Latest news with #CosmicMicrowaveBackground
Yahoo
4 days ago
- General
- Yahoo
The Big Bang's Glowing 'Echo' May Be Something Else Entirely
Part of the reason scientists have settled on the Big Bang theory as the best explanation of how the Universe came into being is because of an 'afterglow' it emits – but a new study suggests we may need to rethink the source of this faint radiation. Technically, this afterglow is known as Cosmic Microwave Background (CMB) radiation, and it's been traveling through space for more than 13 billion years, since soon after the Big Bang first went bang. It can be picked up by our most advanced telescopes. Now, researchers from Nanjing University in China and the University of Bonn in Germany have run calculations suggesting we've overestimated the strength of the CMB. In fact, it might not even be there at all. The rocking of the cosmological boat, as it were, is driven by new evidence of early-type galaxies (ETGs). Recent data from the James Webb Space Telescope suggests these ETGs might account for some or even all of the CMB, depending on the simulation used. "Our results are a problem for the standard model of cosmology," says physicist Pavel Kroupa, from the University of Bonn. "It might be necessary to rewrite the history of the Universe, at least in part." Scientists already know plenty about ETGs, which are usually elliptical in shape. What's new is that recent studies, and this latest interpretation of them, point to these types of galaxies having formed even earlier than previous models accounted for. If that timeline shifts, then so does the pattern of radiation spreading out across the Universe. In simple terms, the Universe may have moved through its initial phase of gas surges and galaxy formation quicker than we imagined. "The Universe has been expanding since the Big Bang, like dough that is rising," says Kroupa. "This means that the distance between galaxies is increasing constantly." "We have measured how far apart elliptical galaxies are from one another today. Using this data and taking into account the characteristics of this group of galaxies, we were then able to use the speed of expansion to determine when they first formed." This earlier estimate for the formation of these ETGs means that their brightness could emerge "as a non-negligible source of CMB foreground contamination", the researchers write. We should bear in mind that this research is still in its preliminary stages. It's not time yet to start pulping scientific textbooks – or whatever the modern equivalent is. Rewriting Wikipedia, perhaps? But this research certainly raises some big questions. Given the almost unimaginable timescales and distances involved, it's difficult for astrophysicists to always be precise. The researchers suggest anywhere from 1.4 percent to 100 percent of the CMB could be explained by their new models. What's certain is that as our space telescopes and analysis systems get more sophisticated, we're learning more about the surrounding Universe than ever before – and that in turn means some previous assumptions may have to be readjusted, including those about the very formation of the Universe itself. "In the view of the results documented here, it may become necessary to consider [other] cosmological models," write the researchers in their published paper. The research has been published in Nuclear Physics B. A Serious Threat May Be Lurking in The Orbit of Venus, Says Study We Now Know What Switched The Lights on at The Dawn of Time Light Travels Across The Universe Without Losing Energy. But How?
Time of India
18-05-2025
- Science
- Time of India
Dark matter formed when fast particles slowed down and got heavy: Study
ANI file photo WASHINGTON: A study by Dartmouth researchers proposes a new theory about the origin of dark matter, the mysterious and invisible substance thought to give the universe its shape and structure. The researchers report in Physical Review Letters that dark matter could have formed in the early life of the universe from the collision of high-energy massless particles that lost their zip and took on an incredible amount of mass immediately after pairing up, according to their mathematical models. While hypothetical, dark matter is believed to exist based on observed gravitational effects that cannot be explained by visible matter. Scientists estimate that 85 per cent of the universe's total mass is dark matter. Sponsored Links Sponsored Links Promoted Links Promoted Links You May Like 'Swing is King': Mr. Hemant's Strategy Finally Explained in Free Session TradeWise Learn More Undo But the study authors write that their theory is distinct because it can be tested using existing observational data. The extremely low-energy particles they suggest make up dark matter would have a unique signature on the Cosmic Microwave Background , or CMB, the leftover radiation from the Big Bang that fills all of the universe. "Dark matter started its life as near-massless relativistic particles, almost like light," says Robert Caldwell, a professor of physics and astronomy and the paper's senior author. "That's totally antithetical to what dark matter is thought to be, it is cold lumps that give galaxies their mass," Caldwell says. "Our theory tries to explain how it went from being light to being lumps." Hot, fast-moving particles dominated the cosmos after the burst of energy known as the Big Bang that scientists believe triggered the universe's expansion 13.7 billion years ago. These particles were similar to photons, the massless particles that are the basic energy, or quanta, of light. It was in this chaos that extremely large numbers of these particles bonded to each other, according to Caldwell and Guanming Liang, the study's first author and a Dartmouth senior. They theorise that these massless particles were pulled together by the opposing directions of their spin, like the attraction between the north and south poles of magnets. As the particles cooled, Caldwell and Liang say, an imbalance in the particles' spins caused their energy to plummet, like steam rapidly cooling into water. The outcome was the cold, heavy particles that scientists think constitute dark matter. "The most unexpected part of our mathematical model was the energy plummet that bridges the high-density energy and the lumpy low energy," Liang says. "At that stage, it's like these pairs were getting ready to become dark matter," Caldwell says. "This phase transition helps explain the abundance of dark matter we can detect today. It sprang from the high-density cluster of extremely energetic particles that was the early universe." The study introduces a theoretical particle that would have initiated the transition to dark matter. But scientists already know that the subatomic particles known as electrons can undergo a similar transition, Caldwell and Liang say.
