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Astronomers reveal first image of the black hole at the heart of our galaxy

Today, at simultaneous press conferences around the world, including at the European Southern Observatory (ESO) headquarters in Germany, astronomers have unveiled the first image of the supermassive black hole at the centre of our own Milky Way galaxy. This result provides overwhelming evidence that the object is indeed a black hole and yields valuable clues about the workings of such giants, which are thought to reside at the centre of most galaxies. The image was produced by a global research team called the Event Horizon Telescope (EHT) Collaboration, using observations from a worldwide network of radio telescopes.

This artist’s impression depicts a rapidly spinning supermassive black hole surrounded by an accretion disc. This thin disc of rotating material consists of the leftovers of a Sun-like star which was ripped apart by the tidal forces of the black hole. The black hole is labelled, showing the anatomy of this fascinating object. Credit:ESO
This chart shows the location of the field of view within which Sagittarius A* resides — the black hole is marked with a red circle within the constellation of Sagittarius (The Archer). This map shows most of the stars visible to the unaided eye under good conditions. Credit:ESO, IAU and Sky & Telescope

The image is a long-anticipated look at the massive object that sits at the very centre of our galaxy. Scientists had previously seen stars orbiting around something invisible, compact, and very massive at the centre of the Milky Way. This strongly suggested that this object — known as Sagittarius A* (Sgr A*, pronounced “sadge-ay-star”) — is a black hole, and today’s image provides the first direct visual evidence of it.

Black hole our galaxy Sagittarius A* Sgr A*
This is the first image of Sgr A*, the supermassive black hole at the centre of our galaxy. It’s the first direct visual evidence of the presence of this black hole. It was captured by the Event Horizon Telescope (EHT), an array which linked together eight existing radio observatories across the planet to form a single “Earth-sized” virtual telescope. The telescope is named after the event horizon, the boundary of the black hole beyond which no light can escape.   Although we cannot see the event horizon itself, because it cannot emit light, glowing gas orbiting around the black hole reveals a telltale signature: a dark central region (called a shadow) surrounded by a bright ring-like structure. The new view captures light bent by the powerful gravity of the black hole, which is four million times more massive than our Sun. The image of the Sgr A* black hole is an average of the different images the EHT Collaboration has extracted from its 2017 observations.  In addition to other facilities, the EHT network of radio observatories that made this image possible includes the Atacama Large Millimeter/submillimeter Array (ALMA) and the Atacama Pathfinder EXperiment (APEX) in the Atacama Desert in Chile, co-owned and co-operated by ESO is a partner on behalf of its member states in Europe. Credit:
EHT Collaboration

Although we cannot see the black hole itself, because it is completely dark, glowing gas around it reveals a telltale signature: a dark central region (called a shadow) surrounded by a bright ring-like structure. The new view captures light bent by the powerful gravity of the black hole, which is four million times more massive than our Sun.

We were stunned by how well the size of the ring agreed with predictions from Einstein’s Theory of General Relativity,” said EHT Project Scientist Geoffrey Bower from the Institute of Astronomy and Astrophysics, Academia Sinica, Taipei. “These unprecedented observations have greatly improved our understanding of what happens at the very centre of our galaxy, and offer new insights on how these giant black holes interact with their surroundings.” The EHT team’s results are being published today in a special issue of The Astrophysical Journal Letters.

Because the black hole is about 27 000 light-years away from Earth, it appears to us to have about the same size in the sky as a doughnut on the Moon. To image it, the team created the powerful EHT, which linked together eight existing radio observatories across the planet to form a single “Earth-sized” virtual telescope [1]. The EHT observed Sgr A* on multiple nights in 2017, collecting data for many hours in a row, similar to using a long exposure time on a camera.

