Subaru Deep Survey. II. Luminosity Functions and Clustering Properties of Lyα Emitters at z = 4.86 in the Subaru Deep Field

We report on early results from very deep and wide-field narrowband imaging on a 543 arcmin2 area of the Subaru Deep Field. We find 87 Lyα emitters (LAEs) at z = 4.86 ± 0.03 that are photometrically selected by a combination of two broad bands (R and i') and one narrow band (NB711; λc = 7126 Å, Δλ = 73 Å). We derive the luminosity functions (LFs) of the LAEs at Lyα luminosity and at UV-continuum (rest frame 1700 Å) luminosity. The LFs show little evolution between z = 3.4 and 4.86 either in Lyα or UV-continuum emission. The amplitude of the LAE LF tends to decline at the bright magnitudes more rapidly than that of the LBG LF at similar redshifts. We calculate the angular correlation function of our LAEs up to ~15' separations. The angular correlation ω(θ) is found to increase with decreasing angular separations, showing a clear signal of clustering. It is also found that the distribution of LAEs shows a large-density gradient with a scale of ≳15', which would indicate the existence of a large-scale structure of LAEs on ≳20 h-1 Mpc scales. We fit the observed correlation function by Aωθ-0.8 to find Aω = 29 arcsec0.8. The estimated correlation length is r0 = 3.5h-1 Mpc in comoving units (Ωm = 0.3 and ΩΛ = 0.7), which is slightly larger than the value for z ~ 4 LBGs with i′ < 26. We calculate the angular correlation function for two subsamples of the 87 LAEs divided by Lyα luminosity, UV-continuum luminosity, and Lyα equivalent width (EW). The Lyα-bright subsample shows a larger correlation amplitude than the Lyα-faint subsample, while no significant difference is found for the subsamples divided by UV-continuum luminosity or EW. This may indicate that galaxies with bright Lyα emission are possibly biased against the underlying dark matter halos more strongly than those with bright UV continuum.