Scientists have discovered a pair of supermassive black holes that are doomed to merge into one enormous singularity. The findings could help astronomers understand what will happen when our own Milky Way merges with the Andromeda galaxy in 4.5 billion years.
Supermassive black holes are thought to lurk in the heart of every major galaxy, growing larger as they draw in and devour enormous quantities of dust, gas, and stars from the surrounding space environment. When wandering galaxies collide with one another, the monstrous singularities at their cores are also thrown into closer proximity.
The newly discovered black holes were found by scientists observing the aftermath of one such galactic merger that is taking place some 480 million light-years from Earth in the constellation Cancer.
NASA Black Hole Gallery
The energetic pair were spotted feeding on the maelstrom of material disturbed by the cosmic crash, and represent the closest black holes ever discovered by humanity that are locked in the act of merging.
Scientists used the Atacama Large Millimeter/Submillimeter Array (ALMA), to peer through the bright, dusty space environment at the heart of the merger in order to identify the black holes. The chaotic duo – known collectively as UGC4211 – were then targeted by a collection of seven powerful observatories, including the orbital Hubble Space Telescope.
Data from these observations revealed that the black holes had masses of 125 and 200 million times the mass of our Sun, according to a release from the Simons Foundation in New York. These celestial heavyweights are separated by a distance of just 750 light-years, and will likely merge in a few hundred million years.
The scientists behind the paper detailing the discovery – which was published in The Astrophysical Journal Letters – used the data to estimate the amount of supermassive black holes that could be merging throughout the universe. The team estimated that a surprisingly high population likely exists, and that the extreme forces at play during the mergers are likely creating a background chorus of powerful gravitational waves.
Gravitational waves are effectively ripples in spacetime that can be created by the movements of massive bodies such as merging black holes. As a gravitational wave sweeps outward from its source, it squeezes and stretches all matter in its path, creating a disturbance that is measurable on Earth using cutting-edge laser-based instruments.
“There might be many pairs of growing supermassive black holes in the centres of galaxies that we have not been able to identify so far,” said Ezequiel Treister, an astronomer at the Universidad Católica de Chile and co-author of the new paper in a new statement. “If this is the case, in the near future we will be observing frequent gravitational wave events caused by the mergers of these objects across the Universe.”
The discovery will also allow scientists to better understand what will happen to the Milky Way in the distant future. Billions of years from now our galaxy will merge with its larger spiral neighbour – the Andromeda galaxy.
“The Milky Way-Andromeda collision is in its very early stages and is predicted to occur in about 4.5 billion years,” commented senior research scientist at Eureka Scientific, and lead author of the new study, Michael Koss, in the release from the National Radio Astronomy Observatory website.
“What we’ve just studied is a source in the very final stage of collision, so what we’re seeing presages that merger and also gives us insight into the connection between black holes merging and growing and eventually producing gravitational waves.”
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Image Credit: ALMA (ESO/NAOJ/NRAO); M. Weiss, NRAO/AUI/NSF
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Two supermassive black holes have been spotted feasting on cosmic materials as two galaxies in distant space merge — and are the closest to colliding black holes astronomers have ever observed.
Astronomers spotted the pair while using the Atacama Large Millimeter/Submillimeter Array of telescopes, or ALMA, in northern Chile’s Atacama Desert, to observe two merging galaxies about 500 million light-years from Earth.
The two black holes were growing in tandem near the center of the coalescing galaxy resulting from the merger. They met when their host galaxies, known as UGC 4211, collided.
One is 200 million times the mass of our sun, while the other is 125 million times the mass of our sun.
While the black holes themselves aren’t directly visible, both were surrounded by bright clusters of stars and warm, glowing gas — all of which is being tugged by the holes’ gravitational pull.
Over time, they will start circling one another in orbit, eventually crashing into one another and creating one black hole.
After observing them across multiple wavelengths of light, the black holes are located the closest together scientists have ever seen — only about 750 light-years apart, which is relatively close, astronomically speaking.
The results were shared at the 241st meeting of the American Astronomical Society being held this week in Seattle, and published Monday in The Astrophysical Journal Letters.
The distance between the black holes “is fairly close to the limit of what we can detect, which is why this is so exciting,” said study coauthor Chiara Mingarelli, an associate research scientist at the Flatiron Institute’s Center for Computational Astrophysics in New York City, in a statement.
Galactic mergers are more common in the distant universe, which makes them harder to see using Earth-based telescopes. But ALMA’s sensitivity was able to observe even their active galactic nuclei — the bright, compact regions in galaxies where matter swirls around black holes. Astronomers were surprised to find a binary pair of black holes, rather than a single black hole, dining on the gas and dust stirred up by the galactic merger.
