The [O ii] λ3727 luminosity function and star formation rate at z≈1.2 in the COSMOS 2 square degree field and the Subaru Deep Field

We have carried out a wide-field imaging survey for [O II] lambda 3727 emitting galaxies at z approximate to 1: 2 in the HST COSMOS 2 square degree field using the Suprime-Cam on the Subaru Telescope. The survey covers a sky area of 6700 arcmin(2) in the COSMOS field, and a redshift range between 1.17 and 1.20 ( Delta z 0: 03), corresponding to a survey volume of 5: 56; 105 Mpc(3). We obtain a sample of 3176 [O II] emitting galaxies with observed emission-line equivalent widths greater than 268. Since our survey tends to sample brighter [O II] emitting galaxies, we also analyze a sample of fainter [O II] emitting galaxies found in the Subaru Deep Field (SDF). We find an extinction-corrected [ O II] luminosity density of 10(- 0: 06)(40: 35+0: 08) ergs s (-1) Mpc (-3), corresponding to star formation rate density of 0: 32(- 0: 04)(+0: 06) M-circle dot yr(-1) Mpc(-3) in the COSMOS field at z approximate to 1: 2. This is the largest survey for [O II] emitters beyond z 1 currently available.