Tag Archives: matter

Astronomers witness the split of dark and regular matter in the clash of two galaxy clusters

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The two galaxy clusters, known as MACS J0018.5+1626, contain thousands of galaxies each and are located billions of light-years away from Earth. As the clusters hurtled towards each other, dark matter traveled faster than normal matter.

This artist's conceptual illustration shows what happened when two massive clusters of galaxies, collectively known as MACS J0018.5+1626, collided. The dark matter (blue) in the clusters moves ahead of the associated hot gas clouds, or regular matter (orange). Both dark matter and regular matter feel the pull of gravity, but only the regular matter experiences additional effects like shocks and turbulence that slow it down during the collision. Image courtesy of W. M. Keck Observatory/Adam Makarenko.

Galaxy cluster mergers are a rich source of information for testing the astrophysics and cosmology of galaxy clusters.

However, the coalescence of clusters produces complex projection signals that are difficult to physically interpret from individual observation probes.

“Imagine a series of sand-carrying dump trucks colliding, and the dark matter would fly forward like sand,” says astronomer Emily Silich of the California Institute of Technology and the Harvard-Smithsonian Center for Astrophysics.

This separation of dark matter and normal matter has been observed before, most famously in the Bullet Cluster.

In this collision, hot gas can be clearly seen lagging behind dark matter after the two galaxy clusters push through each other.

The situation that occurred in MACS J0018.5+1626 is similar, but the direction of the merger is rotated about 90 degrees relative to the direction of the Bullet Cluster.

In other words, one of the giant galaxy clusters in MACS J0018.5+1626 is flying almost straight towards Earth, while the other is moving away.

This orientation gave the researchers a unique perspective to map the speeds of both dark and normal matter for the first time, and unravel how they separate during galaxy cluster collisions.

“Bullet Cluster makes you feel like you're sitting in the stands watching a car race, taking beautiful snapshots of cars moving from left to right on a straight stretch of road,” said Jack Sayers, a professor at the California Institute of Technology.

“For us, it's like standing in front of an oncoming car on a straight stretch of road with a radar gun and measuring its speed.”

To measure the velocity of ordinary matter, or gas, in galaxy clusters, the astronomers used an observational technique known as the kinetic Sunyaev-Zel'dovich (SZ) effect.

In 2013, they made the first observational detection of the kinetic SZ effect on an individual cosmic object, a galaxy cluster named MACS J0717.

The kinetic SZ effect occurs when photons from the early universe, or the cosmic microwave background radiation (CMB), are scattered by electrons in hot gas on their way to Earth.

Photons undergo a shift called the Doppler shift due to the movement of electrons in the gas cloud along the line of sight.

By measuring the change in brightness of the CMB due to this shift, astronomers can determine the speed of the gas clouds within the cluster.

By 2019, the study authors had made these motional SZ measurements in several galaxy clusters to determine the velocity of the gas, or ordinary matter.

They also measured the speed of galaxies within the cluster, which gave them an indirect idea of ​​the speed of dark matter.

However, at this stage of the study, our understanding of the cluster orientation was limited.

All they knew was that one of them, MACS J0018.5+1626, was showing signs of something strange going on: hot gas, or regular matter, moving in the opposite direction to dark matter.

“We saw a totally strange phenomenon where the velocities were in opposite directions, which initially made us think there might be a problem with the data,” Prof Sayers said.

“Even our colleagues simulating galaxy clusters had no idea what was going on.”

Scientists then used data from NASA's Chandra X-ray Observatory to determine the temperature and location of the gas in the cluster, as well as the extent to which it is being bombarded.

“These cluster collisions are the most energetic events since the Big Bang,” Šilić said.

“Chandra will measure the extreme temperatures of the gas, which will tell us the age of the merger and how recently the galaxy cluster collision took place.”

The authors found that before the collision, the clusters were moving towards each other at about 3,000 kilometers per second, roughly 1 percent of the speed of light.

With a more complete picture of what's going on, they were able to work out why dark matter and normal matter appear to be moving in opposite directions.

They say it's hard to visualize, but the direction of the collision, combined with the fact that dark matter and normal matter separated from each other, explains the strange speed measurements.

It is hoped that more studies like this one will be conducted in the future, providing new clues about the mysterious properties of dark matter.

“This work is a starting point for more detailed studies into the nature of dark matter,” Šilić said.

“We now have a new type of direct probe that shows us how dark matter behaves differently from ordinary matter.”

of Investigation result Published in Astrophysical Journal.

