Wide-Angle View

Science  12 Feb 1999:
Vol. 283, Issue 5404, pp. 931b
DOI: 10.1126/science.283.5404.931b

Astronomers have come up with the largest map to date of our corner of the universe—one that they say is big enough to enable cosmologists to test theories on how the universe has been expanding and structuring itself since the big bang.

Mappers at five U.K. and German institutions combined data from separate optical and infrared surveys to show the locations of about 15,000 galaxies—about 1/5000 of the observable universe. For studies of galaxy clustering and dynamics, scientists need a large map that will furnish a reliable sampling of the universe, says principal investigator Will Saunders of Edinburgh University. For example, he says, “this is the first survey deep enough to show all the structures responsible for our [galaxy's] velocity through space”—which is about 600 kilometers per second.

In the image (see www-astro.physics.ox.ac.uk/∼wjs/pscz.html, third image down), which is over 1 billion light-years in diameter, a computer has used the data to create white blobs that look like potatoes, says Saunders, to indicate areas where the density of galaxies is at least 2.5 times the average. Earth is located in a small potato in the middle called the Local Supercluster.

The map “is the best measure so far of the large-scale galaxy distribution,” says Princeton cosmologist Jim Peebles. He says it adds to evidence that less dense and more dense regions share a topological symmetry—a feature predicted by theories on the universe's expansion. Other renderings of the data can be found at www-astro.physics.ox.ac.uk/∼wjs/pscz.html

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