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Posts tagged "Dark Matter"

kenobi-wan-obi:

Could Tiny ‘Black Hole Atoms’ Be Elusive Dark Matter?

Dark matter, the invisible and mysterious stuff that makes up most of the material universe, might be hiding itself in microscopic black holes, says a team of Russian astrophysicists.

No one knows what dark matter is. But scientists do know that it must exist, because there is not enough visible matter in the cosmos to account for all the gravity that binds galaxies and other large-scale structures together.

Astronomers have been on the hunt for dark matter for decades now, using detectors both on Earth and in space. The new hypothesis, formulated by astrophysicists Vyacheslav Dokuchaev and Yury Eroshenko at the Institute for Nuclear Research of the Russian Academy of Sciences in Moscow, suggests that dark matter could be made of microscopic — or quantum — “black hole atoms.”

The concept is not entirely new; others have suggested that various types of miniature black holes could make up dark matter, which is so named because it apparently neither absorbs nor emits light, and thus cannot be detected directly by telescopes.

Physicists have also long believed that microscopic black holes must have existed in the early universe, because quantum fluctuations in the density of matter just after the Big Bang would have created regions of space dense enough to allow the formation of such tiny black holes.

Some researchers believe that the universe could still be full of such “primordial black holes.”

kenobi-wan-obi:

Dark-Matter Detector to Begin Operations Soon in China

China is entering the race to detect mysterious dark matter in a big way, with a huge facility in Sichuan province set to begin collecting data in the coming weeks.

The $8 million PandaX (Particle and Astrophysical Xenon) experiment — which lies 7,874 feet (2,400 meters) underground, inside a mountain made of marble — will be up and running early this year, IEEE Spectrum reported recently on Discovery News. When it comes online, PandaX will join the world’s other subterranean dark-matter experiments, such as the XENON project in Italy and the Large Underground Xenon (LUX) effort in South Dakota.

These experiments work on the same principle. They’re looking for particles emitted when weakly interacting massive particles (WIMPS) — the postulated major component of dark matter, which is thought to make up more than 80 percent of all mass in the universe — collide with the nuclei of “normal” atoms inside a big tank of liquid xenon. PandaX and the other projects need to be underground, where they’re shielded from most of the cosmic radiation that could generate similar signals.

The first science results are expected from PandaX by the end of the year, IEEE Spectrum reported. If everything works as planned, the project may be scaled up, employing a bigger tank of xenon to increase the chances of detection.

(via afro-dominicano)

heythereuniverse:

Dark Matter Ring in Galaxy Cluster | NASA

I highly suggest you follow [this link] to get the full resolution image. You’d be able to see almost clearly the individual galaxies. 

What a universe we live in.

scienceyoucanlove:

Large-Scale Structure
Courtesy V. Springel, The Virgo Consortium, and the Max Planck Institute for Astrophysics
Computer models, such as the Millennium Simulation, show how dark matter influenced the formation of galaxies after the big bang; without it, there isn’t enough gravitational pull to explain how galaxy clusters, stars, or even humans came to be.
sorry I can’t post more on it, I heard the article is excellent unfortunately it’s behind a pay wall D: But if you have a subscription to popsci then you can a link to the article on the source page 

abluegirl:

Dark Matter Signal Possibly Registered on International Space Station:

A $2-billion particle detector mounted on the International Space Station has registered an excess of antimatter particles in space, the experiment’s lead scientist announced April 3. That excess could come from fast-spinning stellar remnants known as pulsars and other exotic, but visible sources within the Milky Way galaxy. Or the antiparticles might have originated from the long-sought dark matter, the hypothetical massive particles that constitute some 27 percent of the universe.

Full Article

This is really exciting news, because up until now scientists have been unable to directly observe dark matter.  Dark matter is really important. Not only is there four times more of it than regular matter, but due to the gravitational force it exerts on galaxies, it plays an important role in galaxy formation and in determining the structure of the universe itself. Yet, scientists still aren’t really sure what it is, exactly. Gaining direct evidence of its existence goes a long way to figuring that out.

