2011-2012 Salpeter Lecturer - Eliot Quataert, UC Berkeley

Astronomy Colloquium

The Physics of Galaxy Cluster Plasmas

Galaxy clusters are among the largest gravitationally bound objects in the universe.  The majority of the baryonic mass in clusters resides in a hot, low density plasma that pervades the intracluster medium (rather than in stars).  The heating and cooling processes in this plasma must be understood in order to make progress on a number of key problems in galaxy formation, including the formation of the most massive galaxies and black holes in the universe.  An understanding of galaxy cluster thermodynamics is also important for the use of clusters as cosmological probes into the nature of dark matter and dark energy. In this talk, I will describe new insights into the physics of galaxy cluster plasmas, focusing on (1) the physics of novel forms of convection that arise in dilute plasmas, and (2) the subtle imbalance between heating and cooling processes that leads to the development of cool gas embedded in the ambient hot intracluster medium.  I will also describe the importance of this physics for galaxy formation and for the use of clusters as cosmological probes.