“Our study has identified one of the closest pairs of black holes in a galaxy merger, and because we know that galaxy mergers are much more common in the distant Universe, these black hole binaries too may be much more common than previously thought,” said lead study author Michael Koss, a senior research scientist at the Eureka Scientific research institute in Oakland, California, in a statement.
“What we’ve just studied is a source in the very final stage of collision, so what we’re seeing presages that merger and also gives us insight into the connection between black holes merging and growing and eventually producing gravitational waves,” Koss said.
If pairs of black holes — as well as merging galaxies that lead to their creation — are more common in the universe than previously thought, they could have implications for future gravitational wave research. Gravitational waves, or ripples in space time, are created when black holes collide.
It will still take a few hundred million years for this particular pair of black holes to collide, but the insights gained from this observation could help scientists better estimate how many pairs of black holes are close to colliding in the universe.
“There might be many pairs of growing supermassive black holes in the centers of galaxies that we have not been able to identify so far,” said study coauthor Ezequiel Treister, an astronomer at Universidad Católica de Chile in Santiago, Chile, in a statement. “If this is the case, in the near future we will be observing frequent gravitational wave events caused by the mergers of these objects across the Universe.”
Space-based telescopes like Hubble and the Chandra X-ray Observatory and ground-based telescopes like the European Southern Observatory’s Very Large Telescope, also in the Atacama Desert, and the W.M. Keck telescope in Hawaii have also observed UGC 4211 across different wavelengths of light to provide a more detailed overview and differentiate between the two black holes.
“Each wavelength tells a different part of the story,” Treister said. “All of these data together have given us a clearer picture of how galaxies such as our own turned out to be the way they are, and what they will become in the future.”
Understanding more about the end stages of galaxy mergers could provide more insight about what will happen when our Milky Way galaxy collides with the Andromeda galaxy in about 4.5 billion years.
Black hole BANQUET! Scientists discover two supermassive black holes dining side-by-side with just 750 light-years between them
Two supermassive black holes have been spotted ‘dining’ side-by-side
The pair are growing simultaneously just 750 light years apart
Astronomers believe they will eventually combine into a gargantuan black hole
By Xantha Leatham Deputy Science Editor For The Daily Mail
Published: | Updated:
One black hole is mind-boggling enough – a region in space where gravity is so immense that nothing, even light, can escape from it.
Now astronomers have discovered something even more remarkable, as two black holes have been spotted ‘dining’ side-by-side.
The pair are growing simultaneously just 750 light years apart – the closest scientists have ever observed – and will eventually combine into a gargantuan black hole.
They were discovered by researchers using the ALMA telescope, the most powerful telescope for observing molecular gas and dust, which is located in the Atacama desert.
One black hole is mind-boggling enough – a region in space where gravity is so immense that nothing, even light, can escape from it. Now astronomers have discovered something even more remarkable, as two black holes have been spotted ‘dining’ side-by-side
As the team were looking at two galaxies merging in the constellation Cancer, 500 million light years from Earth, they saw something they ‘didn’t expect’.
They spotted two glowing black holes, gluttonously devouring the dust, gas and other material being displaced by the merger, as if at a banquet.
While the black holes are close together in cosmological terms, they won’t merge for a few hundred million years.
Eventually, they will begin circling each other, with the orbit tightening as gas and stars pass between them.
The pair are growing simultaneously just 750 light years apart – the closest scientists have ever observed – and will eventually combine into a gargantuan black hole
Ultimately the black holes will start producing gravitational waves far stronger than any that have previously been detected, the researchers said, before crashing into each other to form one jumbo-sized black hole.
The findings also suggest that binary black holes and the merging galaxies that create them may actually be surprisingly common in the Universe.
Experts said the use of ALMA, which stands for Atacama Large Millimetre/submillimetre Array, was a ‘game changer’ and that finding two black holes so close together could pave the way for additional studies of the phenomenon.
Michael Koss, lead author of the research, is from the National Radio Astronomy Observatory.
He said: ‘ALMA is unique in that it can see through large columns of gas and dust and achieve very high spatial resolution to see things very close together.
‘Our study has identified one of the closest pairs of black holes in a galaxy merger, and because we know that galaxy mergers are much more common in the distant Universe, these black hole binaries too may be much more common than previously thought.’
The results of the new research were published in The Astrophysical Journal Letters and presented at the meeting of the American Astronomical Society in Seattle, Washington.
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BLACK HOLES HAVE A GRAVITATIONAL PULL SO STRONG NOT EVEN LIGHT CAN ESCAPE
Black holes are so dense and their gravitational pull is so strong that no form of radiation can escape them – not even light.
They act as intense sources of gravity which hoover up dust and gas around them. Their intense gravitational pull is thought to be what stars in galaxies orbit around.
