## Galactic Structure and Dynamics¶

Theoretical study of galactic structure at UMass ranges from analytic perturbation theory to kinetic theory of N-body simulations to statistical inference from theoretical models and observational data. For example, new adiabatic theory and the "dispersion relation" approach can be applied to a variety of secular evolution problems in barred galaxy evolution, tidal excitation, Magellanic cloud heating and Milky Way kinematics. All of this work is numerically intensive. The perturbation theory, although formally analytic, demands numerical solutions. To meet this need, three "suites" of parallel numerical codes for production work have been developed by Martin Weinberg: 1) a perturbation theory package called Orbit; 2) an N-body code using the expansion approach which is well suited to studying slow evolution over very long time scales; and 3) a Bayesian statistical package called the "Bayesian Inference Engine" (BIE). This latter project grew out of the need to exploit 2MASS and other catalog data to constrain Milky Way and Local Group theory, but it is a stand-alone general Bayesian platform.