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5 days ago
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The James Webb Telescope May Have Found Primordial Black Holes
JWST observations of light sources before the first galaxies should have formed are raising new questions about our galactic origins Since its launch in late 2021, the James Webb Space Telescope (JWST) has been glimpsing some of the earliest epochs of cosmic time. Its observations have stretched cosmologists' timelines of when galaxies may have first started to form. And now some of the telescope's farthest observations yet have revealed sources of blue ultraviolet light from an epoch when stars shouldn't have existed yet. The observations indicate nine new light sources, with six at redshift 17 and three at redshift 25, when the universe was only 200 million to 100 million years old. 'It's the deepest by a factor of a few compared to any other data obtained by JWST in the whole mission,' says Pablo G. Pérez-González, an astrophysicist at the Center for Astrobiology in Madrid. He is lead author of a preprint paper reporting the findings that has been accepted for publication in the Astrophysical Journal. 'If we confirm that they are truly at those redshifts, the universe was much, much more active its first 200 million years' than astronomers had thought, Pérez-González says. [Sign up for Today in Science, a free daily newsletter] If accurate, the newly sighted objects don't merely expand the timeline of galaxy formation back to a much earlier period; they sit in direct conflict with astronomers' best cosmological models of when stars began to form during the cosmic dawn. For this reason, another group of astronomers have put forward a hypothesis to make sense of these puzzling findings. They have proposed that 'primordial' black holes created right after the big bang may have lit up the universe before the first stars. Their preprint paper has been accepted for publication in the journal Astronomy & Astrophysics. "If stars cannot explain the source of the luminosity and the numbers that we see, something else should be producing the light,' says Andrea Ferrara, an astrophysicist at the Superior Normal School (SNS) in Pisa, Italy, and co-author of the first paper. 'This can only be a primordial black hole.' In other words, it's possible that the first objects to bathe the early universe in light were not stars but rather hungry black holes that burst into existence mere seconds after the big bang itself. The Trouble with Early Galaxies The farther we peer out to our cosmic horizons, the further back in time we see. And because the universe itself is expanding, light traveling from extremely distant sources has stretched its wavelength all the way to the infrared part of the electromagnetic spectrum. This phenomenon is what astrophysicists refer to as redshift. The higher the redshift of a distant object is, therefore, the further back in time you are looking. Before JWST, the highest confirmed redshifted galaxy astronomers had observed was at redshift 9, when the universe was 600 million to 500 million years old. For the first couple of years after its launch, JWST spent a significant amount of its time confirming previously identified galaxies that had been observed by the Hubble Space Telescope (HST). Variables such as the concentration of dark matter—an invisible gravitational source that outweighs visible matter in the universe by six to one—and the necessary conditions needed for star formation provide cosmologists with constraints to determine a rough timeline for the evolution of galaxies in the early universe. But after the summer of 2022, as JWST began revealing galactic candidates at earlier epochs, astronomers started to realize something wasn't quite making sense. 'JWST is finding too many too massive galaxies too early in the universe,' says astrophysicist Allison Kirkpatrick of the University of Kansas, who specializes in galaxy evolution and was not involved in the new studies. To date, the oldest confirmed galaxies observed by JWST are at redshift 14, when the universe was only 300 million years old. 'So the idea here was to go beyond that, to redshift 15 and beyond,' Pérez-González says, "in search of the very first galaxies ever formed.' His team's report of nine new objects at even higher redshifts will need confirmation. To determine whether the objects are as far as they seem to be, astronomers must break up their light into specific wavelengths in a process called spectroscopy. Drawing on data collected by JWST's Near Infrared Camera (NIRCam) over two imaging surveys, Pérez-González and his team identified the new candidate galaxies from a pool of more than 80,000. After imaging a region of the sky with different filters for more than 100 hours, the astronomers were able to identify galaxies at different brightnesses and select the most promising candidates for further observation. Casting a wide net means their sample is less likely to be biased before they zoom in on the most interesting distant objects. The suspected galaxies Pérez-González and his team found shine with bright blue light in the ultraviolet range of the spectrum—exactly the light astronomers believe the massive first stars would have produced. The problem with this scenario, however, is that galaxy evolution models have an extremely tough time producing stars at such early stages of the universe's development. It's doubtful that this time frame would have allowed enough time for gas to cool and gather into clouds large enough to gravitationally collapse into the first generation of stars. 