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The Stellar Populations of Seyfert 2 Nuclei

Published online by Cambridge University Press:  01 December 2006

Marc Sarzi ,
Joseph C. Shields ,
Richard W. Pogge  and
Paul Martini
Marc Sarzi
Affiliation:
Centre for Astrophysics Research, University of Hertfordshire, AL10 9AB Hatfield, UK
Joseph C. Shields
Affiliation:
Physics & Astronomy Department, Ohio University, Athens, OH 45701USA
Richard W. Pogge
Affiliation:
Department of Astronomy, The Ohio State University, Columbus, OH 43210, USA
Paul Martini
Affiliation:
Department of Astronomy, The Ohio State University, Columbus, OH 43210, USA
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Abstract

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We present a preliminary analysis of the stellar populations in the central parsecs of a sample of 22 Seyfert 2 galaxies, based on a careful separation of nebular emission and stellar light in high-spatial resolution HST-STIS spectra. 10% of the surveyed nuclei display stellar populations of intermediate age, ∼1-2 Gyr old, whereas the remaining targets appear to be evenly split between objects showing only very old stellar populations and nuclei requiring also an additional blue featureless component, which we characterise by means of very young, few-Myr-old stars. The small fraction of stellar population of intermediate age seems to argue against the presence of such a young component, however, since the short lifetime of O-stars would imply recurrent star-formation episodes and the build-up over the last 1-2 Gyr of a detectable intermediate-age population. Additionally, a correlation between the luminosity of such a blue component and the emission from highly-ionised species, together with the general absence of Wolf-Rayet features, further suggests that the featureless continuum arises from the central engine rather than from star-forming regions. We discuss our results in the framework of the unification paradigm and of models for star formation close to supermassive black holes.

Keywords

galaxies: nucleigalaxies: Seyfertgalaxies: stellar content
Type
Contributed Papers
Information
Proceedings of the International Astronomical Union , Volume 2 , Symposium S241: Stellar Populations as Building Blocks of Galaxies , December 2006 , pp. 489 - 492
Copyright
Copyright © International Astronomical Union 2007

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