Just keep in mind that dark matter is one possible reason for these results there are of reasons to be suspicious of any conclusions that are drawn from them.

electricspacekoolaid:

Dark Matter Could Play a Role in Creating Life in The Universe

First Image : A Hubble Space Telescope image of Dark Matter mapped in a 3d representation.

Second Image: Abel 1689 galaxy cluster.

Dark matter makes up the majority of mass in our universe. However, we cannot directly measure the stuff as it doesn’t interact with electromagnetic radiation (i.e. it doesn’t emit or reflect any light), but we can indirectly observe its presence. In the Hubble Space Telescope image above, the distribution of mostly dark matter has been calculated and mapped. Basically, the location and density of anything with mass has been plotted in a 3D representation of the cosmos.

A 2011 study suggests that mysterious, invisible dark matter could warm millions of starless planets in regions such as Abell 1689 (image below) and make them habitable.

image

Scientists think the invisible, as-yet-unidentified dark matter which we know exists because of the gravitational effects it has on galaxies, makes up about 85 percent of all matter in the universe.  Current prime candidates for what dark matter might be are massive particles that only rarely interact with normal matter.
These particles could be their own antiparticles, meaning they annihilate each other when they meet, releasing energy. These invisible particles could get captured by a planet’s gravity and unleash energy that could warm that world, according to physicist Dan Hooper and astrophysicist Jason Steffen at the Fermi National Accelerator Laboratory.

Hooper and Steffen’s propose that rocky “super-Earths” in regions with high densities of slow-moving dark matter could be warmed enough to keep liquid water on their surfaces, even in the absence of additional energy from starlight or other sources.The density of dark matter is expected to be hundreds to thousands of times greater in the innermost regions of the Milky Way and in the cores of dwarf spheroidal galaxies than it is in our solar system.

The scientists concluded that on planets in dense “dark-matter” regions, it may be dark matter rather than light that creates the basic elements you need for organic life without a star”

Now take a moment to think how this could change the way we view evolution of life on other worlds. A dark matter evolved life form definitely gives me tingling sensations just trying to think of it despite how theoretical the assertion may be.

(via sagansense)

ikenbot:

Dark Matter Mystery May Soon Be Solved

The hiding spots for the particles making up dark matter are narrowing, and the answer to this cosmic mystery could come within the next three or four years, scientists say.

Image: Astronomers using the W. M. Keck Observatory, the Hubble Space Telescope, and other telescopes on Mauna Kea have studied a giant filament of dark matter in 3D for the first time. Image released Oct. 17. 2012. Credit: Image by ESA; additional elements by K. Teramura, Univ. Hawaii Institute for Astronomy.

Dark matter is an elusive substance that is invisible and almost never detected, except by its gravitational pull. Yet astronomers say it likely makes up a quarter of the entire universe and dwarfs the amount of normal matter (galaxies, stars and planets) out there in space.

Just last week, particle physics discovery from the Large Hadron Collider in Switzerland cast doubt on a theory called supersymmetry, which predicts the existence of particles that are among the leading candidates for dark matter. That finding limited the types of supersymmetric particles that can exist, but didn’t take the supersymmetry explanation off the table completely.

And supersymmetric particles are just one of a number of theorized particles that might account for dark matter. Searches for these and other undiscovered particles have been underway for decades, though none have been detected so far.

“I think we’re looking in enough different ways that unless it’s something that we just haven’t thought of at all yet, it seems to me we’re very likely to find it within the next decade,” said Dan Bauer, a physicist at the Fermi National Accelerator Laboratory in Illinois working on one of the experiments, called CDMS.

Full Article

ikenbot:

Mystery Glow of Dark Matter Halos Fueled by Extragalactic Stars

Stars ripped from their home galaxies as they collide with other galaxies can get slung into giant invisible cocoons of dark matter, researchers say, which might explain mysterious radiation pervading the sky.

