Issue |
A&A
Volume 424, Number 3, September IV 2004
|
|
---|---|---|
Page(s) | 799 - 815 | |
Section | Extragalactic astronomy | |
DOI | https://doi.org/10.1051/0004-6361:20040333 | |
Published online | 06 September 2004 |
Gas flow and dark matter in the inner parts of early-type barred galaxies*
I. SPH simulations and comparison with the observed kinematics
1
Kapteyn Astronomical Institute, University of Groningen, PO Box 800, 9700 AV Groningen, The Netherlands e-mail: isa@astro.rug.nl
2
RSAA, Mt. Stromlo and Siding Spr. Obs., Private Bag, Woden PO, Canberra, ACT 2606, Australia
3
Geneva Observatory, Ch. des Maillettes 51, 1290 Sauverny, Switzerland
Received:
25
February
2004
Accepted:
17
May
2004
This paper presents the dynamical simulations run in the potential
derived from the light distribution of 5 late-type barred spiral
galaxies (IC 5186, NGC 5728, NGC 7267,
NGC 7483 and NGC 5505). The aim is to determine
whether the mass distribution together with the hydrodynamical
simulations can reproduce the observed line-of-sight velocity curves
and the gas morphology in the inner regions of these barred
galaxies. The light distribution is obtained from the H-band and the
I-band combined. The is determined using population synthesis
models. The observations and the methodology of the mass distribution
modelling are presented in a companion paper. The SPH models using
the stellar mass models obtained directly from the H-band light
distributions give a good representation of the gas distribution and
dynamics of the modelled galaxies, supporting the maximum disk
assumption. This result indicates that the gravitational field in the
inner region is mostly provided by the stellar luminous
component. When 40% of the total mass is transferred to an
axisymmetric dark halo, the modelled kinematics clearly depart from
the observed kinematics, whereas the departures are negligible for
dark mass halos of 5% and 20% of the total mass. This result sets a
lower limit for the contribution of the luminous component of about 80%, which is in agreement with the maximum disk definition of the
stellar mass contribution to the rotation curve (about
). This result is in agreement with the results found by
[CITE] for NGC 4123 using a similar
methodology. For two galaxies, NGC 7483 and IC 5186, a very good
agreement with the observed data is found. In these cases the
non-circular motions can help to break the disk-halo degeneracy. For
the other three galaxies (NGC 5728, NGC 7267 and NGC 5505) no definite
results are found: for NGC 7267 and NGC 5505 no steady state is
reached in the simulations and for NGC 5728 there is no good agreement
with the observed kinematics, possibly due to the presence of a
secondary bar decoupled from the primary. However, for this latter
galaxy the
ratio used gives the right amplitude of the rotation
curve, in further support of the
calculation method used
throughout this work. Fast bars give the best fit to the observed
kinematics for NGC 7483 and IC 5186 with corotation at the end of the
bar for NGC 7483 and at
for IC 5186. For
NGC 5505 for which no steady state configuration is found, the
addition of a rigid halo stabilises the gas flows but the derived
kinematics does not fit well the observations.
Key words: galaxies: kinematics and dynamics / galaxies: structure / cosmology: dark matter
© ESO, 2004
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