Galactic bar resonances with diffusion: an analytic model with implications for bar-dark matter halo dynamical friction

• DOI: 10.48550/arxiv.2208.03855
• Publication Date: 2022-01-01
• Authors: Chris J. Hamilton; Elizabeth A. Tolman; Lev Arzamasskiy; V. N. Duarte
• Keywords: Dynamical friction; Test particle; Bar (unit)

The secular evolution of disk galaxies is largely driven by resonances between the orbits 'particles' (stars or dark matter) and rotation non-axisymmetric features (spiral arms a bar). Such may also explain kinematic photometric observed in Milky Way external galaxies. In simplified cases, these resonant interactions are well understood: for instance, dynamics test particle trapped near resonance steadily rotating bar easily analyzed using angle-action tools pioneered Binney, Monari others. However, such treatments do not address stochasticity messiness inherent to real - effects which have, with few exceptions, been previously explored only complex N-body simulations. this paper, we propose simple kinetic equation describing distribution function particles an orbital rigidly bar, allowing diffusion particles' slow actions. We solve various values dimensionless strength $\Delta$, then apply our theory calculation bar-halo dynamical friction. For $\Delta = 0$ recover classic result Tremaine & Weinberg that friction ultimately vanishes, owing phase-mixing orbits. > find suppresses phase-mixing, leading finite torque. Our results suggest be it physical numerical tends increase friction, bars cosmological simulations might experience significant artificial slowdown, even if two-body relaxation time much longer than Hubble time.