Princeton Center for Heliophysics Seminar

Clusters of galaxies are pervaded by plasma which is hot, tenuous, magnetized, and host to a population of relativistic cosmic rays. The cooling time of this gas can be estimated from its observed radiative output, and found to be much shorter than the age of the cluster. This strongly suggesting that the high temperature is maintained by one or more sources of heat, most likely supplied by dynamical processes such as stirring by galaxy motions, outbursts from accretion onto a supermassive black hole, or merging with another galaxy group or cluster. Yet, despite decades of careful work, how that energy is converted to heat and transported through the cluster is not yet well understood. I will discuss our ongoing work on collisionless heating and heat conduction, and give one or more examples of how kinetic-scale processes affect macroscopic phenomena.