How they are formed is still poorly understood. Astronomers believe they may form when a large cloud of gas up to 100,000 times bigger than the sun, collapses into a black hole.
Many of these black hole seeds then merge to form much larger supermassive black holes, which are found at the centre of every known massive galaxy.
Alternatively, a supermassive black hole seed could come from a giant star, about 100 times the sun’s mass, that ultimately forms into a black hole after it runs out of fuel and collapses.
When these giant stars die, they also go ‘supernova’, a huge explosion that expels the matter from the outer layers of the star into deep space.
A supermassive black hole swallowed up a star, ripping it apart, and uniquely expelled a beam of light from its center.
In a scientific research report published on Wednesday, astronomers say a previously unknown black hole was made known to observers when a star passed too close and was devoured.
Astronomers then observed a jetted stream of “afterglow” from the catastrophe, which experts call a Tidal Disruption Event (TDE), heading straight toward the Earth.
“The event started when an ill-fated star approached the supermassive black hole (SMBH) on a nearly parabolic trajectory and was ripped apart into a stream of gaseous debris,” read the scientific paper, published on Nov. 30. “About half of the mass stayed bound to the black hole, underwent general-relativistic apsidal precession as the gas fell back towards the pericenter, and then produced strong shocks at the self-crossing point.”
ASTRONOMERS ARE SHOCKED WHEN BLACK HOLE ‘BURPS’ OUT A STAR
The scientists said the jetted beam — the AT2022cmc, or an “infrared/optical/ultraviolet light curve” — was initially red in color before it decayed over four days and changed to a blue hue.
The astronomers added: “The optical and ultraviolet observations revealed a fast-fading red ‘flare’ that transitioned quickly to a slow blue ‘plateau’, enabling the study of two components generated by the tidal disruption: the relativistic jet and the thermal component from bound stellar debris accreting onto the black hole.”
The blasted remains were so powerfully bright that astronomers detected the TDE from the dwarf galaxy a million light-years away.
The paper added: “Observations of a bright counterpart at other wavelengths, including X-ray, submillimetre and radio, supports the interpretation of AT2022cmc as a jetted TDE containing a synchrotron.”
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The TDE was discovered in Feb. 2022, before the scientific news journal received the paper about it in April 2022, and the research was finally accepted in October 2022.
TDEs have been observed before, like the AT 2020neh in June 2020.
The Herschel Space Observatory has shown that galaxies with the most powerful, active, supermassive black holes at their cores produce fewer stars than galaxies with less active black holes. (Universal History Archive/Universal Images Group via Getty Images)
Ryan J. Foley, a co-author and UC Santa Cruz astronomer, said this initial discovery would lead the way for astronomers to find other TDEs and new dwarf galaxies.
“This discovery has created widespread excitement because we can use tidal disruption events not only to find more intermediate-mass black holes in quiet dwarf galaxies but also to measure their masses,” Foley said in a scientific paper co-published on Nov. 10.
The discovery spanned years of research as the distant galaxy was first observed in June 2020, and was confirmed with Young Supernova Experiment data. It was observed again from July 1, 2020, to July 17, 2020; then from August 5, 2020, to September 6, 2020.
“Over 24 months of YSE operations we observed only one AT 2020neh-like event, monitoring fields for approximately 6 months each. This equates to one event per year within the YSE observational volume,” the scientific paper reads.
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These unique discoveries could result in even more discoveries in distant galaxies that would otherwise be undetectable without visible light from the explosion.
Illustration of a tidal disruption event (TDE). Credit: Carl Knox – OzGrav, ARC Centre of Excellence for Gravitational Wave Discovery, Swinburne University of Technology
Rare Sighting of Luminous Jet Spewed by Supermassive Black Hole
Astronomers discover a bright optical flare caused by a dying star’s encounter with a supermassive
Several things happen, according to University of Maryland (UMD) astronomer Igor Andreoni: first, the star is violently ripped apart by the black hole’s gravitational tidal forces—similar to how the Moon pulls tides on Earth but with greater strength. Next, pieces of the star are captured into a swiftly spinning disk orbiting the black hole. Finally, the black hole consumes what remains of the doomed star in the disk. This is what astronomers call a tidal disruption event (TDE).
However, in some extremely rare cases, the supermassive black hole launches “relativistic jets” after destroying a star. These are beams of matter traveling close to the speed of light. Andreoni discovered one such case with his team in the Zwicky Transient Facility (ZTF) survey in February 2022. After the group publicly announced the sighting, the event was named “AT 2022cmc.” The team published its findings on November 30, 2022, in the journal Nature.
“The last time scientists discovered one of these jets was well over a decade ago,” said Michael Coughlin, an assistant professor of astronomy at the University of Minnesota Twin Cities and co-lead on the project. “From the data we have, we can estimate that relativistic jets are launched in only 1% of these destructive events, making AT 2022cmc an extremely rare occurrence. In fact, the luminous flash from the event is among the brightest ever observed.”
