Latest news with #darkmatter
Yahoo
15-07-2025
- Science
- Yahoo
100 undiscovered galaxies may be orbiting the Milky Way, supercomputer simulations hint
When you buy through links on our articles, Future and its syndication partners may earn a commission. The Milky Way may be surrounded by dozens of yet-to-be-detected satellite galaxies, scientists claim. Using the highest-resolution simulation of our galaxy's dark matter — an invisible entity that shapes the large-scale structure of the universe — and new mathematical models, cosmologists predict that more than 100 additional satellite galaxies beyond the ones already cataloged may be swirling around our own. If those galaxies are spotted by telescopes, they could offer support for the standard model of cosmology — the dominant model of our universe that explains how galaxies form. The researchers presented their findings July 11 at the Royal Astronomical Society's National Astronomy Meeting in Durham, England. "We know the Milky Way has some 60 confirmed companion satellite galaxies, but we think there should be dozens more of these faint galaxies orbiting around the Milky Way at close distances," lead researcher Isabel Santos-Santos, a graduate student at Durham University, said in a statement. "One day soon we may be able to see these 'missing' galaxies, which would be hugely exciting and could tell us more about how the Universe came to be as we see it today." According to the standard theory of cosmology, known as lambda cold dark matter (LCDM), both dwarf galaxies and large ones such as our own take shape within clumps called galactic halos. These vast spheres of stars float like leaves on a pond of dark matter, the mysterious substance believed to make up 85% of the universe's matter. Dark matter doesn't reflect light, so it hasn't been observed directly. But scientists see evidence for it in the shapes of galaxies, the warping of starlight as it passes through them, and the acceleration of stars to otherwise inexplicable speeds as they orbit galactic centers. Related: Scientists discover rare planet at the edge of the Milky Way using space-time phenomenon predicted by Einstein This dark matter halo gives the Milky Way a hefty gravitational pull. The pull is so strong, in fact, that over the course of billions of years, it has captured a number of dwarf galaxies (those containing less than a few billion stars) as satellites. Despite being predicted as plentiful by LCDM, satellite galaxies are faint and therefore hard to detect; many more should exist than astronomers have been able to observe or even simulate. Taken at face value, their absence is yet another crack of doubt in the standard model of cosmology. But the scientists behind the new research propose a reason for this lack of supporting evidence, at least within simulations: They're not precise enough to model galaxy evolution, so the simulated halos get disrupted, leading to the loss of their satellite galaxies. RELATED STORIES —'This doesn't appear in computer simulations': Hubble maps chaotic history of Andromeda galaxy, and it's nothing like scientists expected —Unproven Einstein theory of 'gravitational memory' may be real after all, new study hints —Fast radio burst traced to the outskirts of an ancient 'graveyard' galaxy — and the cause remains a mystery To better simulate the possible hidden galaxies, the astronomers turned to the Aquarius simulation, the highest-resolution reconstruction of a Milky Way dark-matter halo. They used the Aquarius simulation to run the GALFORM model — a code that tracks gas cooling, stars forming and matter clumping to form galaxies similar to our own. According to the simulation, dwarf galaxies have been orbiting the Milky Way for much of the universe's life. Yet during their repeated passes, their dark matter and stars were gradually snatched away by the Milky Way's enormous galactic halo, causing them to appear extremely faint in the present day. This means that anywhere from 80 to over 100 more dwarf galaxies might exist around our galaxy's outskirts, according to the researchers. If these galaxies are really there, it may not be long before they're detected; the new Vera Rubin Observatory, which is equipped with the largest digital camera ever constructed, could resolve some of these hidden galaxies. "If the population of very faint satellites that we are predicting is discovered with new data, it would be a remarkable success of the LCDM theory of galaxy formation," co-researcher Carlos Frenk, a professor of astrophysics at the University of Durham, said in the statement. "It would also provide a clear illustration of the power of physics and mathematics. Using the laws of physics, solved using a large supercomputer, and mathematical modelling we can make precise predictions that astronomers, equipped with new, powerful telescopes, can test."
