A dozen black holes may be 'wandering' through our galaxy — and they're the rarest type in the universe
The Milky Way has millions of small black holes and one giant supermassive black hole at its center . But does the galaxy have any medium-sized black holes? New research suggests the answer is yes: Perhaps a dozen may inhabit the Milky Way, but they are wandering freely through space and are fiendishly difficult to detect.
For decades, researchers have wondered about the prevalence of intermediate-mass black holes (IMBHs). Certainly, every galaxy is capable of producing an enormous number — roughly a handful every century — of small black holes with masses of up to 100 or so times that of the sun. And it appears that when galaxies like the Milky Way first arrived on the cosmic scene, they already had companion supermassive black holes in their hearts. Our own supermassive black hole, Sagittarius A*, has a mass of 4.5 million suns.
But what about the IMBHs? Theoretically, they should have masses of 10,000 to 100,000 solar masses. Finding IMBHs — or disproving their existence — has enormous implications for our understanding of black hole growth and evolution. But so far, there have been only faint, sketchy hints of IMBHs residing in dwarf galaxies, and no direct evidence that they live in a galaxy like the Milky Way.
In April, a team of researchers at the University of Zurich in Switzerland explored whether our current simulations of the universe could conclusively predict if the Milky Way hosts a population of IMBHs. Their paper has been accepted for publication in the journal Monthly Notices of the Royal Astronomical Society.
Related: Is our universe trapped inside a black hole? This James Webb Space Telescope discovery might blow your mind Cannibal galaxies
Galaxies do not grow up alone. Instead, they develop through the cannibalization of their neighbors, by incorporating their stars — and any black holes — within their volumes. The Milky Way has consumed over a dozen dwarf galaxies , and probably many more, in its long history. Presumably, some of those dwarf galaxies held IMBHs. But the common assumption was that large black holes tend to slink down the centers of their host galaxies, where they go on to merge with the central supermassive black hole.
Through their models, the researchers saw a different story unfold. They used a simulation of the evolution of a Milky Way-like galaxy and found that it can contain somewhere between five and 18 'wandering' IMBHs, which are not located near the central core but are left to roam within the disk of the galaxy. The exact number of IMBHs depends on whether they are born near the core of a soon-to-be-consumed dwarf galaxy or in its outskirts.
Get the world's most fascinating discoveries delivered straight to your inbox.
Although the researchers were heartened to find that the Milky Way should host a population of IMBHs, they urged caution in interpreting their results. They could not conclusively state what masses these black holes should have or where they would ultimately reside. So, while the new research strongly hints that IMBHs are out there, we do not yet know where to look.
Hashtags
Try Our AI Features
Explore what Daily8 AI can do for you:
Comments
No comments yet...
Related Articles
CNN
4 hours ago
- CNN
Once inevitable collision between Milky Way and Andromeda galaxies now seems less likely, astronomers say
A collision between our Milky Way galaxy and its largest neighbor, the Andromeda galaxy, predicted to occur in about 4.5 billion years, has been anticipated by astronomers since 1912. But new research suggests that the likelihood of this galactic clash, dubbed 'Milkomeda,' is smaller than it seems. At first glance, it appears likely that the galactic duo — separated by about 2.5 million light-years — is on an inevitable collision course. The Milky Way and Andromeda are barreling toward each other at about 223,694 miles per hour (100 kilometers per second). However, the Local Group, or our corner of the universe, includes 100 known smaller galaxies. A team of astronomers factored in some of the largest among them, including the Large Magellanic Cloud, or LMC, and M33, or the Triangulum galaxy, to see how much of a role they might play on the chessboard of our galaxy's future over the next 10 billion years. After factoring in the gravitational pull of Local Group galaxies and running 100,000 simulations using new data from the Hubble and Gaia space telescopes, the team found there is about a 50% chance of a collision between the Milky Way and Andromeda in the next 10 billion years. There is only about a 2% chance the galaxies will collide in 4 to 5 billion years as previously thought, according to the study published Monday in the journal Nature Astronomy. A merger of the Milky Way and Andromeda galaxies would destroy them both, eventually turning both spiral structures into one elongated galaxy, the study authors said. Collisions between other galaxies have been known to create 'cosmic fireworks, when gas, driven to the center of the merger remnant, feeds a central black hole emitting an enormous amount of radiation, before irrevocably falling into the hole,' said study coauthor Carlos Frenk, professor at Durham University in England. 