Astronomers create largest map yet of dark matter's web

5-year task achieved by observing gravitational effects on ancient light traveling from galaxies

Van Waerbeke, Heymans, CFHTLenS Collaboration

Recent observations show that dark matter in the universe is distributed as a network of gigantic dense (white) and empty (dark) regions, where the largest white regions are about the size of Earth's moon on the sky.

By Ian O'Neill

updated 1/9/2012 11:37:42 AM ET

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Astronomers have created a vast cosmic map revealing an intricate web of dark matter and galaxies spanning a distance of 1 billion light-years.

This unprecedented task was achieved not by observing dark matter directly, but by observing its gravitational effects on ancient light traveling from galaxies that existed when the universe was half the age it is now.

Constructed by astronomers from the University of British Columbia and University of Edinburgh, this is the largest dark matter map ever built and took five years to complete.

The research was presented at the American Astronomical Society meeting in Austin, Texas, on Monday.

ANALYSIS: Mapping dark matter with a cosmic lens

Dark matter pervades the entire observable universe, accounting for 83 percent of the mass of the cosmos. But as it does not scatter or radiate light (or any kind of electromagnetic radiation for that matter), we cannot see it. Naturally, this poses an interesting problem for astronomers hoping to map the stuff.

However, astronomers can indirectly observe dark matter as its mass exerts a gravitational force on the space-time surrounding it. As light travels from distant galaxies, it will be bent around gravitational distortions in space-time — much like the paths of marbles rolling across a bent sheet of plastic — being caused by the dense regions of dark matter.

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With this in mind, the international team of astronomers analyzed light from 10 million galaxies in four regions of the sky — all of which are about 6 billion light-years from Earth. As these galaxies are 6 billion light-years away, it took the light 6 billion years to travel that distance.

ANALYSIS: Dark matter mystery unraveled by dwarf galaxies?

Using a 340 Megapixel camera called "MegaCam" attached to the Canada-France-Hawaii Telescope (CFHT) in Hawaii, the ancient galactic light was analyzed to reveal the distorted paths each source traveled, thereby revealing the gravitational terrain surrounding clouds of dark matter.

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"It is fascinating to be able to 'see' the dark matter using space-time distortion," said Ludovic Van Waerbeke of the University of British Columbia.

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"It gives us privileged access to this mysterious mass in the universe which cannot be observed otherwise."

Catherine Heymans of the University of Edinburgh's School of Physics and Astronomy added: "By analyzing light from the distant universe, we can learn about what it has traveled through on its journey to reach us. We hope that by mapping more dark matter than has been studied before, we are a step closer to understanding this material and its relationship with the galaxies in our Universe."

Both Heymans and Van Waerbeke lead the Canada-France-Hawaii Telescope Lensing Survey (CFHTLenS) team.

ANALYSIS: How low can a dark matter halo go?

It is now hoped that other observatories — such as the Very Large Telescope's (VLT) Survey Telescope in Chile — will build on the CFHTLenS feat and create an even bigger dark matter map.

"Over the next three years we will image more than 10 times the area mapped by CFHTLenS, bringing us ever closer to our goal of understanding the mysterious dark side of the universe," said Koen Kuijken of Leiden University.

Understanding the nature of dark matter is critical to our knowledge of how the Universe evolved to form planets, stars and galaxies. Mapping this vast — yet invisible — cosmic web is a big step in that direction.

Interactive: Why does dark matter matter?

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Explainer: Dark matter revealed

ESA

Step right up and click inside to see dark matter revealed! Scientists think the mysterious substance makes up most of the mass in the universe — but because it doesn't give off light, visible proof of its existence is elusive. Theory suggests that the invisible stuff acts as gravitational glue that keeps the stars and galaxies from flying apart. Now, armed with powerful telescopes, tricky lenses and fast computers, scientists are at last bringing the evidence of dark matter to light.

For example, in this image, the yellowish galaxy cluster in the middle serves as a gravitational lens that bends the light of even more distant galaxies. Those galaxies appear as distorted blue streaks surrounding the cluster. Scientists can analyze the distortions to determine how dark matter is distributed in the cluster.