Black hole our galaxy Sagittarius A* Sgr A*
The Event Horizon Telescope (EHT) Collaboration has created a single image (top frame) of the supermassive black hole at the centre of our galaxy, called Sagittarius A*, or Sgr A* for short, by combining images extracted from the EHT observations.  The main image was produced by averaging together thousands of images created using different computational methods — all of which accurately fit the EHT data. This averaged image retains features more commonly seen in the varied images, and suppresses features that appear infrequently.  The images can also be clustered into four groups based on similar features. An averaged, representative image for each of the four clusters is shown in the bottom row. Three of the clusters show a ring structure but, with differently distributed brightness around the ring. The fourth cluster contains images that also fit the data but do not appear ring-like.   The bar graphs show the relative number of images belonging to each cluster. Thousands of images fell into each of the first three clusters, while the fourth and smallest cluster contains only hundreds of images. The heights of the bars indicate the relative “weights,” or contributions, of each cluster to the averaged image at top.  In addition to other facilities, the EHT network of radio observatories that made this image possible includes the Atacama Large Millimeter/submillimeter Array (ALMA) and the Atacama Pathfinder EXperiment (APEX) in the Atacama Desert in Chile, co-owned and co-operated by ESO is a partner on behalf of its member states in Europe. Credit:
EHT Collaboration

In addition to other facilities, the EHT network of radio observatories includes the Atacama Large Millimeter/submillimeter Array (ALMA) and the Atacama Pathfinder EXperiment (APEX) in the Atacama Desert in Chile, co-owned and co-operated by ESO on behalf of its member states in Europe. Europe also contributes to the EHT observations with other radio observatories — the IRAM 30-meter telescope in Spain and, since 2018, the NOrthern Extended Millimeter Array (NOEMA) in France — as well as a supercomputer to combine EHT data hosted by the Max Planck Institute for Radio Astronomy in Germany. Moreover, Europe contributed with funding to the EHT consortium project through grants by the European Research Council and by the Max Planck Society in Germany.

black hole our galaxy
This image shows the Atacama Large Millimeter/submillimeter Array (ALMA) looking up at the Milky Way as well as the location of Sagittarius A*, the supermassive black hole at our galactic centre. Highlighted in the box is the image of Sagittarius A* taken by the Event Horizon Telescope (EHT) Collaboration. Located in the Atacama Desert in Chile, ALMA is the most sensitive of all the observatories in the EHT array, and ESO is a co-owner of ALMA on behalf of its European Member States. Credit:
ESO/José Francisco Salgado (josefrancisco.org), EHT Collaboration

It is very exciting for ESO to have been playing such an important role in unravelling the mysteries of black holes, and of Sgr A* in particular, over so many years,” commented ESO Director General Xavier Barcons. “ESO not only contributed to the EHT observations through the ALMA and APEX facilities but also enabled, with its other observatories in Chile, some of the previous breakthrough observations of the Galactic centre.” [2]

The EHT achievement follows the collaboration’s 2019 release of the first image of a black hole, called M87*, at the centre of the more distant Messier 87 galaxy.

black hole our galaxy
These panels show the first two images ever taken of black holes. On the left is M87*, the supermassive black hole at the centre of the galaxy Messier 87 (M87), 55 million light-years away. On the right is Sagittarius A* (Sgr A*), the black hole at the centre of our Milky Way. The two images show the black holes as they would appear in the sky, with their bright rings appearing to be roughly the same size, despite M87* being around a thousand times larger than Sgr A*. The images were captured by the Event Horizon Telescope (EHT), a global network of radio telescopes including the Atacama Large Millimeter/submillimeter Array (ALMA) and Atacama Pathfinder EXperiment (APEX), in which ESO is co-owner. Credit:
EHT Collaboration

The two black holes look remarkably similar, even though our galaxy’s black hole is more than a thousand times smaller and less massive than M87* [3].

We have two completely different types of galaxies and two very different black hole masses, but close to the edge of these black holes they look amazingly similar,” says Sera Markoff, Co-Chair of the EHT Science Council and a professor of theoretical astrophysics at the University of Amsterdam, the Netherlands.

This tells us that General Relativity governs these objects up close, and any differences we see further away must be due to differences in the material that surrounds the black holes.

black hole our galaxy
Size comparison of the two black holes imaged by the Event Horizon Telescope (EHT) Collaboration: M87*, at the heart of the galaxy Messier 87, and Sagittarius A* (Sgr A*), at the centre of the Milky Way. The image shows the scale of Sgr A* in comparison with both M87* and other elements of the Solar System such as the orbits of Pluto and Mercury. Also displayed is the Sun’s diameter and the current location of the Voyager 1 space probe, the furthest spacecraft from Earth. M87*, which lies 55 million light-years away, is one of the largest black holes known. While Sgr A*, 27 000 light-years away, has a mass roughly four million times the Sun’s mass, M87* is more than 1000 times more massive. Because of their relative distances from Earth, both black holes appear the same size in the sky. Credit:
EHT collaboration (acknowledgment: Lia Medeiros, xkcd)