Before AT 2022cmc, the only two previously known jetted TDEs were discovered through gamma-ray space missions, which detect the highest-energy forms of radiation produced by these jets. As the last such discovery was made in 2012, new methods were required to find more events of this nature. To help address that need, Andreoni, who is a postdoctoral associate in the Department of Astronomy at UMD and
The Zwicky Transient Facility scans the sky using a state-of-the-art wide-field camera mounted on the Samuel Oschin telescope at the Palomar Observatory in Southern California. Credit: Palomar Observatory/Caltech
Follow-up observations with many observatories confirmed that AT 2022cmc was fading rapidly and the ESO Very Large Telescope revealed that AT 2022cmc was at cosmological distance, 8.5 billion light years away.
See Astronomical Signal Is Black Hole Jet Pointing Straight Toward Earth for related research on AT 2022cmc.
Reference: “A very luminous jet from the disruption of a star by a massive black hole” by Igor Andreoni, Michael W. Coughlin, Daniel A. Perley, Yuhan Yao, Wenbin Lu, S. Bradley Cenko, Harsh Kumar, Shreya Anand, Anna Y. Q. Ho, Mansi M. Kasliwal, Antonio de Ugarte Postigo, Ana Sagués-Carracedo, Steve Schulze, D. Alexander Kann, S. R. Kulkarni, Jesper Sollerman, Nial Tanvir, Armin Rest, Luca Izzo, Jean J. Somalwar, David L. Kaplan, Tomás Ahumada, G. C. Anupama, Katie Auchettl, Sudhanshu Barway, Eric C. Bellm, Varun Bhalerao, Joshua S. Bloom, Michael Bremer, Mattia Bulla, Eric Burns, Sergio Campana, Poonam Chandra, Panos Charalampopoulos, Jeff Cooke, Valerio D’Elia, Kaustav Kashyap Das, Dougal Dobie, José Feliciano Agüí Fernández, James Freeburn, Cristoffer Fremling, Suvi Gezari, Simon Goode, Matthew J. Graham, Erica Hammerstein, Viraj R. Karambelkar, Charles D. Kilpatrick, Erik C. Kool, Melanie Krips, Russ R. Laher, Giorgos Leloudas, Andrew Levan, Michael J. Lundquist, Ashish A. Mahabal, Michael S. Medford, M. Coleman Miller, Anais Möller, Kunal P. Mooley, A. J. Nayana, Guy Nir, Peter T. H. Pang, Emmy Paraskeva, Richard A. Perley, Glen Petitpas, Miika Pursiainen, Vikram Ravi, Ryan Ridden-Harper, Reed Riddle, Mickael Rigault, Antonio C. Rodriguez, Ben Rusholme, Yashvi Sharma, I. A. Smith, Robert D. Stein, Christina Thöne, Aaron Tohuvavohu, Frank Valdes, Jan van Roestel, Susanna D. Vergani, Qinan Wang and Jielai Zhang, 30 November 2022, Nature. DOI: 10.1038/s41586-022-05465-8
Other UMD collaborators include: adjunct associate professor of astronomy Brad Cenko; astronomy professor M. Coleman Miller; graduate student Erica Hammerstein and Tomas Ahumada (M.S. ’20, astronomy).
The research was supported by the National Science Foundation (Grant Nos. PHY-2010970 425, OAC-2117997, 1106171 and AST-1440341), Wenner-Gren Foundation, Swedish Research Council (Reg. No. 427 2020-03330), European Research Council (Grant No. 759194 432 – USNAC), VILLUM FONDEN (Grant No. 19054), the Netherlands Organization for Scientific Research, Spanish National Research Project (RTI2018-098104-J-I00), NASA (Award No. No. 80GSFC17M0002), the Knut and Alice Wallenberg Foundation (Dnr KAW 2018.0067), Heising-Simons Foundation (Grant No. 12540303), European Union Seventh Framework Programme (Grant No. 312430) Caltech, IPAC, the Weizmann Institute for Science, the Oskar Klein Center at Stockholm University, the
NASA’s iconic new observatory has spotted surprising compounds around supermassive black holes.
The James Webb Space Telescope (JWST) has detected carbon-bearing molecules called polycyclic aromatic hydrocarbons (PAHs) in the centers of three active galaxies, where scientists had expected these molecules couldn’t survive. Intriguingly, the observations also suggest that the radiation in the vicinity of the supermassive black holes in these galaxies has altered the overall properties of the PAHs, which could complicate a key technique astronomers use to evaluate star formation, and could also affect their usefulness as biological building blocks.