BBC News
11-07-2025
- Science
- BBC News
Durham Uni research predicts more Milky Way satellite galaxies
The Milky Way could have more satellite galaxies than previously thought, according to new at Durham University predict the existence of between 80 and 100 satellite galaxies surrounding our home galaxy on top of the 60 already used a technique combining high resolution supercomputer simulations and mathematical modelling to reach their researcher Dr Isabel Santos-Santos said the findings could help improve understanding of dark matter. She said that if the galaxies were seen by a telescope it would help support the Lambda Cold Dark Matter (LCDM) theory, which would have "a big significance for the whole community".It is used to explain the large-scale structure of the Universe and proposes there should be many small also suggests 25% of the Universe is cold dark matter."In other models where the particle mass is different, we do not expect that many satellites," Dr Santos-Santos said."So, even if we find them, or if we don't, the implications are very strong for the whole community of cosmologists and astrophysicists in knowing what is the dark matter particle." According to the LCDM model, galaxies form in the centre of gigantic clumps of dark matter called halos. The new research shows that the Milky Way's missing satellites are extremely faint galaxies stripped almost entirely of their parent dark matter halos by the gravity of the Milky Way's halo. These so-called "orphan" galaxies are lost in most simulations, but should have survived in the real is hoped new advances in telescopes and instruments like the Rubin Observatory LSST camera will give astronomers the ability to detect these very faint objects."We expect that in the next five years we will be able to confirm, to test if these satellite galaxies that we are predicting are really there or not," Dr Santos-Santos said. Dr Santos-Santos said previous work had used simulations with lower resolution and could only predict a certain number of galaxies with a certain Durham researchers used the Aquarius simulation and the GALFORM model, a code developed at Durham over the past two findings are being presented on Friday at the Royal Astronomical Society's National Astronomy Meeting, being held at Durham University. Follow BBC North East on X, Facebook, Nextdoor and Instagram.
Yahoo
07-07-2025
- Science
- Yahoo
Dark Matter Search Could Lead Us to a New Kind of Star
Dark dwarfs could be lurking out in the cosmos, according to a new study. These hypothetical, effectively eternal bodies would be powered by dark matter annihilation, and though dim, there is a way we could spot them. Dark matter is expected to pervade the Universe, but being… well, dark, it's hard to find. It doesn't reflect or emit light – its existence is only inferred through its interactions with regular matter via gravity. No direct evidence of it has been found, despite decades of searching. Now, astrophysicists in the UK and US propose a new place we might find dark matter – hiding in the hearts of brown dwarfs. Bigger than gas giant planets but smaller than stars, these substellar objects never gather enough mass to kickstart the nuclear fusion process that powers stars. Instead, they float around space as large, dim, cold worlds. Related: But in some cases, the new study proposes, brown dwarfs might transform into something more intriguing. In areas with a higher density of dark matter, the strange stuff could accumulate in the brown dwarf's core. And if it's a certain type of dark matter, the particles could interact with each other to produce energy that powers the brown dwarf. The team calls these theoretical bodies "dark dwarfs". "These objects collect the dark matter that helps them become a dark dwarf," says Jeremy Sakstein, astrophysicist at the University of Hawai'i. "The more dark matter you have around, the more you can capture. And, the more dark matter ends up inside the star, the more energy will be produced through its annihilation." A hypothesis is only as strong as its testability, and the researchers include a way astronomers could verify the existence of dark dwarfs: look for lithium-7. This particular isotope burns away quickly inside stars due to their intense heat. But in cooler objects like brown dwarfs, lithium-7 can stick around. Astronomers already use the presence of lithium-7 as a signal to confirm that an object is a brown dwarf. However, if the extra energy from dark matter annihilation is powering a brown dwarf, it could appear larger and brighter than even red dwarfs of the same mass. So if you find something that looks like a red dwarf but has a lithium-7 signature, you might just have a black dwarf – and confirmation of dark matter. Of course there are a lot of ifs. For one, dark matter would need to exist in a specific theorized form, made up of weakly interacting massive particles (WIMPs). One of the leading candidates, WIMPs would barely interact with regular matter, besides its gravitational influence, but would interact with themselves. WIMPs would be their own antiparticles, meaning if two of them touch, they'd annihilate each other in a burst of energy. When you cram them densely into a confined place – like the core of a brown dwarf – the energy released from all those collisions would power the object. Not to the extent of a star, of course, but more than your garden-variety brown dwarf. Because this process gives them a constant size, temperature, and brightness, dark dwarfs would be effectively eternal, the team says. However, if dark matter happens to take on a different form, like axions or dark photons, there'd be no way to tell from the outside that it's accumulating inside brown dwarfs. That's if dark matter exists at all – there's always the chance that the effects we attribute to it are caused by some other unknown physics. Still, it's important to come up with various ideas about what dark matter could be and how we might detect it. Different observatories and experiments can look out for different potential signatures of dark matter, allowing us to investigate a wide range of possibilities at once. In this case, the researchers say that the best place to look for dark dwarf signatures would be toward the center of our galaxy, where dark matter would gather most densely. The research is available on preprint server arXiv and will be published in the Journal of Cosmology and Astroparticle Physics. 3D Time Could Solve Physics' Biggest Problem, Says Bizarre New Study Physicists Catch Light in 'Imaginary Time' in Scientific First Not All Uranium Can Be Used in Weapons. Here's What 'Enrichment' Means.
