Chandra Temperature map of the galaxy cluster PKS0745-191"
Credit: Hicks et al., The Astrophysical Journal, vol. 580, pp. 763773, 2002 December 1

Cool Cluster Core

Clusters of galaxies are the largest gravitationally bound objects in the Universe. By studying these objects astronomers can put constraints on models of how the Universe formed and will evolve. Such clusters contain large amounts of gas at temperatures of 10 to 100 million degrees heated by the motion of the member galaxies and from explosions of stars in those galaxies. This gas is invisible to the human eye but glows brightly in X-rays, making X-ray observations a unique probe of cluster properties. The Chandra X-ray Observatory is providing some of the best views of the hot intracluster gas. The above image shows a Chandra observation of the cluster PKS 0745-191. The map above shows the variation in temperature in the cluster as a color map; cool gas (at temperatures of "only" 3 kilo-electron volts, or keV, equivalent to about 30 million degrees) are shown as black-blue, while the hottest gas (temperatures of 10 keV, or about 100 million degrees) is red. Gas is coolest near the center of the cluster (shown by the contour lines) and gets appreciably hotter near the outer part of the cluster.

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Page Author: Dr. Michael F. Corcoran
Last modified December 1, 2002