catch her Breathless and with a beaming smile, astronomer Sara Issaoun from the Center for Astrophysics presented one of the most important observations ever made in astronomy to a German audience.
“This is the first image of the supermassive black hole at the heart of our galaxy, the Milky Way!” she said excitedly at a press conference broadcast around the world.
While we have long suspected that supermassive black holes lurked at the center of black holes, previous observations were based on indirect evidence. All that changed in 2019 when the Event Horizon Telescope captured an image of the surprisingly huge black hole at the center of the galaxy M87. It took eight telescopes several nights to collect that image in 2017, and a couple of years of processing on some of the most powerful computers on Earth to put it together.
But there was a much closer black hole that they also worked on: Sagittarius A* (Sgr A*), the giant that dominates the Milky Way. This image is the first direct evidence of our central supermassive black hole, removing any doubt that the object is anything but a black hole by directly visualizing its event horizon, the point of no return in a black hole, as well as the ” ring”. fire” around him.
Sgr A* is four million times the mass of our Sun, and its dark region, the event horizon, from which light cannot escape, is about the size of Mercury’s orbit, Issaoun said. The incredible new image explains the gravitational well that scientists had long suspected lurked at the center of our galaxy, previously hinted at by the peculiar behaviors of stars and gases there.
The image involved the work of more than 300 researchers, billions of processing hours, 11 radio telescopes spread across the globe, and several petabytes of data that, if printed, would require enough paper to stretch from Earth to the Moon.
EHT captured Sgr A* over a few days in April 2017 through radio wavelengths that were short enough to see the glow of hot material swirling in and out around the black hole’s center.
“To give you an idea, the EHT can see three million times sharper than the human eye,” said Thomas Krichbaum, an EHT collaborator at the Max Planck Institute for Radio Astronomy in Bonn, Germany. “So when you’re sitting in a Munich beer garden, for example, one might see the bubbles in a glass of beer in New York.”
Until today, Issaoun held the record for the best image of Sgr A*.
He was working on images of Sgr A* at lower resolutions, studying the mysterious radio emissions from the Milky Way’s core to see if he could narrow down the details about this possible black hole for his Ph.D. investigate.
After a long run thinking about Sgr A*, “there it was looking at me,” he said during the news conference at the European Southern Observatory (ESO) headquarters near Munich, Germany. “And I felt chills and excitement.”
He recalled that momentous Zoom call, where EHT facility imaging teams gathered to view the images for the first time. Everyone marveled when they saw a ring of the same size in the images, which the EHT collaboration combined into the single shot released Thursday.
Tuned in from Japan at midnight local time. Coincidentally, she attended a conference on the galactic center, “which was quite amusing,” Issaoun said, followed up with a laugh.
Decades in the making, the project has an increasingly exciting future. The initial imaging campaign worked on images of six objects, three of which the EHT collaboration has released: M87, Sgr A*, and a trail of matter near the galaxy Centaurus A, without actually imaging the event horizon. It will also add new telescope sites in the coming years, increasing the resolution of black hole images.