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Astronomers Find Most Distant Galaxy Cluster Yet
Calgary, Alberta (SPX) Jun 7, 2006 Astronomers have found the most distant cluster of galaxies to date and possibly the most massive one yet seen at such an early era in the universe. Almost 10 billion light-years from Earth, the cluster, XMMXCS 2215-1738, contains hundreds of galaxies surrounded by superheated X-ray-emitting gas at more than 10 million degrees. Reporting at the 208th meeting of the American Astronomical Society, members of the XMM Cluster Survey team said they used observations from the European X-ray Multi Mirror Newton satellite to discovery this new cluster and then determined its distance using the 10-meter W. M. Keck telescope in Hawaii. "I couldn't believe it when I saw that this distant cluster appears to be full of old galaxies," said lead research Adam Stanford, of the University of California, Davis, and at Lawrence Livermore National Laboratory. "This cluster is a challenge for our models of how massive galaxies formed, and to our understanding of the way such a massive cluster exists at a relatively early era in the Universe." Co-author Bob Nichol of the University of Portsmouth, England, said the key question associated with the discovery is "What's it doing there? This massive lump of matter is three-quarters the way back to the Big Bang." Principal investigator Kathy Romer, of the University of Sussex, England, said the cluster actually was not difficult to find. She said the XCS team currently is searching the XMM-Newton archive of observations for more clusters like XMMXCS 2215-1738, using algorithms developed by Robert Mann, of the University of Edinburgh, Scotland. "This cluster was confirmed on our first good night at Keck, and we have 1000s more to look at," Romer said. "I can't wait to find out how many more clusters like XMMXCS 2215-1738 there are out there." The real surprise of the XMMXCS 2215-1738 cluster might be its mass. Using the temperature of the X-ray emitting gas, researchers determined the cluster is approximately 500 trillion times the Sun's mass. Such massive clusters are expected to grow through the amalgamation of many smaller masses, such as groups of galaxies, but this process takes time. "Such a massive cluster at this early time in the Universe is only expected in a flat universe full of dark energy, team member and cosmologist Pedro Viana, of the University of Porto, Portugal. "It is yet more evidence that we live in a strange Universe." The team now is embarked on a long-term observing program to find more clusters like XMMXCS 2215-1738 using the 4-meter telescopes of the NOAO at both the Cerro Tololo Inter-American Observatory in Chile and the Kitt Peak National Observatory in Arizona. That does not mean the team already has forgotten about XMMXCS 2215-1738. "It's special," Stanford said. "We will be studying this cluster using all the tools available to us. We are already getting detailed pictures using the Hubble Space Telescope." Related Links ESO Imaging Survey NOAO Keck Observatory XMM Newton
Young Supernova Remnants Not Dusty Enough
Calgary, Alberta (SPX) Jun 07, 2006One of the youngest supernova remnants known - a glowing red ball of dust created by the explosion 1,000 years ago of a supermassive star in the neighboring Small Magellanic Cloud - exhibits the same problem as exploding stars in the Milky Way galaxy: too little dust. |
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