Star-Forming Galaxies at z ≈ 0.24 in the Subaru Deep Field and the Sloan Digital Sky Survey

We made a search for H alpha emitting galaxies at z approximate to 0.24 in the Subaru Deep Field (SDF) using an archival data set obtained with the Subaru telescope. We carefully selected H alpha emitters in the narrow-band filter NB816, using B, V, R-C, i', and z' broad-band colors. We obtained a sample of 258 emitting galaxies with observed equivalent widths of (H alpha + [N II]6548,6584) greater than 12 angstrom. We also analyzed a sample of H alpha emitters taken from the Sloan Digital Sky Survey (SDSS) to constrain the luminous end of the H alpha luminosity function. Using the same selection criteria as those for the SDF, and after excluding AGNs, we obtained 317 H alpha emitting star-forming galaxies. Combining these two samples of H alpha emitters found in both SDF and SDSS, we derived an H alpha luminosity function with best-fit Schechter function parameters of alpha = -1.31(-0.17)(+0.17), log phi* = -2.46(-040)(+0.34) Mpc(-3), and log L* = 41.99(-0.07)(+0.08) ergs s(-1). The extinction-corrected H alpha luminosity density is 4.45(-1.75)(+2.96) x 10(39) ergs s(-1) Mpc(-3). Using the Kennicutt relation between the H alpha luminosity and star-formafion rate, the star-formation rate density in the survey volume was estimated at 0.035(-0.014)(+0.024) M-circle dot yr(-1) Mpc(-3). The angular two-point correlation function of H alpha emitters over 875 arcmin(2) at z = 0.24 was well-fitted by a power-law form with omega(theta) = 0.047(-0.013)(+0.017)theta(-0.66+/-0.08), corresponding to the correlation function xi(r) = vertical bar r/(2.6(-0.8)(+1.0) Mpc)](-1.66+/-0.08). The small correlation length of H alpha emitters may imply a weak clustering of active star-forming galaxies.