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We examine the dynamics structure of the rich cluster A1689, combiningVLT/VIMOS spectroscopy with Subaru/Suprime-Cam imaging. The radial velocitydistribution of $\sim 500$ cluster members is bounded by a pair of clearlydefined velocity caustics, with a maximum amplitude of $\sim|4000|$ km/s at$\simeq$ 300 h$^{-1}$ kpc, beyond which the amplitude steadily declines,approaching zero velocity at a limiting radius of $\sim$ 2 h$^{-1}$ Mpc. Wederive the 3D velocity anisotropy and galaxy number density profiles using amodel-independent method to solve the Jeans equation, simultaneouslyincorporating the observed velocity dispersion profile, the galaxy counts fromdeep Subaru imaging, and our previously derived cluster mass profile from ajoint lensing and X-ray analysis. The velocity anisotropy is found to bepredominantly radial at large radius, becoming increasingly tangential towardsthe center, in accord with expectations. We also analyze the galaxy dataindependently of our previous analysis using two different methods: The firstis based on a solution of the Jeans equation assuming an NFW form for the massdistribution, whereas in the second method the caustic amplitude is used todetermine the escape velocity. The cluster virial mass derived by both of thesedynamical methods is in good agreement with results from our earlier lensingand X-ray analysis. We also confirm the high NFW concentration parameter, withresults from both methods combined to yield $c_{\rm vir}>13$ (1$\sigma$). Theinferred virial radius is consistent with the limiting radius where thecaustics approach zero velocity and where the counts of cluster members dropoff, suggesting that infall onto A1689 is currently not significant.

Dynamical Study of A1689 from Wide-Field VLT/VIMOS Spectroscopy: Mass Profile, Concentration Parameter, and Velocity Anisotropy