Astronomy & Astrophysics

Free access article

A&A 409, 835-850 (2003)
DOI: 10.1051/0004-6361:20031181

The Canada-France deep fields survey-II: Lyman-break galaxies and galaxy clustering at z $\mathsf{\sim3}$

S. Foucaud^{1, 2}, H. J. McCracken^{1, 3}, O. Le Fèvre¹, S. Arnouts^{4, 1}, M. Brodwin⁵, S. J. Lilly⁶, D. Crampton⁷ and Y. Mellier^{8, 9}

¹ Laboratoire d'Astrophysique de Marseille, Traverse du Siphon, 13376 Marseille Cedex 12, France
² Present address: Istituto di Astrofisica Spaziale e Fisica cosmica - Sezione di Milano, via Bassini 15, 20133 Milano, Italy
³ Present address: University of Bologna, Department of Astronomy, via Ranzani 1, 40127 Bologna, Italy
⁴ ESO - European Southern Observatory, Karl-Schwarzschild-Str. 2, 85748 Garching bei München, Germany
⁵ University of Toronto, Department of Astronomy, 60 St. George Street, Toronto, Ontario, Canada M5S 3H8
⁶ Institute of Astronomy - ETH Hoenggerberg, HPF D8, 8093 Zurich, Switzerland
⁷ Herzberg Institute for Astrophysics, 5071 West Saanich Road, Victoria, British Colombia, Canada V9E 2E7
⁸ Institut d'Astrophysique de Paris, 98bis boulevard Arago, 75014 Paris, France
⁹ Observatoire de Paris, LERMA, 61 avenue de l'Observatoire, 75014 Paris, France

(Received 27 February 2003 / Accepted 25 July 2003)

Abstract
We present a large sample of $z\sim3$ U-band dropout galaxies extracted from the Canada-France deep fields survey (CFDF). Our catalogue covers an effective area of $\sim$ 1700 arcmin ² divided between three large, contiguous fields separated widely on the sky. To I_AB=24.5, the survey contains 1294 Lyman-break candidates, in agreement with previous measurements by other authors, after appropriate incompleteness corrections have been applied to our data. Based on comparisons with spectroscopic observations and simulations, we estimate that our sample of Lyman-break galaxies is contaminated by stars and interlopers (lower-redshift galaxies) at no more than ${\sim} 30\%$ . We find that $\omega(\theta)$ is well fitted by a power-law of fixed slope, $\gamma=1.8$ , even at small ( $\theta<10''$ ) angular separations. In two of our three fields, we are able to fit simultaneously for both the slope and amplitude and find $\gamma = 1.8 \pm 0.2$ and r₀ = (5.3^+6.8_-2.2)h^-1 Mpc, and $\gamma = 1.8 \pm 0.3$ and r₀ = (6.3^+17.9_-2.8)h^-1 Mpc (all spatially dependent quantities are quoted for a $\Lambda$ -flat cosmology). Our data marginally indicates in one field (at a $3 \sigma$ level) that the Lyman-break correlation length r₀ depends on sample limiting magnitude: brighter Lyman-break galaxies are more clustered than fainter ones. For the entire CFDF sample, assuming a fixed slope $\gamma=1.8$ we find $r_0=(5.9\pm0.5)h^$ Mpc. Using these clustering measurements and prediction for the dark matter density field computed assuming cluster-normalised linear theory, we derive a linear bias of $b=3.5\pm0.3$ . Finally we show that the dependence of the correlation length with the surface density of Lyman-break galaxies is in good agreement with a simple picture where more luminous galaxies are hosted by more massive dark matter halos with a simple one-to-one correspondence.

Key words: cosmology: observations -- galaxies: high-redshift -- galaxies: evolution -- cosmology: large-scale structure of universe

Offprint request: S. Foucaud, foucaud@mi.iasf.cnr.it

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