XMM-Newton and VLT images of XMMU J2235.3-2557
Credit: C. R. Mullis et al., 2005, The Astrophysical Journal, vol. 623, L85; ESA

Getting Together While Young

Clusters of galaxies are the most important tracers of how matter and energy were distributed in the Big Bang. By finding distant clusters, astronomers can explore how such massive structures formed at early times in the history of the Universe. One of the best methods for finding clusters is by observing the X-rays they emit from the enormous amounts of hot gas held bound in the cluster's deep potential well. Astronomers using the XMM-Newton X-ray observatory have now found the oldest cluster ever detected by X-ray observations. The cluster, called XMMU J2235.3-2557, was formed when the Universe was only about 1/3 of its present age. The image above is a composite image showing the 0.5-2.0 keV X-ray emission in orange, along with a color image obtained by the Very Large Telescope at the European Southern Observatory. In the VLT image the cluster galaxies appear red. This detection presents an unprecedented test of theories of structure formation in the Universe.

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Page Author: Dr. Michael F. Corcoran
Last modified Friday, 20-Apr-2012 15:23:12 EDT