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Probing the stellar population of seyfert galaxies: a near infrared perspective

Published online by Cambridge University Press:  13 April 2010

Rogério Riffel
Affiliation:
Departamento de Astronomia, Universidade Federal do Rio Grande do Sul. Av. Bento, Gonçalves 9500, Porto Alegre, RS, Brazil. email: riffel@ufrgs.br, miriani.pastoriza@ufrgs.br, charles.bonatto@ufrgs.br
Miriani G. Pastoriza
Affiliation:
Departamento de Astronomia, Universidade Federal do Rio Grande do Sul. Av. Bento, Gonçalves 9500, Porto Alegre, RS, Brazil. email: riffel@ufrgs.br, miriani.pastoriza@ufrgs.br, charles.bonatto@ufrgs.br
Alberto Rodríguez-Ardila
Affiliation:
Laboratório Nacional de Astrofísica/MCT - Rua dos Estados Unidos 154, Bairro das Nacões, Itajubá, MG, Brazil. email: aardila@lna.br
Charles Bonatto
Affiliation:
Departamento de Astronomia, Universidade Federal do Rio Grande do Sul. Av. Bento, Gonçalves 9500, Porto Alegre, RS, Brazil. email: riffel@ufrgs.br, miriani.pastoriza@ufrgs.br, charles.bonatto@ufrgs.br
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Abstract

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We employ IRTF SpeX NIR (0.8–2.4μm) spectra to investigate the stellar population (SP), active galactic nuclei (AGN), featureless continuum (FC) and hot dust properties in 9 Sy 1 and 15 Sy 2 galaxies. Both the starlight code and the hot dust as an additional base element were used for the first time in this spectral range. Our synthesis shows significant differences between Sy 1 and Sy 2 galaxies: the hot dust component is required to fit the K-band spectra of ~90% of the Sy 1 galaxies, and only of ~25% of the Sy 2; about 50% of the Sy 2 galaxies require an FC component contribution ≳20%; this fraction increases to about 60% in the Sy 1. In about 50% of the Sy2, the combined FC and young components contribute with more than 20%, while this occurs in 90% of the Sy1, suggesting recent star formation in the central region. The central few hundred parsecs of our galaxy sample contain a substantial fraction of intermediate-age SPs with a mean metallicity near solar. Our SP synthesis confirms that the 1.1μm CN band can be used as a tracer of intermediate-age stellar populations.

Type
Contributed Papers
Copyright
Copyright © International Astronomical Union 2010

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