Image: New research from scientists using NASA’s Spitzer Space Telescope suggests that a mysterious infrared glow across our whole sky is coming from stray stars torn from galaxies. This artwork is adapted, in part, from galaxy images obtained from the NASA/ESA Hubble Space Telescope. Credit: NASA/JPL-Caltech

These findings suggest the halos of dark matter surrounding galaxies are not completely dark after all, but contain a small number of stars, investigators added.

In recent decades, satellite telescopes have detected more infrared light emanating from the sky than known galaxies could account for. Scientists had suggested this strange glow might come from sources too dim for observatories to see directly — for instance, the earliest, most distant galaxies. If such primordial galaxies were responsible for this radiation, that might suggest far more of them existed than before thought, potentially radically altering notions of how the cosmos evolved.

Source

ikenbot:

Giant Strand of Elusive Dark Matter Seen in 3D

Astronomers have taken their first 3D look at a gigantic filament of dark matter, an invisible cosmic structure that can only be detected by its gravitational effects it has on its surroundings.

Image: This enormous image shows Hubble’s view of massive galaxy cluster MACS J0717. The large field of view is a combination of 18 separate Hubble images. The location of the dark matter is revealed in a map of the mass in the cluster and surrounding region, shown here in blue. The filament visibly extends out and to the left of the cluster core. Credit: NASA, ESA, Harald Ebeling (University of Hawaii at Manoa) & Jean-Paul Kneib (LAM)

The universe is thought to be structured like a tangled web, with long strings of mostly dark matter intersecting at giant galaxy clusters. Since dark matter cannot be seen directly, these filaments are difficult to observe. But using the Hubble Space Telescope, astronomers have managed to probe one of the elusive cosmic strands in 3D.

The researchers sought out a 60 million light-year strand of dark matter around the massive galaxy cluster MACS J0717. The galaxy cluster is one of the largest yet seen and is about 5.4 billion light-years from Earth.

continue

ikenbot:

New Research Confirms The Existence of Dark Matter

Image: Don Dixon

Fans of dark matter can rest easy. A study published last month raised eyebrows by suggesting that our cosmic neighbourhood is empty of the extra mass needed to hold the galaxy together. But a re-analysis shows that the dark matter was there all along.

Dark matter is the mysterious, invisible stuff that makes up 83 per cent of the matter in the universe. It is responsible for keeping galaxies from flying apart despite their high spinning speeds, and has aided our understanding of how structures in the universe formed.

The most popular theories say that dark matter is a hitherto undetected particle called a WIMP (weakly interacting massive particle) that is shy of interacting with ordinary matter through any force except gravity.

But several underground detectors waiting for WIMPs have come up empty, or with conflicting results. If the galaxy is so full of dark matter, why hasn’t it shown up yet?

In April, a team led by Christian Moni-Bidin of the University of Concepcion in Chile thought they had a solution: the WIMPs aren’t actually there.

The team tracked the motions of more than 400 stars within 13,000 light years of Earth to estimate the mass of matter – visible and dark – in the sun’s local neighbourhood. They concluded that the mass they found could be explained by the visible matter alone, with no need for dark matter.

But the team made a subtle error, say Jo Bovy and Scott Tremaine of the Institute for Advanced Study in Princeton, New Jersey.

Moni-Bidin and colleagues considered stars whose orbits take them far above or below the Milky Way’s main bright disc, and used the speed at which they orbit the centre of the galaxy to figure out how much of a pull they feel from the nearby mass of stars and dark matter. They assumed that the stars’ speeds would be the same no matter how far they were from the galactic centre. Observations of dust clumps have shown that this assumption is true for young stars orbiting in the galactic disc, which mostly move in a near-perfect circle.

But the stars that orbit high above or far below the disc can’t have circular orbits, Bovy says. The only stars that reach such great heights have been kicked away from the disc by matter in the galaxy’s spiral arms, which sent them on highly elliptical orbits.

Full Article: Crisis averted: Dark matter was there all along

ikenbot:

New Research Confirms The Existence of Dark Matter

Image: Don Dixon

Fans of dark matter can rest easy. A study published last month raised eyebrows by suggesting that our cosmic neighbourhood is empty of the extra mass needed to hold the galaxy together. But a re-analysis shows that the dark matter was there all along.

