Refreshments at 3:45pm, talk begins at 4pm

Abstract:
Intracluster medium (ICM) is filled with hot and dilute gas. Global thermodynamic properties of this gas are now routinely measured from Chandra and XMM-Newton data. However, our understanding of gas motions is very limited mainly due to insufficient spectral resolution of current X-ray observatories. This limits our ability to probe important physical process in the ICM such as, e.g., heating of the gas, biases in hydrostatic mass measurements, mechanisms of particle acceleration and the origin of radio halos. I will show how we can overcome the problem of limited spectral resolution and measure the velocities of gas motions through high-resolution X-ray images of galaxy clusters. I will discuss the effective equation of state of gas fluctuations in the ICM, the measurements of velocity power spectra on a broad range of spatial scales and the role of turbulent dissipation in mechanical radio-mode AGN feedback. Finally, I will overview first direct velocity measurements with the Hitomi observatory and  discuss their consistency with other indirect velocity probes.
 

Host: Mark Bautz