YCAA Seminar,”Physics of gas perturbations in galaxy clusters” - Irina Zhuravleva, Stanford University

X-ray observations revealed a wealth of structures present in the hot gas in galaxy clusters. Such perturbations reflect density and temperature fluctuations induced by shocks, gas motions, bubbles of relativistic plasma, mergers with subhalos, etc. Instead of following the standard approach in X-ray astrophysics of focusing on specific features and special regions within the clusters, I probe statistical properties of gas fluctuations over a range of spatial scales. In my talk I will address the questions on the nature and energetics of the AGN-driven perturbations in the brightest nearby galaxy clusters, which were deeply observed by the Chandra observatory. I will show that in these clusters the energy from the central black hole is channeled to the gas predominantly through slow gas motions and bubbles - consistent with the picture of the radio-mechanical AGN feedback. The measurements of the velocity power spectrum through the analysis of density fluctuations will be discussed and compared with the direct velocity measurements from the Hitomi observatory. Finally, I will talk about turbulent dissipation and its role in gas heating inside and outside the cluster cores.