their combination, $Y_X={M_{\rm g}}\times T$ [e.g., @2014MNRAS.437.1171M; @mantz.etal.2016 for recent and detailed studies on X-ray scaling relations]. The $Y_X$ parameter was firstly introduced as proxy of pressure by [@2006ApJ...650..128K] who proved its advantages through the analysis of hydrodynamical simulations. Since then, it has been diffusely adopted in X-ray cosmological studies. The biggest benefit of this parameter relies on the different reactions by the gas mass and temperature in non-equilibrium situations such as a powerful AGN burst activity [@2011MNRAS.416..801F] that can be triggered by gravitational mergers. The AGN reduces the gas mass by expelling some gas from the core and, at the same time, it heats the ICM. Due to these behaviors the $Y_X$ parameter does not substantially depend on the dynamical state or on the central AGN activity.

One of the X-ray measurements most represented in scaling-relation studies is the [*X-ray luminosity*]{} because it can easily and immediately be obtained from shallow observations. Scaling relations involving the luminosity, in particular the $L-M$ relation, are used to determine the connection between the flux limits of a planned survey with the minimum mass that can be observed. This relation, therefore, plays a crucial role in establishing the selection function of X-ray samples 