Clustering Properties of Rest-Frame UV-Selected Galaxies. II. Migration of Star Formation Sites with Cosmic Time from GALEX and CFHTLS

Abstract

We analyze the clustering properties of ultraviolet-selected galaxies by using GALEX-SDSS data at z < 0.6 and CFHTLS deep u' imaging at z ~ 1. These data sets provide a unique basis at z ≤ 1 which can be directly compared with high-redshift samples built with similar selection criteria. We discuss the dependence of the correlation function parameters (r_0 and δ) on the ultraviolet luminosity, as well as the linear bias evolution. We find that the bias parameter shows a gradual decline from high (b_8 ≳ 2) to low redshift (b_8 ≃ 0.79_(−0.08)^(+0.1)). When accounting for the fraction of the star formation activity enclosed in the different samples, our results suggest that the bulk of star formation migrated from high-mass dark matter halos at z > 2 (10^(12) M_⊙ ≤ M_(min) ≤ 10^(13) M_⊙, located in high-density regions) to less massive halos at low redshift (M_(min) ≤ 10^(12) M_⊙, located in low-density regions). This result extends the "downsizing" picture (shift of the star formation activity from high stellar mass systems at high z to low stellar mass at low z) to the dark matter distribution.

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