Bibcode
DOI
Martinez-Valpuesta, Inma; Shlosman, Isaac; Heller, Clayton
Bibliographical reference
The Astrophysical Journal, Volume 637, Issue 1, pp. 214-226.
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1
2006
Journal
Citations
378
Refereed citations
315
Description
Evolution of stellar bars in disk galaxies is accompanied by dynamical
instabilities and secular changes. Following the vertical buckling
instability, the bars are known to weaken dramatically and develop a
pronounced boxy/peanut shape when observed edge-on. Using
high-resolution N-body simulations of stellar disks embedded in live
axisymmetric dark matter halos, we have investigated the long-term
changes in the bar morphology, specifically the evolution of the bar
size, its vertical structure, and the exchange of angular momentum. We
find that following the initial buckling, the bar resumes its growth
from deep inside the corotation radius and follows the ultraharmonic
resonance thereafter. We also find that this secular bar growth triggers
a spectacular secondary vertical buckling instability that leads to the
appearance of characteristic boxy/peanut/X-shaped bulges. The secular
bar growth is crucial for the recurrent buckling to develop.
Furthermore, the secondary buckling is milder, persists over a
substantial period of time, ~3 Gyr, and can have observational
counterparts. Overall, the stellar bars show recurrent behavior in their
properties and evolve by increasing their linear and vertical extents,
both dynamically and secularly. We also demonstrate explicitly that the
prolonged growth of the bar is mediated by continuous angular momentum
transfer from the disk to the surrounding halo and that this angular
momentum redistribution is resonant in nature: a large number of lower
resonances trap disk and halo particles, and this trapping is robust, in
broad agreement with the earlier results in the literature.