The 2dF Galaxy Redshift Survey: the amplitudes of fluctuations in the 2dFGRS and the CMB, and implications for galaxy biasing

Lahav, O.; Bridle, Sarah; Percival, Will J.; Peacock, J. A.; Efstathiou, G.; Baugh, C. M.; Bland-Hawthorn, Joss; Bridges, Terry J.; Cannon, R. D.; Cole, Shaun; Colless, Matthew; Collins, Chris; Couch, Warrick J.; Dalton, Gavin; Propris, Roberto De; Driver, Simon P.; Ellis, Richard S.; Frenk, Carlos S.; Glazebrook, Karl; Jackson, C. A.; Lewis, Ian; Lumsden, S. L.; Maddox, S.; Madgwick, Darren; Moody, Stephen J.; Norberg, Peder; Peterson, Bruce A.; Sutherland, William J.; Taylor, Keith

doi:10.1046/j.1365-8711.2002.05485.x

Cited by 190 publications

(155 citation statements)

References 56 publications

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“…Observationally, the bi-spectrum analysis of the 2dFGRS showed almost no deviation from linear biasing [40] and combined analysis of 2dFGRS with CMB data on scales of 0.02 < k < 0.15 h Mpc −1 [39] gave b ∼ 1 for L * galaxies. Furthermore, the ratio of the power-spectra of blue and red galaxies in 2dFGRS [64] is almost constant over the range of our analysis, 0.02 < k < 0.15 h Mpc −1 .…”

Section: Scale-dependent Biasmentioning

confidence: 88%

“…As the analysis in [40] was performed for a different range of scales than those involved in the analysis of the linear part of the 2dFGRS power spectrum, and did not take neutrino masses into account (even though the cosmology dependence in the bispectrum analysis is mild) and questions have been raised about this approach [66], it is worthwhile to take a closer look at the WMAP approach. To do this, we need to go into the issue of a constant bias and redshift-space distortions in more detail than in the previous sections, and we will do so following [39]. The WMAP analysis was more detailed [65], but we think that our simplified version captures the main points.…”

Section: The Case Of Scale-independent Bias In More Detailmentioning

confidence: 99%

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Upper limits on neutrino masses from the 2dFGRS and WMAP: the role of priors

Elgarøy¹,

Lahav²

2003

J. Cosmol. Astropart. Phys.

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Abstract. Solar, atmospheric, and reactor neutrino experiments have confirmed neutrino oscillations, implying that neutrinos have non-zero mass, but without pinning down their absolute masses. While it is established that the effect of neutrinos on the evolution of cosmic structure is small, the upper limits derived from large-scale structure could help significantly to constrain the absolute scale of the neutrino masses. In a recent paper the 2dF Galaxy Redshift Survey (2dFGRS) team provided an upper limit m ν,tot < 2.2 eV , i.e. approximately 0.7 eV for each of the three neutrino flavours, or phrased in terms of their contribution to the matter density, Ω ν /Ω m < 0.16. Here we discuss this analysis in greater detail, considering issues of assumed 'priors' like the matter density Ω m and the bias of the galaxy distribution with respect to the dark matter distribution. As the suppression of the power spectrum depends on the ratio Ω ν /Ω m , we find that the out-of-fashion Mixed Dark Matter model, with Ω ν = 0.2, Ω m = 1 and no cosmological constant, fits both the 2dFGRS power spectrum and the CMB data reasonably well, but only for a Hubble constant H 0 < 50 km s −1 Mpc −1 . As a consequence, excluding low values of the Hubble constant, e.g. with the HST Key Project, is important in order to get a strong upper limit on the neutrino masses. We also comment on the improved limit obtained by the WMAP team, and point out that the main neutrino signature comes from the 2dFGRS and the Lyman α forest.PACS numbers: 95.35.+d, 14.60.Pq, 98.62.Py, 98.80.Es Upper limits on neutrino masses from the 2dFGRS and WMAP: the role of priors 2

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Section: Scale-dependent Biasmentioning

confidence: 88%

Section: The Case Of Scale-independent Bias In More Detailmentioning

confidence: 99%

Upper limits on neutrino masses from the 2dFGRS and WMAP: the role of priors

Elgarøy¹,

Lahav²

2003

J. Cosmol. Astropart. Phys.

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“…By measurements of two-point correlation function, the 2dFGRS team reported the redshift distortion parameter of ε = f /κ = 0.49 ± 0.09 at z = 0.15, where κ is the bias parameter describing the difference in the distribution of galaxies and their masses. Verde et al (2003) used the bispectrum of 2dFGRS galaxies [81,82] and obtained κ verde = 1.04 ± 0.11 which gave f = 0.51 ± 0.10. Now we fit the growth index at the present time derived from the equation (63) to have a better confinement of the parameters, we combine this fitting with those of SNIa+CMB+SDSS which have been discussed in the previous section.…”

