Observational Cosmology

Abstract

This chapter will present in a more detail the observational foundations of the standard cosmology. We first quickly pass in review the astronomical objects found on various scales. Section 2.1 is concerned with the compact objects that produce the visible photons in the universe either through combustion of nuclear fuel (in stars) or through gravitational collapse (in core collapse supernovae and quasars). The two subsequent sections show how stars are grouped together in galaxies and in clusters of galaxies. In Sect. 2.4 we will review present efforts to elucidate the nature of the dark matter that dominates the mass of the universe. Finally, in Sect. 2.5, we summarize the present measurements of the parameters of the standard model of cosmology i.e., the expansion rate and the various universal densities. A discussion of observations of the CBR photons will be delayed until Chap. 7.