Effect of X-ray emissivity distribution on modulating the dominant velocity power spectrum we probe. The X-ray emissivity acts as a velocity high-pass filter, allowing us to probe only the largest scales smaller than 1/ℓ_eff in k-space (see Appendix A.3 for definition and calculation of ℓ_eff). The pink regions depict the range of spatial scales that dominate the gas kinematic energy in the measurements. In this work, we focus on merger-driven, large-scale gas motions, which are likely to correspond to the situation shown on the left (see Sect. 4.3).