Key Science Issues of the SKA
The international community has developed a detailed and compelling science case for the SKA, as described in detail in New Astronomy Reviews, volume 48 (2004). The core of the science case is five Key Science Projects; each project represents an unanswered question in fundamental physics or astrophysics, is science either unique to the SKA or for which the SKA plays a key role, and is something which can excite the broader community. The five Key Science Projects are:
What is the design for the SKA that can be built on the required timescales and within the target cost?
Where will the SKA be located?
What is the legal framework and governance structure under which the globally-funded SKA project will operate?
What is the most cost-effective mechanism for the procurement of the various components of the SKA? This must take into account the global nature of the SKA and the essential involvement of industry.
How will the SKA be funded? This question is especially important as different countries around the world have different natural cycles to their major funding decisions and may wish to join the project at different times.
The SKA has been conceived as a observational facility that will test fundamental physical laws and transform our current picture of the Universe. However, the scientific challenges outlined above are today's problems; will they still be the outstanding problems that will confront astronomers in the period 2020-2050 and beyond, when the SKA will be in its most productive years? Thus, the SKA community has adopted "Exploration of the Unknown" as a goal for the facility as part of a firmly founded expectation that the most exciting things to be discovered by the SKA are those that we have not yet conceived.
The science capability of the SKA will evolve as the telescope is constructed. Phase I will enable revolutionary science at decimetre wavelengths, with a particular focus on pulsars and gravitational wave astronomy, magnetism, H I and the nearby Universe, and exploration of the dynamic radio sky.
With its wider wavelength range and 5 times greater sensitivity, Phase 2 will transform our understanding of many key areas including: the formation of the first structures as the universe made its transition from a largely neutral state to its largely ionised state today; cosmology including dark energy via baryonic oscillations seen in neutral hydrogen; the properties of galaxy assembly and evolution; the origin, evolution and structure of magnetic fields across cosmic time; strong field tests of gravity using pulsars and black holes including measurements of black hole spin and theories of gravity, and the exploration of the dynamic radio sky with far greater sensitivity and instantaneous sky coverage.
The high frequency capability of Phase 3 will enable detailed study of planet formation in proto-planetary disks and the detection of the first metals in the universe via observations of molecules such as CO, HCN and HCO+.