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Emily M. Silich others. 2024. ICM-SHOX. I. Methodology overview and discovery of gas-dark matter velocity separation in the MACS J0018.5+1626 merger. ApJ 968, 74; doi: 10.3847/1538-4357/ad3fb5

This article is a version of a press release provided by Caltech.

Source: www.sci.news

Experiments in Basic Physics Could Uncover Hidden Dark Matter in Additional Dimensions

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We don’t tend to dwell on the fact that we exist in three dimensions. Front to back, left to right, up to down – these are the axes along which we move through the world. When we try to imagine something else, we usually conjure up the most outlandish science fiction images of portals in the fabric of space-time and parallel universes.

But serious physicists have long been fascinated by the possibility of extra dimensions. Despite their intangibility, extra dimensions hold the promise of solving some big questions about the deepest workings of the universe. And just because they’re hard to imagine and even harder to observe doesn’t mean we can rule them out. “There’s no reason they have to be three-dimensional,” says David Schneider, a physics professor at the University of California, San Diego. Georges Obie At Oxford University. “It could have been two, it could have been four, it could have been ten.”

Still, there comes a time when any self-respecting physicist wants hard evidence. That’s why it’s so exciting that over the past few years, researchers have developed several techniques that may finally provide evidence of extra dimensions. For example, we might be able to detect gravity leaking into extra dimensions. We might see subtle signatures of it in black holes, or we might find its signature in particle accelerators.

But now, in an unexpected twist, Ovid and his colleagues claim that there is an extra dimension that is fundamentally different from any previously conceived. This “dark dimension” hides ancient particles whose gravity could solve the mystery of dark matter, the force that is thought to have shaped the universe. Crucially, this dimension is relatively…

Source: www.newscientist.com

The importance of passwords in the AI era: Why they still matter | Apple

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AI, whether it stands for artificial intelligence or Apple intelligence, is a hot topic today. It’s time to have a conversation about it. [sits backwards on chair] password.

One significant change coming to Apple’s platform next year is the creation of a new Password app. This was somewhat overshadowed by the reporting from last night’s Apple event in Cupertino and New York by Kari Paul and Nick Robbins-Early.

9to5Mac reports that the new passwords app on iPhone home screens this fall will enhance the security of computing for average users who may not be familiar with password management apps.

The new Passwords app consolidates and simplifies existing password features on iOS and macOS, making them more accessible to users. It will display a list of all user logins after verifying identity.

Apple has expanded its password management capabilities over the years, offering security audits, alerting users to compromised passwords, sharing options, and data import/export features.

The focus on identity, rather than just passwords, highlights Apple’s aim with the new Passwords app. Managing digital identity remains a challenge, with passwords serving as the primary method of online identity verification but coming with inherent security risks.

Password managers like 1Password have emerged as a solution, but the industry is exploring alternatives like passkeys to address the limitations of traditional password systems.

While passkeys promise a password-free future, their adoption has been slow due to limited support from websites and initial user challenges. Despite the potential benefits, concerns remain about the security and user experience of passkeys.

From password managers to passkeys, the quest for secure and user-friendly authentication methods continues.

The evolution of identity verification extends beyond passwords to technologies like AI avatars. While the concept of AI systems participating in meetings remotely is not yet fully realized, advancements in voice synthesis and AI present new challenges and opportunities for digital identity verification.

As technology progresses, ensuring secure and seamless identity verification methods remains a crucial aspect of digital life.

The Wider TechScape

European brown bears play in the pool at Bristol Zoo’s Wild Place Project in 2020.

Source: www.theguardian.com

Galactic anomalies suggesting dark matter presence are more puzzling than anticipated

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A dark matter halo (yellow) forms around the galaxy

Ralph Koehler/SLAC National Accelerator Laboratory

When you think of the Milky Way, “delicate” may not be the first word that comes to mind.But when Mariangela Lisanti She started tinkering with the Our Galaxy recipe, but found it surprisingly fragile.

Lisanti, a particle physicist at Princeton University, wonders what would happen if dark matter, a mysterious substance thought to make up more than 80 percent of all matter in the universe, was more exotic than researchers usually assume. I was simulating something. She replaced a small portion of standard dark matter with something more complex. “We thought we could just add 5% and everything would be fine,” she says. “And we destroyed the galaxy.”

There are good reasons for such interference. Since the 1980s, astronomical signs have shown that dark matter is a single type of slow-moving particle that does not interact with itself. Particle physicists have spent a great deal of effort searching for that particle. But decades later, it remains a no-show. Perhaps because dark matter is not what we tend to imagine.

