Unstable spiral modes in disk-shaped galaxies: Enhancement of growth rate
نویسندگان
چکیده
منابع مشابه
Unstable Bar and Spiral Modes of Disk Galaxies
We study bisymmetric modes of angular wavenumber 2 for flat stellar disks in potentials with smooth cores. Stars either all circulate in the same direction or a small fraction may counter-rotate. The bisymmetric modes are unstable unless there is a sufficiently large external halo or bulge. We find two modes for each disk: a more central fundamental mode and a more extensive and more spiral (tr...
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I utilize the Petrov-Galerkin formulation and develop a new method for solving the unsteady collisionless Boltzmann equation in both the linear and nonlinear regimes. In the first order approximation, the method reduces to a linear eigenvalue problem which is solved using standard numerical methods. I apply the method to the dynamics of a model stellar disk which is embedded in the field of a s...
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I decompose the unstable growing modes of stellar disks to their Fourier components and present the physical mechanism of instabilities in the context of resonances. When the equilibrium distribution function is a non-uniform function of the orbital angular momentum, the capture of stars into the corotation resonance imbalances the disk angular momentum and triggers growing bar and spiral modes...
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We present a systematic observational study of the relationship between bars and boxy/peanut-shaped (B/PS) bulges. We Ðrst review and discuss proposed mechanisms for their formation, focusing on accretion and bar-buckling scenarios. Using new methods relying on the kinematics of edge-on disks, we then look for bars in a large sample of edge-on spiral galaxies with a B/PS bulge and in a smaller ...
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Simulations and observations of galactic bars suggest they do not commonly evolve into bulges, although it is possible that the earliest bars formed bulges long ago, when galaxies were smaller, denser, and had more gas. The most highly evolved of today’s bars may become lenses over a Hubble time. Most galaxies in the early Universe are extremely clumpy, with ∼ 10 −10 M⊙ blue clumps that resembl...
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ژورنال
عنوان ژورنال: Proceedings of the National Academy of Sciences
سال: 1976
ISSN: 0027-8424,1091-6490
DOI: 10.1073/pnas.73.11.3785