NDTV
27-04-2025
- Science
- NDTV
Universe's Largest Structure Could Be 50% Bigger Than Previously Thought
The contender for the largest known structure in the universe, the Hercules-Corona Borealis Great Wall (or Great Wall, for short), might be even larger than scientists had previously thought. As per a new study published on the preprint server arXiv, the Great Wall, which is located 10 billion light-years from Earth, could be as large as 15 billion light-years in size, up from the previous estimate of 10 billion light-years long. Using a recently developed methodology, scientists re-examined the Great Wall, which was first discovered, more than a decade ago. "Evidence is provided that the Hercules-Corona Borealis Great Wall cluster is larger than previously thought. The extension of this cluster's size does not appear to have been due to statistical variations or sampling biases," the study highlighted. By analysing the gamma-ray bursts that are produced during extreme cosmic events such as the collapse of a supernova, the birth of a black hole, or the collision of two neutron stars, scientists managed to figure out the new length of the Great Wall. The team examined 542 gamma-ray bursts with known redshifts, which showed that the Great Wall may extend from a redshift of 0.33 to a redshift of 2.43 -- a total distance of around 15 billion light-years "We also found evidence that the Hercules-Corona Borealis Great Wall is larger than previously identified and that it appears to encompass several smaller clusters," it added. Quipu superstructure In February this year, scientists claimed to have discovered another large superstructure called Quipu, believed to measure 1.3 billion light-years across, which is over 13,000 times the length of the Milky Way. As per the study, Quipu is responsible for a "large part of the gravitational pull that causes the peculiar motion of the Local Group with respect to the Cosmic Microwave Background (CMB) frame". However, more information is needed to identify the effects of such a structure on its neighbourhood. The scientists added that while the superstructure was massive in size currently, it would soon collapse and form independent units. Studying an object as massive as the Great Wall or Quipu could help scientists broaden their understanding of how galaxies evolve and improve the existing cosmological models.
Yahoo
18-04-2025
- Science
- Yahoo
50% of the Universe's Matter Has Been Missing for Years. Scientists Just Found It.
