Evolution of the Non-Linear Galaxy Bias up to Redshift z=1.5

Abstract

Deep redshift surveys of the universe provide the basic ingredients to compute the probability distribution function (PDF) of galaxy fluctuations and to constrain its evolution with cosmic time. When this statistic is combined with analytical CDM predictions for the PDF of mass, useful insights into the biasing function relating mass and galaxy distributions can be obtained. In this paper, we focus on two issues: the shape of the biasing function and its evolution with redshift. We constrain these quantities by using a preliminary sample of galaxies spectroscopically surveyed by the Vimos-VLT Deep Survey in a deep cone 0.4<z<1.5 covering 0.4x0.4 sq. deg. We show that the ratio between the amplitude of galaxy fluctuations and the underlying mass fluctuations declines with cosmic time, and that its evolution rate is a function of redshift: biasing evolution is marginal up to z~0.8 and more pronounced for z > 0.8.

8 pages, 3 figures. To appear in the proceedings of the XLIst Rencontres de Moriond, XXVIth Astrophysics Moriond Meeting: "From dark halos to light", Eds. L.Tresse, S. Maurogordato and J. Tran Thanh Van (Editions Frontieres)