Recently, a series of galactic anomalies have sparked a scramble to find alternatives. This “complex” dark matter can be as simple as subatomic particles bouncing off each other, or as complex as dark particles forming dark atoms, stars, and even galaxies. There are a number of mind-boggling possibilities.

But now observations of anomalies in our galaxy promise to finally help narrow down the options. and…

Source: www.newscientist.com

New computer model provides evidence for dark matter hypothesis

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A new study led by the University of California, Irvine, addresses a fundamental debate in astrophysics: the existence of invisible dark matter is necessary to explain how the universe works. Is there an observation, or can physicists explain how things work based only on matter that we can know directly?

Dark photons are hypothetical dark sector particles that have been proposed as force carriers, similar to electromagnetic photons but potentially related to dark matter. Image credit: University of Adelaide.

“Our paper shows how a real-world observed relationship can be used as a basis for testing two different models for describing the universe,” said Dr. One Dr. Francisco Mercado said:

“We conducted robust tests to distinguish between the two models.”

“This test required us to run computer simulations using both types of matter, normal matter and dark matter, to account for the presence of interesting features measured in real galaxies.”

“The features we discovered in galaxies would be expected to appear in a universe with dark matter, but would be difficult to explain in a universe without dark matter.”

“We have shown that such features appear in observations of many real galaxies. If we take these data at face value, the dark matter model is the one that best explains the universe we live in. It is reconfirmed that.”

These features explain patterns in the movement of stars and gas within galaxies that appear to be possible only in a universe with dark matter.

“The observed galaxies appear to follow a close relationship between the matter we see and the dark matter we inferred to detect, hence what we call dark matter. Some have even suggested that this is actually evidence that our theory of gravity is wrong,'' New York University said. Professor James Block of Irvine, California;

“What we have shown is that dark matter not only predicts that relationship, but for many galaxies it can explain what we see more naturally than modified gravity.”

“I am even more convinced that dark matter is the correct model.”

This feature has also appeared in observations by proponents of a dark matter-free universe.

“The observations we looked at, the very observations that discovered these features, were made by proponents of the no-dark-matter theory,” said Dr. Jorge Moreno, a researcher at Pomona College. Ta.

“Despite their obvious existence, there has been little analysis of these functions by the community.”

“We needed scientists like us who work with both ordinary matter and dark matter to start the conversation.”

“We hope that this study will spark a debate within our research community, but such features can only be found in our planet if both dark matter and normal matter are present on Earth.” We also found that it appears in simulations, so there may be room for commonalities in the universe. “

“When stars are born and die, they explode into supernovae, which can form the centers of galaxies, providing a natural explanation for the existence of these features.”

“Simply put, the features we investigated in our observations require both the presence of dark matter and the incorporation of normal matter physics.”

Now that the dark matter model of the universe appears to be a promising model, the next step is to see whether it remains consistent across the dark matter universe.

“It will be interesting to see if this same relationship can even be used to distinguish between different dark matter models,” Dr. Mercado said.

“Understanding how this relationship changes under individual dark matter models could help constrain the properties of dark matter itself.”

of paper Published online on Royal Astronomical Society Monthly Notices.

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Francisco J. Mercado other. Hooks and bends in the radial acceleration relationship: Discrimination test between dark matter and MOND. MNRAS 530 (2): 1349-1362; doi: 10.1093/mnras/stae819

Source: www.sci.news

Physicists suggest that the capture and annihilation of dark matter could reignite dormant neutron stars

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A team of particle physicists from the University of Melbourne, Australian National University, King’s College London, and Fermi National Accelerator Laboratory has discovered that the energy transferred when dark matter particles collide and annihilate inside a cold neutron star. They calculated that the star could be heated rapidly. Previously, this heating was thought to be irrelevant because this energy transfer takes a very long time, in some cases longer than the age of the universe itself.

An artist’s impression of a neutron star.

A number of recent studies have focused on trapping dark matter in neutron stars as sensitive probes of the interaction of dark matter with ordinary matter.

This could potentially be used to test dark matter interactions in a way that is highly complementary to experiments on Earth, especially since dark matter is accelerated to relativistic speeds during a fall into a neutron star. there is.

In some cases, neutron star technology may be able to probe interactions that are difficult or impossible to observe with direct dark matter detection experiments. These include dark matter, which is too light to leave a detectable signal in nuclear recoil experiments, and interactions where non-relativistic scattering cross sections are momentum suppressed.

