Impact of systematic uncertainties. Left: Ratio between the value of α derived under the assumption of hydrostatic equilibrium (α_HSE) and the true value of α when assuming two possible nonthermal pressure profiles Angelinelli et al. (2020), blue; Nelson et al. (2014), orange) as a function of the input value of α. Right: Stellar mass of the BCG within 100 kpc in the BAHAMAS CDM (red) and SIDM1 simulations (blue) as a function of the halo mass. The black stars show the measured BCG stellar masses within the same aperture in X-COP clusters (see Paper i).