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

By G. Efstathiou, S. Moody, J. Peacock, Will J. Percival, C. Baugh, Joss Bland-Hawthorn, T. Bridges, R. Cannon, Shaun Cole, M. Colless and 17 more. 2001

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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 n(s) and n(t). On its own, the 2dFGRS sets Light limits on the parameter combination Omega(m)h, but relatively weak limits on the fraction of the cosmic matter density in baryons Omega(b)/Omega(m)- (Here h is Hubble's constant H-0 in units of 100 km s(-1) Mpc(-1). The cosmic densities in baryons, cold dark matter and vacuum energy are denoted by Omega(b), Omega(c) and Omega(Lambda), respectively. The total matter density is Omega(m) = Omega(b) + Omega(c) and the curvature is fixed by Omega(k) = 1 - Omega(m) - Omega(Lambda).) 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 (omega(b) = Omegabh(2) and omega(c) = Omega(c)h(2)). 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 +/-2sigma, range of 0.65 < U(U) < 0.85, independently of constraints on Omega(Lambda) derived from Type Ia supernovae.

Subfields: Astronomy and Astrophysics

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Citations in the corpus

Cosmological constraints from the X-ray gas mass fraction in relaxed lensing clusters observed with Chandra (2002, result): “We show that the results obtained are in good agreement with those from recent studies of anisotropies in the cosmic microwave background radiation, the large-scale distribution of galaxies, and the properties of distant supernovae (e.g. Jaffe et al. 2001; Efstathiou et al. 2001).”
The Hubble Higher z Supernova Search: Supernovae to z ≈ 1.6 and Constraints on Type Ia Progenitor Models (2004, background): “…Anisotropy Probe (WMAP; Bennett et al. 2003) and large-scale structure from the Two Degree Field Survey (Peacock et al. 2001; Percival et al. 2001; Efstathiou et al. 2002) congruously show evidence for a low matter density ( M ¼ 0:3) and a nonzero cosmological constant ( ¼ 0:7), but neither…”
The New Galaxy: Signatures of Its Formation (2002, background): “For a world model with (ΩΛ = 0.7, Ωm = 0.3), the Big Bang occurred 14 Ga ago (Efstathiou et al. 2002) – in our view, there is no compelling evidence for an age crisis from a comparison of estimates in the near and far field.”
The power spectrum of galaxies in the 2dF 100k redshift survey (2001, methodology): “Tantalizing evidence for baryonic wiggles in the galaxy power spectrum has been discussed (Percival et al. 2001; Miller et al. 2001), and cosmological models have been constrained in conjunction with cosmic microwave background (CMB) data (Efstathiou et al. 2002).”
The 2dF Galaxy Redshift Survey: The bias of galaxies and the density of the Universe (2001, result): “This result is consistent with other recent determinationsby other methods such as combining CMB with large-scale structu e or supernova measurements (e.g. Percival et al. 2001; Jaffeet al. 2001; Efstathiou et al. 2001) and from early weak lensing measurements (Hoekstra, Yee & Gladders 2001).”
The shear power spectrum from the COMBO-17 survey (2002, methodology): “We have taken the valueh = 0.68, found from a joint analysis of the CMB and 2dF data for a flat Universe and for a scalar-only spectral index,ns (Percival et al. 2002; Efstathiou et al. 2002).”
The 2dF Galaxy Redshift Survey: correlation functions, peculiar velocities and the matter density of the Universe (2002, unknown): “Lahav et al. (2002) combined the estimate of the 2dF power spectrum, P(k) (Percival et al. 2001), with results previous to the Wilkinson Microwave Anisotropy Probe (WMAP) from the cosmic microwave background (CMB) to obtain an estimate of b, but this value is also dependent on m.”
Constraining Cosmological Parameters Based on Relative Galaxy Ages (2001, methodology): “…done, based on forthcoming high-precision data from theMicrowave Anisotrophy Probe satellite (MAP)8 and the Sloan Digital Sky Survey (SDSS).9 Preliminary attempts to determine mð0Þ by combining microwave background and large-scale structure data appear promising (see, e.g., Efstathiou et al. 2002).”
The Formation of a Realistic Disk Galaxy in Λ-dominated Cosmologies (2002, unknown): “SIMULATION PARAMETERS AND INITIAL CONDITIONS We adopted a flatΛ-dominated cosmology:Ω0 = 0.3, Λ=0.7, h = 0.7, σ8 = 1, shape parameterΓ = 0.21, andΩb = 0.039 (Perlmutter et al. 1997, Efstathiou et al. 2002).”
The 2dF Galaxy Redshift Survey: spherical harmonics analysis of fluctuations in the final catalogue (2004, background): “The extra information from galaxy surveys helps to lift many of the degeneracies intrinsic to the CMB data and enhances the scientific potential of both data sets (e.g. Efstathiou et al. 2002; Percival et al. 2002; Spergel et al. 2003; Verde et al. 2003).”
Detection of the Baryon Acoustic Peak in the Large-Scale Correlation Function of SDSS Luminous Red Galaxies (2005, background): “While the agreement between recent results on the broadband shape of the matter power spectrum (Efstathiou et al. 2002; Tegmark et al. 2004a; McDonald et al. 2004), the galaxy three-point correlation function (e.g., Feldman et al. 2001), and the inferences from the CMB (e.g., Spergel et al. 2003)…”
Cosmological baryonic and matter densities from 600 000 SDSS luminous red galaxies with photometric redshifts (2006, background): “Measurements of large-scale structure have continued to constitute an important component of cosmological parameter fits (e.g. Efstathiou et al. 2002; Percival et al. 2002; Spergel et al. 2003; Pope et al. 2004; Tegmark et al. 2004b; Seljak et al. 2005; Sanchez et al. 2006).”