EDP Sciences
Free access
Volume 366, Number 1, January IV 2001
Page(s) 1 - 6
Section Cosmology
DOI http://dx.doi.org/10.1051/0004-6361:20000350

A&A 366, 1-6 (2001)
DOI: 10.1051/0004-6361:20000350

Lifting cosmic degeneracy within a single quasar survey

B. F. Roukema1 and G. A. Mamon2, 3

1  Inter-University Centre for Astronomy and Astrophysics, Post Bag 4, Ganeshkhind, Pune, 411 007, India
2  Institut d'Astrophysique de Paris (CNRS UPR 341), 98bis Bd Arago, 75014 Paris, France
3  DAEC (CNRS UMR 8631), Observatoire de Paris-Meudon, 5 place Jules Janssen, 92195 Meudon Cedex, France

(Received 8 September 2000 / Accepted 19 October 2000 )

In the almost Friedmann-Lemaître model of the Universe, the density parameter, $\Omega_{{\rm m}}$, and the cosmological constant, $\Omega_\Lambda$, measure curvature. Several linearly degenerate relations between these two parameters have recently been measured. Here, large scale structure correlations at $\sim 100{-}150$ h-1 Mpc are found in the comoving three-dimensional separations of redshift $z\approx 2$ quasars. These function as a comoving standard rod of length $L_{\rm LSS} \approx 130\pm10$ h-1 Mpc. A local maximum in the correlation function at $\approx L_{\rm LSS}/2$ also appears to be significant. By combining separate radial and tangential standard ruler analyses, the lifting of the $\Omega_{{\rm m}}-\Omega_\Lambda$ linear degeneracy within a single data set is demonstrated for the first time.

Key words: cosmology: observations -- cosmology: theory -- distance scale -- quasars: general -- large-scale structure of Universe -- reference systems

Offprint request: B. F. Roukema

© ESO 2001