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More on the subaru Telescope:

Japanese Telescope Grabs Gobs of Galactic Light

A Japanese telescope has photographed a slice of the universe that accounts for most of the region's near-infrared galactic light and bests Hubble Space Telescope images of deep space for that wavelength.

[Ernest_at_the_Beach]

A Japanese telescope has photographed a slice of the universe that accounts for most of the region's near-infrared galactic light and bests Hubble Space Telescope images of deep space for that wavelength.

Astronomers from the National Astronomical Observatory of Japan, the University of Tokyo and Kyoto University analyzed the image taken soon after the Subaru Telescope went on line in 1999 atop Mauna Kea in Hawaii.

The "Subaru Deep Field" image captured more than 90 percent of all the galactic light along this line of sight, a higher fraction than similar Hubble deep-field images, the team said.

Among the dots of light in the image are some of the faintest galaxies ever observed, down to magnitude 24.5. For comparison, most stars in the Big Dipper and Orion are about magnitude 2.

Like Hubble, Subaru is now seeing almost to the edge of the universe and very little extra light from fainter galaxies would be seen with more sensitive observations.

The Earth-orbiting Hubble remains the most powerful telescope for most infrared wavelengths, said Harry Ferguson, a scientist with the Space Telescope Science Institute. That Maryland-based organization oversees Hubble science.

"We have observations of (shorter wavelengths) and you are seeing fainter galaxies than they are seeing," he said. "On the other hand, they are going almost as deep as the Hubble Deep Field is going and they are doing it at longer wavelengths."

The results are published in the April 1 issue of the Astrophysical Journal Letters.

Extragalactic background light

Although the Subaru telescope can account for nearly all the light emitted by galaxies in the slice of the universe where it focuses, there must be another source of light in the universe beyond galaxies.

The Cosmic Background Explorer, or COBE, satellite, designed to measure diffuse infrared and microwave radiation from the early universe, has discovered that the total amount of "extragalactic background light" is three times greater than galactic light.

It was previously believed that all the near-infrared extragalactic light came from discrete galaxies; but these latest observations reveal that there is a great deal of light unaccounted for, which cannot be due to normal galaxies.

Top candidates for the missing IR light in the universe include some decaying particles from the early universe or extremely young star clusters that are individually too small and faint to see but which contribute some lump sum of light, Ferguson said.