摘要：Aims. We use the first release of the VImos Public Extragalactic
Redshift Survey of galaxies (VIPERS) of ~50
000 objects to measure the biasing relation between galaxies and mass
in the redshift range z = [
0.5,1.1 ].
Methods. We estimate the 1-point distribution function [PDF] of VIPERS
galaxies from counts in cells and, assuming a model for the mass PDF, we infer their mean
bias relation. The reconstruction of the bias relation is performed through a novel method
that accounts for Poisson noise, redshift distortions, inhomogeneous sky coverage. and
other selection effects. With this procedure we constrain galaxy bias and its deviations
from linearity down to scales as small as 4 h-1 Mpc and out to z = 1.1.
Results. We detect small (up to 2%) but statistically significant (up to
3σ)
deviations from linear bias. The mean biasing function is close to linear in regions above
the mean density. The mean slope of the biasing relation is a proxy to the linear bias
parameter. This slope increases with luminosity, which is in agreement with results of
previous analyses. We detect a strong bias evolution only for z> 0.9, which is in
agreement with some, but not all, previous studies. We also detect a significant increase
of the bias with the scale, from 4 to 8 h-1 Mpc , now seen for the first time
out to z = 1.
The amplitude of non-linearity depends on redshift, luminosity, and scale, but no clear
trend is detected. Owing to the large cosmic volume probed by VIPERS, we find that the
mismatch between the previous estimates of bias at z ~ 1 from zCOSMOS and
VVDS-Deep galaxy samples is fully accounted for by cosmic variance.
Conclusions. The results of our work confirm the importance of going
beyond the over-simplistic linear bias hypothesis showing that non-linearities can be
accurately measured through the applications of the appropriate statistical tools to
existing datasets like VIPERS.
关键词：cosmological parameters;dark matter;large-scale structure of Universe
