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ANOMALOUSLY WEAK DYNAMICAL FRICTION IN HALOS

  • J. A. Sellwood
  • Victor P. Debattista
Part of the Astrophysics and Space Science Proceedings book series (ASSSP)

Abstract

A bar rotating in a pressure-supported halo generally loses angular momentum and slows down due to dynamical friction. Valenzuela & Klypin report a counter-example of a bar that rotates in a dense halo with little friction for several Gyr, and argue that their result invalidates the claim by Debattista & Sellwood that fast bars in real galaxies require a low halo density. We show that it is possible for friction to cease for a while should the pattern speed of the bar fluctuate upward. The reduced friction is due to an anomalous gradient in the phase-space density of particles at the principal resonance created by the earlier evolution. The result obtained by Valenzuela & Klypin is probably an artifact of their adaptive mesh refinement method, but anyway could not persist in a real galaxy. The conclusion by Debattista & Sellwood still stands.

Keywords

Dynamical Friction Phase Space Density Frictional Torque Pattern Speed Principal Resonance 
These keywords were added by machine and not by the authors. This process is experimental and the keywords may be updated as the learning algorithm improves.

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Copyright information

© Springer 2007

Authors and Affiliations

  • J. A. Sellwood
    • 1
  • Victor P. Debattista
    • 2
  1. 1.Department of Physics & AstronomyRutgers UniversityPiscatawayUSA
  2. 2.Astronomy DepartmentUniversity of WashingtonSeattleUSA

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