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The Cosmological Constant and Quintessence from a Correlation Function Comoving Fine Feature in the 2dF Quasar Redshift Survey | | B. F. Roukema
; G. A. Mamon
; S. Bajtlik
; | | Date: |
7 Jun 2001 | | Journal: | Astronomy & Astrophysics 382 (2002) 397 | | Subject: | astro-ph | | Affiliation: | Obs.Paris-Meudon, Inst d’Astro de Paris, N. Copernicus Astronomical Centre | | Abstract: | Detections of local maxima in the density perturbation spectrum at characteristic comoving scales L~100-200h^{-1}Mpc have previously been claimed. Here, this cosmic standard ruler is sought in the ``10K’’ release of the 2dF QSO Redshift Survey (2QZ-10K), by estimating the comoving, spatial correlation functions xi(r) of the three-dimensional distribution of the N=2378 quasars in the most completely observed and ``covered’’ sky regions, over the three redshift ranges 0.6 < z < 1.1, 1.1 < z < 1.6 and 1.6 < z < 2.2. Because of the selection method of the survey and sparsity of the data, the analysis was done conservatively to avoid non-cosmological artefacts. (i) Avoiding ’a priori’ estimates of the length scales of features, local maxima in xi(r) are found in all three redshift ranges. The requirement that a local maximum be present in all three redshift ranges at a fixed comoving length scale implies strong, purely geometric constraints on the local cosmological parameters. The length scale of the local maximum common to the three redshift ranges is 2L= (244pm17)h^{-1}Mpc. (ii) For a standard FLRW model, the matter density Omm and cosmological constant Omega_Lambda are constrained to Omm= 0.25pm0.10, Omega_Lambda=0.65pm0.25 (68% confidence), Omm= 0.25pm0.15, Omega_Lambda=0.60pm0.35 (95%), respectively, *from the 2QZ-10K alone*. Independently of the SNe Ia data, the zero cosmological constant model (Omega_Lambda=0) is rejected at the 99.7% confidence level. (iii) For an effective quintessence (w_Q) model and zero curvature, w_Q<-0.5 (68%), w_Q<-0.35 (95%) are found, again *from the 2QZ-10K alone*. | | Source: | arXiv, astro-ph/0106135 | | Services: | Forum | Review | PDF | Favorites | |
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