Click to see what else scientists have found out about dark matter.

— John Roach, msnbc.com contributor
Super clumpy

NASA / ESA

Dark matter, it turns out, may be rather clumpy stuff. This image shows a galaxy supercluster -- a grouping of hundreds of interacting galaxies -- about 2.6 billion light years from Earth. The bright blue spots are the visible galaxies, superimposed over magenta-tinted clumps that represent a detailed map of dark matter. The map was created by inferring how the light from even more distant galaxies is bent as it passes through the gravitational field of the supercluster, which is called Abell 901/902. Astronomers found that the supercluster's galaxies lie within the clumps of dark matter, and the irregular shapes of the clumps match the distribution of the galaxies.
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Invisible scaffolding

Todd Marshall

This 3-D map of the large-scale distribution of dark matter in the universe provides compelling evidence that the invisible stuff serves as the scaffolding upon which the stars and galaxies are hung. The map reveals a network of filaments that grow over time and intersect in massive structures at places where galaxy clusters are located. To make the map, astronomers used ground and space telescopes to determine the shape of half a million distant galaxies. This galactic light was bent and warped by the gravity of other galaxies as it traveled to the telescopes. By analyzing the shapes of these distant galaxies, astronomers were able infer the distribution of dark matter.
Bullet proof

Parsons

For proof that dark matter really exists, scientists turn to this image of a collision between two massive galaxy clusters that contains a bullet-shaped cloud of superheated gas. Theory suggests that during such a collision, a type of cosmic air resistance should slow down the hefty hot gas — but not the dark matter. That's what this image shows. The hot gas, pictured in red, is separated by the dark matter, pictured in blue. Scientists say the image serves as strong evidence that dark matter really does exist.
Train wreck

Prof. Rodolfo Coria / Ap

A massive collision of galaxy clusters about 3 billion years ago has proven to be a train wreck of sorts for dark matter theory. The prevailing theory suggests that the force of gravity should keep dark matter and galaxies together even during violent collisions, but that hot gas should lag behind due to the cosmic equivalent of air resistance. This image, however, shows the dark matter (blue) separated from most of the galaxies (yellow and orange). Scientists speculate that a gravitational slingshot effect may have separated the galaxies from the dark matter, or that the dark matter is interacting with some force other than gravity. Neither explanation fits well with existing theory. A third possibility is that the observations and calculations are off. Further research may yield an answer.
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Ghostly ring

Msnbc.com

Some rings signify marriage, others a Super Bowl victory. This one may signify that dark matter exists. Astronomers made this composite image of a ghostly ring of apparent dark matter (mapped in blue) around a cluster of galaxies about 5 billion light years away. Computer simulations of the ancient galactic collision that created the cluster provide clues to how the ring formed. During the smash-up, dark matter fell to the center of the combined cluster and then started to slosh back out toward the edges. But the pull of gravity caused the dark matter to slow and pile up like cars speeding into a traffic jam on the freeway.
Cold or warm?

Science

Assuming dark matter does exist, is it cold or warm? If some of the universe's earliest stars can be found, computer simulations suggest the issue could be resolved. Slow-moving particles of cold dark matter would have caused single, massive stars to form in isolation. Faster-moving particles of warm dark matter, in contrast, would have caused the stars of differing sizes to form on long, thin filaments of dark matter — as pictured here. Since small stars are long-lived, they may still be lurking in our universe. Scientists hope to find them with new telescopes.

