New results from a study of distant galaxy clusters, observed as they were when the universe was only half as old as it is today, lead to some surprising conclusions.
The observations were obtained by the European Space Agency's (ESA) satellite XMM in the context of an international collaboration involving researchers from two laboratories (the Laboratoire d'Astrophysique and the Centre d'Etude Spatiale des Rayonnements (CESR) at the Observatoire Midi-Pyrénées (OMP ) in Toulouse, the Institut d'Astrophysique Spatiale (IAS) in Paris, the Collège de France, the Service d'Astrophysique (SAp) in Saclay, and the ESA center ESTEC in Holland.
The scientific interpretation of these observations will soon appear as a letter in Astronomy and Astrophysics. The observations indicate that the abundance of X-ray luminous galaxy clusters was much lower at this ancient epoch, which suggests that the matter density of the Universe is significantly larger than what has been commonly assumed since the observations of the cosmic background radiation reported by NASA's WMAP satellite.
This new result could call into question the need for vacuum energy!
In any case, the results indicate that certain basic assumptions adopted by cosmologists will have to be modified: If galaxy clusters behave as commonly assumed, then one must abandon the ideal of a universe dominated by vacuum energy -- a radical change relative to recent ideas in the field; otherwise, one will have to understand the physical processes operating to make galaxy clusters more complicated objects than expected.
Laboratoire d'Astrophysique Observatoire Midi-Pyrénées
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Galactic Winds Blow Away Idea Of Island Universe
College Park - Nov 24, 2003
It was the 17th Century English preacher and poet John Donne who wrote the immortal lines "No man is an island, entire of itself; every man is a piece of the continent, a part of the main."
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