Clustering and lifetime of Lyman Alpha Emitters in the Epoch of Reionization

We calculate Lyman Alpha Emitter (LAE) angular correlation functions (ACFs) at z ≃ 6.6 and the fraction of lifetime (for the 100 Myr preceding z ≃ 6.6) galaxies spend as Lyman Break Galaxies (LBGs) or as LBGs with Lyman Alpha (Lyα) emission using a model that combines smoothed particle hydrodynamics cosmological simulations (GADGET-2), dust attenuation and a radiative transfer code (pCRASH). The ACFs are a powerful tool that significantly narrows the 3D parameter space allowed by LAE Lyα and UV luminosity functions (LFs) alone. With this work, we simultaneously constrain the escape fraction of ionizing photons f_esc = 0.05-0.5, the mean fraction of neutral hydrogen in the intergalactic medium (IGM) < χ _{H I} > ≲ 0.01 and the dust-dependent ratio of the escape fractions of Lyα and UV continuum photons f_α/f_c = 0.6-1.2. Our results show that reionization has the largest impact on the amplitude of the ACFs, and its imprints are clearly distinguishable from those of f_esc and f_α/f_c. We also show that galaxies with a critical stellar mass of M_* = 10^8.5(10^9.5) M_⊙ produce enough luminosity to stay visible as LBGs (LAEs). Finally, the fraction of time during the past 100 Myr prior to z = 6.6 a galaxy spends as an LBG or as an LBG with Lyα emission increases with the UV magnitude (and the stellar mass M_*); considering observed (dust and IGM attenuated) luminosities, the fraction of time a galaxy spends as an LBG (LAE) increases from 65-100 per cent (≃ 0-100 per cent) as M_UV decreases from M_UV = -18.0 to -23.5 (M_* increases from 10⁸-10^10.5 M_⊙). Thus in our model, the brightest (most massive) LBGs most often show Lyα emission.