This achievement was considerably more difficult than for M87*, even though Sgr A* is much closer to us. EHT scientist Chi-kwan (‘CK’) Chan, from Steward Observatory and Department of Astronomy and the Data Science Institute of the University of Arizona, USA, explains:

The gas in the vicinity of the black holes moves at the same speed — nearly as fast as light — around both Sgr A* and M87*. But where gas takes days to weeks to orbit the larger M87*, in the much smaller Sgr A* it completes an orbit in mere minutes. This means the brightness and pattern of the gas around Sgr A* were changing rapidly as the EHT Collaboration was observing it — a bit like trying to take a clear picture of a puppy quickly chasing its tail.

The researchers had to develop sophisticated new tools that accounted for the gas movement around Sgr A*. While M87* was an easier, steadier target, with nearly all images looking the same, that was not the case for Sgr A*. The image of the Sgr A* black hole is an average of the different images the team extracted, finally revealing the giant lurking at the centre of our galaxy for the first time.

The effort was made possible through the ingenuity of more than 300 researchers from 80 institutes around the world that together make up the EHT Collaboration. In addition to developing complex tools to overcome the challenges of imaging Sgr A*, the team worked rigorously for five years, using supercomputers to combine and analyse their data, all while compiling an unprecedented library of simulated black holes to compare with the observations.

Scientists are particularly excited to finally have images of two black holes of very different sizes, which offers the opportunity to understand how they compare and contrast. They have also begun to use the new data to test theories and models of how gas behaves around supermassive black holes. This process is not yet fully understood but is thought to play a key role in shaping the formation and evolution of galaxies.

Now we can study the differences between these two supermassive black holes to gain valuable new clues about how this important process works,” said 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 black holes in the Universe — so we can go a lot further in testing how gravity behaves in these extreme environments than ever before.

Progress on the EHT continues: a major observation campaign in March 2022 included more telescopes than ever before. The ongoing expansion of the EHT network and significant technological upgrades will allow scientists to share even more impressive images as well as movies of black holes in the near future.

This visible light wide-field view shows the rich star clouds in the constellation of Sagittarius (the Archer) in the direction of the centre of our Milky Way galaxy. The entire image is filled with vast numbers of stars — but far more remain hidden behind clouds of dust and are only revealed in infrared images. This view was created from photographs in red and blue light and form part of the Digitized Sky Survey 2. The field of view is approximately 3.5 degrees x 3.6 degrees. Credit:ESO and Digitized Sky Survey 2. Acknowledgment: Davide De Martin and S. Guisard (www.eso.org/~sguisard)

The black hole at the heart of our galaxy
Notes

[1] The individual telescopes involved in the EHT in April 2017, when the observations were conducted, were: the Atacama Large Millimeter/submillimeter Array (ALMA), the Atacama Pathfinder EXperiment (APEX), the IRAM 30-meter Telescope, the James Clerk Maxwell Telescope (JCMT), the Large Millimeter Telescope Alfonso Serrano (LMT), the Submillimeter Array (SMA), the UArizona Submillimeter Telescope (SMT), the South Pole Telescope (SPT). Since then, the EHT has added the Greenland Telescope (GLT), the NOrthern Extended Millimeter Array (NOEMA) and the UArizona 12-meter Telescope on Kitt Peak to its network.

ALMA is a partnership of the European Southern Observatory (ESO; Europe, representing its member states), the U.S. National Science Foundation (NSF), and the National Institutes of Natural Sciences (NINS) of Japan, together with the National Research Council (Canada), the Ministry of Science and Technology (MOST; Taiwan), Academia Sinica Institute of Astronomy and Astrophysics (ASIAA; Taiwan), and Korea Astronomy and Space Science Institute (KASI; Republic of Korea), in cooperation with the Republic of Chile. The Joint ALMA Observatory is operated by ESO, the Associated Universities, Inc./National Radio Astronomy Observatory (AUI/NRAO) and the National Astronomical Observatory of Japan (NAOJ). APEX, a collaboration between the Max Planck Institute for Radio Astronomy (Germany), the Onsala Space Observatory (Sweden) and ESO, is operated by ESO. The 30-meter Telescope is operated by IRAM (the IRAM Partner Organizations are MPG [Germany], CNRS [France] and IGN [Spain]). The JCMT is operated by the East Asian Observatory on behalf of The National Astronomical Observatory of Japan; ASIAA; KASI; the National Astronomical Research Institute of Thailand; the Center for Astronomical Mega-Science and organisations in the United Kingdom and Canada. The LMT is operated by INAOE and UMass, the SMA is operated by Center for Astrophysics | Harvard & Smithsonian and ASIAA and the UArizona SMT is operated by the University of Arizona. The SPT is operated by the University of Chicago with specialised EHT instrumentation provided by the University of Arizona.

