Dark matter/energy gravitation: Constraints from astrophysics

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Recently, precise measurements have been made of the distances to supernovas and the fluctuations in intensity of the radiation field between the galaxies. Most cosmologists now admit that the universe is both simpler and more complicated than they thought.  It is simpler in that its density is close to a special value which arises in Einstein's theory of general relativity.  But it is more complicated because the bulk of the material is dark matter and dark energy, which imply a need to revise that underlying theory. It is also widely acknowledged that there is a need to extend Einstein's theory as a means of unifying the force of gravity with the interactions of particle physics. Our group has expertise in both dark matter/energy and extended gravitational theory. Our aims are to identify the former and constrain the latter, using astrophysical data.  In this our latest application for funds, we wish to focus on several related problems: Is the dark matter composed of weakly-interacting massive particles (WIMPs)? Is some part of it the elusive particles being detected by the Sudbury Neutrino Observatory, i.e. massive neutrinos? Is the dark energy the remnant of a decaying cosmological "constant", or another scalar field, and if so then how can we modify Einstein's theory? Are there other viable tests of such a new theory, to do with the motions of galaxies and the behaviour of test masses abroad a satellite in orbit around the Earth? We intend to work out these issues and confront them with observations, in order to better understand the universe.