10/4/08

Scientific Rationale

Highly collimated supersonic jets and outflows are very frequent in several astrophysical environments. They are seen in young stellar objects (YSOs), proto-planetary nebulae, compact objects (like galactic black holes or microquasars, and X-ray binary stars), active galactic nuclei, and are also possibly associated to gamma-ray bursts (GRBs), the most energetic events in the Universe, and to ultra-high energy cosmic rays sources (UHECRs). Despite their different physical scales, all these outflow classes have strong morphological similarities, but questions like - what physics do they share? - or - can we find a universal mechanism of acceleration and collimation that operates in all classes? - remain a matter of debate.
The most accepted mechanism for their origin relies on a rotating accretion disk threaded by perpendicular large-scales magnetic fields and, though most of the systems producing jets contain an accretion disk around the central source, the real role that rotation and magnetic fields play on these processes is still not fully understood, nor the highly non-linear physical processes connected to these jet-disk systems in the large parameter space involved.
Recent years have been marked by worldwide reviving interest in the studies of magnetic disk accretion and outflows both because of their potential relation to several astrophysical phenomena that are not well understood yet like GRBs and UHECRs, and also because of the fast advance in multi-dimensional computational modeling of these systems and the large improvement in the observations with the building of new instrumentation and techniques that allow to resolve some outflows bases very near the sources and combine multi-wavelength data. We thus believe it is time to revive the discussion of the origin of the astrophysical jets and their effects on the astrophysical environments.
The main scientific goals of the meeting will focus on understanding the driving mechanisms of jets from proto-stars (including their possible crucial link with star and planet formation) to microquasars and AGNs trying to emphasize their differences/similarities; the basic physics of the accretion-jet process in magnetized disks, which is not fully understood yet in the large parameter space involved, including the transport of angular momentum and the development of reconnection and turbulent dynamo; cooling/heating processes, instabilities, shock structures and particle acceleration mechanisms in the jets; the impact of the jets on energy balance and turbulence feeding in the astrophysical environments; and the potential association of jet-accretion phenomena with GRBs and UHECRs.