FM 18: Scale-free processes in the universe

Most of the distribution functions in the universe, including those for mass, energy, and structure of components like dark matter, galaxy clusters, galaxies, magnetic fields, cosmic rays, star clusters, and stars, have power-law shapes indicating a lack of definite scales in whatever processes determine their formation and organization. As these scale-free behaviors are obtained without fine-tuning, they are by definition self-organized critical, which raises fascinating questions regarding the respective roles of long-range (gravity) and short-range (collisional) interactions. These questions touch on the interaction between dark matter, baryons, cosmic rays and magnetic fields, the importance of scales where the power-laws break down, the observed deviations from power-laws, and the range of scales that are truly coupled. Computer simulations now include a large enough range of scales to reproduce some of these power-laws, and recent theoretical analyses attempt to unify them.

The main objective of this Focus Meeting is to gather cosmologists, astrophysicists and statistical physicists, whether they are observers, theoreticians or numericists. It will provide an opportunity to exchange ideas from different horizons and plan the next steps in this global investigation.