On February 24, 2026, at 3:00 PM CET, Brian McNamara (University of Waterloo) will present “XRISM’s New Perspective on the X-ray Atmospheres of Galaxy Clusters.” 

Abstract: The XRISM X-ray observatory has observed nearly two dozen cluster and group atmospheres since its launch in 2023. XRISM’s main camera, Resolve, offers a spectral resolution of ~5 eV from approximately 1 keV to over 6 keV. Atmospheric radial velocities and velocity dispersions are measured with an accuracy of tens of km/s. Mass motions with velocities exceeding 300 km/s reveal complex atmospheric gas flows associated with mergers in bright clusters. However, the kinetic-to-thermal energy ratios of only a small percentage or less contradict some cosmological models. The level of atmospheric turbulence in cooling flux clusters with powerful radio sources is surprisingly low. No trend has been observed between jet power and atmospheric velocity dispersion. In most systems, turbulent dissipation heating driven by jets and bubbles would have great difficulty counteracting atmospheric cooling. Abundance measurements of peak iron elements Fe, Ni, Cr, and lighter elements such as Ca, Ar, S, and Si are beginning to provide new insights into the cosmic history of chemical enrichment. Finally, the discovery of relatively cold (<2 keV) and highly velocity-dispersed (~300 km/s) gas in four clusters suggests an exciting new atmospheric gaseous component of unknown origin. I will briefly review these and other interesting results from XRISM and present my perspective on the future of this line of research. 

The connection details for the webinar are as follows: https://rediris.zoom.us/j/99783070475?pwd=NbKWzgrq7oOYcY6xIOHpvWp9IEJpO…; Access code: 083854 

More information, including the code of conduct, can be found on the dedicated website.