Bulletin of the American Physical Society
2009 APS April Meeting
Volume 54, Number 4
Saturday–Tuesday, May 2–5, 2009; Denver, Colorado
Session C4: Plasma Astrophysics of Intracluster Media |
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Sponsoring Units: GPAP DAP Chair: Maxim Lyutikov, Purdue University Room: Plaza F |
Saturday, May 2, 2009 1:30PM - 2:06PM |
C4.00001: Edges, Bubbles, Ripples and Shocks: Observational Signatures of a Dynamic ICM Invited Speaker: High angular resolution X-ray observations with Chandra and XMM have allowed us to map the temperature, density, entropy, and abundances in the intracluster gas (ICM) of galaxy clusters with unprecedented precision. Deep X-ray images of many of these clusters show edges, cavities, buoyant bubbles, shocks and ripples that chronicle the motions, heating and chemical enrichment of the cluster gas. In this talk I will review recent X-ray observations of these features in groups and clusters, and show how, when combined with radio and optical data, these observations place important constraints on the 3-dimensional motions of the gas in the underlying dark matter potential, and on microphysical processes, such as turbulence, magnetic forces, particle acceleration, and thermal conduction, that affect the transport of matter and energy throughout the ICM. [Preview Abstract] |
Saturday, May 2, 2009 2:06PM - 2:42PM |
C4.00002: Heat transport and instabilities in galaxy-cluster plasmas Invited Speaker: Small-scale plasma physics has a large impact on the global structure of the intracluster medium. This talk will focus on two examples of this micro/macro connection: anisotropic transport and buoyancy instabilities. In the first part of the talk, I will review some important theoretical developments relevant to both topics. In the second part, I will describe recent global cluster models that illustrate how plasma processes affect observable quantities such as the temperature, density, and iron abundance profiles of the intracluster medium. [Preview Abstract] |
Saturday, May 2, 2009 2:42PM - 3:18PM |
C4.00003: A Tale of Two Instabilities: Simulation of Buoyancy Instabilities in the Intracluster Medium Invited Speaker: In many dilute astrophysical plasmas, the mean free path along magnetic field lines can be very large compared to the gyroradius. As a result, thermal conduction is anisotropic along, but not across, magnetic field lines. In this regime, the condition for convective stability is significantly modified by the anisotropic heat flux, resulting in two buoyancy instabilities: the magnetothermal instability (MTI) and the heat-flux-driven buoyancy instability (HBI). Using MHD simulations with anisotropic thermal conduction, I demonstrate that these instabilities drive a magnetic dynamo, realign magnetic fields, and enhance or suppress thermal conduction, respectively. I discuss the application of these instabilities to the intracluster medium of clusters of galaxies in relation to their large-scale thermal structure, magnetic fields, and cooling flows. I also briefly discuss the relevance of the HBI to cold fronts in the ICM, such as in Abell 3667. Finally, I will briefly mention some ongoing work on heating of cooling cores with buoyant bubbles and discuss the long-standing cooling flow problem. [Preview Abstract] |
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