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Tag: dark matter

  • First breathtaking images from Euclid telescope’s map of the universe

    First breathtaking images from Euclid telescope’s map of the universe

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    New Scientist. Science news and long reads from expert journalists, covering developments in science, technology, health and the environment on the website and the magazine.

    The interaction between two distant galaxies, captured by Euclid

    ESA

    A mosaic of images from the European Space Agency’s Euclid space telescope captures more than 14 million galaxies, offering a first glimpse of a “cosmic atlas”. The mapping project could add to our understanding of the role dark matter and dark energy play in the structure of the universe.

    “The scale is utterly incomprehensible,” Carole Mundell, the director of science at the ESA, said at a meeting of the International Astronautical Congress in Italy on 15 October. Representing the image at full resolution would require more than 16,000 4K TV screens, she said.

    New Scientist. Science news and long reads from expert journalists, covering developments in science, technology, health and the environment on the website and the magazine.

    Euclid’s first mosaic image represents only 1 per cent of the final map

    ESA

    The mosaic of 260 images is the first glimpse into Euclid’s project to create the largest and most accurate map of the universe yet. The vast number of galaxies was captured during a two-week survey in April and represents only 1 per cent of the final map. The image covers an area of the southern sky about 500 times the size of the full moon.

    The wispy blue band across the image is dust and gas in the nearby Milky Way, known as “galactic cirrus”, said Mundell. Zooming in reveals swirling galaxies interacting hundreds of millions of light years away, some with a supermassive black hole at their centre that can produce gravitational waves measurable on Earth.

    Over the next six years, the telescope will autonomously scan about a third of the night sky. The researchers anticipate the final map will show around 8 billion galaxies, each with billions of stars, stretching across 10 billion years of cosmic history.


    By observing clusters of galaxies and other phenomena, such as how gravity bends light, “Euclid will measure the cosmic web – the distribution of matter in space and time”, said the ESA’s Valeria Pettorino at the meeting. Because dark energy and dark matter affect the formation of voids between clusters of galaxies, measuring these voids could help us understand the characteristics of these elusive substances, she said.

    “We’re testing the fundamental laws of physics at the extreme scales of the cosmos,” said Mundell.

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  • Dark matter may allow giant black holes to form in the early universe

    Dark matter may allow giant black holes to form in the early universe

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    The long-standing mystery of how supermassive black holes grew so huge so quickly could be solved by decaying dark matter

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  • Dark matter could be hiding inside strange failed stars

    Dark matter could be hiding inside strange failed stars

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    Illustration of a swiftly rotating brown dwarf

    NASA/JPL-Caltech

    Dark matter-fuelled brown dwarfs could be lurking at the centres of galaxies. If astronomers manage to spot them, they could teach us about how dark matter interacts with regular matter.

    Brown dwarfs are vast balls of gas, between 13 and 72 times as massive as Jupiter but smaller than stars and with too little matter to sustain the nuclear fusion of hydrogen in their cores. The threshold at which they start fusing hydrogen and become stars, known…

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  • Another blow for dark matter as biggest hunt yet finds nothing

    Another blow for dark matter as biggest hunt yet finds nothing

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    An array of sensors at the LUX-ZEPLIN dark matter experiment in South Dakota

    Matthew Kapust/Sanford Underground Research Facility

    The latest hunt for dark matter has come up empty handed so far, but the upside is that physicists can now set the tightest constraints ever on the nature of this mysterious substance. New measurements from the LUX-ZEPLIN (LZ) experiment in South Dakota mean we are either closer than ever to finding particles of dark matter or ruling out the most popular explanation for it.

    Dark matter doesn’t interact much with regular matter or with light, so we can’t see it. We only know that it exists because of its gravitational effects, but those effects indicate it makes up over 80 per cent of all matter. The leading explanation for dark matter has long been that it is made up of weakly interacting massive particles (WIMPs), but hunts for these fundamental entities have found nothing yet.

    LUX-ZEPLIN, a dark matter detector made of 7 tonnes of liquid xenon buried 1.5 kilometres underground, is the most sensitive yet – but after 280 days of searching, it hasn’t found any WIMPs. “We’re the world’s best at not finding dark matter,” says LZ spokesperson Chamkaur Ghag at University College London.

    While this result may seem like a disappointment, it has allowed physicists to place tight constraints on the nature of dark matter, reducing the range of properties it could have. The constraints are nearly five times tighter than the previous best, drastically narrowing down the possibilities for WIMPs. This work was presented at two physics conferences – TeV Particle Astrophysics in the US and LIDINE in Brazil – on 26 August.

