The CaT strength in Seyfert nuclei revisited: analysing young stars and non-stellar light contributions to the spectra.

In a former paper, we have presented spectra of 64 active, nine normal and five starburst galaxies in the region around the near-infrared calcium triplet (CaT) absorption lines and the [S iii]λ9069 line. In the present paper, we analyse the CaT strength ( W_CaT) and kinematical products derived in that study, namely stellar and ionized gas (σ_gas) velocity dispersions. Our main results may be summarized as follows. (1) Type 2 Seyfert galaxies show no sign of dilution in W_CaT with respect to the values spanned by normal galaxies, even when optical absorption lines such as the Ca ii K band at 3933 Å are much weaker than in old, bulge-like stellar populations. (2) The location of type 2 Seyfert galaxies in the plane is consistent with evolutionary synthesis models. The implication is that the source responsible for the dilution of optical lines in these active galactic nuclei (AGN) is a young stellar population, rather than an AGN featureless continuum, confirming the conclusion of the pioneer study of Terlevich, Díaz & Terlevich. (3) In type 1 Seyfert galaxies, both and W_CaT tend to be diluted due to the presence of a non-stellar component, in agreement with the unification paradigm. (4) A comparison of with σ_gas (obtained from the core of the [S iii] emitting line) confirms the existence of a correlation between the typical velocities of stars and clouds of the narrow line region. The strength and scatter around this correlation are similar to those previously obtained from the [O iii]λ5007 linewidth. [ABSTRACT FROM AUTHOR]