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Photos: Month in Space: April 2012

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Elephant face on Mars
A lava flow in Mars' Elysium Planitia region takes on the appearance of an elephant in this picture from the High Resolution Imaging Science Experiment on NASA's Mars Reconnaissance Orbiter, captured on March 19 and released April 4. (NASA/JPL/Univ. of Arizona) Share Back to slideshow navigation
Blast from the sun
This image provided by NASA's Solar Dynamics Observatory shows the sun releasing a M1.7 class flare associated with a prominence eruption on April 16. This visually spectacular explosion occurred on the sun's northeastern limb and was not directed at Earth. (NASA/SDO/AIA) Share Back to slideshow navigation
Whirlwind on Mars
A dust devil the size of a terrestrial tornado towers above the Martian surface on a springtime afternoon in Amazonis Planitia. The picture was captured on March 14 by the High Resolution Imaging Science Experiment (HiRISE) on NASA's Mars Reconnaissance Orbiter, and released by the space agency on April 4. (NASA/JPL/University of Arizona) Share Back to slideshow navigation
Zeroing in on alien planets
An image from the European Southern Observatory's Atacama Large Millimeter/Submillimeter Array, or ALMA, shows the dust ring around the bright star Fomalhaut in orange. The underlying blue picture is an earlier view obtained by the Hubble Space Telescope. The new ALMA image, released on April 12, has led astronomers to conclude that the dust ring is held in place by two exoplanets. One planet is within the ring, and the other is outside the ring. Astronomers think the planets are bigger than Mars but no larger than several times the size of Earth. (ESO/NAOJ/NRAO/NASA/ESA) Share Back to slideshow navigation
Cosmic Egg
The Hubble Space Telescope has been at the cutting edge of research into what happens to stars like our sun at the ends of their lives. One stage that stars pass through as they run out of nuclear fuel is the preplanetary nebula. This Hubble image of the Egg Nebula, released April 23, shows one of the best views to date of this brief but dramatic phase in a star’s life. (ESA/NASA) Share Back to slideshow navigation

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North Korea's launch pad
A March 28 satellite image from DigitalGlobe shows the North Korean launch site at Tongchang-ri. North Korea launched its Kwangmyongsong-3 satellite on April 13, but the rocket fell apart within minutes, bringing the controversial mission to a premature end. (Digitalglobe via EPA) Share Back to slideshow navigation

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Liftoff from India
India's Polar Satellite Launch Vehicle C-19 blasts off on April 26, lofting the country's first radar imaging satellite RISAT-1 into orbit from the Satish Dhawan space center at Sriharikota, north of the southern Indian city of Chennai. The remote sensing satellite is equipped with a synthetic aperture radar that can look through clouds and capture Earth imagery day and night. (Reuters) Share Back to slideshow navigation
Tracking Discovery
Sixth-graders visiting the U.S. Capitol from the Stratford Academy in Macon, Ga., watch the final voyage of the space shuttle Discovery as it soars above Washington on April 17. Discovery, the world's most traveled spaceship, was retired from service last year and is now an attraction at the Smithsonian National Air and Space Museum's Stephen F. Udvar-Hazy Center in Chantilly, Va., next to Dulles International Airport. (J. Scott Applewhite / AP) Share Back to slideshow navigation
Last landing
The space shuttle Discovery makes its final landing on the back of a modified Boeing 747 jet at Washington's Dulles International Airport on April 17. After landing, Discovery was towed to the Smithsonian National Air and Space Museum's Steven F. Udvar-Hazy Center, next to the airport. (Paul J. Richards / AFP - Getty Images) Share Back to slideshow navigation
Nose to nose
The space shuttles Enterprise, left, and Discovery sit nose-to-nose at the beginning of a transfer ceremony at the Smithsonian's Steven F. Udvar-Hazy Center on April 19. Enterprise, which had been on exhibit for years at the museum in Virginia, was replaced by Discovery. (Carolyn Russo / Smithsonian Institution) Share Back to slideshow navigation
Enterprise hits the Big Apple
The prototype space shuttle Enterprise, mounted atop its modified 747 carrier jet, is seen off in the distance behind the Statue of Liberty and the Empire State Building on April 27. Enterprise was the first shuttle built for NASA and performed test flights in the atmosphere, but was incapable of spaceflight. For years the craft was housed at the Smithsonian's Steven F. Udvar-Hazy Center near Washington. In April, it was moved out to make room for the shuttle Discovery. The Enterprise eventually will be put on display at the Intrepid Sea, Air and Space Museum in New York. (NASA / Reuters) Share Back to slideshow navigation