Yahoo
05-07-2025
- Science
- Yahoo
Rubin observatory will be a new step in accessing far reaches of space
An exciting new step in access to the far reaches of space and time increasingly will become available when the new Vera C. Rubin Observatory comes into full operation ('Providing a detailed look at the cosmos,' June 25). Funded by the National Science Foundation and the US Department of Energy's Office of Science, and located on an Andean mountain in Chile, its unprecedented telescopic and camera capacity will secure data and imagery essential to further knowledge of the dark energy and dark matter composing most of the universe. In my opinion, telescopic exploring of the cosmos, along with extraterrestrial probes and telescopes, deserve top priority over anything like a plan to colonize Mars. Cannot far-flung telescopes, robotic craft and AI be combined to obviate the need for human presence requiring a transported environment? Would that not be a better investment of resources? Putting humans on Mars would be a new place for old problems. Thomas Hughson SJ, emeritus Marquette University, Milwaukee Letters: Wisconsin GOP's real problem is lousy campaigns, not party chairman Schimming Opinion: Statistics don't support UW-Milwaukee shuttering materials engineering program Here are some tips to get your views shared with your friends, family, neighbors and across our state: Please include your name, street address and daytime phone. Generally, we limit letters to 200 words. Cite sources of where you found information or the article that prompted your letter. Be civil and constructive, especially when criticizing. Avoid ad hominem attacks, take issue with a position, not a person. We cannot acknowledge receipt of submissions. We don't publish poetry, anonymous or open letters. Each writer is limited to one published letter every two months. All letters are subject to editing. Write: Letters to the editor, Milwaukee Journal Sentinel, 330 E. Kilbourn Avenue, Suite 500, Milwaukee, WI, 53202. Fax: (414)-223-5444. E-mail: jsedit@ or submit using the form that can be found on the on the bottom of this page. This article originally appeared on Milwaukee Journal Sentinel: Telescopes, robots, AI could end need for human transport | Letters
Yahoo
04-07-2025
- Science
- Yahoo
Biting the 'Bullet': Amazing new JWST photo shows titanic collision of galaxy clusters
When you buy through links on our articles, Future and its syndication partners may earn a commission. NASA's James Webb Space Telescope (JWST) has produced a new image of the Bullet Cluster, which is a titanic collision between two individual galaxy clusters. The image, produced in conjunction with NASA's Chandra X-ray Observatory, reveals not only the location and mass of dark matter present, but also points the way toward one day figuring out what dark matter is actually made of. In the new image, we see the hot gas within the Bullet Cluster in false-color pink, detected by Chandra. The inferred location of dark matter is represented in blue (also false color), as measured by the JWST. Note that the blue and the pink are separate — what has caused the dark matter and the gas to separate, and how were astronomers able to produce this map of the material within the Bullet Cluster? Located 3.9 billion light-years away, the Bullet Cluster has been an occasionally controversial poster child for dark-matter studies. Back in 2006, the Hubble Space Telescope and the Chandra X-ray Observatory worked together to image the Bullet, showing the presence of its dark matter based on how light from more distant galaxies was being gravitationally lensed by the dark matter's mass. Collisions between galaxy clusters are the perfect laboratories for testing our ideas about dark matter, because they are nature's way of throwing together huge amounts of the stuff. This gives us a chance to test how dark matter particles interact with each other, if at all, and the degree of any interaction would be a huge clue as to the properties of the mysterious dark matter particle. Yet despite the dramatic Hubble and Chandra images, the Bullet Cluster — and, indeed, other galaxy cluster collisions — haven't always played ball. For instance, the velocities at which the sub-clusters are colliding seem too high for the standard model of cosmology to explain. Now the JWST has entered into the fray. A team led by Ph.D. student Sangjun Cha of Yonsei University in Seoul, South Korea, and professor of astronomy James Jee at both Yonsei and the University of California, Davis, have used the most powerful space telescope ever built to get a best-ever look at