Journal Article

The VLT LBG Redshift Survey – I. Clustering and dynamics of ≈1000 galaxies at <i>z</i>≈ 3*

R. M. Bielby, T. Shanks, P. M. Weilbacher, L. Infante, N. H. M. Crighton, C. Bornancini, N. Bouché, P. Héraudeau, D. G. Lambas, J. Lowenthal, D. Minniti, N. Padilla, P. Petitjean and T. Theuns

in Monthly Notices of the Royal Astronomical Society

Published on behalf of The Royal Astronomical Society

Volume 414, issue 1, pages 2-27
Published in print June 2011 | ISSN: 0035-8711
Published online June 2011 | e-ISSN: 1365-2966 | DOI:
The VLT LBG Redshift Survey – I. Clustering and dynamics of ≈1000 galaxies at z≈ 3*

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We present the initial imaging and spectroscopic data acquired as part of the Very Large Telescope (VLT) VIMOS Lyman-break galaxy Survey. UBR (or UBVI) imaging covers five ≈36 × 36 arcmin2 fields centred on bright z > 3 quasi-stellar objects (QSOs), allowing ≈21 000 2 < z < 3.5 galaxy candidates to be selected using the Lyman-break technique. We performed spectroscopic follow-up using VLT VIMOS, measuring redshifts for 1020 z > 2 Lyman-break galaxies and 10 z > 2 QSOs from a total of 19 VIMOS pointings. From the galaxy spectra, we observe a 625 ± 510 km s−1 velocity offset between the interstellar absorption and Lyman α emission-line redshifts, consistent with previous results. Using the photometric and spectroscopic catalogues, we have analysed the galaxy clustering at z≈ 3. The angular correlation function, w(θ), is well fitted by a double power law with clustering scalelength, r0= 3.19+0.32−0.54 h−1 Mpc and slope γ= 2.45 for r < 1 h−1 Mpc and r0= 4.37+0.43−0.55 h−1 Mpc with γ= 1.61 ± 0.15 at larger scales. Using the redshift sample we estimate the semiprojected correlation function, wp(σ), and, for a γ= 1.8 power law, find r0= 3.67+0.23−0.24 h−1 Mpc for the VLT sample and r0= 3.98+0.14−0.15 h−1 Mpc for a combined VLT+Keck sample. From ξ(s) and ξ(σ, π), and assuming the above ξ(r) models, we find that the combined VLT and Keck surveys require a galaxy pairwise velocity dispersion of ≈700 km s−1, higher than ≈400 km s−1 assumed by previous authors. We also measure a value for the gravitational growth rate parameter of β(z= 3) = 0.48 ± 0.17, again higher than that previously found and implying a low value for the bias of b= 2.06+1.1−0.5. This value is consistent with the galaxy clustering amplitude which gives b= 2.22 ± 0.16, assuming the standard cosmology, implying that the evolution of the gravitational growth rate is also consistent with Einstein gravity. Finally, we have compared our Lyman-break galaxy clustering amplitudes with lower redshift measurements and find that the clustering strength is not inconsistent with that of low-redshift L* spirals for simple ‘long-lived’ galaxy models.

Keywords: intergalactic medium; galaxies: kinematics and dynamics; cosmology: observations; large-scale structure of Universe

Journal Article.  19516 words.  Illustrated.

Subjects: Astronomy and Astrophysics

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