It was recently pointed out that an isolated old neutron star near the Sun could be heated by the capture of dark matter, increasing its temperature by 2000 K.

Once older than 10 million years, an isolated neutron star is expected to cool to temperatures below this unless reheated by standard matter accretion or internal heating mechanisms.

As a result, observations of local neutron stars may place severe constraints on dark matter interactions. Importantly, neutron stars with temperatures in this range produce near-infrared radiation that could be detected by future telescopes.

“Our new calculations show for the first time that most of the energy is stored in just a few days,” said Professor Nicole Bell from the University of Melbourne, lead author of the study.

“The search for dark matter is one of science’s greatest detective stories.”

“Dark matter makes up 85% of the matter in the universe, but we can’t see it.”

“It doesn’t interact with light. It doesn’t absorb, reflect, or emit light.”

“This means that even if we know it exists, we can’t directly observe it with our telescopes.”

“Rather, its attraction to an object that we can see tells us that it must be there.”

“Predicting dark matter theoretically and observing it experimentally are two different things.”

“Earth-based experiments are limited by the technical challenges of building a large enough detector.”

“But neutron stars act as huge natural dark matter detectors, collecting dark matter over astronomically long timescales, so they are a good place to focus our efforts.”

“Neutron stars form when supermassive stars run out of fuel and collapse,” Professor Bell said.

“They have a similar mass to our sun and are squeezed into a sphere just 20km wide. If they got any denser, they would become black holes.”

“Dark matter is the main type of matter in the universe, but it is very difficult to detect because it interacts very weakly with normal matter.”

“In fact, dark matter is so weak that it can pass straight through the Earth and even the Sun.”

“But neutron stars are different. Because neutron stars are so dense, dark matter particles are much more likely to interact with the star.”

“If dark matter particles collide with neutrons inside a star, they lose energy and become trapped.”

“Over time, this will lead to an accumulation of dark matter within the star.”

“We expect this to cause old, cold neutron stars to heat up to a point where they can be observed in the future, or even cause the star to collapse into a black hole,” said the University of Melbourne doctor. candidate Michael Vilgat, co-author of the study.

“If the energy transfer happens quickly enough, the neutron star will heat up.”

“For this to happen, the dark matter would have to collide within the star many times, transferring more and more of the dark matter’s energy until all the energy is stored in the star.”

“Until now it was unknown how long this process takes, because as dark matter particles become less and less energetic, they become less and less likely to interact again.”

“As a result, it was thought that it would take a very long time to transfer all the energy, in some cases longer than the age of the universe.”

Instead, the researchers calculated that 99% of the energy is transferred in just a few days.

“This is good news, because it means dark matter can potentially heat neutron stars to detectable levels,” Birgat said.

“As a result, observations of cold neutron stars will provide important information about the interactions between dark matter and ordinary matter and shed light on the nature of this elusive matter.”

“If we are to understand the ubiquity of dark matter, it is important to use every technology at our disposal to understand what the hidden matter in our universe actually is.” .”

of study Published in Journal of Cosmology and Astroparticle Physics.

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Nicole F. Bell other. 2024. Thermalization and extinction of dark matter in neutron stars. JCAP 04,006; doi: 10.1088/1475-7516/2024/04/006

Source: www.sci.news

Astrophysicist declares universe devoid of dark matter

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Professor Rajendra Gupta of the University of Ottawa is challenging current theoretical models of the composition of the universe by showing that there is actually no room for dark matter in the universe.

This artist's impression shows the evolution of the universe, starting with the Big Bang on the left and continuing with the emergence of the Cosmic Microwave Background. The formation of the first stars ends the Dark Ages of the universe, followed by the formation of galaxies. Image credit: M. Weiss / Harvard-Smithsonian Center for Astrophysics.

In cosmology, the term dark matter refers to anything that does not appear to interact with light or electromagnetic fields, or that can only be explained by gravity.

Although we can't see it and don't know what it's made of, it helps us understand how galaxies, planets, and stars work.

Professor Gupta reached this conclusion using a combination of covariation coupling constant (CCC) and “tired light” (TL) theory (CCC+TL model).

His model combines two ideas: how the forces of nature diminish over cosmic time and that light loses energy as it travels long distances.

It has been tested and shown to be consistent with several observations, including how galaxies spread and how light from the early universe evolved.

The discovery challenges the common understanding of the universe, which suggests that about 27% of the universe is made up of dark matter, less than 5% is normal matter, and the rest is dark energy.

“This new discovery confirms previous research, which found that the universe is 26.7 billion years old, and found that the existence of dark matter is not necessary for the universe,” said Gupta. the professor said.