Although we're still searching for observational evidence of dark matter, scientists haven't been able to account for about 15 percent of the regular matter in the universe with just stars, planets, and other celestial objects. A new study by 75 scientists across institutions around the world suggests that this missing matter is actually ionized hydrogen gas surrounding galaxies, which stretches much further than we thought. Understanding the location of this gas is vital to producing accurate simulations and understanding the formation and evolution of galaxies. We often think of stars, planets, asteroids, and all the other celestial object as the stuff that makes up the universe. But when you count up all that stuff—including one septillion stars or so—it only makes up roughly seven percent of all the matter in the universe. Combine that figure with the oft-cited approximately 85 percent of the universe attributed to dark matter, and that still leaves a sizable chunk of something that we haven't found yet. Now, a new study co-authored by 75 scientists from institutions from around the world claims to have finally solved this missing matter mystery. By analyzing the images of 7 million galaxies—provided by the Dark Energy Spectroscopic Instrument (DESI), which is a telescope located in Tucson, Arizona—all located within 8 billion light-years of Earth, scientists discovered that the diffuse clouds of ionized hydrogen gas surrounding galaxies account for more matter than we originally believed possible. In a preprint uploaded to arXiv and awaiting peer review for publishing in the journal Physical Research Letters, the team explains that this gas likely makes up the missing portion of the 15 percent of matter that isn't dark matter. When analyzing these millions of luminous red galaxies, the team used Cosmic Microwave Background (CMB) data—the primeval radiation emitted just after the Big Bang—to measure the dimming and brightening caused by scattering radiation in the ionized gas. This scattering process is known as the Sunyaev-Zel'dovich effect. 'The cosmic microwave background is in the back of everything we see in the universe. It's the edge of the observable universe,' Simone Ferraro, a co-author of the study from Lawrence Berkeley National Laboratory, said in a press statement. 'So you can use that as a backlight to see where the gas is.' The team discovered that centers of black holes are more active than originally thought, which causes the ionized gas surrounding galaxies to be much more diffuse and farther afield than originally believed. In fact, the team's estimates suggest that this gas stretches five times farther out from the centers of galaxies that previous estimates suggest. Astronomers previously believed that supermassive black holes are most active (and therefore classified as Active Galactic Nuclei, or AGN) during galaxy formation But this new data suggests that they could be active at other points in their lifecycle, as well. 'One problem we don't understand is about AGNs, and one of the hypotheses is that they turn on and off occasionally in what is called a duty cycle,' Boryana Hadzhiyska, a co-author of the study and postdoctoral fellow from the University of California Berkeley, said in a press statement. New models and simulations of the galaxy formation and evolution will benefit from including this missing piece of the cosmological puzzle in their calculations. By underestimating this gas expulsion by black holes, astronomers may have been missing insights into some of the theories surrounding dark matter (such as the idea that gas follows dark matter) and the 'lumpiness' of the universe. 'Knowing where the gas is has become one of the most serious limiting factors in trying to get cosmology out of current and future surveys. We've kind of hit this wall, and this is the right time to address these questions,' Ferraro said. 'Once you know where the gas is, you can ask, 'What's the consequence for cosmological problems?'' You Might Also Like The Do's and Don'ts of Using Painter's Tape The Best Portable BBQ Grills for Cooking Anywhere Can a Smart Watch Prolong Your Life?
Yahoo
27-03-2025
- Science
- Yahoo
Unknown physics may help dark energy act as 'antigravity' throughout the universe
When you buy through links on our articles, Future and its syndication partners may earn a commission. Dark energy could have an accomplice that helps it slow the growth of large cosmic structures, such as vast superclusters made up of clusters of galaxies. A new analysis of astronomical data suggests unknown physics is at work assisting dark energy in acting almost as "antigravity," undoing the work of gravity, which clumps together matter to build vast structures. The large-scale structure of the universe refers to vast, interconnected patterns of galaxies, galaxy clusters, and superclusters organized into filaments, voids, and walls that comprise the "cosmic web." Gravity has shaped this structure over billions of years. The team found that it is forming more slowly today compared to the rate at which it formed in the 13.8 billion-year-old universe's distant past. Researchers discovered these hints at new physics using data from the Baryon Oscillation Spectroscopic Survey (BOSS). BOSS maps the spatial distribution of luminous red galaxies (LRGs) and black hole-powered quasars to detect variations in matter in the early universe, or "baryon acoustic oscillations," which are "frozen into" a cosmic fossil called the Cosmic Microwave Background (CMB). "We found that structure formation in the late universe, as probed by galaxies in the BOSS survey, seems to be suppressed relative to expectations," team leader and Princeton University researcher Shi-Fan (Stephen) Chen told "In fact, our results suggest that the suppression is quite independent of dark energy." Dark energy is the placeholder name for whatever is accelerating the expansion of the universe. Discovered by two independent teams of astronomers in 1998, dark energy is thought to account for around 70% of the