  Hybridization between $f$ electrons and conduction bands ($c$-$f$
hybridization) is a driving force for many unusual phenomena. To provide
insight into it, systematic studies of CeCoIn$_5$ heavy fermion superconductor
have been performed by angle-resolved photoemission spectroscopy (ARPES) in a
large angular range at temperature of $T=6$ K. The used photon energy of 122 eV
corresponds to Ce $4d$-$4f$ resonance. Calculations carried out with
relativistic multiple scattering Korringa-Kohn-Rostoker method and one-step
model of photoemission yielded realistic simulation of the ARPES spectra
indicating that Ce-In surface termination prevails. Surface states, which have
been identified in the calculations, contribute significantly to the spectra.
Effects of the hybridization strongly depend on wave vector. They include a
dispersion of heavy electrons and bands gaining $f$-electron character when
approaching Fermi energy. We have also observed a considerable variation of
$f$-electron spectral weight at $E_F$, which is normally determined by both
matrix element effects and wave vector dependent $c$-$f$ hybridization. Fermi
surface scans covering a few Brillouin zones revealed large matrix element
effects. A symmetrization of experimental Fermi surface, which reduces matrix
element contribution, yielded a specific variation of $4f$-electron enhanced
spectral intensity at $E_F$ around $\bar{\Gamma}$ and $\bar{M}$ points.
Tight-binding approximation calculations for Ce-In plane provided the same
universal distribution of $4f$-electron density for a range of values of the
parameters used in the model.
