Thursday, December 03, 2009

Suzaku Spies Treasure Trove of Intergalactic Metal

The Perseus galaxy cluster
Every cook knows the ingredients for making bread: flour, water, yeast, and time. But what chemical elements are in the recipe of our universe?

Most of the ingredients are hydrogen and helium. These cosmic lightweights fill the first two spots on the famous periodic table of the elements.

Less abundant but more familiar to us are the heavier elements, meaning everything listed on the periodic table after hydrogen and helium. These building blocks, such as iron and other metals, can be found in many of the objects in our daily lives, from teddy bears to teapots.

Recently astronomers used the Suzaku orbiting X-ray observatory, operated jointly by NASA and the Japanese space agency, to discover the largest known reservoir of rare metals in the universe.

Suzaku detected the elements chromium and manganese while observing the central region of the Perseus galaxy cluster. The metallic atoms are part of the hot gas, or "intergalactic medium," that lies between galaxies.

"This is the first detection of chromium and manganese from a cluster," says Takayuki Tamura, an astrophysicist at the Japan Aerospace Exploration Agency who led the Perseus study. "Previously, these metals were detected only from stars in the Milky Way or from other galaxies. This is the first detection in intergalactic space."

The cluster gas is extremely hot, so it emits X-ray energy. Suzaku's instruments split the X-ray energy into its component wavelengths, or spectrum. The spectrum is a chemical fingerprint of the types and amounts of different elements in the gas.

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