    “It’s as if we’ve been told there’s some magical fish that lives in the ocean and we have no idea where it is,” says Ghag. “We get into the ocean, swim around, get out, get a snorkel, swim around, still don’t find it, get a submarine.” If the magical fish is a WIMP, researchers have now explored about 75 per cent of the ocean without finding it, he says.

    “This is the next big step forward, and it’s one in a long line of such steps,” says Dan Hooper at the Fermi National Accelerator Laboratory in Illinois, who wasn’t involved in this work. “In any one of these steps forward, it might be fair to say we don’t expect to see anything. But if you take enough of these steps, it seems not unlikely that we could see something.”

    At this point, many initially popular ideas for possible types of WIMPs have been ruled out. There are still some left, but LZ isn’t done yet – it is expected to make 1000 days of observations in total before it ends in 2028. “If LZ doesn’t see WIMPs, and the next generation detector, XLZD, does not see WIMPs, it’s kind of over for WIMPs,” says Ghag. The XLZD project is still in the planning phase.

    If WIMPs don’t make up dark matter, that will be a huge paradigm shift, but physicists won’t give up entirely on finding dark matter. “If you’re trying to solve a murder investigation, and you’ve got 20 suspects, and you find out that 10 of them have good [alibis], you don’t go, ‘well I guess there wasn’t a murder’. You just have a better idea of who the right suspect might be,” says Hooper. “We cross some of our suspects off the list, and the search gets narrower and more focused – that’s what progress looks like in this field.”

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  • Our galaxy may host strange black holes born just after the big bang

    Our galaxy may host strange black holes born just after the big bang

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    The Milky Way may be home to strange black holes from the first moments of the universe, and the best candidates are the three closest black holes to Earth

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  • Galaxy cluster smash-up lets us observe dark matter on its own

    Galaxy cluster smash-up lets us observe dark matter on its own

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    When galaxy clusters collided, the dark matter (blue) sailed ahead of the normal matter (orange)

    W.M. Keck Observatory/Adam Makarenko

    When two enormous clusters of galaxies collided billions of years ago, their dark matter shot right out of them, leaving behind the gas and stars that made up the remains of the clusters. Understanding this process could help us figure out the nature of dark matter and its effects on the universe.

    Clashes between galaxy clusters are difficult to observe. We have to catch the collisions at exactly the right time, and at the right angle with respect to Earth, to…

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  • How a simple physics experiment could reveal dark matter hiding in an extra dimension

    How a simple physics experiment could reveal dark matter hiding in an extra dimension

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    New Scientist. Science news and long reads from expert journalists, covering developments in science, technology, health and the environment on the website and the magazine.

    We tend not to dwell on the fact that we exist in three dimensions. Forwards-back, left-right, up-down; these are the axes on which we navigate the world. When we try to imagine something else, it typically conjures images from the wildest science fiction – of portals in the fabric of space-time and parallel worlds.

    Yet serious physicists have long been spellbound by the prospect of extra dimensions. For all their intangibility, they promise to resolve several big questions about the deepest workings of the universe. Besides, they can’t be ruled out simply because they are difficult to imagine and even harder to observe. “There’s no reason why it has to be three,” says Georges Obied at the University of Oxford. “It could have been two; it could have been four or 10.”

    Still, there comes a point when any self-respecting physicist wants hard evidence. Which is why it is so exciting that, over the past few years, researchers have developed a handful of techniques that could finally snare proof of extra dimensions. We might yet spot gravity leaking into them, for instance. We may see their subtle imprint on black holes or find their traces in particle accelerators.

    But now, in an unexpected twist, Obied and others are making the case for an extra dimension that is radically unlike any we have concocted previously. This “dark dimension” would conceal particles from the dawn of time that could solve the mystery of dark matter, whose gravitational pull is thought to have shaped the cosmos. Crucially, it should also be relatively…

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  • Odd black holes smaller than protons may have once littered the cosmos

    Odd black holes smaller than protons may have once littered the cosmos

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    Colour-charged black holes may have formed in the early universe

    betibup33/Shutterstock

    The universe may have once been speckled with tiny black holes with a strange property called colour charge. These exotic objects, if they existed, would have formed in the instants after the big bang and evaporated just as quickly, but they could have upset the balance of elements that formed in the early universe.

