2017ApJ...850....5M

We combined deep U-band and optical/near-infrared imaging, in order to select Lyman Break Galaxies (LBGs) at z∼3 using U - V and V-R_c colors in the Subaru Deep Field. The resulting sample of 5161 LBGs gives a UV luminosity function (LF) down to M_UV=-18, with a steep faint-end slope of α=-1.78±0.05. We analyze UV-to-NIR energy distributions (SEDs) from optical photometry and photometry on IR median-stacked images. In the stacks, we find a systematic background depression centered on the LBGs. This results from the difficulty of finding faint galaxies in regions with higher-than-average surface densities of foreground galaxies, so we corrected for this deficit. Best-fit stellar population models for the LBG SEDs indicate stellar masses and star formation rates of log₁₀(M_*/M_☉)≃10 and ≃50 M_☉ yr^–1 at <i_AB^′^>=24, down to log₁₀(M_*/M_☉)≃8 and ≃3 M_☉ yr^–1 at <i_AB^′^>=27. The faint LBGs show a ∼1 mag excess over the stellar continuum in K-band. We interpret this excess flux as redshifted [O III]λλ4959,5007 lines. The observed excesses imply equivalent widths that increase with decreasing mass, reaching EW₀([O III]4959,5007+Hβ) 1500 Å (rest-frame). Such strong [O III] emission is seen only in a miniscule fraction of local emission-line galaxies, but is probably universal in the faint galaxies that reionized the universe. Our halo occupation distribution analysis of the angular correlation function gives a halo mass of log₁₀(<M_h>/h^–1M_☉)=11.29±0.12 for the full sample of LBGs, and log₁₀(<M_h>/h^–1M_☉)=11.49±0.1 for the brightest half of the sample.