the Bullet Cluster. Hubble and Chandra had previously shown that, as the two individual galaxy clusters in the Bullet Cluster collided, the galaxies and their surrounding dark matter haloes had passed right through each other. This makes sense for the galaxies — the distances between them are so great that the chance of a head-on collision between any two is slim. It also suggests that the degree with which dark matter particles interact with each other — what we refer to as their collisional cross section — is small; otherwise, the interaction would have slowed the clouds of dark matter down, and we would detect it closer to where Chandra sees the hot, X-ray emitting intracluster gas. In contrast to the dark matter, these huge gas clouds can't get out of each other's way, so they slam into each other and don't progress any further. The end result is that the hot gas is found stuck in the middle of the collision, and the galaxies and dark matter belonging to each sub-cluster are found on opposite sides, having glided right through one another. "Our JWST measurements support this," Jee told "The galaxy distribution closely traces the dark matter." JWST was able to produce a better map of the distribution of matter, both ordinary and dark, in the Bullet Cluster by detecting, for the first time, the combined glow from billions of stars that have been thrown out of their galaxies and are now free-floating in the space between the galaxies in each sub-cluster. Cha and Jee's team were then able to use the light from these "intracluster stars" to trace the presence of dark matter and gain a more accurate map of its distribution in the Bullet Cluster. However, this has just raised more mysteries. The more refined map of the dark matter shows that, in the larger sub-cluster, on the left, the dark matter is arranged in an elongated, "hammerhead" shape that, according to Jee, "cannot be easily explained by a single head-on collision." This elongated mass of dark matter is resolved into smaller clumps centered on what we call the brightest cluster galaxies — giant elliptical galaxies that are the brightest galaxies in the sub-cluster located at its gravitational core. In contrast, the dark matter halo around the sub-cluster on the opposite side is smaller and more compact. Cha and Jee's team suspect that the elongated, clumpy mass of dark matter could only have formed when that particular sub-cluster, which was a galaxy cluster in its own right before the Bullet collision, underwent a similar collision and merger with another galaxy cluster billions of years before the formation of the Bullet. "Such an event would have stretched and distorted the dark-matter halo over time, resulting in the elongated morphology that we observe," said Jee. Despite the new discoveries such as this from JWST's more refined observations of the Bullet cluster, it is still not enough to resolve the issue of the collision velocities of the two sub-clusters. "Even with these updates, the required collision velocity remains high relative to expectations from cosmological simulations," said Jee. "The tension persists and remains an active area of research." RELATED STORIES — What is dark matter? — James Webb Space Telescope (JWST) — A complete guide — Astonishing 'halo' of high-energy particles around giant galaxy cluster is a glimpse into the early universe Dark matter makes up over a quarter of all the mass and energy in the universe, and roughly 85% of all matter, so figuring out its secrets, in particular its collisional cross-section and the cause of those high velocities, is going to be essential if we want to better understand this universe in which we live. Alas, the JWST observations of the Bullet Cluster alone are not enough to confirm what the collisional cross-section of dark matter must be. However, they do tighten the estimate of the upper limit for the value of the cross-section, constraining the list of possibilities. Astronomers are already in the process of rigorously measuring as many galaxy cluster collisions as possible, seen from all angles and distances, to try and constrain this value further. Gradually, we'll be able to rule out different models for what dark matter could be, until we're left with just a few. Coupled with experimental data from direct dark matter searches from detectors deep underground, such as the LUX-ZEPLIN experiment at the Sanford Underground Research Facility in South Dakota, we could soon be on the cusp of answering one of science's greatest mysteries: what is dark matter? The JWST observations were reported on June 30 in The Astrophysical Journal Letters.
