Galaxy Evolution, Cosmology and Dark Energy – Further Information
In addition to detecting hydrogen emission in galaxies, the SKA will also perform the deepest ever radio continuum survey, probing the star formation history of the Universe as a function of redshift in a manner independent of the dust extinction (dust hiding objects behind it, which affects optical telescopes).
With radio surveys, the dust which blocks a large proportion of the visible light is penetrated, revealing the complex structures and individual stars which lie within.
It will be of great interest to scientists who will be able to link the star formation properties of galaxies to their hydrogen contents, as a function of redshift and environment. Furthermore, a high resolution radio continuum survey over wide areas allows a precise measurement of the coherent shape distortions of distant galaxies imparted by the foreground cosmic web, distortions similar to that created by a lens being placed in front of an object being seen in visible light, but using the force of gravity instead of a lens.
This weak gravitational lensing encodes a vast body of cosmological information, and its exploitation will become one of our key cosmological probes within the next decade.
Radio wavebands are particularlyadvantageous for this experiment because the point-spread function is well determined and stable (being simply the interferometer baseline distribution), solving the principle systematic difficulty inherent in the method.