Clusters of galaxies as astrophysical laboratories
Kavli Institute (Stanford University)
Clusters of galaxies are the largest, gravitationally-bound objects in the Universe. They are mainly filled with dark matter, hot, X-ray-emitting gas and stars. Being the largest and most massive, clusters are important cosmological probes for tracing the growth of structures in the Universe over time. X-ray, radio and sub-millimeter observations allow us to study a variety of astrophysical phenomena in the hot gas, the evolution of giant elliptical galaxies, the interactions between supermassive black holes and intracluster medium (ICM). Despite significant progress over the past decade, there are still many questions which are poorly understood. What are the properties of turbulence and bulk motions of the gas? How do supermassive black holes transfer their energy to the ICM? How important are transport processes, such as gas viscosity and thermal conduction? Does magnetic field affect the ICM plasma? How to accelerate particles and explain the origin of the observed radio halos? In my talk, I will discuss recent progress that has been done to address these questions. In particular, I will show how X-ray images of galaxy clusters can be used to measure velocity power spectra, the equation of state of gas perturbations driven by the black hole - hot gas interaction, and to directly see the effects of magnetic fields and plasma instabilities on hot gas. I will highlight recent results from new, high-resolution spectral data from the Hitomi satellite. Finally, I will discuss near and more distant future perspectives in the field.
Date: Tuesday, 27 February 2018 Time: 10:30 Where: Université de Montréal Pavillon Claire-McNicoll, local Z-240 Contact: Julie Hlavacek-Larrondo