Density distribution (log ρ) of run 3Dang_ref in the plane y–z (left) and y–x (right) showing the wing formation along the z and x axis respectively. The asymmetry in wing formation i.e. the bending of back-flowing materials before reaching centre can be seen here along the x-axis, whose morphological relevance is discussed in Sect. 3.2. The dynamical age of this structure is 3.91 Myr. Here lengths are defined with respect to 4 kpc.