1204.3635 (R. Bielby et al.)

The VLT LBG Redshift Survey - III. The clustering and dynamics of Lyman-break galaxies at z ~ 3    [PDF]

R. Bielby, M. D. Hill, T. Shanks, N. H. M. Crighton, L. Infante, C. G. Bornancini, H. Francke, P. Heraudeau, D. G. Lambas, N. Metcalfe, D. Minniti, N. Padilla, T. Theuns, P. Tummuangpak, P. Weilbacher

We present a survey of 2,148 galaxy redshifts from the VLT LBG Redshift Survey (VLRS), a spectroscopic survey of z ~ 3 galaxies in wide fields centred on background QSOs made using the VLT VIMOS instrument. To make a definitive LBG clustering analysis, we have combined the VLRS redshifts with the 813 Keck LBG redshifts of Steidel et al, with the statistical power of VLRS at large scales complementing the accuracy of the Keck sample at small scales. From the semi-projected correlation function for the VLRS and combined surveys, we find that the results are well fit with a single power law model for the real space correlation function with clustering scale lengths of respectively r0 = 3.32 \pm 0.41 and 3.75 \pm 0.24 Mpc/h. We note that the corresponding combined slope is flatter than for local galaxies at {\gamma} = 1.55 \pm 0.09. This flat slope is confirmed by the z-space correlation function and in the range 10 < s < 100 Mpc/h the VLRS shows a 2.5{\sigma} excess over the {\Lambda}CDM linear prediction. This excess may be consistent with recent evidence for non-Gaussianity in clustering results at z \approx 1. We then analyse the LBG z-space distortions using the 2-D correlation function finding for the combined sample a large scale infall parameter of {\beta} = 0.32 \pm 0.20 and a velocity dispersion of 540 \pm 200 km/s. Fixing this velocity dispersion, we fit the 2D clustering for the matter density and infall parameter and break their degeneracy using low-redshift data to find {\Omega}m(z = 0) = 0.30+0.32-0.18. Finally, based on our measured {\beta}, we are able to determine the gravitational growth rate, finding a value of f(z = 3) = 0.83 \pm 0.46, which is the highest redshift measurement of the growth rate via galaxy clustering and is consistent with {\Lambda}CDM.

View original: http://arxiv.org/abs/1204.3635