Subaru deep survey. II. Luminosity functions and clustering properties of Ly alpha 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 arcmin(2) area of the Subaru Deep Field. We find 87 Lyalpha 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; lambda(c) = 7126 Angstrom, Deltalambda = 73 Angstrom). We derive the luminosity functions (LFs) of the LAEs at Lyalpha luminosity and at UV-continuum ( rest frame 1700 Angstrom) luminosity. The LFs show little evolution between z = 3.4 and 4.86 either in Lyalpha 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 similar to15' separations. The angular correlation omega(theta) 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 greater than or similar to15', which would indicate the existence of a large-scale structure of LAEs on e greater than or similar to20 h(-1) Mpc scales. We fit the observed correlation function by A(omega)theta(-0.8) to nd A(omega) = 29 arcsec(0.8). The estimated correlation length is r(0) = 3.5(-0.3)(+0.3) h(-1) Mpc in comoving units (Omega(m) = 0.3 and Omega(Lambda) = 0.7), which is slightly larger than the value for z similar to 4 LBGs with i' < 26. We calculate the angular correlation function for two subsamples of the 87 LAEs divided by Ly alpha luminosity, UV-continuum luminosity, and Ly alpha equivalent width (EW). The Ly alpha-bright sub-sample shows a larger correlation amplitude than the Ly alpha-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 Ly alpha emission are possibly biased against the underlying dark matter halos more strongly than those with bright UV continuum.