Spitzer IRS spectroscopy of 3CR radio galaxies and quasars:: testing the unified schemes

With the Spitzer Space Telescope Infrared Spectrograph (IRS) we have observed seven powerful FR2 radio galaxies and seven quasars. Both samples, the galaxies and the quasars, are comparable in isotropic 178 MHz luminosity (10(26.5) W/Hz less than or similar to P-178MHz less than or similar to 10(29.5) W/Hz) and in redshift range (0.05 less than or similar to z less than or similar to 1.5). We find for both samples similar distributions in the luminosity ratios of high- to low-excitation lines ([NeV](14.3 mu m) / [NeII](12.8 mu m)) and of high-excitation line to radio power ([NeV])(24.3 mu m) / P-178 MHz). This solves the long debate about the apparent parent difference of quasars and radio galaxies in favor of the orientation-dependent unified schemes. Furthermore, the luminosity ratio [OIII](500.7 nm) / [OIV](25.9 mu m) of most galaxies is by a factor of ten lower than that of the quasars. This suggests that the optical emission from the central NLR is essentially absorbed (A(V) greater than or similar to 3) in the powerful FR 2 galaxies and that the [OIII](500.7 nm) luminosity does not serve as isotropic tracer for testing the unified schemes.