May 20, 2024

First Direct Visual Evidence That the Object in the Center of the Milky Way Is Indeed a Black Hole

Example of a simulation of how the gas orbits the black hole in the center of our Milky Way and gives off radio waves at 1.3 mm. Credit: Younsi, Fromm, Mizuno & & Rezzolla (University College London, Goethe University Frankfurt
Although we can not see the black hole itself, because it is entirely dark, radiant gas around it exposes a tell-tale signature: a dark main region (called a “shadow”) surrounded by a bright ring-like structure. The brand-new view captures light bent by the effective gravity of the black hole, which is 4 million times more huge than our Sun.
” We were stunned by how well the size of the ring concurred with predictions from Einsteins theory of general relativity,” says EHT Project Scientist Geoffrey Bower from the Institute of Astronomy and Astrophysics, Academia Sinica, Taipei. “These unprecedented observations have significantly improved our understanding of what occurs at the very center of our galaxy and use new insights on how these giant black holes connect with their environments.”
What does it take to capture a picture of the great void at the center of our galaxy? This video discusses how the Event Horizon Telescope (EHT) works, and how astronomers managed to produce one huge Earth-sized telescope big enough to “see” at the edge of black holes. Credit: ESO
Because the great void is about 27,000 light-years away from Earth, it appears to us to have about the very same size in the sky as a donut on the Moon. To image it, the team created the powerful EHT, which connected together 8 existing radio observatories throughout the planet to form a single “Earth-sized” virtual telescope. The EHT observed Sgr A * on multiple nights, gathering data for many hours in a row, similar to utilizing a long exposure time on a video camera.
For this, a research study team led by theoretical astrophysicist Luciano Rezzolla from Goethe University Frankfurt used supercomputers to mimic how a black hole could look like when observed by the EHT– based on what had currently been known about Sgr A *. They compared this image library with the thousands of different images of the EHT to deduce the residential or commercial properties of Sgr A *.
The development follows the EHT Collaborations 2019 release of the first image of a black hole, called M87 *, at the center of the more distant Messier 87 galaxy.
Luciano Rezzolla, Professor für Theoretische Astrophysik, Goethe-Universität Frankfurt. Credit: Juergen Lecher
The 2 great voids look incredibly similar, although our galaxys black hole is more than a thousand times smaller and less enormous than M87 *. “We have two completely different kinds of galaxies and 2 very different black hole masses, however near the edge of these great voids they look surprisingly comparable,” says Sera Markoff, Vice Chair of the EHT Science Council and a teacher of theoretical astrophysics at the University of Amsterdam, the Netherlands. “This tells us that general relativity governs these things up close, and any distinctions we see even more away need to be due to distinctions in the material that surrounds the black holes.”
This accomplishment was considerably harder than for M87 *, although Sgr A * is much closer to us. EHT scientist Chi-kwan ( CK) Chan, from Steward Observatory, the Department of Astronomy and the Data Science Institute at the University of Arizona, US, explains: “The gas in the area of the great voids moves at the same speed– almost as fast as light– around both Sgr A * and M87 *. Where gas takes days to weeks to orbit the larger M87 *, in the much smaller sized Sgr A * it finishes an orbit in simple minutes. This means the brightness and pattern of the gas around Sgr A * was altering rapidly as the EHT Collaboration was observing it– a bit like attempting to take a clear image of a pup rapidly chasing its tail.”

This is the first picture of Sagittarius A * (Sgr A *), the supermassive great void at the center of our galaxy, caught by the Event Horizon Telescope (EHT). It is the very first direct visual evidence of the presence of this great void. Credit: EHT Collaboration
Astronomers expose the very first image of the black hole at the heart of our galaxy. It is the very first direct visual evidence of a ring-like structure like M87 *. Theoretical Physicists of Goethe University Frankfurt contributed in interpreting the data.
Astronomers have actually revealed the first image of the supermassive black hole at the center of our own Milky Way galaxy. This result offers frustrating proof that the object is undoubtedly a black hole and yields important clues about the functions of such giants, which are believed to reside at the center of most galaxies. The image was produced by a worldwide research study team called the Event Horizon Telescope (EHT) Collaboration, utilizing observations from a worldwide network of radio telescopes. Theoretical Physicists from Goethe University Frankfurt contributed in translating the information.
The image is a long-anticipated appearance at the huge item that sits at the very center of our galaxy. Researchers had previously seen stars orbiting around something unnoticeable, compact, and very huge at the center of the Milky Way. This strongly suggested that this object– known as Sagittarius A * (Sgr A *, pronounced “sadge-ay-star”)– is a great void, and this new image provides the first direct visual evidence of it.

