The K20 survey -: IV.: The redshift distribution of Ks > 20 galaxies:: A test of galaxy formation models

We present the redshift distribution of a complete sample of 480 galaxies with K-s<20 distributed over two independent fields covering a total area of 52 arcmin(2). The redshift completeness is 87% and 98% respectively with spectroscopic and high-quality and tested photometric redshifts. The redshift distribution of field galaxies has a median redshift z(med)∼0.80, with ∼32% and ∼9% of galaxies at z>1 and z>1.5 respectively. A "blind" comparison is made with the predictions of a set of the most recent LambdaCDM hierarchical merging and pure luminosity evolution (PLE) models. The hierarchical merging models overpredict and underpredict the number of galaxies at low-z and high-z respectively, whereas the PLE models match the median redshift and the low-z distribution, still being able to follow the high-z tail of N(z). We briefly discuss the implications of this comparison and the possible origins of the observed discrepancies. We make the redshift distribution publicly available.