Ismael García-Bernete, an astrophysicist at Oxford University in the U.K., led a group of astronomers who have analyzed observations of three active galaxies gathered by JWST’s Mid-Infrared Instrument (MIRI). The three galaxies are NGC 6552, which is 370 million light-years away from Earth in the constellation Draco; NGC 7319, that is one of the five galaxies in the famous Stephan’s Quintet some 311 million light-years away in Pegasus; and NGC 7469, which is also in Pegasus at a distance of about 200 million light-years.
Gallery: James Webb Space Telescope’s 1st photos
PAHs are molecules characterized by rings of carbon atoms. These molecules are very common in the universe, found everywhere from distant galaxies to comets in our own solar system. Their ubiquity is what makes them useful potential building blocks for life, but it also makes them important tracers for star-formation. PAHs emit strongly at infrared wavelengths detectable by MIRI when they are illuminated by the ultraviolet radiation in starlight, so usually, where astronomers detect PAHs this way they can be sure there are hot, young stars nearby.
García-Bernete’s aim was to determine whether PAH emission in the dense, ultraviolet-rich environment at the center of an active galaxy was the same as PAH emissions in calmer star-forming regions in the spiral arms of galaxies. While stars can form in the cores of active galaxies, the process of gas falling onto a supermassive black hole can also release torrents of ultraviolet light that cause the PAHs to glow.
Previous models had predicted that the harsh radiation around the supermassive black hole at the core of an active galaxy would actually destroy all PAH molecules. Instead, MIRI discovered that PAHs were plentiful in the central regions of all three galaxies studied. However, the observations showed that the emission was coming from larger and electrically neutral PAH molecules, indicating that radiation had indeed eradicated smaller, electrically charged PAHs. The larger PAH molecules may have survived because they were protected by dense, enveloping clouds of molecular gas, the team speculated.
The loss of the smaller, electrically charged PAHs is a problem for astronomers using these compounds to trace star formation, because star-forming regions are typically richer in electrically charged PAHs. But if these are destroyed in the cores of active galaxies, astronomers cannot track where stars might be forming.
“The next step is to analyze a larger sample of active galaxies with different properties,” García-Bernete said in a statement. “This will enable us to better understand how PAH molecules survive and which are their specific properties in the nuclear region [of galaxies]. Such knowledge is key to using PAHs as an accurate tool for characterizing the amount of star formation in galaxies, and how galaxies evolve over time.”
The research was published Sept. 30 in the journal Astronomy and Astrophysics.
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Astronomers have spotted signs of a ‘hot spot’ orbiting Sagittarius A*, the black hole at the center of our galaxy.
Astronomers have spotted signs of a ‘hot spot’ orbiting Sagittarius A*, the
This shows a still image of the supermassive black hole Sagittarius A*, as seen by the Event Horizon Collaboration (EHT), with an artist’s illustration indicating where the modeling of the ALMA data predicts the hot spot to be and its orbit around the black hole. Credit: EHT Collaboration, ESO/M. Kornmesser (Acknowledgment: M. Wielgus)
The observations were made with ALMA in the Chilean Andes, during a campaign by the Event Horizon Telescope (EHT) Collaboration to image black holes. ALMA is — a radio telescope co-owned by the European Southern Observatory (ESO). In April 2017 the EHT linked together eight existing radio telescopes worldwide, including ALMA, resulting in the recently released first-ever image of Sagittarius A*. To calibrate the EHT data, Wielgus and his colleagues, who are members of the EHT Collaboration, used ALMA data recorded simultaneously with the EHT observations of Sagittarius A*. To the research team’s surprise, there were more clues to the nature of the black hole hidden in the ALMA-only measurements.
Using ALMA, astronomers have found a hot bubble of gas that swirls around Sagittarius A*, the black hole at the center of our galaxy, at 30% of the speed of light.
By chance, some of the observations were done shortly after a burst or flare of X-ray energy was emitted from the center of our galaxy, which was spotted by This video shows an animation of a hot spot, a bubble of hot gas, in orbit around Sagittarius A*, a black hole four million times more massive than our Sun that resides at the center of our
Credit: EHT Collaboration, ESO/L. Calçada (Acknowledgment: M. Wielgus)
“Perhaps these hot spots detected at infrared wavelengths are a manifestation of the same physical phenomenon: as infrared-emitting hot spots cool down, they become visible at longer wavelengths, like the ones observed by ALMA and the EHT,” adds Jesse Vos. He is a PhD student at Radboud University, the Netherlands, and was also involved in this study.
The flares were long thought to originate from magnetic interactions in the very hot gas orbiting very close to Sagittarius A*, and the new findings support this idea. “Now we find strong evidence for a magnetic origin of these flares and our observations give us a clue about the geometry of the process. The new data are extremely helpful for building a theoretical interpretation of these events,” says co-author Monika Moscibrodzka from Radboud University.
