Hubble Maps the Cosmic Web of "Clumpy" Dark Matter in 3-D

Jay-qu · January 8, 2007

An international team of astronomers using NASA's Hubble Space Telescope has created the first three-dimensional map of the large-scale distribution of dark matter in the universe.

lefthttp://hypography.com/gallery/files/1/1/0/1/Dist-dark-matter_thumb.jpg[/img]Dark matter is an invisible form of matter whose total mass in the universe is more than five times that of "normal" matter (i.e., atoms). The nature of dark matter is still unknown. Its presence in the universe is inferred from its current influence within galaxies and clusters of galaxies, and the gravitational effect it has had on the evolution of structure in the universe. The first direct detection of dark matter was made this past year through observations of the Bullet Cluster of galaxies.

This new map provides the best evidence to date that normal matter, largely in the form of galaxies, accumulates along the densest concentrations of dark matter. The map reveals a loose network of filaments that grew over time and intersect in massive structures at the locations of clusters of galaxies.

The map stretches halfway back to the beginning of the universe and shows how dark matter has grown increasingly "clumpy" as it collapses under gravity.

The dark matter map was constructed by measuring the shapes of half a million faraway galaxies. To reach Hubble, the light of the galaxies traveled through intervening dark matter. The dark matter deflected the light slightly as it traveled through space. Researchers used the observed, subtle distortion of the galaxies' shapes to reconstruct the distribution of intervening mass along Hubble's line of sight, a method called "weak gravitational lensing."

For astronomers, the challenge of mapping dark matter in the universe has been similar to mapping a city from nighttime aerial snapshots showing only streetlights. Dark matter is invisible, so only the luminous galaxies can be seen directly. These new map images are equivalent to seeing a city, its suburbs and country roads in daylight for the first time. Major arteries and intersections become evident, and a variety of neighborhoods are visible.

Mapping dark matter's distribution in space and time is fundamental to understanding how galaxies grew and clustered over billions of years. Tracing the growth of clustering in dark matter may eventually also shed light on dark energy, a repulsive form of gravity that would have influenced how dark matter clumps.

The research results appeared online today in the journal Nature and were presented at the 209th meeting of the American Astronomical Society in Seattle, Wash., by Richard Massey and Nick Scoville. Both researchers are from the California Institute of Technology, Pasadena, Calif.

"It's reassuring how well our map confirms the standard theories for structure formation," said Massey. He calls dark matter the "scaffolding" inside of which stars and galaxies have been assembled over billions of years.

Researchers created the map using the Hubble's largest survey to date of the universe, the Cosmic Evolution Survey, otherwise known as COSMOS. The survey covers an area of sky nine times the area of the Earth's moon. This allows for the large-scale filamentary structure of dark matter to be evident. To add 3-D distance information, the Hubble observations were combined with multicolor data from powerful ground-based telescopes, Europe's Very Large Telescope in Chile, Japan's Subaru telescope in Hawaii, the U.S.'s Very Large Array radio telescope, New Mexico, as well as the European Space Agency's orbiting XMM-Newton X-ray telescope.

The Hubble Space Telescope is a project of international cooperation between NASA and the European Space Agency. The Space Telescope Science Institute, Baltimore, conducts Hubble science operations. The Institute is operated for NASA by the Association of Universities for Research in Astronomy, Inc., Washington.

For more information and images about this research, visit:

NASA - Hubble

HubbleSite - NewsCenter - Hubble Maps the Cosmic Web of "Clumpy" Dark Matter in 3-D (01/07/2007) - Introduction

Tormod · January 8, 2007

I interviewed a cosmologist for the space centre website today, and he pointed out that this study, which is the largest ever undertaken with the Hubble Space Telescope, in fact provides evidence for inflationary theory. The computer models created to simulate the rapid expansion and the distribution of matter matches the observation very well. Thus the COSMOS project has gone a long way to not only prove that inflation happened, but also that the standard model (ie, the Big Bang) is correct.

There is still, however, no indication as to what may have caused inflation, and obviously no hint as to what caused the Big Bang.

TheBigDog · January 8, 2007

This is extraordinary stuff!! I am so glad that NASA decided to upgrade and repair Hubble one more time before the Shuttles are retired. I can only hope that we find another way of repairing it again in 2015 and on into the future.

Bill

wine · January 10, 2007

word.

Tormod · January 10, 2007

This is extraordinary stuff!! I am so glad that NASA decided to upgrade and repair Hubble one more time before the Shuttles are retired. I can only hope that we find another way of repairing it again in 2015 and on into the future.

Bill

Luckily the James Webb telescope is in place by then (if all goes well), and there are numerous other exiting space telescopes on the drawing board.

Some are even closer to launch, like the Herschel/Planck satellite.

Both will be located at Lagrange 2, away from the Sun.

TheBigDog · January 11, 2007

Luckily the James Webb telescope is in place by then (if all goes well), and there are numerous other exiting space telescopes on the drawing board.

Some are even closer to launch, like the Herschel/Planck satellite.

Both will be located at Lagrange 2, away from the Sun.

The Prophesy crew is building the 24 unit array telescope with a one kilometer span in the constant shadow of Jupiter. Talk about some good pictures!

Bill