Speaker
Description
Large upcoming cosmic shear experiments like Euclid and LSST are attempting to retrieve cosmological information by constraining the matter power spectrum in the local Universe and its redshift evolution. This approach requires that the shape and evolution of the power spectrum can be accurately predicted from cosmological parameters. In recent years, it has become clear that baryonic processes, namely ejection of gas from dark matter halos through energy injection by supermassive black holes (SMBH), modify the distribution of matter on scales as large as several Mpc compared to the dark-matter-only case. Cosmological simulations are unable to predict this effect from first principles, which represents a major source of systematic uncertainty for cosmic shear experiments. In this talk, I will present our ongoing efforts to pinpoint baryonic effects on the large-scale structure through observations of the hot atmospheres of galaxy groups. The gas content of galaxy groups acts as a sensitive calorimeter of injected SMBH energy, as the total non-gravitational energy is comparable to the gravitational binding energy of gas particles. I will present the properties of the medium in a carefully selected sample of 49 galaxy groups with deep X-ray data. I will then outline how the measurements can be used to predict power spectrum suppression on scales k>1 Mpc-1.