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Measuring the cosmological constant with redshift surveys  W. E. Ballinger
; J. A. Peacock
; A. F. Heavens
;  Date: 
3 May 1996  Subject:  astroph  Affiliation:  Institute for Astronomy and Royal Observatory, Edinburgh  Abstract:  It has been proposed that the cosmological constant $Lambda$ might be measured from geometric effects on largescale structure. A positive vacuum density leads to correlationfunction contours which are squashed in the radial direction when calculated assuming a matterdominated model. We show that this effect will be somewhat harder to detect than previous 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 redshiftspace distortions caused by the peculiar velocities associated with the growth of galaxy clustering. These depend on the density and bias parameters via the combination $etaequiv Omega^{0.6}/b$, and we show that the main practical effect of a geometrical flattening factor $F$ is to simulate gravitational instability with $eta_{
m eff}simeq 0.5(F1)$. Nevertheless, with datasets of sufficient size it is possible to distinguish the two effects; we discuss in detail how this should be done. Newgeneration redshift surveys of galaxies and quasars are potentially capable of detecting a nonzero vacuum density, if it exists at a cosmologically interesting level.  Source:  arXiv, astroph/9605017  Services:  Forum  Review  PDF  Favorites 


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