Long-Lived Double-Barred Galaxies: Critical Mass and Length Scales

Abstract

A substantial fraction of disk galaxies is double-barred. We analyze the dynamical stability of such nested bar systems by means of Liapunov exponents,by fixing a generic model and varying the inner (secondary) bar mass. We show that there exists a critical mass below which the secondary bar cannot sustain its own orbital structure, and above which it progressively destroys the outer (primary) bar-supporting orbits. In this critical state, a large fraction of the trajectories (regular and chaotic) are aligned with either bar, suggesting the plausibility of long-lived dynamical states when secondary-to-primary bar mass ratio is of the order of a few percent. Qualitatively similar results are obtained by varying the size of the secondary bar, within certain limits, while keeping its mass constant. In both cases, an important role appears to be played by chaotic trajectories which are trapped around (especially) the primary bar for long periods of time.

arXiv comment7 pages, 1 figure, to be published in Astrophysical Journal Letters (Vol. 595, 9/20/03 issue). Replaced by revised figure and corrected typos

References in corpus (11)

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• Dynamical Decoupling of Nested Bars: Self-Gravitating Gaseous Nuclear Bars
• Why Are AGN and Host Galaxies Misaligned?
• Induced Nested Galactic Bars Inside Assembling Dark Matter Halos
• Regular and chaotic orbits in barred galaxies - I. Applying the SALI/GALI method to explore their distribution in several models
• Mass Supply to Galactic Center due to Nested Bars in the Galaxy
• Modeling Evolution of Galactic Bars at Cosmic Dawn
• Regular motions in double bars. II. Survey of trajectories and 23 models