Of the myriad galaxies we've seen in the night sky, NGC 6240 has always stood out for its peculiar shape and unusual infrared brightness. It was thought to be the result of two galaxies colliding - until now. All the way back in 1983, astronomers reported evidence of a double active nucleus - two active supermassive black holes at the centre of NGC 6240. Now, for the first time, researchers have found evidence of a third supermassive black hole. This new finding suggests that not two, but three galaxies are in the process of merging, each bringing its own supermassive black hole galactic nucleus to the party. "Through our observations with extremely high spatial resolution," explained astrophysicist Wolfram Kollatschny from the University of Göttingen in Germany, "we were able to show that the interacting galaxy system NGC 6240 hosts not two - as previously assumed - but three supermassive black holes in its centre." Since 1983, numerous studies of the galaxy have been conducted, confirming that finding of two active galactic nuclei at the heart of NGC 6240, which lies 300 million light-years away as the photon flies. However, because the supermassive black holes are so close together, exactly where they are within the bright centre has remained elusive. Kollatschny and his team used the MUSE 3D spectrograph mounted on the European Southern Observatory's eight-metre Very Large Telescope in Chile to take high-resolution spectroscopic observations of the galaxy. These images revealed three nodes at the centre of NGC 6240 - one northern component and two southern. However, the new finding doesn't mean the previous research was wrong; the new evidence suggests that only two of the black holes are actively accreting matter, and the third is dormant. Each of the supermassive black holes clocks in at over 90 million times the mass of the Sun (the Milky Way's supermassive black hole, Sagittarius A*, is 4 million solar masses). All three are locked in an orbit in an area less than 1 kiloparsec across (3,260 light-years), slowly spiralling inward towards each other. And the two southern black holes are separated by a distance of just 198 parsecs (645 light-years). niverse," said astrophysicist Peter Weilbacher of the Leibniz Institute for Astrophysics Potsdam in Germany. "The present case provides evidence of a simultaneous merging process of three galaxies along with their central black holes." Earlier this year another triple merger was discovered, with three supermassive black holes in the process of inspiralling at the centre of a galaxy called SDSS J084905.51+111447.2; but that system had separations between each pair of black holes of around 10 kiloparsecs. That the black holes at the centre of NGC 6240 are closer to each other means NGC 6240 is in a later stage of its merger, a process that takes more than a billion years. This more advanced stage also means the galaxy is closer to what is known as the final parsec problem. As we have previously reported, according to theoretical modelling the black holes of two merging galaxies are inexorably drawn together, transferring their orbital energy to the gas and stars around them, and thus orbiting in an ever-tighter spiral. We know that pairs of stellar-mass black holes will eventually come together and form a single object. With supermassive black holes, there's a theoretical problem. As their orbit shrinks, so too does the region of space to which they can transfer energy. By the time they're one parsec apart (around 3.2 light-years), theoretically this region of space is no longer large enough to support further orbital decay, so they remain in a stable binary orbit - potentially for billions of years. This balance is known as the 'final parsec problem'. Triple mergers might be a solution to this problem, since the third black hole could provide the extra kick the objects need to close that final gap. Of course, the black holes at the centre of NGC 6240 won't get anywhere close to that final parsec any time soon - it could take another billion years or two, and who even knows if humanity will be around at that point. But the black holes are expected to be producing gravitational waves. We can't detect them yet, but by studying systems such as these, we may be able to figure out how to detect them with future instruments, and figure out what happens at that last parsec.