'Galaxies cannot form quickly because the gas in the early universe is very hot, preventing it from collapsing into galaxies and stars,' Kirkpatrick says. 'Instead dark matter structure grows first, and the immense gravity funnels gas to the center to grow the first stars and galaxies. This all takes time, more time than 100 million years.' Black Holes from the Very Beginning To get around this problem, Ferrara and his collaborators propose that primordial black holes—a distinct population of black holes that may have emerged in the first few seconds after the big bang—were consuming gas in the early universe. This feeding frenzy could have released light that we are now detecting with JWST at periods before the first stars formed. Bizarrely, black holes, not stars, might have been the first significant sources of light in the early universe. Typically, black holes form when massive stars collapse after they run out of fuel or when a large cloud of gas directly collapses in on itself, bypassing the stellar phase. Primordial black holes, however, are different. 'What we are proposing is that primordial black holes formed less than one second to five seconds after the big bang,' Ferrara says. 'These have been essentially there forever, from the beginning.' Initially, these black holes would have started out small, 'no larger than the size of an atom,' Kirkpatrick says. Scientists think that within the first second of the universe as we know it bursting into existence, a rapid period of expansion, known as inflation, caused space to increase in size by 35 orders of magnitude, equivalent to an atom stretching to the size of the solar system. 'This has a lot of consequences, including the creation of very small black holes,' Kirkpatrick says. Although starting out tiny, after 100 million years, these black holes may have swelled to 10,000 times the mass of the sun, Ferrara and his team suspect. When gas gets near a black hole, it gets heated to scorching temperatures, and this superheated matter emits light. From a distance, it might look similar to the atmosphere of a star. For this reason, the difference between the primordial black hole explanation and the stellar explanation, based on the current imaging data, is nearly impossible to disentangle. But there may be other clues. One way to distinguish if these light sources are primordial black holes or first-generation stars would be to look at the sizes of galaxies. If they appear more pointlike, then the primordial black hole explanation would make more sense because a massive black hole is still tiny compared with a whole galaxy. But if the light sources are diffuse and extended, then they might be more likely to be stars. "So we measured the sizes, and some of the candidates are, to the best of our knowledge with the data that we have, pointlike but not all of them. Some of them are extended. So maybe 30 percent of them are consistent with what a primordial black hole might look like," Pérez-González says. Right now the data are hardly definitive. Because primordial black holes have hypothetically been around since the very beginning of the universe, they should also leave traces in the cosmic microwave background (CMB), a snapshot of the universe as it existed 380,000 years after the big bang. 'Our pictures of the CMB maps are still a little bit too blurred in order to see the fine-structure details that primordial black holes may have introduced,' Ferrara says. For now, a definitive answer is just beyond reach. The possible presence of primordial black holes may, however, make sense of another cosmological conundrum: the existence of supermassive black holes at the centers of galaxies at early epochs. 'We haven't yet proved how the first supermassive black hole seeds form, and this could be one pathway. It would help resolve some of the tension with JWST observations and cosmological models,' Kirkpatrick says. 'These observations are difficult, and we are pushing the JWST to its limit,' Ferrara says. 'We have to be careful because maybe these galaxies could turn out to be contaminants or lower-redshift galaxies or something else.' But whether these mysterious black beacons outshone the first stars is a question we may soon have an answer to. It's Time to Stand Up for Science Before you close the page, we need to ask for your support. 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Yahoo
22-06-2025
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Scientists Working to Decode Signal From Earliest Years of Universe
