CARS: the CFHTLS-Archive-Research Survey. II. Weighing dark matter halos of Lyman-break galaxies at z = 3–5

Abstract

Aims. We measure the clustering properties for a large samples of u- (z ~ 3), g- (z ~ 4), and r- (z ~ 5) dropouts from the Canada-France-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.

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