Subaru Discovers an Exploding Galaxy at the Edge of the Universe

Astronomers using the Subaru Telescope have discovered an exploding galaxy at the edge of the known universe.

The team, led by astronomers from Tohoku University in Japan, say the galaxy rapidly formed stars when the Universe was less than a billion years old. Images and spectra from the Subaru and Keck telescopes reveal that the galaxy has a high-speed outflow of hydrogen gas believed to be caused by a massive burst of star formation.

The galaxy is more than 14 billion light years from Earth, and is currently the most distant galaxy known to harbor such a phenomenon. Studying such distant galaxies is made possible by combining careful technique and large telescopes, and is expected to reveal how galaxies are born and evolve in the early stage of the Universe.

The newly discovered galaxy is so far away that the light now reaching Earth began its journey 14 billion years ago. Only large telescopes like Subaru can collect enough light to observe these very faint and distant galaxies to study what the Universe was like in its infancy. Because the Universe is expanding, the light emitted from these distant galaxies is stretched out to longer wavelengths as it travels toward us, a phenomenon astronomers call redshift. The further an object is from us, the greater its redshift.

Hoping to find star-forming galaxies at the farthest reaches of the Universe, the team installed a special filter into Subaru's prime focus camera, the Suprime-Cam. They observed a region of sky about the size of the full moon around a distant quasar named SDSSp J104433.04-012502.2 in the constellation Sextant. The team included Tohoku University graduate student Masaru Ajiki and associate professor Yoshiaki Taniguchi, researchers at the National Astronomical Observatory of Japan (NAOJ), the University of Tokyo, the University of Hawaii, and the University of Maryland.

Quasars are believed to be objects powered by black holes about a billion times the mass of the Sun and, due to their extreme luminosities, can be readily discovered even at very large distances. The special filter was designed to transmit only a very narrow color range of light.

After a 10-hour observation in February 2002, more than 15 galaxies were discovered which could only be seen in the image taken through the narrow filter. One of these galaxies was then observed with Subaru's Faint Object Camera and Spectrograph (FOCAS) in March 2002, which confirmed that it was a very distant galaxy. Additional, more detailed, observations with the Echellette Spectrograph and Imager (ESI) on the Keck II telescope supported the Subaru results and indicated that hydrogen gas is flowing from the galaxy at speeds of several hundred kilometers per second.

Stars more than about 10 times the mass of our Sun end their lives in vast explosions called supernovae. When many such stars are being formed in a short space of time, the combined force of these explosions can cause gas to be ejected out of the galaxy. Such an outflow, called a "superwind", can be seen in the nearby galaxy Messier 82. If the outflow seen in this young galaxy is also produced by a superwind, it would be the most distant example of this phenomenon yet discovered. This would mean that large-scale star formation must have begun within several hundred million years after the start of the Universe.

By discovering more distant galaxies and studying them in detail, astronomers expect to learn what galaxies were like when the Universe was very young, and understand how they are born and evolve. Says Professor Taniguchi, "For the past 15 years while Subaru was being planned and built, Keiichi Kodaira [former Director of NAOJ and now President of the Graduate University for Advanced Studies] and I have had a dream to look at distant galaxies, more than 10 billion light years away. At last that dream has come true."

These results will be published in the September 1, 2002 issue of The Astrophysical Journal.

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Images

High Redshift Starburst Galaxy LAE J1044-0130. CREDIT: Subaru Telescope

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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.

Well, enjoy when you can!

I am a native Californian (refugee for the foreseeable future).
I miss the place but NOT the eco-wackos, Mt. Shasta worshippers, Bay Area "gay pride" types, tree spikers, limo libs, spoiled children of same, career welfare slobs, "gimme" minority spokespeople, trash who dump same into ravines, roving gangs, roving packs of dogs...

Still, I do miss the place and will visit the relatives next summer.

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