Star Formation Histories From Faint Galaxy Counts

Multispectral faint galaxy counts, including the deepest Hubble DeepField, are interpreted with the help of our evolution model PEGASE(Fioc and Rocca-Volmerange, 1997). The best fits correspond to galaxyformations at high redshifts, a pure luminosity evolution andclassical luminosity functions. The adopted cosmology is a flatuniverse with the matter density parameter Ω_M =0.3 and acosmological constant Ω_Λ =0.7. A solution with Ω_M=0.01 (open universe) is also acceptable. But a flat universe withΩ_M =1 is clearly excluded. The star formation histories for galaxytypes are derived from scenarios of evolution. The comparison with resultsalready published in the litterature, arises puzzling problems needinga further analysis of star formation tracers, specifically for bright galaxies. This revised version was published online in July 2006 with corrections to the Cover Date.