There’s a supermassive black hole – 4 million times our sun’s mass – in the center of our Milky Way galaxy. Astronomers who’ve measured star movements near this central black hole are now saying there might be a 2nd companion black hole near it. Do supermassive black holes have friends? The nature of galaxy formation suggests that the answer is yes, and in fact, pairs of supermassive black holes should be common in the universe. I am an astrophysicist and am interested in a wide range of theoretical problems in astrophysics, from the formation of the very first galaxies to the gravitational interactions of black holes, stars and even planets. Black holes are intriguing systems, and supermassive black holes and the dense stellar environments that surround them represent one of the most extreme places in our universe. The supermassive black hole that lurks at the center of our galaxy, called Sgr A*, has a mass of about 4 million times that of our sun. A black hole is a place in space where gravity is so strong that neither particles or light can escape from it. Surrounding Sgr A* is a dense cluster of stars. Precise measurements of the orbits of these stars allowed astronomers to confirm the existence of this supermassive black hole and to measure its mass. For more than 20 years, scientists have been monitoring the orbits of these stars around the supermassive black hole. Based on what we’ve seen, my colleagues and I show that if there is a friend there, it might be a second black hole nearby that is at least 100,000 times the mass of the sun. Supermassive black holes and their friends Almost every galaxy, including our Milky Way, has a supermassive black hole at its heart, with masses of millions to billions of times the mass of the sun. Astronomers are still studying why the heart of galaxies often hosts a supermassive black hole. One popular idea connects to the possibility that supermassive holes have friends. To understand this idea, we need to go back to when the universe was about 100 million years old, to the era of the very first galaxies. They were much smaller than today’s galaxies, about 10,000 or more times less massive than the Milky Way. Within these early galaxies the very first stars that died created black holes, of about tens to thousand the mass of the sun. These black holes sank to the center of gravity, the heart of their host galaxy. Since galaxies evolve by merging and colliding with one another, collisions between galaxies will result in supermassive black hole pairs – the key part of this story. The black holes then collide and grow in size as well. A black hole that is more than a million times the mass of our sun is considered supermassive. If indeed the supermassive black hole has a friend revolving around it in close orbit, the center of the galaxy is locked in a complex dance. The partners’ gravitational tugs will also exert its own pull on the nearby stars disturbing their orbits. The two supermassive black holes are orbiting each other, and at the same time, each is exerting its own pull on the stars around it. The gravitational forces from the black holes pull on these stars and make them change their orbit; in other words, after one revolution around the supermassive black hole pair, a star will not go exactly back to the point at which it began. Using our understanding of the gravitational interaction between the possible supermassive black hole pair and the surrounding stars, astronomers can predict what will happen to stars. Astrophysicists like my colleagues and me can compare our predictions to observations, and then can determine the possible orbits of stars and figure out whether the supermassive black hole has a companion that is exerting gravitational influence. Using a well-studied star, called S0-2, which orbits the supermassive black hole that lies at the center of the galaxy every 16 years, we can already rule out the idea that there is a second supermassive black hole with mass above 100,000 times the mass of the sun and farther than about 200 times the distance between the sun and the Earth. If there was such a companion, then I and my colleagues would have detected its effects on the orbit of SO-2. But that doesn’t mean that a smaller companion black hole cannot still hide there. Such an object may not alter the orbit of SO-2 in a way we can easily measure. The physics of supermassive black holes Supermassive black holes have gotten a lot of attention lately. In particular, the recent image of such a giant at the center of the galaxy M87 opened a new window to understanding the physics behind black holes. The proximity of the Milky Way’s galactic center – a mere 24,000 light-years away – provides a unique laboratory for addressing issues in the fundamental physics of supermassive black holes. For example, astrophysicists like myself would like to understand their impact on the central regions of galaxies and their role in galaxy formation and evolution. The detection of a pair of supermassive black holes in the galactic center would indicate that the Milky Way merged with another, possibly small, galaxy at some time in the past. That’s not all that monitoring the surrounding stars can tell us. Measurements of the star S0-2 allowed scientists to carry out a unique test of Einstein’s general theory of relativity. In May 2018, S0-2 zoomed past the supermassive black hole at a distance of only about 130 times the Earth’s distance from the sun. According to Einstein’s theory, the wavelength of light emitted by the star should stretch as it climbs from the deep gravitational well of the supermassive black hole. The stretching wavelength that Einstein predicted – which makes the star appear redder – was detected and proves that the theory of general relativity accurately describes the physics in this extreme gravitational zone. I am eagerly awaiting the second closest approach of S0-2, which will occur in about 16 years, because astrophysicists like myself will be able to test more of Einstein’s predictions about general relativity, including the change of the orientation of the stars’ elongated orbit. But if the supermassive black hole has a partner, this could alter the expected result. Finally, if there are two massive black holes orbiting each other at the galactic center, as my team suggests is possible, they will emit gravitational waves. Since 2015, the LIGO-Virgo observatories have been detecting gravitational wave radiation from merging stellar-mass black holes and neutron stars. These groundbreaking detections have opened a new way for scientists to sense the universe. Any waves emitted by our hypothetical black hole pair will be at low frequencies, too low for the LIGO-Virgo detectors to sense. But a planned space-based detector known as LISA may be able to detect these waves, which will help astrophysicists figure out whether our galactic center black hole is alone or has a partner. Smadar Naoz, Associate Professor of Physics & Astronomy, University of California, Los Angeles This article is republished from The Conversation under a Creative Commons license. Read the original article. Bottom line: Measurements of star orbits near the massive black hole in the center of the Milky Way galaxy suggest that there may be a second companion black hole nearby.