Dark matter is the mysterious, invisible stuff that makes up 83 per cent of the matter in the universe. It is responsible for keeping galaxies from flying apart despite their high spinning speeds, and has aided our understanding of how structures in the universe formed.

The most popular theories say that dark matter is a hitherto undetected particle called a WIMP (weakly interacting massive particle) that is shy of interacting with ordinary matter through any force except gravity.

But several underground detectors waiting for WIMPs have come up empty, or with conflicting results. If the galaxy is so full of dark matter, why hasn’t it shown up yet?

In April, a team led by Christian Moni-Bidin of the University of Concepcion in Chile thought they had a solution: the WIMPs aren’t actually there.

The team tracked the motions of more than 400 stars within 13,000 light years of Earth to estimate the mass of matter – visible and dark – in the sun’s local neighbourhood. They concluded that the mass they found could be explained by the visible matter alone, with no need for dark matter.

But the team made a subtle error, say Jo Bovy and Scott Tremaine of the Institute for Advanced Study in Princeton, New Jersey.

Moni-Bidin and colleagues considered stars whose orbits take them far above or below the Milky Way’s main bright disc, and used the speed at which they orbit the centre of the galaxy to figure out how much of a pull they feel from the nearby mass of stars and dark matter. They assumed that the stars’ speeds would be the same no matter how far they were from the galactic centre. Observations of dust clumps have shown that this assumption is true for young stars orbiting in the galactic disc, which mostly move in a near-perfect circle.

But the stars that orbit high above or far below the disc can’t have circular orbits, Bovy says. The only stars that reach such great heights have been kicked away from the disc by matter in the galaxy’s spiral arms, which sent them on highly elliptical orbits.

Full Article: Crisis averted: Dark matter was there all along

Closing in on Dark Matter: Another “Tentative” Step.
Photo Above: A galaxy cluster with the distribution of dark matter marked by purple overlay. Credit: NASA, ESA, E. Julio (JPL/LAM), P. Natarajan (Yale) and J-P. Kneib (LAM).

When physicists and mathematicians want to get an idea into circulation before going through all the hoo-hah of peer-reviewed publication, they often post a paper on the arXiv server, where anyone who is curious can go and read it. Some arXiv papers turn out to be important, but much evaporates on closer inspection. Judging whether a new arXiv paper is one or the other can be extremely difficult. That is certainly the case with physicist Christoph Weniger’s paper, “A Tentative Gamma-Ray Line from Dark Matter Annihilation at the Fermi Large Area Telescope,” posted on April 12, on dark matter.

Continue Reading…

ikenbot:

Has Our Galaxy’s Dark Matter Gone Missing?

If a new study is true, then the search for dark matter just got a lot weirder. Our little corner of the Milky Way contains no observable concentration of the mysterious stuff whose gravity binds the galaxy, claims one team of astronomers.

That finding would present a major problem for models of how galaxies form and may undermine the whole notion of dark matter, the researchers claim. But some scientists doubt the reliability of the team’s method for measuring the elusive substance.

“This is not just some piddling little detail,” says Frederic Hessman, an astronomer at the University of Göttingen in Germany who was not involved in the work. “If this is right, it turns everything totally upside-down.” But that’s a big if, says Julio Navarro, an astrophysicist at the University of Victoria in Canada: “The argument is provocative, but it remains inconclusive, in my opinion.”

According to standard cosmology, we should be swimming in dark matter. Measurements of the afterglow of the big bang—the so-called cosmic microwave background—and of the distribution of the galaxies suggest that 85% of all matter in the universe is dark matter. What’s more, decades of astronomical observations show that the stars within galaxies swirl about faster than they could if only the gravity of the others stars were holding them in. In fact, the speed with which the sun goes around the center of our galaxy suggests that dark matter ought to be about as abundant as ordinary matter at our distance from the galactic center, about 27,000 light-years.