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Space strummer
NASA astronaut Dan Burbank, commander of the International Space Station, strums the strings of his guitar on April 14 during some weekend leisure time. (ESA/NASA) Share Back to slideshow navigation
Fireball over Nevada
A meteor blazes over Reno, Nev., at around 8 a.m. PDT on April 22. Reports of the fireball came in from as far north as Sacramento, Calif. and as far east as North Las Vegas, Nev. Bill Cooke of the Meteoroid Environments Office at NASA's Marshall Space Flight Center estimated that the object was about the size of a minivan, weighed in at around 154,300 pounds and at the time of disintegration released energy equivalent to a 5-kiloton explosion of TNT. (Lisa Warren / NASA/JPL via AP) Share Back to slideshow navigation
Down to Earth
Ground personnel carry Russian cosmonaut Anton Shkaplerov from his space capsule shortly after landing outside the town of Arkalyk, Kazakhstan, on April 27. Shklaplerov, fellow cosmonaut Anatoly Ivanishin and NASA astronaut Dan Burbank landed safely in a Russian Soyuz capsule after a stay of over five months aboard the International Space Station. Returning spacefliers are traditionally carried from the landing site while they readjust to Earth's gravity. (Sergei Remezov / Pool via EPA) Share Back to slideshow navigation

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Strange swirls on Mars
An image from the HiRISE camera on NASA's Mars Reconnaissance Orbiter, released April 26, shows lava flows in the shape of coils located near Mars' equatorial region. Analyzing high-resolution images of the region, researchers have determined the area was sculpted by volcanic activity in the recent geologic past. This is the first time such geologic features have been discovered beyond Earth. (NASA) Share Back to slideshow navigation

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Tarantula in space
A Hubble Space Telescope composite image shows a stellar breeding ground in 30 Doradus, located in the heart of the Tarantula Nebula, 170,000 light-years away in a satellite galaxy known as the Large Magellanic Cloud. The telescope imaged 30 separate fields with its Wide Field Camera 3 and Advanced Camera for Surveys during October 2011 to produce this picture. The image was released April 17 in honor of Hubble's 22nd anniversary. (NASA/European Southern Observatory/Space Telescope Science Institute/Hubble Space Telescope) Share Back to slideshow navigation
UFO Galaxy
NGC 2683 is a spiral galaxy seen almost edge-on, giving it the shape of a science-fiction spaceship. That's the reason it was nicknamed the "UFO Galaxy." It's 35 million light-years away in the northern constellation Lynx. This picture of the galaxy, captured by the Hubble Space Telescope, was released March 26 as the European Hubble team's Picture of the Week. (ESA / NASA) Share Back to slideshow navigation
Auroras on Uranus
These composite images from the Hubble Space Telescope show two bright spots that scientists say are auroral displays on the planet Uranus. The ice giant's faint rings can also be seen in the pictures, which were taken in November 2011 and released on April 13. (Laurent Lamy) Share Back to slideshow navigation

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A galactic double-take
This infrared vision from NASA's Spitzer Space Telescope, released April 24, shows the Sombrero Galaxy in the constellation Virgo. The galaxy was given its nickname because in visble light it looks like a wide-brimmed hat. The infrared imagery shows that the galaxy is in fact two galaxies in one: an inner disk that is seen here in a shade of blue-green, and an outer disk in red. (NASA/JPL-Caltech) Share Back to slideshow navigation

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Norwegian lights
Thorbjørn Haagensen took this picture of the northern lights on April 3 from Hillesøy, close to Tromsø in northern Norway. The winter season is prime time for auroral displays, but with the onset of spring, the northern lights begin to pale up north. "Beginning in the middle of May, the midnight sun brings sunshine all night long," Haagensen said. (Thorbjørn Haagensen) Share Back to slideshow navigation

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Astronomers create largest map yet of dark matter's web

5-year task achieved by observing gravitational effects on ancient light traveling from galaxies

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