1 research outputs found
Halpha Kinematics of S4G Spiral Galaxies - III. Inner rotation curves
We present a detailed study of the shape of the innermost part of the
rotation curves of a sample of 29 nearby spiral galaxies, based on high angular
and spectral resolution kinematic Halpha Fabry-Perot observations. In
particular, we quantify the steepness of the rotation curve by measuring its
slope dRvc(0). We explore the relationship between the inner slope and several
galaxy parameters, such as stellar mass, maximum rotational velocity, central
surface brightness ({\mu}0), bar strength and bulge-to-total ratio. Even with
our limited dynamical range, we find a trend for low-mass galaxies to exhibit
shallower rotation curve inner slopes than high-mass galaxies, whereas steep
inner slopes are found exclusively in high-mass galaxies. This trend may arise
from the relationship between the total stellar mass and the mass of the bulge,
which are correlated among them. We find a correlation between the inner slope
of the rotation curve and the morphological T-type, complementary to the
scaling relation between dRvc(0) and {\mu}0 previously reported in the
literature. Although we find that the inner slope increases with the Fourier
amplitude A2 and decreases with the bar torque Qb, this may arise from the
presence of the bulge implicit in both A2 and Qb. As previously noted in the
literature, the more compact the mass in the central parts of a galaxy (more
concretely, the presence of a bulge), the steeper the inner slopes. We conclude
that the baryonic matter dominates the dynamics in the central parts of our
sample galaxies.Comment: 11 pages, 11 figures, accepted for publication in MNRA