The Greenland Telescope (GLT) is operated by ASIAA and the Smithsonian Astrophysical Observatory (SAO). The GLT is part of the ALMA-Taiwan project, and is supported in part by the Academia Sinica (AS) and MOST. NOEMA is operated by IRAM and the UArizona 12-meter telescope at Kitt Peak is operated by the University of Arizona.

A montage of the radio observatories that form the Event Horizon Telescope (EHT) network, used to image the Milky Way’s central black hole, Sagittarius A*. These include the Atacama Large Millimeter/submillimeter Array (ALMA), the Atacama Pathfinder EXperiment (APEX), IRAM 30-meter telescope, James Clark Maxwell Telescope (JCMT), Large Millimeter Telescope (LMT), Submillimeter Array (SMA), Submillimetere Telescope (SMT) and South Pole Telescope (SPT).   The slightly transparent telescopes in the background, represent the three telescopes added to the EHT Collaboration after 2018: the Greenland Telescope, the NOrthern Extended Millimeter Array (NOEMA) in France, and the UArizona ARO 12-meter Telescope at Kitt Peak. These telescopes were added to the array after the 2017 observations of Sagittarius A*. Credit:
ESO/M. Kornmesser. Images of individual telescopes:
ALMA: ESO
APEX: ESO
LMT: INAOE Archives
GLT: N. Patel
JCMT: EAO-W. Montgomerie
SMT: D. Harvey
30m: N. Billot
SPT: Wikipedia
SMA: S. R. Schimpf
NOEMA: IRAM
Kitt Peak: Wikipedia
Milky Way: N. Risinger (skysurvey.org)
A montage of the radio observatories that form the Event Horizon Telescope (EHT) network used to image the Milky Way’s central black hole, Sagittarius A*. These include the Atacama Large Millimeter/submillimeter Array (ALMA), the Atacama Pathfinder EXperiment (APEX), IRAM 30-meter telescope, James Clark Maxwell Telescope (JCMT), Large Millimeter Telescope (LMT), Submillimeter Array (SMA), Submillimeter Telescope (SMT) and South Pole Telescope (SPT).   The slightly transparent telescopes in the background represent the three telescopes added to the EHT network after 2018: the Greenland Telescope, the NOrthern Extended Millimeter Array (NOEMA) in France, and the UArizona ARO 12-meter Telescope at Kitt Peak. These telescopes were added to the array after the 2017 observations of Sagittarius A*. Credit:
ESO/M. Kornmesser. Images of individual telescopes:
ALMA: ESO
APEX: ESO
LMT: INAOE Archives
GLT: N. Patel
JCMT: EAO-W. Montgomerie
SMT: D. Harvey
30m: N. Billot
SPT: Wikipedia
SMA: S. R. Schimpf
NOEMA: IRAM
Kitt Peak: Wikipedia
Milky Way: N. Risinger (skysurvey.org)

[2] A strong basis for the interpretation of this new image was provided by previous research carried out on Sgr A*. Astronomers have known the bright, dense radio source at the centre of the Milky Way in the direction of the constellation Sagittarius since the 1970s. By measuring the orbits of several stars very close to our galactic centre over a period of 30 years, teams led by Reinhard Genzel (Director at the Max –Planck Institute for Extraterrestrial Physics in Garching near Munich, Germany) and Andrea M. Ghez (Professor in the Department of Physics and Astronomy at the University of California, Los Angeles, USA) were able to conclude that the most likely explanation for an object of this mass and density is a supermassive black hole. ESO’s facilities (including the Very Large Telescope and the Very Large Telescope Interferometer) and the Keck Observatory were used to carry out this research, which shared the 2020 Nobel Prize in Physics.

[3] Black holes are the only objects we know of where mass scales with size. A black hole a thousand times smaller than another is also a thousand times less massive.