“Standard cosmology says that the accelerating expansion of the universe is caused by dark energy, but it's actually because the forces of nature weaken as the universe expands, not by dark energy.”

In his research, Professor Gupta analyzed data from a recent paper on the distribution of galaxies at low redshifts and the angular size of the sound horizon in the literature at high redshifts.

“There are several papers that question the existence of dark matter, but to my knowledge, my paper does not support the existence of dark matter, while being consistent with the major cosmological observations that we have had time to confirm.” “This is the first paper to exclude ,” he said.

“By challenging the need for dark matter in the universe and providing evidence for a new cosmological model, this study opens up new avenues for exploring the fundamental properties of the universe.”

of paper Published in astrophysical journal.

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Rajendra P.Gupta other. 2024. Testing the CCC+TL cosmology with observed baryon acoustic vibration signatures. APJ 964, 55; doi: 10.3847/1538-4357/ad1bc6

Source: www.sci.news

Huge Neutron Stars Could Have Cores Composed of Unconfined Quark Matter

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The core of a neutron star contains the highest density of matter in the universe. This highly compressed matter can undergo a phase transition in which nuclear matter dissolves into unconfined quark matter, releasing its constituent quarks and gluons. However, it is currently unknown whether this transition occurs inside at least some physical neutron stars. In a new study, physicists from the University of Helsinki, the University of Stavanger, the Flatiron Institute, and Columbia University quantified this possibility by combining information from astrophysical observations and theoretical calculations.

Artist's impression of a neutron star. Image credit: Sci.News.

Neutron stars are extreme astrophysical objects containing the densest matter found in the modern universe.

It has a radius of about 10 km (6 miles) and a mass of about 1.4 solar masses.

“A long-standing unresolved question concerns whether the enormous central pressure of a neutron star can compress protons and neutrons into a phase called cold quark matter. In this exotic state, individual protons and neutrons no longer exist. We don’t,” said Professor Aleksi Vuorinen of the University of Helsinki.

“The quarks and gluons that make them up are instead freed from typical color confinement and can move almost freely.”

In a new paper, Professor Vuorinen and colleagues provide the first quantitative estimate of the possibility of a core of quark matter existing inside a massive neutron star.

They showed that quark matter is almost inevitable in the most massive neutron stars, based on current astrophysical observations. The quantitative estimates they extracted put the likelihood in the 80-90% range.

For there to be a small chance that all neutron stars are composed only of nuclear matter, the change from nuclear matter to quark matter must occur through a strong primary phase similar to the phenomenon in which liquid water turns to ice. Must be a metastasis.

This type of rapid change in the properties of neutron star matter could destabilize the star in such a way that even the formation of a tiny quark matter core could cause the star to collapse into a black hole.

An artist's impression of the various layers inside a giant neutron star. The red circle represents a significant amount of quark matter core. Image credit: Jyrki Hokkanen, CSC.

“A key element in deriving the new results is a series of large-scale supercomputer calculations that utilize Bayesian inference, a branch of statistical deduction that estimates the likelihood of various model parameters through direct comparison with observed data. “, the authors explained.

“We demonstrate that the Bayesian component allows us to derive new limits on the properties of neutron star matter, approaching the so-called conformal behavior near the center of the most massive and stable neutron stars.”

Dr. Joonas Nettila from the University of Helsinki added: “It is interesting to see specifically how each new neutron star observation improves the ability to estimate the properties of the neutron star material.” .

“Being able to compare theoretical predictions with observations and constrain the possibility of quark-matter nuclei requires hundreds of supercomputers,” said Jonas Hirvonen, a doctoral student at the Flatiron Institute and Columbia University. “We had to spend tens of thousands of CPU hours.”

“We are very grateful to the Finnish Supercomputer Center CSC for providing us with all the necessary resources.”

of paper It was published in the magazine nature communications.

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E.Annara other. 2023. Strongly interacting matter exhibits unconfined behavior in massive neutron stars. Nat Commune 14, 8451; doi: 10.1038/s41467-023-44051-y

Source: www.sci.news

Astrophysical mysteries unraveled by new dark matter theory

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Researchers have advanced our understanding of dark matter through simulations that support the self-interacting dark matter (SIDM) theory. This theory has the potential to resolve the discrepancy in dark matter density observed in different galaxies, poses a challenge to traditional cold dark matter (CDM) models, and highlights the dynamic nature of dark matter. Credit: SciTechDaily.com

Dark matter may be more active than previously thought, reports a study from the University of California, Riverside.

