In the past decade, a series of seven workshops devoted to the study of microquasars -accreting compact objects with relativistic jets- have been held in various locations every two years. The series of workshops have resulted in a significant increase of our knowledge of relativistic jets from galactic sources. From the first detection of superluminal ejections, we now have observed the presence of jets in a large number of neutron-star and black-hole binaries and even in cataclysmic variables. Massive young stellar objects are also known to generate jets and, at their endpoints, non-thermal emission has been detected.
The availability of powerful facilities at all wavelengths has allowed to probe the connection between the accretion of plasma onto the central object (observed in the X-ray band) and the emission of jets (as observed in the infrared and radio bands). The field is still in rapid expansion with new space missions such as AGILE and Fermi already active, and ground-based atmospheric Cherenkov telescopes like HESS, MAGIC, and VERITAS doing amazing discoveries, concerning both galactic and extragalactic jets. In the meanwhile, new missions like ASTROSAT, extensions of the high-energy telescope arrays like MAGIC II, HESS II, and large-scale instruments like LOFAR, SKA, ALMA, CTA, and AGIS, along with the forthcoming neutrino telescopes, will increase dramatically our observational power and will open a wide discovery space for this research field. Extensive numerical simulations of jets are also in rapid progress, which helps understanding the physical mechanism producing jets.
The time is now ripe to start a detailed comparison of all sources containing jets such as Microquasars, Active Galactic Nuclei, and Gamma-Ray Bursts. Both deep theoretical and observational insights can result from an inter-disciplinary discussion of the fundamental physics underlying the different objects and phenomena. The Symposium is aimed at putting the various communities devoted to the study of relativistic jets in closer contact. The past two workshops, both titled "Microquasars and Beyond", have shown that this approach can be very fruitful and that such an exchange would contribute significantly to the advance of the field. Now it is time to go a step further and to organize an international Symposium to deal in depth with jet physics and phenomenology at all scales.