Xp. Wu et al., ENVIRONMENTAL-EFFECT ON THE ASSOCIATIONS OF BACKGROUND QUASARS WITH FOREGROUND OBJECTS .2. NUMERICAL SIMULATIONS, The Astrophysical journal, 488(2), 1997, pp. 557-562
Using numerical simulations of cluster formation in the standard cold
dark matter (CDM) model and in a low-density, flat CDM model with a co
smological constant, we investigate the gravitational lensing explanat
ion for the reported associations between background quasars and foreg
round clusters. Under the thin-lens approximation and the unaffected-b
ackground hypothesis, we show that the recently detected quasar overde
nsity around clusters of galaxies on scales of similar to 10' cannot b
e interpreted as a result of gravitational lensing by cluster matter o
r by their environmental and projected matter along the line of sight,
which is consistent with the analytical result based on the observed
cluster and galaxy correlations. It appears very unlikely that uncerta
inties in the modeling of the gravitational lensing can account for th
e disagreement between the theoretical predictions and the observation
s. We conclude that either the detected signal of the quasar-cluster a
ssociations is a statistical fluke or the associations are generated b
y mechanisms other than the magnification bias.