Were you wondering what galaxy is the Earth in? You’ll probably recognize the answer: it’s the Milky Way Galaxy. If you go to a dark spot, away from the bright city lights, and look up, you should be able to see the Milky Way as a cloudy band stretching across the sky. It really does look like spilt milk spread across the sky. But if you take a telescope and examine it more closely, you’ll see that the clouds are actually the collective light from thousands of stars. Since we’re embedded inside the Milky Way, we’re seeing our home galaxy edge-on, from the inside. To get a better idea, grab a dinner plate and take a look at it edge on, so you can’t see the circular shape of the galaxy. You can only see the edge of the plate. The Milky Way is an example of a barred spiral galaxy. It measures approximately 100,000 light years across and it’s only 1,000 light years thick; although, it’s more thick at the core where the galaxy bulges out. If you could fly out of the Milky Way in a rocket and then look back, you’d see a huge spiral shaped galaxy with a bar at the center. At the ends of this bar, there are two spiral arms which twist out forming the structure of the Milky Way. The Earth is located in the Solar System, and the Solar System is located about 25,000 light-years away from the core of the galaxy. This also means that we’re about 25,000 light-years away from the outer edge of the Milky Way. We’re located in the Orion Spur, which is a minor arm located in between the two major galactic arms.

At the center of our galaxy, a supermassive black hole churns. Learn about the types of black holes, how they form, and how scientists discovered these invisible, yet extraordinary objects in our universe. About National Geographic: National Geographic is the world's premium destination for science, exploration, and adventure. Through their world-class scientists, photographers, journalists, and filmmakers, Nat Geo gets you closer to the stories that matter and past the edge of what's possible.

What if every single black hole that formed in our universe sparked the big bang of a new universe? Cosmological natural selection proposes exactly this - but even better, it claims to be able to test the hypothesis. Physicists have been struggling for some time to figure out why our universe is so comfy. Why, for example, are the fundamental constants - like the mass of the electron or the strength of the forces - just right for the emergence of life? Tweak them too much and life, stars, galaxies, the universe as we know it wouldn’t exist. In recent episodes we explored one possible explanation for this - the anthropic principle and the idea of the multiverse. If there are countless universes with different fundamental constants, then it’s not surprising that a few exist with the right numbers for life - and certainly not surprising that we find ourselves in one of those good ones. But if you don’t like the anthropic principle - and many scientists don’t - then rest assured, there’s an alternative. You only need to accept two things: that our universe formed inside a black hole, and that universes can evolve.