Dark matter, which is thought to make up 85% of the matter in the universe, does not emit light and its properties are still poorly understood. Normal matter absorbs, reflects, and emits light, but dark matter cannot be seen directly, making it difficult to detect. A theory called “self-interacting dark matter” (SIDM) claims that dark matter particles self-interact with each other due to dark forces, causing them to collide strongly with each other near the centers of galaxies.

Among the works published in of Astrophysics Journal LetterA research team led by Haibo Yu, a professor of physics and astronomy at the University of California, Riverside, reports that SIDM can simultaneously explain two extreme astrophysical puzzles.

Understanding dark matter halos and gravitational lenses

“The first is a halo of dense dark matter in a giant elliptical galaxy,” Yu said. “The halo is detected by observations of strong gravitational lenses, and its density is so high that it is extremely unlikely under the prevailing cold dark matter theory. Second, the density of dark matter halos in superdiffuse galaxies is extremely low. is extremely low and difficult to explain using cold dark matter theory.”

A dark matter halo is an invisible halo of matter that permeates and surrounds a galaxy or galaxy cluster. Gravitational lensing occurs when light traveling across space from a distant galaxy is bent around a massive object. The cold dark matter (CDM) paradigm/theory assumes that dark matter particles do not collide. As the name suggests, superdiffuse galaxies have extremely low luminosity and a dispersed distribution of stars and gas.

Hai-Bo Yu is a theoretical physicist at the University of California, Riverside, with expertise in the particle properties of dark matter.Credit: Samantha Tiu

Yu was also joined in the study by Ethan Nadler, a postdoctoral fellow at the Carnegie Observatory and the University of Southern California, and Danen Yang, a postdoctoral fellow at UCR.

To show that SIDM can explain two puzzles in astrophysics, the research team presents a theory of cosmic structure formation with strong dark matter self-interactions at relevant mass scales for strong lenticular halos and superdiffuse galaxies. We conducted our first high-resolution simulation.

“These self-interactions cause heat transfer within the halo and diversify the halo density in the central region of the galaxy,” Nadler said. “In other words, some halos have higher center densities and others have lower center densities compared to their CDM counterparts, the details of which depend on the evolutionary history of the Universe and the environment of the individual halo.”

Challenges to the CDM paradigm and future research

According to the research team, these two puzzles pose a formidable challenge to the standard CDM paradigm.

“CDM takes on the challenge of explaining these mysteries,” Yang said. “SIDM is probably a good candidate for reconciling two opposing extremes. There are no other explanations in the literature. We now know that dark matter may be more complex and active than we expected. There is an interesting possibility that there is.”

The study also demonstrates the ability to investigate dark matter through astrophysical observations using computer simulation tools of cosmic structure formation.

“We hope that our study will encourage further research in this promising research area,” Yu said. “This is a particularly timely development given the expected influx of data in the near future from observatories such as the James Webb Space Telescope and the upcoming Rubin Observatory.”

Since around 2009, the work of Yu and his collaborators has popularized SIDM in the particle physics and astrophysics communities.

References: Ethan O. Nadler, Danen Yang, and Haibo Yu, “Self-interacting dark matter solutions for the extreme diversity of low-mass halo properties,” November 30, 2023. Astrophysics Journal Letter.
DOI: 10.3847/2041-8213/ad0e09

This research was supported by the John Templeton Foundation and the U.S. Department of Energy.

Source: scitechdaily.com

Is Pulsar Light the Key to Solving the Dark Matter Mystery?

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New research explores the possibility that dark matter is composed of theoretical particles called axions, and focuses on detecting them through additional light from pulsars. Although axions have not yet been confirmed in early observations, this research is critical to understanding dark matter.

A central question in the ongoing search for dark matter is: What is dark matter made of? One possible answer is that dark matter is made up of particles known as axions. A recent study by astrophysicists at the University of Amsterdam and Princeton University suggests that if dark matter is indeed made of axions, it could manifest itself in the form of subtle additional glow emanating from pulsating stars.

Dark matter may be the most sought-after building block in our universe. Remarkably, this mysterious form of matter, so far undetectable by physicists and astronomers, is thought to make up a huge portion of what exists on Earth. It is suspected that more than 85% of the matter in the universe is “dark”, and at the moment it is only recognized by the gravitational force it exerts on other celestial bodies. Naturally, scientists want to look directly detect its existence rather than just inferring it from gravitational effects. And of course they want to know what of course, solve two problems One thing is clear: dark matter cannot be the same kind of matter that makes up you and me. If so, dark matter would simply behave like ordinary matter. Dark matter will form star-like objects, will glow, and will no longer be “dark.” So scientists are looking for something new, a type of particle that no one has detected yet, and perhaps one that only interacts very weakly with the types of particles we know about.

