Patterns in the Outer Parts of Galactic Disks

Abstract

This paper describes test particle simulations of the response of the outer parts of Galactic disks to barring and spiral structure. Simulations are conducted for cold Mestel disks and warm quasi-exponential disks with completely flat rotation curves, subjected to pure quadrupoles and logarithmic spirals. Even though the starting velocity distributions are smooth, the end-points of the bar simulations show bimodality and multi-peaked structures at locations near the outer Lindblad resonance (OLR), although spirality can make this smoother. The growth of a bar may cause the disk isophotes to become boxy at the OLR, as stars accummulate particularly along the minor axis. The growth of a bar is also accompanied by substantial heating of the disk stars near the OLR. For the growth of a $10^{10}{M}_{\odot }$ bar, the radial velocity dispersion is typically quadrupled for initially cold disks (initial \sigmau $\sim 10$ \kms), and typically doubled for disks with final \sigmau $\sim 45$ \kms. Simulations performed of the growth and dissolution of bars give very similar results, demonstrating that the heat once given to disk stars is very difficult to remove.

14 pages, 19 figures

References in corpus (3)

• The Geneva-Copenhagen survey of the Solar neighbourhood: Ages, metallicities, and kinematic properties of 14,000 F and G dwarfs
• Orbital dynamics of three-dimensional bars: IV. Boxy isophotes in face-on views
• Evidence for a Large Stellar Bar in the LSB Galaxy UGC 7321

Cited by in corpus (7)

• Phase Space Structure in the Solar Neighbourhood
• Calculation of the Local Standard of Rest from 20,574 Local Stars in the New Hipparcos Reduction with Known Radial Velocities
• Kinematics of planet-host stars and their relation with dynamical streams in the solar neighbourhood
• Modelling resonances and orbital chaos in disk galaxies. Application to a Milky Way spiral model
• Quantifying Chaos in Models of the Solar Neighbourhood
• On the long-term evolution of razor-thin galactic discs: Balescu-Lenard prediction and perspectives
• Bayesian Covariance Modelling of Large Tensor-Variate Data Sets $\&$ Inverse Non-parametric Learning of the Unknown Model Parameter Vector