This show was converted to 4K/UHD using an AI program. What do you think? For the best collection of 4k Space-Science content, go to... This SpaceRip classic explores one of the greatest mysteries in modern science: a series of brief but extremely bright flashes of ultra-high energy light coming from somewhere out in space. These gamma ray bursts were first spotted by spy satellites in the 1960s. It took three decades and a revolution in high-energy astronomy for scientists to figure out what they were: black holes at the moment of their birth. Far out in space, in the center of a seething cosmic maelstrom. Extreme heat. High velocities. Atoms tear, and space literally buckles. Photons fly out across the universe, energized to the limits found in nature. Billions of years later, they enter the detectors of spacecraft stationed above our atmosphere. Our ability to record them is part of a new age of high-energy astronomy, and a new age of insights into nature at its most extreme. What can we learn by witnessing the violent birth of a black hole? The outer limits of a black hole, call the event horizon, is subject to what Albert Einstein called frame dragging, in which space and time are pulled along on a path that leads into the black hole. As gas, dust, stars or planets fall into the hole, they form into a disk that spirals in with the flow of space time, reaching the speed of light just as it hits the event horizon. The spinning motion of this so-called "accretion disk" can channel some of the inflowing matter out into a pair of high-energy beams, or jets. How a jet can form was shown in a supercomputer simulation of a short gamma ray burst. It was based on a 40-millisecond long burst recorded by Swift on May 9, 2005. It took five minutes for the afterglow to fade, but that was enough for astronomers to capture crucial details. It had come from a giant galaxy 2.6 billion light years away, filled with old stars. Scientists suspected that this was a case of two dead stars falling into a catastrophic embrace. Orbiting each other, they moved ever closer, gradually gaining speed. At the end of the line, they began tearing each other apart, until they finally merged. NASA scientists simulated the final 35 thousandths of a second, when a black hole forms. Chaos reigns. But the new structure becomes steadily more organized, and a magnetic field takes on the character of a jet. Within less than a second after the black hole is born, it launches a jet of particles to a speed approaching light. A similar chain of events, in the death of a large star, is responsible for longer gamma ray bursts. Stars resist gravity by generating photons that push outward on their enormous mass. But the weight of a large star's core increases from the accumulation of heavy elements produced in nuclear fusion. In time, its outer layers cannot resist the inward pull... and the star collapses. The crash produces a shock wave that races through the star and obliterates it. In the largest of these dying stars, known as collapsars or hypernovae, a black hole forms in the collapse. Matter flowing in forms a disk. Charged particles create magnetic fields that twist off this disk, sending a portion out in high-speed jets. Simulations show that the jet is powerful enough to plow its way through the star. In so doing, it may help trigger the explosion. The birth of a black hole does not simply light up the universe. It is a crucial event in the spread of heavy elements that seed the birth of new solar systems and planets. But the black hole birth cries that we can now register with a fleet of high-energy telescopes are part of wider response to gravity's convulsive power.

At the center of a galaxy more than 55 million light-years away, there's a supermassive black hole with the mass of several billion suns. And now, for the first time ever, we can see it. Astrophysicist Sheperd Doeleman, head of the Event Horizon Telescope collaboration, speaks with TED's Chris Anderson about the iconic, first-ever image of a black hole -- and the epic, worldwide effort involved in capturing it. The TED Talks channel features the best talks and performances from the TED Conference, where the world's leading thinkers and doers give the talk of their lives in 18 minutes (or less). Look for talks on Technology, Entertainment and Design -- plus science, business, global issues, the arts and more.

How would it look to have four suns in the sky? Planets of the HD 98800 system, if they exist, would experience such a view. HD 98800 is a multiple star system about 150 light years from Earth - right in our section of the Milky Way Galaxy. For years it has been known that HD 98800 consists of two pairs of double stars, with one pair surrounded by a disk of dust. Recent data from the Earth-trailing Spitzer Space Telescope in infrared light indicate that the dust disk has gaps that appear consistent with being cleared by planets orbiting in the disk. If so, one planet appears to be orbiting at a distance similar to Mars of our own Solar System. Pictured below is an artist's drawing of how the HD 98800 system might appear to a nearby observer.