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| CfA Colloquium Schedule Fall 2007 | ||
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11 October 2007Speaker: Jeremiah P. Ostriker (Princeton University) Title: X-Ray Emitting Clusters of Galaxies - How Do They Work and How Can We Use Them? Abstract: X-ray emitting clusters of galaxies are the most massive self-gravitating objects in the Universe and the most steadily luminous. They provided the first definitive evidence for "dark matter" and they now are among the tools of choice to determine the properties of the "dark energy." Studied since the 30s of the last century, we still cannot answer some of the most obvious questions. What is the distribution of stars, gas and dark matter? Are relativistic components important? What are the principle energy inputs? If cooling flows do not occur, why not? How can we use them for the upcoming, elaborate "dark energy searches," if we understand them only imperfectly at best? We will try to show how recent X-ray observations and new theoretical calculations can help to answer these questions.
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