Modelling of Lyman-alpha emitting galaxies and ionized bubbles at the epoch of reionization

Understanding {Ly{α}} emitting galaxies (LAEs) can be a key to reveal cosmic reionization and galaxy formation in the early Universe. Based on halo merger trees and {Ly{α}} radiation transfer calculations, we model redshift evolution of LAEs and their observational properties at z ≥ 6. We consider ionized bubbles associated with individual LAEs and IGM (integer-galactic medium) transmission of {Ly{α}} photons. We find that {Ly{α}} luminosity tightly correlates with halo mass and stellar mass, while the relation with star formation rate has a large dispersion. Comparing our models with the observed luminosity function by Konno et al., we suggest that LAEs at z ∼ 7 have galactic wind of V_out ≳ 100 km s^{-1} and H I column density of N_HI ≳ 10^{20} cm^{-2}. Number density of bright LAEs rapidly decreases as redshift increases, due to both lower star formation rate and smaller H II bubbles. Our model predicts future wide deep surveys with next-generation telescopes, such as James Webb Space Telescope, European Extremely Large Telescope, and Thirty Metre Telescope, can detect LAEs at z ∼ 10 with a number density of n_LAE ∼ {a few } × 10^{-6} Mpc^{-3} for the flux sensitivity of 10^{-18} erg cm^{-2} s^{-1}. When giant H II bubbles are formed by clustering LAEs, the number density of observable LAEs can increase by a factor of few. By combining these surveys with future 21-cm observations, it could be possible to detect both LAEs with L_{Lyα }≳ 10^{42} erg s^{-1} and their associated giant H II bubbles with the size {≳ } 250 kpc at z ∼ 10.