This is the first image of Sgr A*, the supermassive black hole at the center 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 that 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. Credit: EHT Collaboration
ALMA allows astronomers to study polarized radio emission from Sagittarius A*, which can be used to unveil the black hole’s magnetic field. The team used these observations together with theoretical models to learn more about the formation of the hot spot and the environment it is embedded in, including the magnetic field around Sagittarius A*. Their research provides stronger constraints on the shape of this magnetic field than previous observations, helping astronomers uncover the nature of our black hole and its surroundings.
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 center. 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
The observations confirm some of the previous discoveries made by the GRAVITY instrument at ESO’s
Wide-field view of the center of the Milky Way. This visible light wide-field view shows the rich star clouds in the constellation of Sagittarius (the Archer) in the direction of the center 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 forming 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 team is also hoping to be able to directly observe the orbiting gas clumps with the EHT, to probe ever closer to the black hole and learn more about it. “Hopefully, one day, we will be comfortable saying that we ‘know’ what is going on in Sagittarius A*,” Wielgus concludes.
More information
Reference: “Orbital motion near Sagittarius A* – Constraints from polarimetric ALMA observations” by M. Wielgus, M. Moscibrodzka, J. Vos, Z. Gelles, I. Martí-Vidal, J. Farah, N. Marchili, C. Goddi and H. Messias, 22 September 2022, Astronomy & Astrophysics. DOI: 10.1051/0004-6361/202244493
The team is composed of M. Wielgus (Max-Planck-Institut für Radioastronomie, Germany [MPIfR]; Nicolaus Copernicus Astronomical Centre, Polish Academy of Sciences, Poland; Black Hole Initiative at Harvard University, USA [BHI]), M. Moscibrodzka (Department of Astrophysics, Radboud University, The Netherlands [Radboud]), J. Vos (Radboud), Z. Gelles (Center for Astrophysics | Harvard & Smithsonian, USA and BHI), I. Martí-Vidal (Universitat de València, Spain), J. Farah (Las Cumbres Observatory, USA; University of California, Santa Barbara, USA), N. Marchili (Italian ALMA Regional Centre, INAF-Istituto di Radioastronomia, Italy and MPIfR), C. Goddi (Dipartimento di Fisica, Università degli Studi di Cagliari, Italy and Universidade de São Paulo, Brazil), and H. Messias (Joint ALMA Observatory, Chile).
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 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 organization 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 center and planetarium, the ESO Supernova, are located close to Munich in Germany, while the Chilean Atacama Desert, a marvelous 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 millimeter and submillimeter 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.
Astronomers have spotted signs of a ‘hot spot’ orbiting Sagittarius A*, the black hole at the center of our galaxy.
Astronomers have spotted signs of a ‘hot spot’ orbiting Sagittarius A*, the
This shows a still image of the supermassive black hole Sagittarius A*, as seen by the Event Horizon Collaboration (EHT), with an artist’s illustration indicating where the modeling of the ALMA data predicts the hot spot to be and its orbit around the black hole. Credit: EHT Collaboration, ESO/M. Kornmesser (Acknowledgment: M. Wielgus)
The observations were made with ALMA in the Chilean Andes, during a campaign by the Event Horizon Telescope (EHT) Collaboration to image black holes. ALMA is — a radio telescope co-owned by the European Southern Observatory (ESO). In April 2017 the EHT linked together eight existing radio telescopes worldwide, including ALMA, resulting in the recently released first-ever image of Sagittarius A*. To calibrate the EHT data, Wielgus and his colleagues, who are members of the EHT Collaboration, used ALMA data recorded simultaneously with the EHT observations of Sagittarius A*. To the research team’s surprise, there were more clues to the nature of the black hole hidden in the ALMA-only measurements.
Using ALMA, astronomers have found a hot bubble of gas that swirls around Sagittarius A*, the black hole at the center of our galaxy, at 30% of the speed of light.
By chance, some of the observations were done shortly after a burst or flare of X-ray energy was emitted from the center of our galaxy, which was spotted by This video shows an animation of a hot spot, a bubble of hot gas, in orbit around Sagittarius A*, a black hole four million times more massive than our Sun that resides at the center of our
Credit: EHT Collaboration, ESO/L. Calçada (Acknowledgment: M. Wielgus)
“Perhaps these hot spots detected at infrared wavelengths are a manifestation of the same physical phenomenon: as infrared-emitting hot spots cool down, they become visible at longer wavelengths, like the ones observed by ALMA and the EHT,” adds Jesse Vos. He is a PhD student at Radboud University, the Netherlands, and was also involved in this study.
