researchers could begin to piece together the picture To tease out an image from the initial massive jumble of data, the collaboration team needed years of work, complicated computer simulations and observations of various types of light from other telescopes
Those “multiwavelength” data from the other telescopes were crucial to assembling the image “By looking at these things simultaneously and all together, we’re able to come up with a complete picture,” says theorist of the University of Amsterdam
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