Section: Constraints By Large Scale Structurementioning

confidence: 99%

Observational Constraints with Recent Data on the DGP Modified Gravity

2008

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We study one of the simplest covariant modified-gravity models based on the Dvali-Gabadadze-Porrati (DGP) brane cosmology, a self-accelerating universe. In this model gravitational leakage into extra dimensions is responsible of late-time acceleration. We mainly focus on the effects of the model parameters on the geometry and the age of universe. Also we investigate the evolution of matter density perturbations in the modified gravity model, and obtain an analytical expression for the growth index, f . We show that increasing Ωr c leads to less growth of the density contrast δ, and also decreases the growth index. We give a fitting formula for the growth index at the present time and indicate that dominant term in this expression verifies the well-known approximation relation f ≃ Ω γ m . As the observational test, the new Supernova Type Ia (SNIa) Gold sample and Supernova Legacy Survey (SNLS) data, size of baryonic acoustic peak from Sloan Digital Sky Survey (SDSS), the position of the acoustic peak from the CMB observations and the Cluster Baryon Gas Mass Fraction (gas) are used to constrain the parameters of the DGP model. We also combine previous results with large scale structure formation (LSS) from the 2dFGRS survey. Finally to check the consistency of the DGP model, we compare the age of old cosmological objects with age of universe in this model.

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“…By measurements of twopoint correlation function, the 2dFGRS team reported the redshift distortion parameter of β = f /b = 0.49±0.09 at z = 0.15, where b is the bias parameter describing the difference in the distribution of galaxies and their masses. Verde et al (2003) used the bispectrum of 2dFGRS galaxies [51,52] and obtained b verde = 1.04 ± 0.11 which gave f = 0.51 ± 0.10. Now we fit the growth index at the present time derived from the equation (57) with the observational value.…”

Section: Constraints By Large Scale Structurementioning

confidence: 99%

Consistency off(R)=R2−R02gravity with cosmological observations in the Palatini formalism

2007

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In this work we study the dynamics of universe in f (R) = R 2 − R 2 0 modified gravity with Palatini formalism. We use data from recent observations as Supernova Type Ia (SNIa) Gold sample and Supernova Legacy Survey (SNLS) data, size of baryonic acoustic peak from Sloan Digital Sky Survey (SDSS), the position of the acoustic peak from the CMB observations and large scale structure formation (LSS) from the 2dFGRS survey to put constraint on the parameters of the model. To check the consistency of this action, we compare the age of old cosmological objects with the age of universe. In the combined analysis with the all the observations, we find the parameters of model as R0 = 6.192 [1,2]. Analysis of SNIa and the Cosmic Microwave Background radiation (CMB) observations indicates that about 70% of the total energy of the Universe is made by the dark energy and the rest of it is in the form of dark matter with a few percent of Baryonic matter [3][4][5]. The "cosmological constant" is a possible explanation of the present dynamics of the universe [6]. This term in Einstein field equations can be regarded as a fluid with the equation of state of w = −1. However, there are two problems with the cosmological constant, namely the fine-tuning and the cosmic coincidence. In the framework of quantum field theory, the vacuum expectation value is 123 order of magnitude larger than the observed value of 10 −47 GeV 4 . The absence of a fundamental mechanism which sets the cosmological constant to zero or to a very small value is the cosmological constant problem. The second problem known as the cosmic coincidence, states that why are the energy densities of dark energy and dark matter nearly equal today?There are various solutions for this problem as the decaying cosmological constant models. A non-dissipative minimally coupled scalar field, so-called Quintessence can play the role of this time varying cosmological constant [7][8][9]. The ratio of energy density of this field to the matter density in this model increases by the expansion of the universe and after a while dark energy becomes the dominant term of the energy-momentum tensor. Another approach dealing with this problem is using the modified gravity by changing the Einstein-Hilbert action. Recently a great attention has been devoted to this era because of the prediction of early and late time accelerations in these models [22]. While it seems that the modified gravity and dark energy models are completely different approaches to explain cosmic acceleration, it is possible to unify them in one formalism [23].In this work we obtain the dynamics of the modified gravity f (R) = R 2 − R 2 0 in the Palatini formalism [24] and use the cosmological observations as SNIa, SDSS acoustic peck in CMB and structure formation to put constraint on the parameter of the action. In Sec. II we derive the dynamics of Hubble parameter and scale factor in Palatini formalism for general case of f (R) gravity. In Sec. III using action f (R) = R 2 − R 2 0 we obtain the dynamics of univers...

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The 2dF Galaxy Redshift Survey: the amplitudes of fluctuations in the 2dFGRS and the CMB, and implications for galaxy biasing

Cited by 190 publications

References 56 publications

Upper limits on neutrino masses from the 2dFGRS and WMAP: the role of priors

Upper limits on neutrino masses from the 2dFGRS and WMAP: the role of priors

Observational Constraints with Recent Data on the DGP Modified Gravity

Consistency off(R)=R2−R02gravity with cosmological observations in the Palatini formalism

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