  We revisit the formulations and simulations of angular distributions in
polarization-dependent core-level photoemission spectra of strongly correlated
electron systems, in order to explain the recently discovered linear dichroism
(LD) in the core-level photoemission of 4f-based rare-earth compounds. Owing to
the selection rules for the optical process of core-level excitations, the LD
originating from the anisotropic outer localized charge distributions
determined by the ground-state orbital symmetry can be observed. Our
simulations show that core d-level excitations are essential for the LD in
localized ions having a cubic symmetry, which is absent in the p-orbital
excitations.
