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Spitzer Sees Back 9 Billion Years
Pasadena CA (SPX) Mar 21, 2006 Astronomers have captured an image of the most distant cluster of galaxies ever seen, located about 9 billion light-years away from Earth � and photographed at a stage when the universe was only about one-third of its present age. Up to now, clusters of galaxies in the very distant universe rarely have been detected beyond a distance of about 7 billion light-years. The astronomers carefully sifted through infrared images from the Spitzer Space Telescope, as well as ground-based galactic catalogs. They estimated distances based on the cluster galaxies' colors, then verified the candidates using a spectrograph instrument at the W.M. Keck Observatory in Hawaii. The resulting images show galaxies clustered when the universe was only 4.5 billion years old � compared with its current estimated age of 13.7 billion years. "Detecting a galaxy cluster 9 billion light-years away is very exciting," said lead investigator Peter Eisenhardt of NASA's Jet Propulsion Laboratory. "It's really amazing that Spitzer's 85-centimeter telescope can see 9 billion years back in time." Using the same methods, the astronomers found three other clusters residing between 7 billion and 9 billion light-years away. "Spitzer is an excellent instrument for detecting very distant galaxy clusters because they stand out so brightly in the infrared," said co-investigator Mark Brodwin, also of JPL. "You can think of these distant galaxy cluster surveys as a game of 'Where's Waldo?' With an optical telescope you can spot 'Waldo,' or the distant galaxy clusters, by carefully searching for them amongst a sea of faint galaxies." In the Spitzer data, however, he added, "it's as though Waldo is wearing a bright neon hat and can be easily picked out of the crowd." Galaxy clusters are the largest gravitationally bound structures in the universe. A typical cluster can contain thousands of galaxies and trillions of stars. Because of their huge size and mass, they are relatively rare. If Earth represented the entire universe, then the planet's 200+ countries would be the equivalent of galaxies, and the seven continents would be the galaxy clusters. Galaxy clusters grow like snowballs, picking up new galaxies from gravitational interactions over billions of years. For this reason, however, astronomers think clusters should be even rarer in the very distant universe. The team is preparing for more observations this spring using the Keck instrument to confirm the distance of other galactic clusters in their sample. Community Email This Article Comment On This Article Related Links Spitzer JPL Understanding Time and Space
WMAP Detects Universes Oldest Light
Greenbelt MD (SPX) Mar 16, 2006Scientists said Thursday they have compiled the best evidence yet that the phenomenon called inflation occurred during an astoundingly brief interval about 13.7 billion years ago, growing the universe's three-dimensional space from the size of a marble to astronomical dimensions in less than a trillionth of a second. |
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