Credit: NASA/IoA/A.Fabian et al.

Youngest X-ray Galaxy Cluster

Clusters of galaxies are among the largest structures in the Universe; in fact the Universe itself is in many ways just a collection of these clusters (and clusters of clusters, called superclusters). Galaxy clusters are usually surrounded by a halo of very hot gas (at temperatures of millions of degrees). Since these gas halos are so hot they produce mostly X-ray radiation, and so may be studied best using X-ray telescopes. The Chandra X-ray Observatory has now imaged an X-ray halo around a distant cluster centered on a galaxy known as 3C 294. The image above shows the galaxy as a blue-white dot at the center of the image surrounded by an X-ray halo, seen as a faint red haze. The colors in this image represent X-ray energy, so that low energy X-rays are red, medium energy X-rays are green, and high energy X-rays are blue; a source which emits equally at all X-ray energies would thus appear white. Thus the galaxy itself emits high energy X-rays but also some lower energy X-rays; the halo emits only low-energy X-rays. The study of X-ray halos allows astronomers to determine the mass hidden in the cluster, and to determine the chemistry of the gas in the halo. With its capability to study the most distant clusters, Chandra lets astronomers see how clusters of galaxies drive the evolution of the Universe.

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Page Author: Dr. Michael F. Corcoran
Last modified June 25, 2001