Angular correlation functions of bright Lyman-break galaxies at 3 ≲ z ≲ 5

Abstract

We investigate the clustering of Lyman-break galaxies at redshifts of 3 ≲ z ≲ 5 within the COSMOS field by measuring the angular two-point correlation function. Our robust sample of ∼60 000 bright (mUV ≲ 27) Lyman-break galaxies was selected based on spectral energy distribution fitting across 14 photometric bands spanning optical and near-infrared wavelengths. We constrained both the 1- and 2-halo terms at separations up to 300 arcsec, finding an excess in the correlation function at scales corresponding to <20 kpc, consistent with enhancement due to clumps in the same galaxy or interactions on this scale. We then performed Bayesian model fits on the correlation functions to infer the Halo Occupation Distribution parameters, star formation duty cycle, and galaxy bias in three redshift bins. We examined several cases where different combinations of parameters were varied, showing that our data can constrain the slope of the satellite occupation function, which previous studies have fixed. For an MUV-limited sub-sample, we found galaxy bias values of bg = 3.18+0.14−0.14 at z ≃ 3, bg = 3.58+0.27−0.29 at z ≃ 4, bg = 4.27+0.25−0.26 at z ≃ 5. The duty cycle values are 0.62+0.25−0.26, 0.40+0.34−0.22, and 0.39+0.31−0.20, respectively. These results suggest that, as the redshift increases, there is a slight decrease in the host halo masses and a shorter time-scale for star formation in bright galaxies, at a fixed rest-frame UV luminosity threshold.