2008MNRAS.384.1363F

Using a simple method to interpret the luminosity function of Lyα emitters, we explore properties of Lyα emitters from 5.7 ≤ z ≤ 8.8 with various assumptions about metallicity and stellar mass spectra. We constrain a mass-to-`observed light' ratio, M<sub>h</sub>/L<sub>band</sub>, where M<sub>h</sub> refers to the total mass of the host halo and L<sub>band</sub> refers to the observed luminosity of the source. For narrow-band surveys, L<sub>band</sub> is simply related to the intrinsic Lyα luminosity with a survival fraction of Lyα photons, α<sub>esc</sub>. The mass-to-`bolometric light', M_h/L_bol, can also be deduced, once the metallicity and stellar mass spectrum are given. The inferred M_h/L_bol is more sensitive to metallicity than to the mass spectrum. We find the following constraints on a mass-to-light ratio of Lyα emitters from 5.7 ≤ z ≤ 7: (M_h/L_bol)(α_escε^1/γ)^–1 = 21-38,14-26 and 9-17 for Z = 0, 1/50 and 1Z_☉, respectively, where ε is the `duty cycle' of Lyα emitters and γ ∼ 2 is a local slope of the cumulative luminosity function, N(>L) ∝ L^–γ, to which the current data are sensitive. Only weak lower limits are obtained for z = 8.8. Therefore, Lyα emitters are consistent with either starburst galaxies (M_h/L_bol∼ 0.1-1) with a smaller Lyα survival fraction, α_escε^1/γ ∼ 0.01-0.05, or normal populations (M_h/L_bol∼ 10) if a good fraction of Lyα photons survived, α_escε^1/γ ∼ 0.5-1. We find no evidence for the end of reionization in the luminosity functions of Lyα emitters discovered in the current Lyα surveys, including recent discovery of one Lyα emitter at z = 7. The data are consistent with no evolution of intrinsic properties of Lyα emitters or neutral fraction in the intergalactic medium up to z = 7. No detection of sources at z = 8.8 does not yield a significant constraint yet. We also show that the lack of detection at z = 8.8 does not rule out the high-z galaxies being the origin of the excess near-infrared background.