March 16, 2005

Cornell Discovers New Galaxies With Spitzer Telescope

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In the dorm rooms of most college students, a little bit of dust is simply a fact of life; but in outer space, dust can cause big problems, even hide entire galaxies.

A Cornell-led research team recently discovered a population of galaxies so concealed by dust that it required the Infrared Spectrograph (IRS) component of NASA’s Spitzer Space Telescope to discern.

The IRS, the largest of the three main instruments on the Spitzer Telescope, is superior to its optical counterparts in that it is able to detect wavelengths in the infrared spectrum that are often enshrouded in dust or absorbed by the Earth’s atmosphere.

“[It] would be like looking at a candle in the middle of a building fire,” said Dr. Keven Uchida, radiophysics & space research, of merely attempting to look at these wavelengths from Earth. The Spitzer Space Telescope (formerly SIRTF, the Space Infrared Telescope Facility) was launched into space by a Delta rocket from Cape Canaveral, Florida on Aug. 25, 2003.

The Spitzer Telescope will be the final mission in NASA’s Great Observatories Program — a family of four orbiting observatories, each observing the Universe in a different kind of light (visible, gamma rays, X-rays, and infrared).

“You can look through the dust, and see what we wouldn’t see with optical.” said Daniel Devost, radiophysics & space research, about the strength of IRS.

Spitzer obtains images and spectra by detecting the infrared energy, or heat, radiated by objects in space between wavelengths of 3 and 180 microns.

The galaxies discovered earlier this month are located about 11 billion light years away. The discovered galaxies are unique for a number of reasons, the most prominent being their luminosity.

“There are no galaxies this luminous in the nearby universe,” said Dr. James Higdon, radiophysics & space research.

One theory on the causes of the galaxies’ intense luminosity is the presence of an active galactic nuclei (AGN) which are powered by the in-fall of matter to a black hole.

Although researchers cannot see the black holes themselves, they can detect the tremendously bright light surrounding the extremely high gravitational fields.

“[The presence of a black hole] would be an indication of a state of an early universe…most galaxies that harbor a black hole are very bright around [it],” said Devost.

This new collection of galaxies could lead researchers to discover more about how our own galaxy formed and what it may have looked like in its early stages.

Researchers can also tell a great deal about the type of environment in which the galaxy is forming by looking at the dust surrounding it.

Crystalline dust structures require a calmer, more stable environment to form, while dust structures amorphous in composition are indicative of violent and turbulent surroundings. It may be too early to tell exactly what these findings imply about the formation of our own galaxy, the Milky Way.

Due to the nature of light travel, and the extreme distances of the galaxies from Earth, researchers are essentially looking at these objects as they appeared in the past. “We’re looking at objects that were in existence when the Earth was 20 percent of its current age.” said Higdon.

With further research, scientists will have a more accurate idea of what, exactly, they are dealing with in these new galaxies and what this means for future understanding of our own galaxy.

Archived article by Keri Frank
Sun Contributor