SILVERRUSH. V. Census of Lyα, [O iii] λ5007, Hα, and [C ii] 158 μm Line Emission with ∼1000 LAEs at z = 4.9–7.0 Revealed with Subaru/HSC

Abstract

We investigate Ly α , [O iii ] λ 5007, H α , and [C ii ] 158 μ m emission from 1124 galaxies at z  = 4.9–7.0. Our sample is composed of 1092 Ly α emitters (LAEs) at z  = 4.9, 5.7, 6.6, and 7.0 identified by Subaru/Hyper-Suprime-Cam (HSC) narrowband surveys covered by Spitzer Large Area Survey with Hyper-Suprime-Cam (SPLASH) and 34 galaxies at z  = 5.148–7.508 with deep ALMA [C ii ] 158 μ m data in the literature. Fluxes of strong rest-frame optical lines of [O iii ] and H α (H β ) are constrained by significant excesses found in the SPLASH 3.6 and 4.5 μ m photometry. At z  = 4.9, we find that the rest-frame H α equivalent width and the Ly α escape fraction f Ly α positively correlate with the rest-frame Ly α equivalent width . The correlation is similarly found at z  ∼ 0–2, suggesting no evolution of the correlation over z  ≃ 0–5. The typical ionizing photon production efficiency of LAEs is log( ξ ion /[Hz erg −1 ]) ≃ 25.5, significantly (60%–100%) higher than those of LBGs at a given UV magnitude. At z  = 5.7–7.0, there exists an interesting turnover trend that the [O iii ]/H α flux ratio increases in and then decreases out to . We also identify an anticorrelation between a ratio of [C ii ] luminosity to star formation rate ( L [C ii ] /SFR) and at the >99% confidence level.. We carefully investigate physical origins of the correlations with stellar-synthesis and photoionization models and find that a simple anticorrelation between and metallicity explains self-consistently all of the correlations of Ly α , H α , [O iii ]/H α , and [C ii ] identified in our study, indicating detections of metal-poor (∼0.03 Z ⊙ ) galaxies with .