On the current distribution of main belt objects: Constraints for evolutionary models

Context. It is widely accepted that the current distribution of material in the main asteroidal belt (MB) is a product of the evolutionary history of the solar system during its whole lifetime of similar to 4.5 billions of years and is, consequently, a major witness of the diverse stages of this evolution. Aims. The purpose of this paper is twofold: first, we study the principal aspects of the distribution of the asteroids in proper element space, mass, and, physical composition for a complete picture of the current MB. Second, we analyze if and how these current distributions can be explained by the long-lasting dynamical e ff ects of the planets on this region of the solar system. Methods. We studied the distribution in the proper element space for the sample that consists of about 350 000 objects whose proper orbital elements are available from the database AstDyS. We studied the distribution in size and physical composition using the most recent and large available datasets. We constructed the dynamical portrait of the MB in form of the dynamical and averaged maps via the spectral analysis method. Results. The main properties of the current distributions of MB objects are identified. A comparison of the distributions of real objects with dynamical maps allows us to detect principal mechanisms of the di ff usive transportation of the objects. These mechanisms are related to mean-motion resonances (MMRs) and secular resonances (SRs), overlaying with the slow dissipative Yarkovsky /Yorp drift. Conclusions. We identify the most relevant distributions of the material in the MB and show that many of the current features of the MB can be explained by the interplay of diverse dynamical mechanisms due to the planetary perturbations over 4 Gyr with nongravitational e ff ects, without the need of `catastrophic' events or `ad hoc' migration mechanisms during the early stages of the solar system. In this sense, the obtained distributions can provide relevant constraints for modeling the origin and evolution of the MB. (AU)