We. Ballinger et al., MEASURING THE COSMOLOGICAL CONSTANT WITH REDSHIFT SURVEYS, Monthly Notices of the Royal Astronomical Society, 282(3), 1996, pp. 877-888
It has been proposed that the cosmological constant A might be measure
d from geometric effects on large-scale structure. A positive vacuum d
ensity leads to correlation function contours which are squashed in th
e radial direction when calculated assuming a matter-dominated model.
We show that this effect will be somewhat harder to detect than previo
us calculations have suggested: the squashing factor is likely to be <
1.3, given realistic constraints on the matter contribution to Omega.
Moreover, the geometrical distortion risks being confused with the re
dshift-space distortions caused by the peculiar velocities associated
with the growth of galaxy clustering. These depend on the density and
bias parameters via the combination beta = Omega(0.6)/b, and we show t
hat the main practical effect of a geometrical flattening factor F is
to simulate gravitational instability with beta(eff) similar or equal
to 0.5(F - 1). Nevertheless, with datasets of sufficient size it is po
ssible to distinguish the two effects. We discuss in detail how this s
hould be done, and give a maximum-likelihood method for extracting Lam
bda and beta from anisotropic power-spectrum data. New-generation reds
hift surveys of galaxies and quasars are potentially capable of detect
ing a non-zero vacuum density, if it exists at a cosmologically intere
sting level.