As mysterious as the Big Bang that gave birth to the universe is the brief but tumultuous period that immediately followed it. How did the cosmos transform from a uniform sea of darkness into a chaotic swirl brimming with radiant stars? What were these first stars like, and how were they born? So far, we have very strong suspicions, but no hard answers. One reason is that the light from this period, called the cosmic dawn, is extremely faint, making it nearly impossible to infer the traits of these first cosmic objects, let alone directly observe them. But that's about to change, according to a team of international astronomers. In a new study published in the journal Nature Astronomy, the astronomers argue that we're on the verge of finally decoding a radio signal that was emitted just one hundred millions years after the Big Bang. Known as the 21 centimeter signal, which refers to its distinct wavelength, this burst of radiation was unleashed as the inchoate cosmos spawned the earliest stars and black holes. "This is a unique opportunity to learn how the universe's first light emerged from the darkness," said study co-author Anastasia Fialkov, an astronomer from the University of Cambridge in a statement about the work. "The transition from a cold, dark universe to one filled with stars is a story we're only beginning to understand." After several hundred thousand years of cooling following the Big Bang, the first atoms to form in the universe were overwhelmingly neutral hydrogen atoms made of one positively charged proton and one negatively charged electron. But the formation of the first stars unbalanced that. As these cosmic reactors came online, they radiated light energetic enough to reionize this preponderance of neutral hydrogen atoms. In the process, they emitted photons that produced light in the telltale 21 centimeter wavelength, making it an unmistakeable marker of when the first cosmic structures formed. Deciphering these emissions would be tantamount to obtaining a skeleton key to the dawn of the universe. And drum roll, please: employing the Radio Experiment for the Analysis of Cosmic Hydrogen telescope, which is currently undergoing calibration, and the enormous Square Kilometer Array, which is under construction Australia, the researchers say they've developed a model that can tease out the masses of the first stars, sometimes dubbed Population III stars, that are locked inside the 21 centimeter signal. While developing the model, their key revelation was that, until now, astronomers weren't properly accounting for the impact of star systems called x-ray binaries among these first stars. These are systems where a black hole or neutron star is stripping material off a more ordinary star that's orbiting it, producing light in the x-ray spectrum. In short, it appears that x-ray binaries are both brighter and more numerous than what was previously thought. "We are the first group to consistently model the dependence of the 21-centimeter signal of the masses of the first stars, including the impact of ultraviolet starlight and X-ray emissions from X-ray binaries produced when the first stars die," said Fialkov. "These insights are derived from simulations that integrate the primordial conditions of the universe, such as the hydrogen-helium composition produced by the Big Bang." All told, it's another promising leap forward in the field of radio astronomy, where recent advances have begun to reveal an entire "low surface brightness" universe — and a potentially profound one as well, with the promise to illuminate our understanding of the cosmic dawn as never never before. "The predictions we are reporting have huge implications for our understanding of the nature of the very first stars in the universe," said co-author Eloy de Lera Acedo, a Cambridge astronomer and a principal investigator of the REACH telescope. "We show evidence that our radio telescopes can tell us details about the mass of those first stars and how these early lights may have been very different from today's stars." More on astronomy: Scientists Investigating Small Orange Objects Coating Surface of the Moon
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14-06-2025
- Science
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Science news this week: Overdue earthquakes and star-shaped brain cells
When you buy through links on our articles, Future and its syndication partners may earn a commission. This week's science news saw us looking deep into the cosmos and the depths of our oceans. To understand the universe today, we need to look back at its earliest epoch, a period about 13 billion years ago known as the cosmic dawn. Until now, space-based telescopes have been our only way to peer back this far, but this week astronomers detected traces of light left by the first stars using a ground-based telescope — a feat scientists previously thought was impossible. From deep space to the deep ocean, researchers uncovered more secrets about the "world's richest shipwreck" off the Colombian coast, while other scientists captured a haunting blood-red squid on camera for the first time. Meanwhile, while researchers have spotted some remarkable things underwater, something that should normally live there recently