Dynamic picture of the main asteroid belt

Using the Spectral Analysis Method introduced by Michtchenko et al. (2002), we construct a dynamic portrait of the main asteroid belt. For this task, we use information extracted from the distribution of test particles (which were initially placed on a perfectly rectangular grid of initial conditions) after 4.2 Myr of gravitational interactions with the Sun and five planets, from Mars to Neptune. We illustrate in detail the asteroidal behavior on the dynamical, averaged and frequency maps. On the maps, we superpose information on the proper elements and proper frequencies of real objects, extracted from the data base, AstDyS (http://hamilton.dm.unipi.it/astdys), constructed by Milani and Knežević (2003). A comparison of the maps with the distribution of real objects allows us to detect dynamical mechanisms acting in the domain under study. These mechanisms are related to meanmotion and secular resonances. We note that the twoand three-body mean-motion resonances and the secular resonances (strong linear and weaker non-linear) play an important role in the diffusive transportation of the objects and the formation of the clumps which could be misidentified as asteroid families. The longlasting action of the resonances, overlaid with the Yarkovsky effect, may explain many observed features of the density, size and taxonomic distributions of the asteroids.