  The main purpose of this research was to investigate how energetic processes
associated with Active Galactic Nuclei are related to those due to nuclear or
circumnuclear star formation activity. Photometric and spectroscopic data were
used to discriminate these processes in a sample of starburst, infrared
galaxies and AGNs. Herein, we propose new diagnostic diagrams based on the 7.7
{\mu}m polycyclic aromatic hydrocarbon emission band, the L(MIR, FIR) infrared
ratio and the q parameter. The diagnostic diagrams allow us to discriminate the
behavior of quasars and Seyfert 1-Seyfert 2 galaxies from starburst and
LIRGs-ULIRGs objects.

Cosmology and Nongalactic Astrophysics