cosmos's total matter-energy current "best explanation" for dark energy is the "cosmological constant" represented by the Greek letter lambda (Λ) in the so-called standard model of cosmology, also known as the Lambda Cold Dark Matter (ΛCDM) model. The cosmological constant represents "vacuum energy," or the energy of empty space. This may sound very strange as it is connected to pairs of matter and antimatter particles popping in and out of existence. If a matter and antimatter particle pair is created with equal and opposite energy within a limited space, then the total energy of that space is still zero. This is akin to the universe's overdraft facility, but rather than lending money, it lends energy. Just like a bank, however, the universe demands this energy to be paid back, which virtual particles do by annihilating each other. This means that "empty space" can't ever really be guaranteed to be empty. As crazy as the idea of matter appearing from nothing sounds, we've verified it experimentally. The Casimir effect, observed in labs across the globe, is a very famous example of virtual particles and the quantum fluctuations that create them and thus vacuum energy. Here's the kicker: if dark energy is the cosmological constant, it should be exactly that, constant. So in the ΛCDM, even though dark energy causes a change in the rate at which the universe expands, the cosmological constant shouldn't change. Recently, however, anomalies in results from the Dark Energy Spectroscopic Instrument (DESI) caused a stir with cosmologists when they indicated that dark energy is changing over time. Thus, this changing or "dynamical dark energy" is contrary to ΛCDM. "Recent results from DESI suggest that dark energy may not be a cosmological constant, but rather might evolve over time— we were curious to see if this tension with ΛCDM could be tied to the suppression of structure," Chen said. If anything, checking DESI findings with data from BOSS has left the team with a larger mystery on their hands. Whatever dark energy is, be it the cosmological constant or something else, the expansion of spacetime works on extremely large scales, so you won't see your coffee cup stretching away from you, and dark energy won't make your journey to work longer each morning (there is another excuse out of the window, sorry). However, we can see distant galaxies moving away from us at ever-accelerating speeds. We can also see their effects in the BAO fluctuations frozen into the CMB because this fossil light from an event just after the Big Bang is almost evenly spread across the entire universe. As such, it should come as no surprise that dark energy, as a force pushing apart galaxies, plays a role in stopping large-scale structures like galaxy clusters and superclusters from forming. What is remarkable about the results obtained by Chen and colleagues is that they show that large-scale structures are even less common today than predicted by both the ΛCDM model of cosmology and when dark energy is allowed to vary. That implies something else, something new, is also at play, the identity of which is unknown. "Many different theoretical explanations have been given for why the measured amplitude of cosmic structure at late times seems to come in slightly below expectations," Chen said. "At present, there are no conclusive answers." However, there is one clue regarding the suppression of large-scale cosmic structures. This suppression seems to have kicked in around the same time dark energy came to dominate the universe. Dark energy may rule the universe now. But this wasn't always the way. Immediately after the Big Bang, the universe was dominated by radiation, driving its rapid inflation. Around 70,000 years after the Big Bang, the universe had cooled enough to allow gravity to overwhelm radiation pressure. This slowed the initial Big Bang-driven expansion, bringing it to a near stop, and the first aggregates of matter, stars and galaxies were allowed to form. At around 9 to 10 billion years after the Big Bang, or about 5 to 4 billion years ago, something strange began to happen. The universe started to expand again. Not only that, but this expansion began accelerating, and it is still accelerating today. This is the beginning of the dark energy-dominated epoch; the problem is that no one knows how the switch from matter to dark energy domination happened. "The BOSS data probes the universe when dark energy is beginning to kick in, and we think that this suppression cannot have occurred much earlier than that," Chen said. So while dark energy seems linked to this suppression, this mysterious force still can't solely explain why the formation of large cosmic structures is slowed in the modern universe. "When combining probes of the peculiar velocities of these galaxies, known as redshift-space distortions, and their cross correlation with the weak lensing of the CMB, we find that the probability of our results occurring due to random chance is 1 in 300,000," Chen said. "That suggests either that there's some unknown physics at work or that there's some unknown systematic error in the BOSS data." Related Stories: — Supermassive black holes in 'little red dot' galaxies are 1,000 times larger than they should be, and astronomers don't know why — 'Superhighways' connecting the cosmic web could unlock secrets about dark matter — How does the Cosmic Web connect Taylor Swift and the last line of your 'celestial address?' The researcher added that with better data on the horizon, including the first public data on galaxy clustering from DESI released last week, the team will re-apply their methods, compare their results with their current findings, and detect any statistically significant differences. "I think there are more questions than answers at this point," Chen said. "This research certainly enforces the idea that different cosmological datasets are beginning to be in tension when interpreted within the standard ΛCDM model of cosmology." The team's research was published in the journal Physical Review Letters.
