Plot of the pressure acting on the “surface” of a dwarf galaxy (blue sphere) with orbit E050 at the look-back time t_lb = 9 Gyr (see the text for further details and Fig. 5). Orange pistons represent the pressure intensity on the dwarf, where the higher the piston, the higher the pressure. Yellow shadows span ϑ ∈ [− 40,40]deg in steps of 10 deg and are the angular validity from standard potential flow approximation.