Observing clusters of galaxies in the X-ray domain

le 11 décembre 2020, 11h à 13h, Nicolas Clerc, salle Coriolis

Observations of galaxy clusters at X-ray wavelengths offer a unique window to understanding the physical processes governing the assembly of large-scale structure in our Universe. X-rays signpost the hot and tenuous gas that permeates the entire volume of galaxy clusters; in fact, these extremely massive objects are the most luminous extended X-ray sources. Being shaped by gravity in the expanding Universe, galaxy clusters are sensitive probes of cosmological models, especially relevant to the study of the ‘dark energy’ component. How many galaxy clusters are known and what does it take to find them all? How do they form and evolve and how diverse are they? What is the interplay between galaxies, dark matter and the hot gas in these systems? I will describe the available techniques and recent progress accomplished in the field of galaxy cluster surveys, with particular emphasis on results obtained by the XMM-Newton and Chandra observatories and the upcoming german-russian eROSITA survey. I will finally highlight the challenges and opportunities offered by high-resolution spectroscopy in the X-ray, such as enabled by future facilities like Athena.