Census of and Lyα, [OIII]5007, Hα, and [CIII]158 μm line emission wiht ∼1000 galaxies at z = 4.9 - 7.0 revealed with Subaru/HSC, Spitzer, and ALMA

We investigate rest-frame UV to far-infrared emission lines and SEDs from 1124 galaxies at z = 4.9 - 7.0. Our sample is composed of 1092 Lyα emitters (LAEs) at z = 4.9-7.0 identified by Subaru/Hyper Suprime-Cam (HSC) narrowband surveys and 34 galaxies at z = 5.148-7.508 with deep [CII]158μm ALMA data. The SEDs clearly show flux excesses in the Spitzer/IRAC 3.6 and 4.5μm bands, suggesting strong rest-frame optical emission lines of [OIII] and/or Hα. We model the galaxy SEDs with a flexible code combining stellar population and photoionization models (BEAGLE; Chevallard & Charlot 2016), and investigate relations between the emission lines of Lyα, [OIII], Hα, and [CII]. We find 1) a positive correlation between the rest-frame Hα equivalent width (EW) and the Lyα, EW, ${EW {^0_Lyα}} $, 2) an interesting turn-over trend that the [OIII]/Hα flux ratio increases in ${EW {^0_Lyα}} $ ≃ 0-30 Å, and then decreases out to ${EW {^0_Lyα}} $ ≃ 130 Å, and 3) a > 99% anti-correlation between a [CII] luminosity to star-formation rate ratio L_[CII]/SFR) and ${EW {^0_Lyα}} $. Modeling with BEAGLE also suggests that a simple anticorrelation between ${EW {^0_Lyα}} $ and metallicity explains self-consistently all of the relations of Lyα, Hα, [OIII]/Hα, and [CII] in our study, indicative of detections of very metal-poor (∼0.03Z⊙) galaxies with ${EW {^0_Lyα}} $ ∼200 Å.