    Minuscule black holes formed right at the beginning of the cosmos are known as primordial black holes. Because of their…

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  • The Hunt for Ultralight Dark Matter

    The Hunt for Ultralight Dark Matter

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    If or when SLAC’s planned project, the Light Dark Matter Experiment (LDMX), receives funding—a decision from the Department of Energy is expected in the next year or so—it will scan for light dark matter. The experiment is designed to accelerate electrons toward a target made of tungsten in End Station A. In the vast majority of collisions between a speeding electron and a tungsten nucleus, nothing interesting will happen. But rarely—on the order of once every 10,000 trillion hits, if light dark matter exists—the electron will instead interact with the nucleus via the unknown dark force to produce light dark matter, significantly draining the electron’s energy.

    That 10,000 trillion is actually the worst-case scenario for light dark matter. It’s the lowest rate at which you can produce dark matter to match thermal-relic measurements. But Schuster says light dark matter might arise in upward of one in every 100 billion impacts. If so, then with the planned collision rate of the experiment, “that’s an inordinate amount of dark matter that you can produce.”

    LDMX will need to run for three to five years, Nelson said, to definitively detect or rule out thermal relic light dark matter.

    Ultralight Dark Matter

    Other dark matter hunters have their experiments tuned for a different candidate. Ultralight dark matter is axionlike but no longer obliged to solve the strong CP problem. Because of this, it can be much more lightweight than ordinary axions, as light as 10 billionths of a trillionth of the electron’s mass. That tiny mass corresponds to a wave with a vast wavelength, as long as a small galaxy. In fact, the mass can’t be any smaller because if it were, the even longer wavelengths would mean that dark matter could not be concentrated around galaxies, as astronomers observe.

    Ultralight dark matter is so incredibly minuscule that the dark-force particle needed to mediate its interactions is thought to be massive. “There’s no name given to these mediators,” Schuster said, “because it’s outside of any possible experiment. It has to be there [in the theory] for consistency, but we don’t worry about them.”

    The origin story for ultralight dark matter particles depends on the particular theoretical model, but Toro says they would have arisen after the Big Bang, so the thermal-relic argument is irrelevant. There’s a different motivation for thinking about them. The particles naturally follow from string theory, a candidate for the fundamental theory of physics. These feeble particles arise from the ways that six tiny dimensions might be curled up or “compactified” at each point in our 4D universe, according to string theory. “The existence of light axionlike particles is strongly motivated by many kinds of string compactifications,” said Jessie Shelton, a physicist at the University of Illinois, “and it’s something that we should take seriously.”

    Rather than trying to create dark matter using an accelerator, experiments looking for axions and ultralight dark matter listen for the dark matter that supposedly surrounds us. Based on its gravitational effects, dark matter seems to be distributed most densely near the Milky Way’s center, but one estimate suggests that even out here on Earth, we can expect dark matter to have a density of almost half a proton’s mass per cubic centimeter. Experiments try to detect this ever-present dark matter using powerful magnetic fields. In theory, the ethereal dark matter will occasionally absorb a photon from the strong magnetic field and convert it into a microwave photon, which an experiment can detect.

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  • Gravitational waves: We are about to hear echoes in the fabric of space for the first time

    Gravitational waves: We are about to hear echoes in the fabric of space for the first time

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    New Scientist Default Image

    Did  you hear the one about the star that died twice? In 2014, astronomers saw the explosion of the Refsdal supernova. Then, 360 days later, it went bang again.

    This bizarre sequence of events was down to a phenomenon called gravitational lensing, in which massive objects warp the fabric of space enough to cause light to bend. The path of the flash from the supernova was changed in this way on its journey to us, so that portions of it took different routes and arrived at different times – almost a year apart in this extreme case.

    As that story shows, gravitational lensing has been around for a while, but now it is about to enter a compelling new chapter. Scientists know it isn’t just light that can be lensed, but gravitational waves too. It is a mind-bending concept: ripples in space-time themselves being distorted by the curvature of space. It is also a deeply important phenomenon that could illuminate the secret interiors of neutron stars, settle a mystery about the power of dark energy and test gravity itself more keenly than ever. And here is the best part: we may be on the cusp of spotting our first lensed gravitational wave.

    No one is under any illusions that this will be anything other than fiendishly difficult. Still, there is a sense it will happen sooner or later – and there are tricks we can pull to expedite the discovery. “It’s exciting, and it’s going to happen,” says Simon Birrer at Stony Brook University in New York. “There’s…

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