'Until now we thought this was the fate that awaited our Milky Way galaxy,' Frenk said. 'We now know that there is a very good chance that we may avoid that scary destiny.' However, there are many unknown factors that make it difficult to predict the ultimate fate of our galaxy, according to the study authors. And, Frenk warns, the Milky Way has a greater chance of colliding with the LMC within 2 billion years, which could fundamentally alter our galaxy. The LMC orbits the Milky Way, while M33 is a satellite of Andromeda. The LMC's mass is only about 15% of the Milky Way's. But the team found that the satellite galaxy has a gravitational pull, perpendicular to Andromeda, that changes the Milky Way's motion enough to reduce the chance of a merger between the two giant galaxies. It's a similar case for M33. 'The extra mass of Andromeda's satellite galaxy M33 pulls the Milky Way a little bit more towards it,' said lead study author Dr. Till Sawala, astronomer at the University of Helsinki in Finland. 'However, we also show that the LMC pulls the Milky Way off the orbital plane and away from Andromeda. It doesn't mean that the LMC will save us from that merger, but it makes it a bit less likely.' Previous research also has assumed most likely values for unknown data, such as the uncertainties in the present positions, motions and masses of the Local Group galaxies. In the new study, the team accounted for 22 different variables, including those unknowns, that could contribute to a collision. 'We ran many thousands of simulations, which allowed us to account for all the observational uncertainties,' Sawala said. 'Because there are so many variables that each have their errors, that accumulates to rather large uncertainty about the outcome, leading to the conclusion that the chance of a direct collision is only 50% within the next 10 billion years.' In just over half of the simulations predicting what could occur in 8 to 10 billion years, the Milky Way and Andromeda galaxies initially sailed somewhat closely past each other before circling back and then losing enough orbital energy to collide and merge as one galaxy. These initial close encounters between each galaxy's halo — a large envelope of gas — would eventually lead to a collision. 'In general, the merger would most likely involve a strong starburst, during which many new stars would form, followed by a period of intense radiation caused by exploding young stars and the newly active supermassive black hole, eventually shutting down star formation completely,' Sawala said. 'A few billion years later, any traces of the former Milky Way and Andromeda would disappear, and the remnant would be a largely featureless elliptical galaxy.' In the other simulations, both galaxies crossed paths without disturbing each other. Geraint Lewis, a professor of astrophysics at the University of Sydney's Institute for Astronomy, finds the results showing the gravitational influence of M33 and the LMC interesting. He has previously authored research on a potential collision between Andromeda and the Milky Way. 'We won't know if the collision is definitely off in the future, but this clearly shows that the story that people tell — that there will be a collision that will destroy the Milky Way and Andromeda — is not as clear or certain that people think,' Lewis said. 'But even if there is a pretty close encounter rather than smashing head-on, the gravitational tearing that each will assert on each other is likely to leave the two large galaxies in a sorry state.' While including the LMC's gravitational effects on the Milky Way is important, accounting for uncertainties is the most important aspect of the new study, said Scott Lucchini, a postdoctoral fellow in the Institute for Theory and Computation at the Center for Astrophysics, Harvard & Smithsonian. 'Here, they've sampled from the uncertainties in the positions, velocities, and masses of the galaxies to obtain the relative probabilities of different outcomes,' Lucchini wrote in an email. 'This really gives us the whole picture of what could happen in the future.' Galaxies are full of intricacies. Their shapes can become distorted, interactions can change their orbits and they can lose mass in different ways. Such complexities make predictions difficult, Lucchini said. That essentially leaves the fate of the Milky Way 'completely open,' the study authors wrote in the new paper. However, more data coming from the Gaia space telescope in the summer of 2026 will provide measurements that refine some of the uncertainties about the speed and direction at which Andromeda is moving across the sky, Sawala said. The fate of the sun may have a bigger impact on Earth's future than the motions of galaxies, according to the researchers. Our sun is 4.5 billion years old. When it starts to die in another 5 billion years, it will swell into a red giant that engulfs Mercury, Venus and potentially Earth, according to NASA. 