Bibcode
Comerón, S.; Knapen, J. H.; Beckman, J. E.
Referencia bibliográfica
Astronomy and Astrophysics, Volume 485, Issue 3, 2008, pp.695-705
Fecha de publicación:
7
2008
Revista
Número de citas
27
Número de citas referidas
27
Descripción
Context: Local reductions of the stellar velocity dispersion in the
central regions of galaxies are known as sigma-drops (σ-drops).
Knowing the origin of these features can lead to better understanding of
inner galactic dynamics. Aims: We present a sample of 20
σ-drop galaxies matched with a control sample of galaxies without
σ-drop in order to search for correlations between σ-drops
and the properties, primarily morphological, of the nuclear zones and
discs of their host galaxies. Methods: We study the dust and
Hα distribution at 0.1 arcsec scale, using Hubble Space Telescope
imaging, in the circumnuclear zones of the two samples of galaxies,
searching for differences and trying to establish a link between the
nuclear kinematics and the host morphology. We have also considered the
CO and H i emission of the galaxies and their luminosity profiles. Results: We classify the two samples following both morphological
parameters and the luminosity profiles. We find a larger fraction of
nuclear dust spirals and Hα rings in the σ-drop sample. We
also find that the fraction of Seyfert galaxies in the σ-drop
sample is bigger than that of LINERs and that the reverse is true for
the control sample. Conclusions: Our findings are evidence that a
σ-drop is very probably due to inflow-induced star formation in a
dynamically cool disc, or in a gas ring, shock focused by an inner
Lindblad resonance above a certain critical density level. The same
mechanism that feeds the nuclear ring or the nuclear disc is probably
reponsible for the higher rate of Seyfert galaxies among the
σ-drop hosts.
Appendices A-D are only available in electronic form at
http://www.aanda.org
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