The researchers had to establish sophisticated new tools that represented the gas movement around Sgr A *. While M87 * was a much easier, steadier target, with nearly all images looking the same, that was not the case for Sgr A *. The image of the Sgr A * great void is an average of the various images the team extracted, finally revealing the giant lurking at the center of our galaxy for the first time.
The effort was enabled through the resourcefulness of more than 300 scientists from 80 institutes all over the world that together comprise the EHT Collaboration. In addition to developing complex tools to get rid of the difficulties of imaging Sgr A *, the team worked rigorously for five years, using supercomputers to integrate and examine their information, all while compiling an extraordinary library of simulated black holes to compare with the observations.
Luciano Rezzolla, professor of Theoretical Astrophysics at Goethe University Frankfurt, describes: “The mass and range of the things were understood very specifically before our observations. We hence utilized these tight constraints on the size of the shadow to dismiss other compact items– such as boson stars or wormholes– and conclude that: What were seeing absolutely looks like a great void!”.
Utilizing sophisticated mathematical codes, theorists in Frankfurt have performed substantial calculations on the homes of the plasma accreting onto the great void. Rezzolla: “We handled to compute three million artificial images varying the accretion and radiation emission designs, and thinking about the variations seen by observers at various inclinations with respect to the great void.”.
This last operation was needed because the image of a black hole can be radically different when seen by observers at different inclinations. “Indeed, a reason our images of Sgr A * and M87 * are rather comparable is because were seeing the 2 black holes from an almost similar angle,” Rezzolla explains.
” To comprehend how the EHT has produced a picture of Sgr A * one can think about producing an image of a mountain peak based upon a time-lapse video. While many of the time the peak will show up in the time-lapse video, there are times when it is not because it is obscured by clouds. Usually, however, the peak is plainly there. Something comparable holds true likewise for Sgr A *, whose observations result in countless images that have actually been collected in four classes and after that balanced according to their properties. The end outcome is a clear first picture of the black hole at the center of the Milky Way.” Rezzolla concludes.
Scientists are particularly delighted to finally have images of two great voids of extremely various sizes, which offers the chance to understand how they compare and contrast. They have actually also begun to utilize the brand-new information to test theories and designs of how gas acts around supermassive black holes. This procedure is not yet fully understood but is believed to play a crucial function in shaping the development and development of galaxies.
” Now we can study the distinctions in between these 2 supermassive black holes to gain valuable new ideas about how this important process works,” states EHT scientist Keiichi Asada from the Institute of Astronomy and Astrophysics, Academia Sinica, Taipei. “We have images for two black holes– one at the large end and one at the small end of supermassive great voids in the Universe– so we can go a lot even more in screening how gravity behaves in these extreme environments than ever in the past.”.
Progress on the EHT continues: a significant observation project in March 2022 included more telescopes than ever in the past. The continuous expansion of the EHT network and significant technological upgrades will allow researchers to share even more impressive images along with videos of black holes in the future.