 

The black hole at the heart of our galaxy: more information

This research was presented in six papers published today in The Astrophysical Journal Letters.

A global map showing the radio observatories that form the Event Horizon Telescope (EHT) network used to image the Milky Way’s central black hole, Sagittarius A*. The telescopes highlighted in yellow were part of the EHT network during the observations of Sagittarius A* in 2017. These include the Atacama Large Millimeter/submillimeter Array (ALMA), the Atacama Pathfinder EXperiment (APEX), IRAM 30-meter telescope, James Clark Maxwell Telescope (JCMT), Large Millimeter Telescope (LMT), Submillimeter Array (SMA), Submillimetere Telescope (SMT) and South Pole Telescope (SPT).   Highlighted in blue are the three telescopes added to the EHT Collaboration after 2018: the Greenland Telescope, the NOrthern Extended Millimeter Array (NOEMA) in France, and the UArizona ARO 12-meter Telescope at Kitt Peak. Credit:ESO/M. Kornmesser

The EHT collaboration involves more than 300 researchers from Africa, Asia, Europe, North and South America. The international collaboration aims to capture the most detailed black hole images ever obtained by creating a virtual Earth-sized telescope. Supported by considerable international efforts, the EHT links existing telescopes using novel techniques — creating a fundamentally new instrument with the highest angular resolving power that has yet been achieved.

This image shows the locations of some of the telescopes making up the EHT, as well as a representation of the long baselines between the telescopes. Credit:ESO/L. Calçada

The EHT consortium consists of 13 stakeholder institutes; the Academia Sinica Institute of Astronomy and Astrophysics, the University of Arizona, the Center for Astrophysics | Harvard & Smithsonian, the University of Chicago, the East Asian Observatory, Goethe-Universitaet Frankfurt, Institut de Radioastronomie Millimétrique, Large Millimeter Telescope, Max Planck Institute for Radio Astronomy, MIT Haystack Observatory, National Astronomical Observatory of Japan, Perimeter Institute for Theoretical Physics, and Radboud University.

This view shows several of the ALMA antennas and the central regions of the Milky Way above. In this wide field view, the zodiacal light is seen upper right and at lower left Mars is seen. Saturn is a bit higher in the sky towards the centre of the image. The image was taken during the ESO Ultra HD (UHD) Expedition. Credit:ESO/B. Tafreshi (twanight.org)

The Atacama Large Millimeter/submillimeter Array (ALMA), an international astronomy facility, is a partnership of ESO, the U.S. National Science Foundation (NSF) and the National Institutes of Natural Sciences (NINS) of Japan in cooperation with the Republic of Chile. ALMA is funded by ESO on behalf of its Member States, by NSF in cooperation with the National Research Council of Canada (NRC) and the Ministry of Science and Technology (MOST) and by NINS in cooperation with the Academia Sinica (AS) in Taiwan and the Korea Astronomy and Space Science Institute (KASI). ALMA construction and operations are led by ESO on behalf of its Member States; by the National Radio Astronomy Observatory (NRAO), managed by Associated Universities, Inc. (AUI), on behalf of North America; and by the National Astronomical Observatory of Japan (NAOJ) on behalf of East Asia. The Joint ALMA Observatory (JAO) provides the unified leadership and management of the construction, commissioning and operation of ALMA.

The slumbering Atacama Pathfinder Experiment (APEX) telescope sits beneath reddened skies amongst the snow covered Chajnantor landscape. Snow not only blankets the ground, but also the many peaks that encircle the Chilean plateau which also hosts the Atacama Large Millimeter/submillimeter Array (ALMA). Credit:Carlos A. Durán/ESO

APEX, Atacama Pathfinder EXperiment, is a 12-metre diameter telescope, operating at millimetre and submillimetre wavelengths — between infrared light and radio waves. ESO operates APEX at one of the highest observatory sites on Earth, at an elevation of 5100 metres, high on the Chajnantor plateau in Chile’s Atacama region. The telescope is a collaboration between the Max Planck Institute for Radio Astronomy (MPIfR), the Onsala Space Observatory (OSO), and ESO.

