Diffuse Lyα haloes around Lyα emitters at z = 3: do dark matter distributions determine the Lyα spatial extents?

Using stacks of Lyα images of 2128 Lyα emitters (LAEs) and 24 proto-cluster UV-selected galaxies (LBGs) at z = 3.1, we examine the surface brightness profiles of Lyα haloes around high-z galaxies as a function of environment and UV luminosity. We find that the slopes of the Lyα radial profiles become flatter as the Mpc-scale LAE surface density increases, but that they are almost independent of the central UV luminosity. The characteristic exponential scalelength of the Lyα haloes appears to be proportional to the square of the LAE surface density ((r_(Lyα) ∝ Σ^2_(LAE)). Including the diffuse, extended Lyα haloes, the rest-frame Lyα equivalent width of the LAEs in the densest regions approaches EW_0 ∼ 200 Å, the maximum value expected for young (