Ivan Minchev, Benoit Famaey, Alice C. Quillen
Disc non-axisymmetrc components, such as spirals and central bars, are
nowadays known to play an important role in shaping galactic discs. Here we use
Tree-SPH N-body simulations to examine the effect of these perturbers on two
aspects: the occurrence of multiple patterns in discs and the effects of radial
migration on disc thickening. We find that, in addition to a central bar,
multiple spiral patterns and lopsided modes develop in all models. Interaction
among these asymmetric features results in a large scale stellar migration.
However, we show that, despite the strong radial mixing, discs cannot be
thickened sufficiently to match observed thick discs. We relate this to the
adiabatic cooling as stars migrate radially outwards. We also find that the
contribution to a thick disc component from a bulge for an Sa-type galaxy is
less than 1% at ~2.5 disc scale-lengths and zero in the case of a Milky
Way-like, Sb-type. Our findings cast doubt on the plausibility of thick disc
formation via stellar radial migration.
View original:
http://arxiv.org/abs/1111.0195
No comments:
Post a Comment