Astronomy and Astrophysics – Astrophysics
Scientific paper
2005-08-05
Mon.Not.Roy.Astron.Soc.375:425-459,2007
Astronomy and Astrophysics
Astrophysics
30 pages, 19 figures, submitted to Monthly Notices. For paper with figures at full resolution: http://www.astro.umass.edu/~w
Scientific paper
10.1111/j.1365-2966.2006.11306.x
Only through resonances can non-axisymmetric features such as spiral arms and bars exert torques over large scales and change the overall structure of a near-equilibrium galaxy. We describe the resonant interaction mechanism in detail and derive explicit criteria for the particle number required to simulate these dynamical processes accurately using N-body simulations and illustrate them with numerical experiments. To do this, we perform direct numerical solution of perturbation theory and make detailed comparisons with N-body simulations. The criteria include: sufficient particle coverage in phase space near the resonance and enough particles to minimize gravitational potential fluctuations that will change the dynamics of the resonant encounter. Some of our more surprising findings are as follows. First, the Inner-Lindblad-like resonance (ILR), responsible for coupling the bar to the central halo cusp, requires almost 10^9 equal mass particles within the virial radius for a Milky-Way-like bar in an NFW profile. Second, orbits that linger near the resonance receive more angular momentum than orbits that move through the resonance quickly. Small-scale fluctuations present in state-of-the-art particle-particle simulations can knock orbits out of resonance, preventing them from lingering and, thereby, decrease the torque. The required particle numbers are sufficiently high for scenarios of interest that apparent convergence in particle number is misleading: the convergence is in the noise-dominated regime. State-of-the-art simulations are not adequate to follow all aspects of secular evolution driven by the bar-halo interaction. We present a procedure to test the requirements for individual N-body codes for the actual problem of interest. [abridged]
Katz Neal
Weinberg Martin D.
No associations
LandOfFree
The Bar--Halo Interaction--I. From Fundamental Dynamics to Revised N-body Requirements does not yet have a rating. At this time, there are no reviews or comments for this scientific paper.
If you have personal experience with The Bar--Halo Interaction--I. From Fundamental Dynamics to Revised N-body Requirements, we encourage you to share that experience with our LandOfFree.com community. Your opinion is very important and The Bar--Halo Interaction--I. From Fundamental Dynamics to Revised N-body Requirements will most certainly appreciate the feedback.
Profile ID: LFWR-SCP-O-522109