One common hypothesis is that dark matter may be made of: Axion. This hypothetical type of particle was first introduced in the 1970s when he solved a problem that had nothing to do with dark matter. The separation of positive and negative charges inside a neutron, one of the building blocks of a normal atom, turns out to be unexpectedly small. Of course, scientists wanted to know why. It turns out that the presence of a previously undetected type of particle that interacts very weakly with components of neutrons can cause just such an effect. Frank Wilczek, who later won the Nobel Prize, came up with the name for this new particle. Axion – as well as similar to another particle name such as protons, neutrons, and electrons. photon, but it’s also inspired by the laundry detergent of the same name. Axion existed to solve problems. In fact, it might clean up the two even if it’s not detected. Several theories about elementary particles, including string theory, one of the leading candidate theories for unifying all the forces in nature, seem to predict the possibility of axion-like particles.

Fortunately, there appears to be a way out of this conundrum for axions. If the theory predicting axions is correct, not only would axions be expected to be produced in large quantities in the universe, but some axions could also be converted to light in the presence of strong electromagnetic fields. If there is light, we can see. Could this be the key to detecting axions and, by extension, dark matter? To answer this question, scientists first had to ask themselves where in the universe the strongest known electric and magnetic fields occur. The answer is known in the region around rotating neutron stars. pulsar. These pulsars (short for “pulsating stars”) are dense objects with a mass about the same as the Sun, but a radius about 100,000 times smaller, or only about 10 km. Because pulsars are so small, they rotate at enormous frequencies and emit bright, narrow beams of radio radiation along their axis of rotation. Just like a lighthouse pulsarThe beam can sweep across the Earth, making it easy to observe the pulsating star. But the pulsar’s massive rotation does more than that. it is, neutron star It turns into a very powerful electromagnet. That could mean Pulsar is a highly efficient axion factory. The average pulsar can produce 50 orders of magnitude axions per second. Because of the strong electromagnetic fields surrounding pulsars, some of these axions can be converted into observable light.

As always in science, carrying out such observations in practice is, of course, not so easy. The light emitted by axions (which can be detected in the form of radio waves) is only a fraction of the total light these bright cosmic lighthouses send back to us. Much less can we quantify the difference and turn it into a measurement of the amount of dark matter. This is exactly what a team of physicists and astronomers are currently doing. Through a collaboration between the Netherlands, Portugal, and the United States, the research team has uncovered details about how axions are created, how axions escape the neutron star’s gravity, and…

First observational tests were performed on the theory and simulation results…referencesystem, simulate a subtle glow

Next, first observational tests were performed on the theory and simulation results…referencesystem to show that it is very unlikely that axions are a component of…s

Note: The original content contained HTML tags, it’s been removed in the rewrite.

Source: scitechdaily.com

Active Matter Theory sheds new light on longstanding biological enigmas

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November 22, 2023A team of scientists has developed a new algorithm to solve theoretical equations for active materials, deepening our understanding of living materials. This research is of vital importance in biology and computational science, paving the way for new discoveries in cell morphology and the creation of artificial biological machines. Advanced open-source supercomputer algorithms predict the patterns and dynamics of living matter and enable exploration of its behavior across space and time. Biological materials are made up of individual components, such as tiny motors that convert fuel into motion. This process creates a pattern of movement, guiding the shape of the material itself through a consistent flow driven by constant energy consumption. Such permanently driven substances are called “active substances.”

How cells and tissues work can be explained by active matter theory, a scientific framework for understanding the shape, flow, and form of living matter. Active matter theory consists of many difficult mathematical equations. Scientists from Dresden’s Max Planck Institute for Molecular Cell Biology and Genetics (MPI-CBG), the Dresden Center for Systems Biology (CSBD), and the Dresden University of Technology have developed an algorithm implemented in open-source supercomputer code. For the first time, you can solve active matter theory equations in realistic scenarios. These solutions bring him a big step closer to solving his century-old mystery of how cells and tissues acquire their shape, and to designing artificial biological machines. 3D simulation of active substances in a dividing cell-like geometry. Credit: Singh et al. Physics of Fluids (2023) / MPI-CBG