The flares were long thought to originate from magnetic interactions in the very hot gas orbiting very close to Sagittarius A*, and the new findings support this idea. “Now we find strong evidence for a magnetic origin of these flares and our observations give us a clue about the geometry of the process. The new data are extremely helpful for building a theoretical interpretation of these events,” says co-author Monika Moscibrodzka from Radboud University.
This is the first image of Sgr A*, the supermassive black hole at the center 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 that 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. Credit: EHT Collaboration
ALMA allows astronomers to study polarized radio emission from Sagittarius A*, which can be used to unveil the black hole’s magnetic field. The team used these observations together with theoretical models to learn more about the formation of the hot spot and the environment it is embedded in, including the magnetic field around Sagittarius A*. Their research provides stronger constraints on the shape of this magnetic field than previous observations, helping astronomers uncover the nature of our black hole and its surroundings.
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 center. 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
The observations confirm some of the previous discoveries made by the GRAVITY instrument at ESO’s
Wide-field view of the center of the Milky Way. This visible light wide-field view shows the rich star clouds in the constellation of Sagittarius (the Archer) in the direction of the center 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 forming 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 team is also hoping to be able to directly observe the orbiting gas clumps with the EHT, to probe ever closer to the black hole and learn more about it. “Hopefully, one day, we will be comfortable saying that we ‘know’ what is going on in Sagittarius A*,” Wielgus concludes.
More information
Reference: “Orbital motion near Sagittarius A* – Constraints from polarimetric ALMA observations” by M. Wielgus, M. Moscibrodzka, J. Vos, Z. Gelles, I. Martí-Vidal, J. Farah, N. Marchili, C. Goddi and H. Messias, 22 September 2022, Astronomy & Astrophysics. DOI: 10.1051/0004-6361/202244493
The team is composed of M. Wielgus (Max-Planck-Institut für Radioastronomie, Germany [MPIfR]; Nicolaus Copernicus Astronomical Centre, Polish Academy of Sciences, Poland; Black Hole Initiative at Harvard University, USA [BHI]), M. Moscibrodzka (Department of Astrophysics, Radboud University, The Netherlands [Radboud]), J. Vos (Radboud), Z. Gelles (Center for Astrophysics | Harvard & Smithsonian, USA and BHI), I. Martí-Vidal (Universitat de València, Spain), J. Farah (Las Cumbres Observatory, USA; University of California, Santa Barbara, USA), N. Marchili (Italian ALMA Regional Centre, INAF-Istituto di Radioastronomia, Italy and MPIfR), C. Goddi (Dipartimento di Fisica, Università degli Studi di Cagliari, Italy and Universidade de São Paulo, Brazil), and H. Messias (Joint ALMA Observatory, Chile).
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 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 organization 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 center and planetarium, the ESO Supernova, are located close to Munich in Germany, while the Chilean Atacama Desert, a marvelous 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 millimeter and submillimeter 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.
The weird behavior of a galaxy around a billion light-years away suggests that it might contain one of the most highly anticipated events in modern astronomy.
Fluctuations in light from the center of the galaxy SDSS J1430+2303 look suspiciously like a pair of supermassive black holes with a combined mass of around 200 million Suns destined for an imminent collision with each other.
“Imminent” in cosmic terms can often stretch on for whole lifetimes. Fortunately in this case, astronomers predict that if the signal is indeed the result of colossal black holes they will merge within the next three years.
It may be our best shot yet to see two supermassive black holes collide… but we still don’t know for sure if that’s what is going on at the heart of J1429+2303. Scientists advise that we continue watching the strange galaxy to see if it can be conclusively identified.
The first detection of colliding black holes back in 2015 launched a bold new era for astronomy. Since then, many more detections have been made thanks to the gravitational waves these massive events send rippling through space-time.
To date, almost all of these mergers have been binary pairs of black holes with masses comparable to individual stars. There’s a very good reason for this. LIGO and Virgo, the gravitational wave instruments responsible for the detections, are designed for this mass range.
The more ponderous ripples generated by inspiralling and colliding supermassive black holes, in the range of millions to billions of times the mass of the Sun, are in a frequency range too low for our current observatories.
Still, the merger of a pair of supermassive black holes would be a freaking sweet thing to observe. Even without a detector capable of sensing low frequency gravitational waves, scientists expect to see an immense outburst of light across the spectrum.
The data packed into that outburst could tell us so much about how these events play out. We’re not entirely sure how supermassive black holes get so big, but there are a few clues to suggest that one mechanism is binary mergers.
We know that galaxies have supermassive black holes in their centers, and we’ve observed not just pairs and groups of galaxies colliding, but supermassive black holes circling each other in mutual, decaying orbits in the centers of these post-merger galaxies. These are inferred from oscillations in the light emitted from the galactic center of these galaxies, on regular timescales that suggest an orbit.