Recommendation: “First Sagittarius A * Event Horizon Telescope Results. I. The Shadow of the Supermassive Black Hole in the Center of the Milky Way” by Kazunori Akiyama, Antxon Alberdi, Walter Alef, Juan Carlos Algaba, Richard Anantua, Keiichi Asada, Rebecca Azulay, Uwe Bach, Anne-Kathrin Baczko, David Ball, Mislav Balokovic, John Barrett, Michi Bauböck, Bradford A. Benson, Dan Bintley, Lindy Blackburn, Raymond Blundell, Katherine L. Bouman, Geoffrey C. Bower, Hope Boyce, Michael Bremer, Christiaan D. Brinkerink, Roger Brissenden, Silke Britzen, Avery E. Broderick, Dominique Broguiere, Thomas Bronzwaer, Sandra Bustamante, Do-Young Byun, John E. Carlstrom, Chiara Ceccobello, Andrew Chael, Chi-kwan Chan, Koushik Chatterjee, Shami Chatterjee, Ming-Tang Chen, Yongjun Chen, Xiaopeng Cheng, Ilje Cho, Pierre Christian, Nicholas S. Conroy, John E. Conway, James M. Cordes, Thomas M. Crawford, Geoffrey B. Crew, Alejandro Cruz-Osorio, Yuzhu Cui, Jordy Davelaar, Mariafelicia De Laurentis, Roger Deane, Jessica Dempsey, Gregory Desvignes, Jason Dexter, Vedant Dhruv, Sheperd S. Doeleman, Sean Dougal, Sergio A. Dzib, Ralph P. Eatough, Razieh Emami, Heino Falcke, Joseph Farah, Vincent L. Fish, Ed Fomalont, H. Alyson Ford, Raquel Fraga-Encinas, William T. Freeman, Per Friberg, Christian M. Fromm, Antonio Fuentes, Peter Galison, Charles F. Gammie, Roberto García, Olivier Gentaz, Boris Georgiev, Ciriaco Goddi, Roman Gold, Arturo I. Gómez-Ruiz, José L. Gómez, Minfeng Gu, Mark Gurwell, Kazuhiro Hada, Daryl Haggard, Kari Haworth, Michael H. Hecht, Ronald Hesper, Dirk Heumann, Luis C. Ho, Paul Ho, Mareki Honma, Chih-Wei L. Huang, Lei Huang, David H. Hughes, Shiro Ikeda, C. M. Violette Impellizzeri, Makoto Inoue, Sara Issaoun, David J. James, Buell T. Jannuzi, Michael Janssen, Britton Jeter, Wu Jiang, Alejandra Jiménez-Rosales, Michael D. Johnson, Svetlana Jorstad, Abhishek V. Joshi, Taehyun Jung, Mansour Karami, Ramesh Karuppusamy, Tomohisa Kawashima, Garrett K. Keating, Mark Kettenis, … John Test, Karl Torstensson, Paulina Venegas, Craig Walther, Ta-Shun Wei, Chris White, Gundolf Wieching, Rudy Wijnands, Jan G. A. Wouterloot, Chen-Yu Yu, Wei Yu and Milagros Zeballos, 12 May 2022, The Astrophysical Journal Letters.DOI: 10.3847/ 2041-8213/ ac6674.
A number of scientists from Goethe University are connected with the EHT Collaboration. Together with Professor Luciano Rezzolla, Dr. Alejandro Cruz Orsorio, Dr. Prashant Kocherlakota and Kotaro Moriyama, also Prof Mariafelicia De Laurentis (University of Naples), Dr. Christian Fromm (University of Würzburg), Prof Roman Gold (University of Southern Denmark), Dr. Antonios Nathanail (University of Athens), and Dr. Ziri Younsi (University College London) have actually supplied important contributions to the theoretical research in the EHT Collaboration.
This work has been supported by the European Research Council.

For this, a research study group led by theoretical astrophysicist Luciano Rezzolla from Goethe University Frankfurt used supercomputers to mimic how a black hole could look like when observed by the EHT– based on what had actually already been understood about Sgr A *. The two black holes look remarkably similar, even though our galaxys black hole is more than a thousand times smaller sized and less enormous than M87 *. “We have two totally various types of galaxies and two very different black hole masses, however close to the edge of these black holes they look remarkably similar,” says Sera Markoff, Vice Chair of the EHT Science Council and a teacher of theoretical astrophysics at the University of Amsterdam, the Netherlands. EHT researcher Chi-kwan ( CK) Chan, from Steward Observatory, the Department of Astronomy and the Data Science Institute at the University of Arizona, US, discusses: “The gas in the vicinity of the black holes moves at the same speed– almost as fast as light– around both Sgr A * and M87 *. The image of the Sgr A * black hole is an average of the different images the team extracted, finally exposing the huge hiding at the center of our galaxy for the first time.