| Type |
Journal Article |
| Names |
Ch. Theis, L. Sparke, J. Gallagher |
| Publication |
Astronomy and Astrophysics |
| Volume |
446 |
| Issue |
3 |
| Pages |
905-918 |
| Date |
February 1, 2006 |
| URL |
http://adsabs.harvard.edu/abs/2006A%26A...446..905T |
| Library Catalog |
NASA ADS |
| Abstract |
To investigate the stability properties of polar disks we performed
two-dimensional hydrodynamical simulations for flat polytropic gaseous
self-gravitating disks which were perturbed by a central S0-like
component. Our disk was constructed to resemble that of the
proto-typical galaxy NGC 4650A. This central perturbation induces
initially a stationary two-armed tightly-wound leading spiral in the
polar disk. For a hot disk (Toomre parameter Q>1.7), the structure
does not change over the simulation time of 4.5 Gyr. In case of colder
disks, the self-gravity of the spiral becomes dominant, it decouples
from the central perturbation and grows, until reaching a saturation
stage in which an open trailing spiral is formed, rather similar to that
observed in NGC 4650A. The timescale for developing non-linear
structures is 1-2 Gyr; saturation is reached within 2-3 Gyr. The main
parameter controlling the structure formation is the Toomre parameter.
The results are surprisingly insensitive to the properties of the
central component. If the polar disk is much less massive than that in
NGC 4650A, it forms a weaker tightly-wound spiral, similar to that seen
in dust absorption in the dust disk of NGC 2787. Our results are derived
for a polytropic equation of state, but appear to be generic as the
adiabatic exponent is varied between γ = 1 (isothermal) and
γ = 2 (very stiff). |
| Tags |
GALAXIES: EVOLUTION, galaxies: individual: NGC 4650 A, galaxies: kinematics and dynamics |