But that’s not what Christian Moni Bidin, an astronomer at the University of Concepción in Chile, and colleagues find. Using data gathered with several telescopes, they studied old stars called red giants in a cylindrical region a couple of light-years wide and extending 13,000 light-years above the plane of the galaxy.

Treating the stars a bit like atoms in a gas, researchers assumed that they were trapped in the gravitational “well” of the galaxy. So by studying distributions of the stars’ speeds in three dimensions, they could deduce the well’s shape and hence the total distribution of mass from both dark and ordinary matter along the cylinder. Subtracting the distribution of ordinary matter as determined from star counts would then reveal the distribution of dark matter.

Continue..

(via afro-dominicano)

cosmictoquantum:

Dark Matter Collides with Human Tissue an Average of once a Minute, Study Finds

A dark matter particle smacks into an average person’s body about once a minute, and careens off oxygen and hydrogen nuclei in your cells, according to theoretical physicists. Dark matter is streaming through you as you read this, most of it unimpeded.

Dark matter is arguably the greatest mystery in modern physics. Observations from multiple sources across a few decades now shows that most of the universe is made of matter we can’t see — hence the name — but no one has been able to find it. One strong candidate for this dark material is called a WIMP, for weakly interacting massive particle, and there are a variety of observatories in Europe and the U.S. that are looking for these things. Some have found promising hints, but others have seen a whole lot of nothing.

Still, cosmologists generally agree there’s a halo of dark matter particles out there, and our solar system and our planet are flying through it. In a new paper, Katherine Freese at the University of Michigan and Christopher Savage at Stockholm University in Sweden thought about what this means for our bodies.

We know dark matter does not interact normally with regular matter — otherwise we’d be able to see it — so that means most of the particles pass through us. But some might interact with a hydrogen or oxygen nucleus, changing their energies or spins. The researchers use a 70-kg human (about 155 pounds) as an example, and calculate how many particles may be careening around based on signals from the DAMA, CoGeNT and CRESST experiments. Of the billions of high-energy WIMPs passing through a body every second, fewer than 10 hit a body’s nuclei in a given year. But lower energy WIMPs make impact much more frequently, around 100,000 collisions per person per year. That’s about one per minute.

What does this mean? Maybe nothing, in terms of impacts on human health — cosmic and solar radiation also rains down on us all the time, and it has many more detrimental effects. But it’s interesting to think that we ourselves could be dark matter detectors. The paper is posted on the astrophysics arXiv preprint server.

Rebecca Boyle, Popsci.com

the-star-stuff:

Getting a full picture of an elusive subject

The recent work on Abell 383 provides one of the most detailed 3-D pictures yet taken of dark matter in a galaxy cluster. By Chandra X-ray Center, Cambridge, MassachusettsPublished: March 15, 2012
Two teams of astronomers have used data from NASA’s Chandra X-ray Observatory and other telescopes to map the distribution of dark matter in a galaxy cluster known as Abell 383, which is located about 2.3 billion light-years from Earth. Not only were the researchers able to find where the dark matter lies in the two dimensions across the sky, but they were also able to determine how the dark matter is distributed along the line of sight.

ikenbot:

Galactic Pile-Up Leaves Behind Mysterious Dark Matter Core

Astronomers have found an enormous and strange clump of dark matter left behind following a violent collision of galaxy clusters.

The clump is located in the Abell 520 cluster, a diffuse collection of galaxies located 2.4 billion light-years away in the constellation Orion. The celestial object, sometimes called the Train Wreck cluster, is thought to be the remnant of a chaotic crash between several galaxy clusters.

Galaxy clusters are massive collections containing tens or even thousands of galaxies gravitationally bound together. They contain large amounts of dark matter — a strange form of matter that interacts through gravity but gives off no light — which is thought to provide an anchor attracting visible matter to a specific spot.

A 2007 study of Abell 520 showed that it was mostly typical: Wherever astronomers saw visible matter, they found a large clump of dark matter. But there was one gigantic and perplexing “dark core” that should have attracted large amounts of visible matter yet contained almost no galaxies.

Read full article..

(via afro-dominicano)