This brings us back to J1430+2303. Earlier this year, a team of astronomers led by Ning Jiang of the University of Science and Technology of China uploaded a paper to preprint server arXiv, describing some really strange behavior. Over a period of three years, the oscillations in the galactic nucleus grew shorter and shorter, from a time period of about a year, down to just one month.
However, it’s not entirely clear that what is happening at the heart of J1430+2303 is the result of a black hole binary at all, never mind one that is about to kaboom. Galactic nuclei are strange places, throwing out signals that are difficult to interpret, meaning it’s possible something else may be causing the variability in the heart of J1430+2303.
To try to get to the bottom of the matter, astronomers turned to X-ray wavelengths. Using data from a range of X-ray observatories, covering a time period of 200 days, a team led by Liming Dou of Guangzhou University in China has attempted to identify high-energy signatures that we would expect to see in a close supermassive black hole binary on a decaying orbit.
They did see variations in the X-ray light emitted by the galaxy, as well as a type of emission associated with iron falling onto a black hole, which the team detected with a 99.96 percent confidence level from two different instruments. This emission can be associated with binary supermassive black holes; however, the team could not measure the “smoking gun” characteristics that would confirm a black hole binary.
Analysis of radio observations published in July were also inconclusive. So it appears we’re still not 100 percent sure about what’s happening with J1430+2303.
What we are able to state with confidence is that something very strange seems to be happening at the galaxy’s center. Above all, it’s a mystery, and a very juicy one; whether it’s a supermassive black hole binary on the brink of collision or not, J1430+2303 seems to warrant closer, more detailed attention.
The paper has been accepted for publication in Astronomy & Astrophysics, and is available on arXiv.
Astronomers have photographed a violent cosmic dance that began between two galaxies a billion years ago, pulling them into a collision that birthed a new chaotic galaxy.
At the heart of that giant collision-born galaxy are two supermassive black holes — each once at the core of respective progenitor galaxies. The duo are the closest supermassive black hole pairing to Earth ever discovered. Eventually, in around 250 million years, these titanic cosmic monsters will also collide and merge like their parent galaxies, creating an even more massive supermassive black hole, according to a statement from the European Southern Observatory, which operates the telescope used in the research.
The galaxy created by this billion-year-long collision, called NGC 7727, is a tremendous and beautiful example of the long, drawn-out process that two galaxies undergo when they bump into each other.
Related: ‘Cosmic butterfly’ wings shimmer in image of violently colliding galaxies
The galaxy NGC 7727, the product of a cosmic dance between two merging galaxies that began a billion years ago. (Image credit: ESO)
Gravity creates tidal forces that drag out trails of dust, gas and stars from each galaxy, spinning these around the whirling collision. This process erases the shape of each galaxy, wiping their features clear. Although the galaxies and their black holes collide, there is enough distance between the stars that make up galaxies that the stars themselves are spared the destructive effects of the merger. (Stars appear as bright blue-purplish spots in the new image.)
Eventually, the collision process creates a new galaxy with a disordered and asymmetrical shape not resembling either of its predecessors.
The newly released image of NGC 7727, which is located about 89 million light-years from Earth, was captured using Focal Reducer and Low Dispersion Spectrograph 2 (FORS2) instrument, which is part of the Very Large Telescope (VLT) located in northern Chile.
The two galactic nuclei at the heart of the galaxy NGC 7727 contain supermassive black holes that will eventually merge. (Image credit: ESO/Voggel et al.)
While this isn’t the first image of this galactic merger, it shows NGC 7727 in intricate and unprecedented detail, including the faint trails of stripped galactic material that wrap around the galaxy’s main body. These long arms of dust, gas and stars that ripped from each progenitor galaxy long ago surround the galaxy their merger has created, almost creating the illusion of a galactic embrace.
The two bright points visible at the center of NGC 7727 are further evidence of the galaxies’ prior violent cosmic tussle. These are the merging galaxies’ cores, each occupied by its own supermassive black hole, some of the last parts of the galaxy to coalesce.
These two supermassive black holes are currently separated by just 1,600 light-years and will merge in around 250 million years, a tiny amount of time in cosmic terms. The collision will leave behind a black hole even larger than either predecessor is today.
A wider view of galaxy NGC 7727. (Image credit: ESO/VST ATLAS team. Acknowledgement: Durham University/CASU/WFAU)
Although the system is the closest supermassive black hole pairing to Earth yet found, the search for such pairs is set to receive a massive boost later in the 2020s when the Extremely Large Telescope (ELT), also located in the Atacama Desert region of Chile, comes online.
The cosmic dance that created NGC 7727 could also give hints of what will happen in billions of years when our Milky Way galaxy runs into its close cosmic neighbor, the Andromeda galaxy, and the pair begin their own violent merger.
