2004ApJ...605L..93S

We reported in a previous paper the discovery of a large-scale structure of Lyα emitters (LAEs) at z=4.86±0.03 with a projected size of 20 h^–1₇₀ Mpcx50 h^–1₇₀Mpc in narrowband data of a 25^'x45^' area of the Subaru Deep Field (Ω₀=0.3, λ₀=0.7, and H₀=70 h₇₀km/s/Mpc). However, the surveyed area, which corresponds to 55 h^–1₇₀Mpc x100 h^–1₇₀Mpc, was not large enough to conclude that what we were seeing was a typical distribution of z≃5 LAEs. In this Letter, we report the results of follow-up imaging of the same sky area using a new narrowband filter (NB704, λ_c=7046 Å and FWHM=100 Å) to detect LAEs at z=4.79, i.e., LAEs lying closer to us by 39 h^–1₇₀Mpc on average than the z=4.86 objects. We detect 51 LAEs at z=4.79±0.04 down to NB704=25.7, and we find that their sky distribution is quite different from the z=4.86 LAEs'. The clustering of z=4.79 LAEs is very weak on any scale, and there is no large-scale high-contrast structure. The shape and the amplitude of the angular correlation function are thus largely different between the two samples. These results demonstrate a large cosmic variance in the clustering properties of LAEs on scales of ∼50 h^–1₇₀Mpc.