Precessing ellipses as the building blocks of spiral arms

Abstract

Stable periodic orbits in spiral galactic models that form families of precessing ellipses can create spiral density waves similar to those that are observed in real grand-design galaxies. We study the range in parameter space for which the amplitude of the spiral perturbation, the pattern speed, and the pitch angle collaborate so as to lead to the creation of density waves that are supported by precessing ellipses and their surrounding matter in ordered motion. Quantitative estimates lead to a correlation between the pitch angle and the amplitude of the spiral perturbation and also between the pitch angle and the pattern speed of the spiral arms. These correlations can be regarded as an orbital analog of a nonlinear dispersion relation in density wave theory.

17 pages, 22 figures

References in corpus (8)

• Dawes Review 4: Spiral Structures in Disc Galaxies
• Constraining dark matter halo profiles and galaxy formation models using spiral arm morphology. I. Method outline
• The morphology of the Milky Way - I. Reconstructing CO maps from simulations in fixed potentials
• Do Bars Drive Spiral Density Waves?
• Galaxy Zoo and SpArcFiRe: Constraints on spiral arm formation mechanisms from spiral arm number and pitch angles
• Galaxy Zoo: Unwinding the Winding Problem - Observations of Spiral Bulge Prominence and Arm Pitch Angles Suggest Local Spiral Galaxies are Winding
• A multi-wavelength study of spiral structure in galaxies. I. General characteristics in the optical
• Dynamics of thick, open spirals in Perlas potentials