2021/02/06 by Philip G. Breen, Simon Rozier, Douglas C. Heggie +1 · 9 citations
Physics and Astronomy · #Anisotropy #Astro and Planetary Science #Astrophysics #Astrophysics and Star Formation Studies #Bar (unit) #Classical mechanics #Distribution (mathematics) #Geometry #Instability #Kinematics #Mathematical analysis #Matrix (chemical analysis) #Mechanics #Parameter space #Phase space #Physics #Quantum mechanics #RADIUS #Rotation (mathematics) #Space (punctuation) #Stability (learning theory) #Stars #Statistical physics #Stellar, planetary, and galactic studies #astro-ph.GA
paper · pdf · doi:10.1093/mnras/stab365
published in Monthly Notices of the Royal Astronomical Society 502(4), 4762-4778 (Oxford University Press) · 17 pages, 18 figures, accepted for publication in MNRAS
openalex publication_date 2021/02/06 · arxiv created 2021/02/08 · arxiv updated 2021/02/17 · openalex created_date 2025/10/10 · openalex updated_date 2026/08/06
ABSTRACT We study the bar instability in collisionless, rotating, anisotropic, stellar systems, using N-body simulations and also the matrix technique for calculation of modes with the perturbed collisionless Boltzmann equation. These methods are applied to spherical systems with an initial Plummer density distribution, but modified kinematically in two ways: the velocity distribution is tangentially anisotropic, using results of Dejonghe, and the system is set in rotation by reversing the velocities of a fraction of stars in various regions of phase space, à la Lynden-Bell. The aim of the N-body simulations is first to survey the parameter space, and, using those results, to identify regions of phase space (by radius and orbital inclination) that have the most important influence on the bar instability. The matrix method is then used to identify the resonant interactions in the system that have the greatest effect on the growth rate of a bar. Complementary series of N-body simulations examine these processes in relation to the evolving frequency distribution and the pattern speed. Finally, the results are synthesized with an existing theoretical framework, and used to consider the old question of constructing a stability criterion.