The 2dF Galaxy Redshift Survey: correlation functions, peculiar velocities and the matter density of the Universe

By E. Hawkins, S. Maddox, Shaun Cole, Ofer Lahav, D. Madgwick, P. Norberg, J. Peacock, I. Baldry, C. Baugh, Joss Bland-Hawthorn and 20 more. 2002

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We present a detailed analysis of the two-point correlation function, xi(sigma, pi), from the 2dF Galaxy Redshift Survey (2dFGRS). The large size of the catalogue, which contains similar to220 000 redshifts, allows us to make high-precision measurements of various properties of the galaxy clustering pattern. The effective redshift at which our estimates are made is z(s) approximate to 0.15, and similarly the effective luminosity, L-s approximate to 1.4L*. We estimate the redshift-space correlation function, xi(s), from which we measure the redshift-space clustering length, s(o) = 6.82 +/- 0.28 h(-1) Mpc. We also estimate the projected correlation function, Xi(sigma), and the real-space correlation function, xi(r), which can be fit by a power law (r/r(o))(-gamma), with r(o) = 5.05 +/- 0.26 h(-1) Mpc, gamma(r) = 1.67 +/- 0.03. For r greater than or similar to 20 h(-1) Mpc, xi drops below a power law as, for instance, is expected in the popular Lambda cold dark matter model. The ratio of amplitudes of the real- and redshift-space correlation functions on scales of 8-30 h(-1) Mpc gives an estimate of the redshift-space distortion parameter beta. The quadrupole moment of xi(sigma, pi) on scales 30-40 h(-1) Mpc provides another estimate of beta. We also estimate the distribution function of pairwise peculiar velocities, f (nu), including rigorously the significant effect due to the infall velocities, and we find that the distribution is well fit by an exponential form. The accuracy of our xi(sigma, pi) measurement is sufficient to constrain a model, which simultaneously fits the shape and amplitude of xi(r) and the two redshift-space distortion effects parametrized by beta and velocity dispersion, a. We find beta = 0.49 +/- 0.09 and a = 506 +/- 52 km s(-1), although the best-fitting values are strongly correlated. We measure the variation of the peculiar velocity dispersion with projected separation, a(or), and find that the shape is consistent with models and simulations. This is the first time that beta and f (v) have been estimated from a self-consistent model of galaxy velocities. Using the constraints on bias from recent estimates, and taking account of redshift evolution, we conclude that beta(L = L*, z = 0) = 0.47 +/- 0.08, and that the present-day matter density of the Universe, Omega(m) approximate to 0.3, consistent with other 2dFGRS estimates and independent analyses.

Subfields: Astronomy and Astrophysics, Instrumentation

View Paper: https://www.semanticscholar.org/paper/2a936cba9a83f069f53cb4d72e321294e148c197

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Citations in the corpus

Modelling galaxy clustering in a high-resolution simulation of structure formation (2006, methodology): “We tested the method presented by Hawkins et al. (2003) for converting w(rp) to ξ(r) on scales less than around 30h−1Mpc.”
The 2dF-SDSS LRG and QSO Survey: the LRG 2-point correlation function and redshift-space distortions (2006, methodology): “To quantify the effect of these so-called ‘fibre collisions’ we have followed previous 2dF studies (e.g. Hawkins et al. 2003; Croom et al. 2004) and calculated the angular correlation function for galaxies in the 2SLAQ parent catalogue, wp(θ ), and for galaxies with redshifts used in our ξ…”
Forecasting cosmological constraints from redshift surveys (2008, methodology): “Analyses using the 2-degree Field Galaxy Redshift Survey (2dFGRS; Colless et al. 2003) have measured redshift-space distortions in both the correlation function (Peacock et al. 2001; Hawkins et al. 2003) and power spectrum (Percival et al. 2004).”
Fast multiscale clustering and manifold identification (2006, result): “The model and observation have been already found similar with respect to density based criteria [20,24].”
Clustering of High-Redshift (z ≥ 2.9) Quasars from the Sloan Digital Sky Survey (2007, background): “Groth & Peebles 1977; Davis & Peebles 1983; Hawkins et al. 2003), although there is an excess above the power law below 2h−1 Mpc, thought to be due to halo occupation effects (Zehavi et al. 2004, 2005).”
The DEEP2 Galaxy Redshift Survey: Clustering of Galaxies in Early Data (2003, background): “In the SSRS2 data Willmer, da Costa, & Pellegrini (1998) find red galaxies with (B − R)0 > 1.3 have a relative bias of ∼ 1.4 compared to blue galaxies, while Zehavi et al. (2002) report that in the SDSS Early Data Release red galaxies (based on a split at u∗ − r∗ = 1.8) have a relative bias of ∼ 1.6”
Towards a concordant model of halo occupation statistics (2006, methodology): “A comparison with the results of Hawkins et al. (2003) revealed that our MGRS based on the best-fitting CLF dramatically overpredicts the PVDs at scales of ∼1 h−1 Mpc by ∼350 km s−1.”
Testing cosmological structure formation using redshift-space distortions (2008, methodology): “Analyses using the 2-degree Field Galaxy Redshift Survey (2dFGRS; Colless et al. 2003) have measured redshiftspace distortions in both the correlation function (Peacock et al. 2001; Hawkins et al. 2003) and power spectrum (Percival et al. 2004).”
The WiggleZ Dark Energy Survey: the growth rate of cosmic structure since redshift z=0.9 (2011, methodology): “The Lorentzian model produces better fits to data (e.g. Hawkins et al. 2003, Cabre & Gaztanaga 2009) and we assume this version of the model in our study.”
CFHTLenS: testing the laws of gravity with tomographic weak lensing and redshift-space distortions (2012, background): “This effect has been observed with heightened precision over the past decade (Peacock et al. 2001; Hawkins et al. 2003; Guzzo et al. 2008; Blake et al. 2011; Beutler et al. 2012; Reid et al. 2012) permitting inferences of the rate at which cosmological structure forms.”
Large-Scale Anisotropic Correlation Function of SDSS Luminous Red Galaxies (2007, methodology): “Peacock et al. (2001) and Hawkins et al. (2003) measured the 2PCF with two variables from the 2dFGRS (Colless et al. 2001) and detected the detailed signature of large-scale coherent infall, and as a result were able to constrain a value of β ≃ Ω0.”
The Luminosity and Color Dependence of the Galaxy Correlation Function (2004, methodology): “…30,000 SDSS galaxies (Zehavi et al. 2002, hereafter Z02) and in studies of the luminosity, spectral type, and color dependence of clustering in the Two-Degree Field Galaxy Redshift Survey (2dFGRS; Colless et al. 2001) byNorberg et al. (2001, 2002),Madgwick et al. (2003), and Hawkins et al. (2003).”
A 2.5 per cent measurement of the growth rate from small-scale redshift space clustering of SDSS-III CMASS galaxies (2014, methodology): “…catalogue, this method performs quite well at recovering the true clustering down to scales well below the BOSS fibre collision radius, and has been successfully applied in a number of other surveys (Hawkins et al. 2003; Li et al. 2006; Ross et al. 2007; White et al. 2011; de la Torre et al. 2013).”