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Business Mayor
22-05-2025
- Science
- Business Mayor
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.
Yahoo
26-03-2025
- Science
- Yahoo
'Very rare' black hole energy jet discovered tearing through a spiral galaxy shaped like our own
When you buy through links on our articles, Future and its syndication partners may earn a commission. Nearly a billion light-years away, a massive spiral galaxy is screaming into the void. The behemoth, nicknamed J2345-0449, is a giant radio galaxy, or "super spiral" galaxy roughly three times the size of the Milky Way. Like our own spiral galaxy, it harbors a supermassive black hole at its center. But unlike the Milky Way's center, J2345-0449's supermassive black hole emits powerful radio jets — streams of fast-moving charged particles that emit radio waves — stretching more than 5 million light-years long. Though scientists don't yet know what fuels the radio jets, a new study, published March 20 in the Monthly Notices of the Royal Astronomical Society, hints at how giant spiral galaxies could form. Such strong radio jets are "very rare for spiral galaxies," Patrick Ogle, an astronomer at the Space Telescope Science Institute in Baltimore, who was not involved in the study, told Live Science. "In general, they can have weak radio jets, but these powerful radio jets typically come from massive elliptical galaxies. The thought behind that is that to power these really big jets requires a very massive black hole, and one that's probably also spinning. So most spiral galaxies don't have massive enough black holes in the centers to create big jets like this." Related: Supermassive black hole at the heart of the Milky Way is approaching the cosmic speed limit, dragging space-time along with it Data from the Hubble Space Telescope, the Giant Metrewave Radio Telescope, and the Atacama Large Millimeter Array suggest that the radio jets currently prevent stars from forming near the galaxy's center. That's likely because the jets heat up nearby gases so much that they can't collapse into new stars — or push them out of the galaxy entirely. Though both J2345-0449 and the Milky Way are spiral galaxies, it's unlikely that we'll observe these powerful jets in our galactic hometown. "This galaxy is so different from the Milky Way," Ogle said. "It's a lot bigger, and the black hole is a lot more massive." Sagittarius A*, the supermassive black hole at the center of the Milky Way, is likely too small to produce radio jets as powerful as the ones observed in J2345-0449, Ogle told Live Science. Still, studying these rare galaxies could help scientists understand how the growth of supermassive black holes and of their host galaxies are related. Based on the shape of the group of stars at the center of the galaxy, it's possible that this black hole and its massive host galaxy have grown together in relative isolation, rather than gaining their mass from galaxy mergers. RELATED STORIES —Could the secret of supermassive black holes lie in ultralight dark matter? —Supermassive black holes in 'little red dot' galaxies are 1,000 times larger than they should be, and astronomers don't know why —Supermassive black hole spotted 12.9 billion light-years from Earth — and it's shooting a beam of energy right at us In the future, detailed studies of the galaxy's supermassive black hole could also explain what powers its massive radio jets. "The extreme rarity of such galaxies implies that whatever physical process had created such huge radio jets in J2345-0449 must be very difficult to realize and maintain for long periods of time in most other spiral/disc galaxies," the researchers wrote in the study. "Understanding these rare galaxies could provide vital clues about the unseen forces governing the universe," study co-author Shankar Ray, an astrophysicist at Christ University, Bangalore, said in a statement. "Ultimately, this study brings us one step closer to unravelling the mysteries of the cosmos, reminding us that the universe still holds surprises beyond our imagination."
