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Evidence for a non-zero Λ and a low matter density from a combined analysis of the 2dF Galaxy Redshift Survey and cosmic microwave background anisotropies

Efstathiou, G. and Moody, Stephen and Peacock, John A. and Percival, Will J. and Baugh, Carlton and Bland-Hawthorn, Joss and Bridges, Terry and Cannon, Russell and Cole, Shaun and Colless, Matthew and Collins, Chris and Couch, Warrick and Dalton, Gavin and De Propris, Roberto and Driver, Simon P. and Ellis, Richard S. and Frenk, Carlos S. and Glazebrook, Karl and Jackson, Carole and Lahav, Ofer and Lewis, Ian and Lumsden, Stuart and Maddox, Steve and Norberg, Peder and Peterson, Bruce A. and Sutherland, Will and Taylor, Keith (2002) Evidence for a non-zero Λ and a low matter density from a combined analysis of the 2dF Galaxy Redshift Survey and cosmic microwave background anisotropies. Monthly Notices of the Royal Astronomical Society, 330 (2). L29-L35. ISSN 0035-8711. doi:10.1046/j.1365-8711.2002.05215.x.

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We perform a joint likelihood analysis of the power spectra of the 2dF Galaxy Redshift Survey (2dFGRS) and the cosmic microwave background (CMB) anisotropies under the assumptions that the initial fluctuations were adiabatic, Gaussian and well described by power laws with scalar and tensor indices of ns and nt. On its own, the 2dFGRS sets tight limits on the parameter combination Ω_mh, but relatively weak limits on the fraction of the cosmic matter density in baryons Ω_b/Ω_m. (Here h is Hubble's constant H0 in units of 100 km s⁻¹ Mpc⁻¹1. The cosmic densities in baryons, cold dark matter and vacuum energy are denoted by Ω_b, Ω_c and Ω_Λ, respectively. The total matter density is Ω_m = Ω_b + Ω_c and the curvature is fixed by Ω_k = 1 − Ω_m − Ω_Λ.) The CMB anisotropy data alone set poor constraints on the cosmological constant and Hubble constant because of a ‘geometrical degeneracy’ among parameters. Furthermore, if tensor modes are allowed, the CMB data allow a wide range of values for the physical densities in baryons and cold dark matter (ω_b = Ω_bh² and ω_c = Ω_ch²). Combining the CMB and 2dFGRS data sets helps to break both the geometrical and tensor mode degeneracies. The values of the parameters derived here are consistent with the predictions of the simplest models of inflation, with the baryon density derived from primordial nucleosynthesis and with direct measurements of the Hubble parameter. In particular, we find strong evidence for a positive cosmological constant with a ±2σ range of 0.65 < Ω_Λ < 0.85, independently of constraints on ΩΛ derived from Type Ia supernovae.

Item Type:Article
Related URLs:
URLURL TypeDescription Paper
Bland-Hawthorn, Joss0000-0001-7516-4016
Colless, Matthew0000-0001-9552-8075
Ellis, Richard S.0000-0001-7782-7071
Norberg, Peder0000-0002-5875-0440
Additional Information:© 2002 RAS. Accepted 2001 November 26. Received 2001 November 26; in original form 2001 September 14. GE thanks Caltech for the award of a Moore Scholarship. The CMB power spectra in this paper were computed using the CMBFAST code of Seljak & Zaldarriaga (1996).
Funding AgencyGrant Number
Gordon and Betty Moore FoundationUNSPECIFIED
Subject Keywords:galaxies: clusters: general, cosmic microwave background, cosmology: miscellaneous, large-scale structure of Universe
Issue or Number:2
Record Number:CaltechAUTHORS:20200601-103013399
Persistent URL:
Official Citation:G. Efstathiou, Stephen Moody, John A. Peacock, Will J. Percival, Carlton Baugh, Joss Bland-Hawthorn, Terry Bridges, Russell Cannon, Shaun Cole, Matthew Colless, Chris Collins, Warrick Couch, Gavin Dalton, Roberto De Propris, Simon P. Driver, Richard S. Ellis, Carlos S. Frenk, Karl Glazebrook, Carole Jackson, Ofer Lahav, Ian Lewis, Stuart Lumsden, Steve Maddox, Peder Norberg, Bruce A. Peterson, Will Sutherland, Keith Taylor, Evidence for a non-zero Λ and a low matter density from a combined analysis of the 2dF Galaxy Redshift Survey and cosmic microwave background anisotropies, Monthly Notices of the Royal Astronomical Society, Volume 330, Issue 2, February 2002, Pages L29–L35,
Usage Policy:No commercial reproduction, distribution, display or performance rights in this work are provided.
ID Code:103587
Deposited By: George Porter
Deposited On:01 Jun 2020 20:53
Last Modified:16 Nov 2021 18:23

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