Aims. We measure the clustering properties for a large samples of u-(z ∼ 3), g-(z ∼ 4), and r-(z ∼ 5) dropouts from the CanadaFrance-Hawaii Telescope Legacy Survey (CFHTLS) Deep fields. Methods. Photometric redshift distributions along with simulations allow us to de-project the angular correlation measurements and estimate physical quantities such as the correlation length, halo mass, galaxy bias, and halo occupation as a function of UV luminosity. Results. For the first time we detect a significant one-halo term in the correlation function at z ∼ 5. The comoving correlation lengths and halo masses of LBGs are found to decrease with decreasing rest-frame UV-luminosity. No significant redshift evolution is found in either quantity. The typical halo mass hosting an LBG is M > ∼ 10 12 h −1 M and the halos are typically occupied by less than one galaxy. Clustering segregation with UV luminosity is clearly observed in the dropout samples, however redshift evolution cannot clearly be disentangled from systematic uncertainties introduced by the redshift distributions. We study a range of possible redshift distributions to illustrate the effect of this choice. Spectroscopy of representative subsamples is required to make high-accuracy absolute measurements of high-z halo masses.

Aims. The clustering properties of a large sample of U-dropouts are investigated and compared to very precise results for B-dropouts from other studies to identify a possible evolution from z = 4 to z = 3. Methods. A population of ∼8800 candidates for star-forming galaxies at z = 3 is selected via the well-known Lyman-break technique from a large optical multicolour survey (the ESO Deep Public Survey). The selection efficiency, contamination rate, and redshift distribution of this population are investigated by means of extensive simulations. Photometric redshifts are estimated for every Lyman-break galaxy (LBG) candidate from its UBVRI photometry yielding an empirical redshift distribution. The measured angular correlation function is deprojected and the resulting spatial correlation lengths and slopes of the correlation function of different subsamples are compared to previous studies. Results. By fitting a simple power law to the correlation function we do not see an evolution in the correlation length and the slope from other studies at z = 4 to our study at z = 3. In particular, the dependence of the slope on UV-luminosity similar to that recently detected for a sample of B-dropouts is confirmed also for our U-dropouts. For the first time number statistics for U-dropouts are sufficient to clearly detect a departure from a pure power law on small scales down to ∼2 reported by other groups for B-dropouts.

Context. Weak gravitational lensing is one of the most promising tools to investigate the equation-of-state of dark energy. In order to obtain reliable parameter estimations for current and future experiments, a good theoretical understanding of dark matter clustering is essential. Of particular interest is the statistical precision to which weak lensing observables, such as cosmic shear correlation functions, can be determined. Aims. We construct a fitting formula for the non-Gaussian part of the covariance of the lensing power spectrum. The Gaussian contribution to the covariance, which is proportional to the lensing power spectrum squared, and optionally shape noise can be included easily by adding their contributions. Methods. Starting from a canonical estimator for the dimensionless lensing power spectrum, we model first the covariance in the halo model approach including all four halo terms for one fiducial cosmology and then fit two polynomials to the expression found. On large scales, we use a first-order polynomial in the wave-numbers and dimensionless power spectra that goes asymptotically towards 1.1 C pt for → 0, i.e., the result for the non-Gaussian part of the covariance using tree-level perturbation theory. On the other hand, for small scales we employ a second-order polynomial in the dimensionless power spectra for the fit. Results. We obtain a fitting formula for the non-Gaussian contribution of the convergence power spectrum covariance that is accurate to 10% for the off-diagonal elements, and to 5% for the diagonal elements, in the range 50 < ∼ < ∼ 5000 and can be used for single source redshifts z s ∈ [0.5, 2.0] in WMAP5-like cosmologies.