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The 2QDES Pilot : the luminosity and redshift dependence of quasar clustering.

Chehade, B. and Shanks, T. and Findlay, J. and Metcalfe, N. and Sawangwit, U. and Irwin, M. and González-Solares, E. and Fine, S. and Drinkwater, M.J. and Croom, S. and Jurek, R.J. and Parkinson, D. and Bielby, R. (2016) 'The 2QDES Pilot : the luminosity and redshift dependence of quasar clustering.', Monthly notices of the Royal Astronomical Society., 459 (2). pp. 1179-1200.


We present a new redshift survey, the 2dF Quasar Dark Energy Survey pilot (2QDESp), which consists of ≈10 000 quasars from ≈150 deg2 of the southern sky, based on VST-ATLAS imaging and 2dF/AAOmega spectroscopy. Combining our optical photometry with the WISE (W1,W2) bands we can select essentially contamination free quasar samples with 0.8 < z < 2.5 and g < 20.5. At fainter magnitudes, optical UVX selection is still required to reach our g ≈ 22.5 limit. Using both these techniques we observed quasar redshifts at sky densities up to 90 deg−2. By comparing 2QDESp with other surveys (SDSS, 2QZ and 2SLAQ) we find that quasar clustering is approximately luminosity independent, with results for all four surveys consistent with a correlation scale of r0 = 6.1 ± 0.1 h−1 Mpc, despite their decade range in luminosity. We find a significant redshift dependence of clustering, particularly when BOSS data with r0 = 7.3 ± 0.1 h−1 Mpc are included at z ≈ 2.4. All quasars remain consistent with having a single host halo mass of ≈2 ± 1 × 1012 h−1 M⊙. This result implies that either quasars do not radiate at a fixed fraction of the Eddington luminosity or AGN black hole and dark matter halo masses are weakly correlated. No significant evidence is found to support fainter, X-ray selected quasars at low redshift having larger halo masses as predicted by the ‘hot halo’ mode AGN model of Fanidakis et al. (2013). Finally, although the combined quasar sample reaches an effective volume as large as that of the original SDSS LRG sample, we do not detect the BAO feature in these data.

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Publisher statement:This article has been accepted for publication in Monthly notices of the Royal Astronomical Society ©: 2016 The Authors Published by Oxford University Press on behalf of the Royal Astronomical Society. All rights reserved.
Date accepted:08 March 2016
Date deposited:22 April 2016
Date of first online publication:15 March 2016
Date first made open access:22 April 2016

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