This image shows the dish of the Atacama Pathfinder Experiment (APEX) telescope seen perfectly from the side, including the starry sky. Credit:C. Duran/ESO
ESO Photo Ambassador Stéphane Guisard captured this astounding panorama from the site of ALMA, the Atacama Large Millimeter/submillimeter Array, in the Chilean Andes. The 5000-metre-high and extremely dry Chajnantor plateau offers the perfect place for this state-of-the-art telescope, which studies the Universe in millimetre- and submillimetre-wavelength light. Numerous giant antennas dominate the centre of the image. When ALMA is complete, it will have a total of 54 of these 12-metre-diameter dishes. Above the array, the arc of the Milky Way serves as a resplendent backdrop. When the panorama was taken, the Moon was lying close to the centre of the Milky Way in the sky, its light bathing the antennas in an eerie night-time glow. The Large and Small Magellanic Clouds, the biggest of the Milky Way’s dwarf satellite galaxies, appear as two luminous smudges in the sky on the left. A particularly bright meteor streak gleams near the Small Magellanic Cloud. On the right, some of ALMA’s smaller 7-metre antennas — twelve of which will be used to form the Atacama Compact Array — can be seen. Still further on the right shine the lights of the Array Operations Site Technical Building. And finally, looming behind this building is the dark, mountainous peak of Cerro Chajnantor. ALMA, an international astronomy facility, is a partnership of Europe, North America and East Asia in cooperation with the Republic of Chile. ALMA construction and operations are led on behalf of Europe by ESO, on behalf of North America by the National Radio Astronomy Observatory (NRAO), and on behalf of East Asia by the National Astronomical Observatory of Japan (NAOJ). The Joint ALMA Observatory (JAO) provides the unified leadership and management of the construction, commissioning and operation of ALMA. Links ESO Photo Ambassadors More about ALMA at ESO The Joint ALMA Observatory. Links
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Credit:ESO/S. Guisard (www.eso.org/~sguisard)

The European Southern Observatory (ESO) enables scientists worldwide to discover the secrets of the Universe for the benefit of all. We design, build and operate world-class observatories on the ground — which astronomers use to tackle exciting questions and spread the fascination of astronomy — and promote international collaboration in astronomy. Established as an intergovernmental organisation in 1962, today ESO is supported by 16 Member States (Austria, Belgium, the Czech Republic, Denmark, France, Finland, Germany, Ireland, Italy, the Netherlands, Poland, Portugal, Spain, Sweden, Switzerland and the United Kingdom), along with the host state of Chile and with Australia as a Strategic Partner. ESO’s headquarters and its visitor centre and planetarium, the ESO Supernova, are located close to Munich in Germany, while the Chilean Atacama Desert, a marvellous place with unique conditions to observe the sky, hosts our telescopes. ESO operates three observing sites: La Silla, Paranal and Chajnantor. At Paranal, ESO operates the Very Large Telescope and its Very Large Telescope Interferometer, as well as two survey telescopes, VISTA working in the infrared and the visible-light VLT Survey Telescope. Also at Paranal ESO will host and operate the Cherenkov Telescope Array South, the world’s largest and most sensitive gamma-ray observatory. Together with international partners, ESO operates APEX and ALMA on Chajnantor, two facilities that observe the skies in the millimetre and submillimetre range. At Cerro Armazones, near Paranal, we are building “the world’s biggest eye on the sky” — ESO’s Extremely Large Telescope. From our offices in Santiago, Chile we support our operations in the country and engage with Chilean partners and society.

This is the first image of Sgr A*, the supermassive black hole at the centre of our galaxy, with an added black background to fit wider screens. It’s the first direct visual evidence of the presence of this black hole. It was captured by the Event Horizon Telescope (EHT), an array which linked together eight existing radio observatories across the planet to form a single “Earth-sized” virtual telescope. The telescope is named after the event horizon, the boundary of the black hole beyond which no light can escape.   Although we cannot see the event horizon itself, because it cannot emit light, glowing gas orbiting around the black hole reveals a telltale signature: a dark central region (called a shadow) surrounded by a bright ring-like structure. The new view captures light bent by the powerful gravity of the black hole, which is four million times more massive than our Sun. The image of the Sgr A* black hole is an average of the different images the EHT Collaboration has extracted from its 2017 observations.  In addition to other facilities, the EHT network of radio observatories that made this image possible includes the Atacama Large Millimeter/submillimeter Array (ALMA) and the Atacama Pathfinder EXperiment (APEX) in the Atacama Desert in Chile, co-owned and co-operated by ESO is a partner on behalf of its member states in Europe. Credit:EHT Collaboration

 

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