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Post Info TOPIC: Lyman Break Galaxies
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RE: Lyman Break Galaxies
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Title: The VLT LBG Redshift Survey - III. The clustering and dynamics of Lyman-break galaxies at z ~ 3
Authors: R. Bielby (Durham), M. D. Hill (Durham), T. Shanks (Durham), N. H. M. Crighton (Durham, MPIA), L. Infante (PUC), C. G. Bornancini (OAC), H. Francke (PUC), P. Heraudeau (Bonn), D. G. Lambas (OAC), N. Metcalfe (Durham) D. Minniti (PUC, Vatican), N. Padilla (PUC), T. Theuns (ICC Durham, Antwerp), P. Tummuangpak (Durham), P. Weilbacher (AIP)

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 ± 0.41 and 3.75 ± 0.24 Mpc/h. We note that the corresponding combined slope is flatter than for local galaxies at gamma = 1.55 ± 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 2.5sigma excess over the Lambda CDM linear prediction. This excess may be consistent with recent evidence for non-Gaussianity in clustering results at z ~ 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 ± 0.20 and a velocity dispersion of 540 ± 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 ± 0.46, which is the highest redshift measurement of the growth rate via galaxy clustering and is consistent with Lambda CDM.

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Title: Spitzer View of Lyman Break Galaxies
Authors: Georgios E. Magdis, Dimitra Rigopoulou

Using a combination of deep MID-IR observations obtained by IRAC, MIPS and IRS on board Spitzer we investigate the MID-IR properties of Lyman Break Galaxies (LBGs) at z~3, establish a better understanding of their nature and attempt a complete characterisation of the population. With deep mid-infrared and optical observations of ~1000 LBGs covered by IRAC/MIPS and from the ground respectively, we extend the spectral energy distributions (SEDs) of the LBGs to mid-infrared. Spitzer data reveal for the first time that the mid-infrared properties of the population are inhomogeneous ranging from those with marginal IRAC detections to those with bright rest-frame near-infrared colours and those detected at 24mu MIPS band revealing the newly discovered population of the Infrared Luminous Lyman Break Galaxies (ILLBGs). To investigate this diversity, we examine the photometric properties of the population and we use stellar population synthesis models to probe the stellar content of these galaxies. We find that a fraction of LBGs have very red colours and large estimated stellar masses M* > 5x10^10Mo. We discuss the link between these LBGs and submm-luminous galaxies and we report the detection of rest frame 6.2 and 7.7mu emission features arising from Polycyclic Aromatic Hydrocarbons (PAH) in the Spitzer/IRS spectrum of an infrared-luminous Lyman break galaxy at z=3.01.

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