turned up in a very unexpected place. From clearing cellular debris to regulating blood flow, star-shaped brain cells known as astrocytes are crucial to keeping your brain healthy, but a new study shows that they could also play a key role in how the brain stores memories. While neurons were once thought to be the brain's sole architects of thought and memory, scientists have used machine learning to understand how astrocytes behave when neurons interact with each other to form connections. They found that astrocytes help store memories through changes in calcium-based signals they send within and between cells, and in turn, these calcium signaling patterns get sent to neurons and tune their activity. Discover more health news —New menstrual pad device tracks period blood for signs of disease —There's a new blood test for Alzheimer's. Here's everything you need to know about it. —HIV/AIDS: Facts about the viral infection that attacks the immune system From hunting prey to finding mates and avoiding predators, the ability to detect odors is crucial for survival in the animal kingdom. But which species reigns supreme when it comes to smelling? —If you enjoyed this, sign up for our Life's Little Mysteries newsletter Earthquakes are notoriously difficult to predict, but a recent study suggests that California's faults are overdue for some quakes. By studying the interval between earthquakes on faults in five quake-prone regions with a long geological record, geoscientists worked out which ones were "overdue" for a quake. While faults in most of these regions were less than 20% overdue, that rocketed to about 45% in the case of the Golden State. Read more planet Earth news —Hidden layer beneath Italy's Campi Flegrei caldera may explain why it's so restless —Russian scientists discover a new island in the Caspian Sea — the world's largest inland body of water —Earth's oceans are a 'ticking time bomb' as acidity levels enter 'danger zone,' study suggests —'Lost Colony' of Roanoke may have assimilated into Indigenous society, archaeologist claims — but not everyone is convinced —IBM will build monster 10,000-qubit quantum computer by 2029 after 'solving science' behind fault tolerance — the biggest bottleneck to scaling up —Ancient DNA from Papua New Guinea reveals centuries of genetic isolation —Roman-era 'fast food' discovered in ancient trash heap on Mallorca —Alan Turing's seminal papers, almost destroyed by a shredder, head to auction Bariatric surgery is an extremely effective weight-loss treatment, but in addition to reducing people's body weights, the procedure is often tied to improvements in mental health. A new study suggests that these improvements may hinge not on the amount of weight lost, but rather on patients experiencing less weight stigma after the surgery. "Weight stigma" refers to negative attitudes, biases and beliefs people hold about those with overweight or obesity; some of those biases stem from the misconception that controlling one's weight is merely a matter of willpower. Among the patients included in the new study, most reported experiencing less stigmatization after bariatric surgery, along with better physical and mental health. A smaller subset of patients continued to experience stigma after their procedures and were then at higher risk of poor mental health and disordered eating. The study fills a "gap" in our understanding of factors that can affect patients' outcomes after these surgeries, which are growing more common. If you're looking for something a little longer to read over the weekend, here are some of the best long reads, book excerpts and interviews published this week. —The best time to see the Milky Way is fast approaching! How to see our galaxy at its best in June [Skywatching] —28 gorgeous nebula photos that capture the beauty of the universe [Picture gallery] —Summer solstice 2025: When is the solstice, why does it happen, and how do cultures celebrate? [Explainer] —Last minute Father's Day deals on telescopes, binoculars and cameras [Deals] This week we were treated to a part of the sun that no one has ever set eyes on before — the solar south pole. Dipping to an angle 17 degrees below the solar equator, the European Space Agency's (ESA) Solar Orbiter captured images of the star's south pole using a large band of visible and ultraviolet wavelengths, bringing to life the tangled web of the sun's magnetic field and chemical elements as they travel on enormous plumes of plasma. These new images will enable scientists to better understand solar wind, space weather and the cycle of the sun's shifting magnetic field. "Today we reveal humankind's first-ever views of the Sun's pole," Carole Mundell, ESA's director of science, said in a statement. "These new unique views from our Solar Orbiter mission are the beginning of a new era of solar science." Want more science news? Follow our Live Science WhatsApp Channel for the latest discoveries as they happen. It's the best way to get our expert reporting on the go, but if you don't use WhatsApp we're also on Facebook, X (formerly Twitter), Flipboard, Instagram, TikTok, Bluesky and LinkedIn.