'The short answer is that the end of the sun is far worse for our planet than the collision with Andromeda,' Sawala said. 'While that merger would mean the end of our galaxy, it would not necessarily be the end of the sun or the Earth. Although our work also shows that earlier studies, that purported to predict precisely what the fate of the solar system would be after the merger, were clearly premature, in general, collisions between stars or planets are extremely rare during galaxy mergers. And while the end of the sun is certain, our study shows that the end of the galaxy is anything but.' While the team didn't model a merger between the LMC and the Milky Way in detail, they found a 'virtual certainty' that a merger between the two galaxies will occur within the next 2 billion years, which aligns with previous research, Sawala said. But the effects will likely be more minor than a merger between the Milky Way and Andromeda. 'The merger (between the Milky Way and the LMC) will not destroy our galaxy but it will change it profoundly, particularly impacting our central supermassive black hole and the galactic halo,' Frenck wrote in an email. He also served as a coauthor on a 2019 paper on the potential merger.
USA Today
8 hours ago
- USA Today
First quarter moon will grace the sky on June 2. How to catch a glimpse.
First quarter moon will grace the sky on June 2. How to catch a glimpse. Show Caption Hide Caption James Webb captures Jupiter's shimmering aurora NASA'S James Webb Space Telescope captured new details of auroras on Jupiter. Half of the moon will be illuminated as it reaches its first quarter phase on Monday, June 2. The first quarter phase marks the quarter point on the moon's monthly journey, according to NASA. During this position, the moon's illuminated side is half-lit, according to the agency. A first-quarter moon is ideal for observing here on Earth, NASA says, because it rises in the afternoon — around noon — and is high above the horizon in the evening before setting around midnight. Here's what to know about the first quarter phase and how to best view the moon. What is the moon's first quarter phase? The moon has both a day and night side, with the sun always illuminating half of the moon. The portion of the illuminated half changes as the moon travels through its orbit. First quarter is the third phase of the moon's eight lunar phases. The cycle repeats about every 29.5 days, according to NASA. During the first quarter phase, one half of the moon will appear illuminated by direct sunlight, per NASA. However, even though the moon is half-visible from Earth during first quarter, it's not actually a half moon. According to NASA, during first quarter, only half of the moon's illuminated half is visible on Earth. A full moon is technically a half moon, because the sun is illuminating the full day side of the moon during that phase, per NASA. When will the moon be half-lit? According to NASA, the moon will reach first quarter, or 50% illuminated, just before 11 p.m. EST, in the Northern Hemisphere on June 2. The exact timing will differ based on location. On the East Coast, the moon is expected to be at first quarter around 11:40 p.m. EST, according to The next first quarter phase will be on July 2, according to NASA. How to see a first quarter moon The moon's first quarter phase will be visible here on Earth. For those looking to catch a glimpse, NASA recommends a set of binoculars or a telescope, which will highlight the moon's texture and terrain. However, bare eyes also work. With no tools on hand, NASA says to look carefully and give your eyes time plenty of time to adjust — what you can see will vary based on your eyesight. When eyeballing the moon, you'll mostly see areas of either white or gray. The gray patches, called lunar maria or seas, are solidified volcanic lavas, according to NASA. NASA has a daily viewing guide which highlights the lunar maria that you may be able to see from Earth. Melina Khan is a national trending reporter for USA TODAY. She can be reached at
Yahoo
8 hours ago
- Yahoo
Signs Of Alien Life? New Study Finds Potential Biosignatures On Ocean World
Data from the James Webb Space Telescope on exoplanet K2-18b has revealed the "strongest hints yet of biological activity outside the solar system," according to a University of Cambridge study. Credit: | animations: ESA/Hubble, M. Kornmesser / NASA | edited by Steve Spaleta
