2002MNRAS.337..578P

We present families, and sets of families, of periodic orbits that provide building blocks for boxy and peanut (hereafter b/p) edge-on profiles. We find cases where the b/p profile is confined to the central parts of the model and cases where a major fraction of the bar participates in this morphology. A b/p feature can be built either by 3D families associated with 3D bifurcations of the x1 family, or, in some models, even by families related with the z -axis orbits and existing over large energy intervals. The `X' feature observed inside the boxy bulges of several edge-on galaxies can be attributed to the peaks of successive x1v1 orbits, provided their stability allows it. However in general, the x1v1 family has to overcome the obstacle of a S ⟶Δ⟶ S transition in order to support the structure of a b/p feature. Other families that can be the backbones of b/p features are x1v4 and z3.1s. The morphology and the size of the boxy or peanut-shaped structures we find in our models are determined by the presence and stability of the families that support b/p features. The present study favours the idea that the observed edge-on profiles are the imprints of families of periodic orbits that can be found in appropriately chosen Hamiltonian systems, describing the potential of the bar.