Primordial Cosmological Fluctuations on Galactic Scales

Abstract

The galactic evolutionary theory is now sufficiently mature to provide information about the galaxy formation phase. From evolutionary models we establish a link between the present features of late type galaxies and the protogalactic density fluctuations. This link is used to estimate the fluctuation power spectrum amplitude at galactic scales. The agreement with the power spectrum derived from galaxy distribution and extrapolated to galactic scales, is satisfactory. Meanwhile, the comparison with respect to the standard cold dark matter power spectrum normalized to COBE satellite meassurements reveals only a marginal agreement. Among the most interesting results, the Tully-Fisher relation and the constant central brightness pointed out by Freeman (1970) appear to be the natural consequences of the initial cosmological conditions.