Properties of barred spiral disks in hydrodynamical cosmological simulations
arXiv:1412.2883
Abstract
We present a quantification of the properties of bars in two N-body+SPH cosmological simulations of spiral galaxies, named GA and AqC. The initial conditions were obtained using the zoom-in technique and represent two dark matter (DM) halos of , available at two different resolutions. The resulting galaxies are presented in the companion paper of Murante et al. (2014). We find that the GA galaxy has a bar of length kpc, present at the two resolution levels even though with a slightly different strength. Classical bar signatures (e.g. pattern of streaming motions, high Fourier mode with roughly constant phase) are consistently found at both resolutions. Though a close encounter with a merging satellite at (mass ratio ) causes a strong, transient spiral pattern and some heating of the disk, we find that bar instability is due to secular process, caused by a low Toomre parameter due to accumulation of mass in the disk. The AqC galaxy has a slightly different history: it suffers a similar tidal disturbance due to a merging satellite at but with a mass ratio of , that triggers a bar in the high-resolution simulation, while at low resolution the merging is found to take place at a later time, so that both secular evolution and merging are plausible triggers for bar instability.
15 pages, 18 figures, MNRAS accepted