We present a clustering analysis of Luminous Red Galaxies (LRGs) in Stripe 82 from the Sloan Digital Sky Survey (SDSS). We study the angular two-point autocorrelation function, w(θ), of a selected sample of over 130 000 LRG candidates via colour-cut selections in izK with the K band coverage coming from UKIRT Infrared Deep Sky Survey (UKIDSS) LAS. We have used the cross-correlation technique of Newman (2008) to establish the redshift distribution of the LRGs. Cross-correlating them with SDSS quasi-stellar objects (QSOs), MegaZ-LRGs and DEEP2 galaxies, implies an average redshift of the LRGs to be z ≈ 1 with space density, n g ≈ 3.20 ± 0.16 × 10 −4 h 3 Mpc −3 . For θ 10 ′ (corresponding to ≈ 10 h −1 Mpc), the LRG w(θ) significantly deviates from a conventional single power-law as noted by previous clustering studies of highly biased and luminous galaxies. A double power-law with a break at r b ≈ 2.4h −1 Mpc fits the data better, with best-fit scale length, r 0,1 = 7.63 ± 0.27 h −1 Mpc and slope γ 1 = 2.01 ± 0.02 at small scales and r 0,2 = 9.92 ± 0.40 h −1 Mpc and γ 2 = 1.64 ± 0.04 at large scales. Due to the flat slope at large scales, we find that a standard Λ cold dark matter (ΛCDM) linear model is accepted only at 2 − 3σ, with the best-fit bias factor, b = 2.74 ± 0.07. We also fitted the halo occupation distribution (HOD) models to compare our measurements with the predictions of the dark matter clustering. The effective halo mass of Stripe 82 LRGs is estimated as M eff = 3.3 ± 0.6 × 10 13 h −1 M ⊙ . But at large scales, the current HOD models did not help explain the power excess in the clustering signal.We then compare the w(θ) results to the results of Sawangwit et al. (2011) from three samples of photometrically selected LRGs at lower redshifts to measure clustering evolution. We find that a long-lived model may be a poorer fit than at lower redshifts, although this assumes that the Stripe 82 LRGs are luminosity-matched to the AAΩ LRGs. We find stronger evidence for evolution in the form of the z ≈ 1 LRG correlation function with the above flat 2-halo slope maintaining to s 50h −1 Mpc. Applying the cross-correlation test of Ross et al. (2011), we find little evidence that the result is due to systematics. Otherwise it may represent evidence for primordial non-Gaussianity in the density perturbations at early times, with f local NL = 90 ± 30. -large-scale structure of Universe. vious works in Section 8. Finally, in Section 9 we summarize and conclude our findings.Throughout this paper, we use a flat Λ-dominated cosmology with Ω m = 0.27, H 0 = 100h kms −1 Mpc −1 , h=0.7, σ 8 = 0.8 and magnitudes are given in the AB system unless otherwise stated. DATA2.

We cross match the NVSS and FIRST surveys with three large photometric catalogues of luminous red galaxies (LRGs) to define radio-loud samples. These have median redshifts 0.35, 0.55 and 0.68 and, by matching rest-frame optical and radio properties, we construct uniform samples across the three surveys. This paper is concerned with the clustering properties of these samples derived from the angular correlation function. The primary aim is to characterise any evolution in the clustering amplitude of radio galaxies bellow z~0.68. We find no evidence for evolution in the large-scale (~1-50h^{-1}Mpc) clustering amplitude. Our radio galaxy autocorrelations are consistent with previous findings indicating little-to-no evolution in the redshift range 0.68 to 0 (~6Gyr of time). We also cross correlate radio galaxies with the parent LRG samples to increase the precision of our results and again find no evidence for evolution. Our results are inconsistent with a long-lived model for the clustering evolution that assumes radio sources randomly sample the LRG population. A model where the halo mass is constant with redshift is consistent with the data. This is similar to QSOs that have clustering amplitudes consistent with a single halo mass at all redshifts. Given that the brightest radio sources show stronger evolution in space density compared to fainter radio sources we restrict our samples to include only objects with L>10^{26}W/Hz and repeat the analysis. Again we find no evidence for evolution in the comoving correlation amplitude. These radio sources appear to inhabit the same mass halos as fainter radio galaxies (~9x10^{13}h^{-1}M_\odot). These halos are ~twice as massive as those of the general LRG population and ~30 times as massive as optical AGN/QSOs.Comment: 9 pages, 8 figures, accepted MNRA

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Two feasibility studies for spectrographs that can deliver at least 4000 MOS slits over a 1° field at the prime focuses of the Anglo-Australian and Calar Alto Observatories have been completed. We describe the design and science case of the Calar Alto eXtreme Multiplex Spectrograph (XMS) for which an extended study, half way between feasibility study and phase-A, was made. The optical design is quite similar than in the AAO study for the Next Generation 1 degree Field (NG1dF) but the mechanical design of XMS is quite different and much more developed. In a single night, 25000 galaxy redshifts can be measured to z~0.7 and beyond for measuring the Baryon Acoustic Oscillation (BAO) scale and many other science goals. This may provide a low-cost alternative to WFMOS for example and other large fibre spectrographs. The design features four cloned spectrographs which gives a smaller total weight and length than a unique spectrograph to makes it placable at prime focus. The clones use a transparent design including a grism in which all optics are about the size or smaller than the clone rectangular subfield so that they can be tightly packed with little gaps between subfields. Only low cost glasses are used; the variations in chromatic aberrations between bands are compensated by changing a box containing the grism and two adjacent lenses. Three bands cover the 420nm to 920nm wavelength range at 10A resolution while another cover the Calcium triplet at 3A. An optional box does imaging. We however also studied different innovative methods for acquisition without imaging. A special mask changing mechanism was also designed to compensate for the lack of space around the focal plane. Conceptual designs for larger projects (AAT 2º field, CFHT, VISTA) have also been done.

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