Yahoo
23-03-2025
- Science
- Yahoo
Scientists detect record-setting explosion outside our galaxy
When you buy through links on our articles, Future and its syndication partners may earn a commission. Groundbreaking observations of a repeating explosion in space, the recurrent nova LMCN 1968-12a, reveal that it's the hottest burst of its kind ever recorded. Located in the Large Magellanic Cloud, a nearby satellite galaxy of the Milky Way, LMCN 1968-12a is the first recurrent nova outside our galaxy to have been studied in near-infrared light. Beyond its extreme temperatures, this nova is also notable for being an extremely violent eruption with unique chemical properties that differ significantly from those observed in our galaxy, the researchers explained in a paper published in the journal Monthly Notices of the Royal Astronomical Society. When a white dwarf, the leftover core of a collapsed star, is in a tight orbit around another star, it can pull material from that star, leading to some pretty dramatic astronomical events. One of these is called a nova, which means "new" in Latin. This event results in a bright flash in the sky, as if a new star had appeared, and lasts a few weeks or months before fading. When the dust clears, the original stars remain (unlike in a supernova, which happens when a star is completely destroyed). In the binary system, as the white dwarf steals gas from its younger companion, the accumulated material forms an accretion disk around the white dwarf. Matter swirls in the disk, and when it reaches the white dwarf's surface and piles up, the pressure and temperature rise so high that it ignites a rapid burning of hydrogen into heavier elements. This is known as a thermonuclear runaway reaction. Related: Scientists find evidence of 'supernova graveyard' at the bottom of the sea — and possibly on the surface of the moon This reaction produces a high-energy blast that expels a huge chunk of material from the white dwarf's surface — resulting in a nova. The nova is called "recurrent" when the white dwarf continues to pull more material from its companion, causing similar short-lived bursts of energy at regular intervals ranging from a few months to several years apart. Not many recurrent novas have been observed in our galaxy, and even fewer have been found outside the Milky Way. Studying novas helps astronomers understand the dynamics of binary systems and the influence of surrounding conditions on these eruptions. LMCN 1968-12a was the first recurrent nova to be found outside our galaxy. Discovered in 1968, the system consists of a white dwarf and a red subgiant star. It erupts every four years, and its eruptions have been observed regularly since 1990. The most recent eruption occurred in August 2024. Following the initial observations, the Magellan Baade telescope and the Gemini South telescope — both in Chile — carried out follow-up observations of LMCN 1968-12a in near-infrared light nine days and 22 days after the outburst, respectively. The observations showed the light emitted by various elements that became highly energized during the eruption. The spectra from the Magellan telescope revealed a clear spike in ionized silicon that was 95 times brighter than the light emitted by the sun added up across all of its wavelengths. A similar dominance of silicon was seen in the spectra from Gemini, although the brightness was lower. The brightness of silicon was unexpected, said study co-author Tom Geballe, an astronomer emeritus at NOIRLab, and the missing spikes were even more surprising. "We would've expected to also see signatures of highly energized sulfur, phosphorus, calcium and aluminum," Geballe said in a statement. Study co-author Sumner Starrfield, Regents professor of astrophysics at Arizona State University, added, "This surprising absence, combined with the presence and great strength of the silicon signature, implied an unusually high gas temperature, which our modeling confirmed." According to the team's estimates, this is one of the hottest novas ever recorded, with the temperature of the expelled gas reaching 5.4 million degrees Fahrenheit (3 million degrees Celsius). The highly violent eruption, indicated by such extreme temperatures, suggests a connection to the conditions surrounding the nova. The Large Magellanic Cloud has a lower metallicity than our galaxy, meaning it contains fewer elements heavier than hydrogen and helium. This results in a greater buildup of matter on the white dwarf's surface before ignition, leading to more violent nova explosions. RELATED STORIES —1st supernovas may have flooded the early universe with water — making life possible just 100 million years after the Big Bang —'We had less than a 2% chance to find this': James Webb telescope uncovers baffling 'Big Wheel', one of the most massive galaxies in the early universe —Did a supernova 6 million years ago kickstart evolution in Africa? New study offers a clue By contrast, in high-metallicity systems, heavy elements alter the process. Moreover, the ejected gas collides with the companion star's atmosphere, creating a shock that raises temperatures. Starrfield predicted that low-metallicity material would cause more-intense nova events, and the observations have come through. The study authors emphasized that using large telescopes like Gemini South to study different galaxies will enhance our understanding of these processes in various chemical environments.
