engleski

Photometric Properties of Lyα Emitters at z ≈ 4.86 in the COSMOS 2 Square Degree Field

We present results of a survey for Lyα emitters at z ≈ 4.86 based on optical narrowband (λ c = 7126 Å, Δλ = 73 Å) and broadband (B, V, r', i', and z') observations of the Cosmic Evolution Survey field using Suprime-Cam on the Subaru Telescope. We find 79 Lyα emitter (LAE) candidates at z ≈ 4.86 over a contiguous survey area of 1.83 deg2, down to the Lyα line flux of 1.47 × 10-17 erg s-1 cm-2. We obtain the Lyα luminosity function with a best-fit Schechter parameters of log L* = 42.9+0.5 -0.3 erg s-1 and phi* = 1.2+8.0 -1.1 × 10-4 Mpc-3 for α = -1.5 (fixed). The two-point correlation function for our LAE sample is ξ(r) = (r/4.4+5.7 -2.9 Mpc)-1.90±0.22. In order to investigate the field-to-field variations of the properties of Lyα emitters, we divide the survey area into nine tiles of 0fdg5 × 0fdg5 each. We find that the number density varies with a factor of sime2 from field to field with high statistical significance. However, we find no significant field-to-field variance when we divide the field into four tiles with 0fdg7 × 0fdg7 each. We conclude that at least 0.5 deg2 survey area is required to derive averaged properties of LAEs at z ~ 5, and our survey field is wide enough to overcome the cosmic variance.

galaxies: distances and redshifts; galaxies: evolution; galaxies: luminosity function; mass function

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