Mon. Not. R. Astron. Soc., 393, 846-857 (2009/March-1)
The CaT strength in Seyfert nuclei revisited: analysing young stars and non-stellar light contributions to the spectra.
VEGA L.R., ASARI N.V., FERNANDES R.C., GARCIA-RISSMANN A., STORCHI-BERGMANN T., GONZALEZ DELGADO R.M. and SCHMITT H.
Abstract (from CDS):
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 [Siii]λ9069 line. In the present paper, we analyse the CaT strength (WCaT) and kinematical products derived in that study, namely stellar (σ*) and ionized gas (σgas) velocity dispersions. Our main results may be summarized as follows. (1) Type 2 Seyfert galaxies show no sign of dilution in WCaT with respect to the values spanned by normal galaxies, even when optical absorption lines such as the Caii 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 WCaT-WCaK 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 W[Siii] and WCaTtend to be diluted due to the presence of a non-stellar component, in agreement with the unification paradigm. (4) A comparison of σ* with σgas(obtained from the core of the [Siii] 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 [Oiii]λ5007 linewidth.
© 2009 The Authors. Journal compilation © 2009 RAS
galaxies: kinematics and dynamics - galaxies: nuclei - galaxies: Seyfert - galaxies: stellar content
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