Yahoo
14-03-2025
- Science
- Yahoo
Distant star explosions could have wiped out life on Earth twice
Most people know the theory that an asteroid smashed into Earth — hitting what is now the Yucatán Peninsula — and killed off many of the dinosaurs about 66 million years ago. But that was not the only mass extinction for the planet — just the most well-known. Scientists believe at least five mass extinctions have occurred in the past 500 million years, and not all of them were caused by menacing space rocks. Perhaps two of them, one 372 million years ago and another 445 million years ago, were ice ages. A new study, based on a census of stars in the Milky Way, suggests those periods of severely cold climates may have begun with stars dying light-years away. "If a massive star were to explode as a supernova close to the Earth, the results would be devastating for life on Earth," said Nick Wright, an astrophysicist at Keele University in the United Kingdom, in a statement. "This research suggests that this may have already happened." SEE ALSO: Hubble sees mini galaxies surrounding Andromeda are pretty wild A fossil of a type of brachiopod, Floweria chemungensis, went extinct in the late Devonian period. Credit: Andrew Bush / National Science Foundation Previous research has yet to determine the cause for either the late Devonian or Ordovician mass extinctions, which occurred 372 and 445 million years ago, respectively. The Ordovician extinction is thought to have killed off about 60 percent of the invertebrate sea creatures at a time when most of Earth's species lived in the ocean; the late Devonian event eliminated 70 percent of all creatures and influenced sweeping changes in the kinds of fish that survived. Scientists have suspected these ice ages followed damage to the ozone layer. Crucially, the team working on the census says supernovas could have triggered the catastrophic changes in Earth's protective atmosphere. The rate of supernovas near Earth is consistent with the timing of both mass extinctions. The team's findings appear in the Monthly Notices of the Royal Astronomical Society. A supernova is a cataclysmic stellar death that leaves behind a black hole or neutron star. It is the biggest, brightest, and most violent type of explosion scientists have observed in the universe. These cosmic blasts are element factories, NASA says: They create carbon, for instance, the same chemical on which humans and much of life on Earth are based. They spread calcium and iron, the same stuff found in bones and blood, across interstellar space. This dispersal seeds new generations of stars and planets. This is what astronomer Carl Sagan meant when he said we're made of "star stuff." The same substances composing our bodies were literally forged within the cores of stars, then flung through the cosmos when they died. It's a great paradox then that supernovas could be both creators and destroyers of life, the authors observed. "Supernova explosions bring heavy chemical elements into the interstellar medium, which are then used to form new stars and planets," said Alexis Quintana, lead author, in a statement. "But if a planet, including the Earth, is located too close to this kind of event, this can have devastating effects." A nearby supernova's blast of various forms of radiation could strip away the ozone layer. By "near," the experts mean within 65 light-years or so. Without the ozone, Earth would be exposed to harmful ultraviolet radiation from the sun and acid rain. Betelgeuse, about 650 light-years away from Earth, is one of the brightest stars in the night sky. Credit: Alan Dyer / VWPics / Universal Images Group via Getty Images Using models that estimate how stars evolve and emit light at different wavelengths, the team analyzed data from large sky surveys, including data from the European Space Agency's recently retired Gaia mission. The census involved nearly 25,000 so-called "OB stars" — very hot, massive stars — within 1,000 parsecs, or roughly 3,260 light-years, of the sun. These stars are so hot, they're at least double the sun's surface temperature. This census allowed the scientists to calculate the rate of supernovas in the local region of the galaxy and throughout the Milky Way as a whole. According to the team's calculations, about one supernova happens every 400 million years within close enough vicinity to Earth that its radiation could impact the atmosphere. The nearest stars that could blow within the next million years are thought to be Antares and Betelgeuse. If that gives you chills, don't worry: Both stars are more than 500 light-years away — far enough that their blasts wouldn't likely trigger an ice age.