Biological processes and behaviors are often highly complex. Physical theory provides a precise and quantitative framework for understanding physical theories. Active matter theory provides a framework for understanding and explaining the behavior of active substances, which are materials made up of individual components that can convert chemical fuels (“food”) into mechanical forces. The development of this theory was led by several Dresden scientists, including Frank Uricher, director of the Max Planck Institute for Complex Systems Physics, and Stefan Grill, director of MPI-CBG. These physical principles allow us to mathematically describe and predict the dynamics of active organisms. However, these equations are very complex and difficult to solve. Therefore, scientists need the power of supercomputers to understand and analyze living matter. There are various ways to predict the behavior of active materials, including by focusing on small individual particles, by studying active materials at the molecular level, and by studying active fluids on a larger scale. These studies help scientists understand how active substances behave at different scales in space and time. Scientist in the research group of Dresden University of Technology Ivo Sbalzarini Professor at the Dresden Center for Systems Biology (CSBD), research group leader at the Max Planck Institute molecular cell The Dean of the Department of Biology and Genetics (MPI-CBG) and Computer Science at the Technical University of Dresden has now developed a computer algorithm to solve the active substance equation. Their research was published in the journal fluid physics and it appeared on the cover. They present an algorithm that is capable of solving complex equations for active materials in three-dimensional and complex-shaped spaces.

“Our approach can handle a variety of shapes in three dimensions over time,” says research mathematician Abhinav Singh, one of the study’s first authors. He continued, “Even when the data points are not regularly distributed, our algorithm employs a novel numerical approach that works seamlessly for complex biologically realistic scenarios, and the theoretical equations Using our approach, we can finally understand the long-term behavior of active materials in both mobile and non-mobile scenarios in order to predict dynamic scenarios. Additionally, theory and simulation can be used to program biological materials and create engines at the nanoscale to extract useful work.” The other first author, Philipp Suhrcke, holds a master’s degree in computational modeling and simulation from the Technical University of Dresden. “Thanks to our research, scientists can predict, for example, the shape of tissues and when biological materials will become unstable or dysregulated, leading to growth and disease. This has far-reaching implications for our understanding of mechanisms.”

The scientists implemented the software using the open source library OpenFPM. This means that others can use it freely. OpenFPM was developed by his Sbalzarini group to democratize large-scale scientific and technical computing. The authors first developed a custom computer language that allows computational scientists to write code for a supercomputer by specifying mathematical formulas that let the computer do the work of writing the correct program code. As a result, you no longer have to start from scratch every time you write code, effectively reducing code development time in scientific research from months or years to days or weeks, greatly increasing productivity.

Because the study of three-dimensional active materials has significant computational demands, using OpenFPM the new code is scalable on shared and distributed memory multiprocessor parallel supercomputers. This application is designed to run on powerful supercomputers, but can also be run on regular office computers to study 2D materials. Ivo Sbalzarini, the study’s lead researcher, summarizes: All this has been integrated into a tool for understanding her three-dimensional behavior of living matter. Our code, which is open source, scalable, and able to handle complex scenarios, opens new avenues in active materials modeling. This could ultimately lead to an understanding of how cells and tissues acquire their shape, addressing fundamental questions in morphogenesis that have puzzled scientists for centuries. There is a gender. But it may also be useful for designing artificial biological machines with minimal components.

References: “Numerical solver for three-dimensional active fluid dynamics and its application to active turbulence” by Abhinav Singh, Philipp H. Suhrcke, Pietro Incardina, and Ivo F. Sbalzarini, October 30, 2023. fluid physics. DOI: 10.1063/5.0169546 This research was funded by the Federal Ministry of Education and Research (Bundesministerium f€ur Bildung und Forschung, BMBF), the Federal Center for Scalable Data Analysis and Artificial Intelligence, ScaDS.AI, and Dresden/Leipzig. The computer code supporting the results of this study is publicly available in the 3Dactive-hydynamics github repository at: https://github.com/mosaic-group/3Dactive-hydrodynamic sThe open source framework OpenFPM is available at: https://github.com/mosaic-group/openfpm_pdataRelated publications for embedded computer languages https://doi.org/10.1016/j.cpc.2019.03.007https://doi.org/10.1140/epje/s10189-021-00121-x (function (d, s, id) {var js, fjs = d.getElementsByTagName (s) [0]; if (d.getElementById (id)) return; js = d.createElement (s); js.id = id; js.src = “https://connect.facebook.net/en_US/sdk.js#xfbml=1&version=v2.6”; fjs.parentNode.insertBefore (js, fjs); } (document, ‘script’, ‘facebook-jssdk’));

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