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Issue A&A Volume 409, Number 2, October II 2003 Page(s) 469 - 477 Section Galactic structure and dynamics DOI 10.1051/0004-6361:20031061

A&A 409, 469-477 (2003)
DOI: 10.1051/0004-6361:20031061

Numerical simulations of central stellar velocity dispersion drops in disc galaxies

H. Wozniak^{1, 2}, F. Combes³, E. Emsellem² and D. Friedli<sup>4, 5

1</sup>  Laboratoire d'Astrophysique de Marseille, 2 place Le Verrier, 13248 Marseille Cedex 4, France
²  Centre de Recherche Astronomique de Lyon, 9 av. Charles André, 69561 Saint-Genis Laval Cedex, France
³  LERMA, Observatoire de Paris, 61 avenue de l'Observatoire, 75014 Paris, France
⁴  Observatoire de Genève, 1290 Sauverny, Switzerland
⁵  Gymnase de Nyon, 1260 Nyon, Switzerland

(Received 28 April 2003 / Accepted 30 June 2003)

Abstract
We present an interpretation of the stellar velocity dispersion drops discovered in the nuclear regions of three barred galaxy hosts of active/starburst galactic nuclei ( NGC 1097 , NGC 1808 and NGC 5728 ) by Emsellem et al. (2001). Using self-consistent N-body simulations including stars, gas and star formation, we show that young stars born in the nuclear regions from dynamically cold gas have a lower velocity dispersion than the older stellar population. The young population (less than 0.9 Gyr old in our models), being more massive and brighter than the older one at near infrared wavelengths, fully dominates the observed line-of-sight kinematics of the circumnuclear regions.

Key words: galaxies: active -- galaxies: kinematics and dynamics -- galaxies: nuclei -- galaxies: Seyfert -- galaxies: evolution -- galaxies: spiral

Offprint request: H. Wozniak, herve.wozniak@obs.univ-lyon1.fr

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