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arXiv · 1711.03735

SILVERRUSH. V. Census of Lya, [OIII]5007, Ha, and [CII]158um Line Emission with ~1000 LAEs at z=4.9-7.0 Revealed with Subaru/HSC

Yuichi Harikane·Masami Ouchi·Takatoshi Shibuya·Takashi Kojima·Haibin Zhang·Ryohei Itoh·Yoshiaki Ono·Ryo Higuchi·Akio K. Inoue·Jacopo Chevallard·Peter L. Capak·Tohru Nagao·Masato Onodera·Andreas L. Faisst·Crystal L. Martin·Michael Rauch·Gustavo A. Bruzual·Stephane Charlot·Iary Davidzon·Seiji Fujimoto·Miftahul Hilmi·Olivier Ilbert·Chien-Hsiu Lee·Yoshiki Matsuoka·John D. Silverman·Sune Toft
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Abstract

We investigate Lya, [OIII]5007, Ha, and [CII]158um emission from 1124 galaxies at z=4.9-7.0. Our sample is composed of 1092 Lya 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 Subaru/HSC (SPLASH) and 34 galaxies at z=5.148-7.508 with deep ALMA [CII]158um data in the literature. Fluxes of strong rest-frame optical lines of [OIII] and Ha (Hb) are constrained by significant excesses found in the SPLASH 3.6 and 4.5um photometry. At z=4.9, we find that the rest-frame Ha equivalent width and the Lya escape fraction f_Lya positively correlate with the rest-frame Lya equivalent width EW^0_Lya. The f_Lya-EW^0_Lya 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 logxi_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 turn-over trend that the [OIII]/Ha flux ratio increases in EW^0_Lya~0-30 A, and then decreases out to EW^0_Lya~130 A. We also identify an anti-correlation between a [CII] luminosity to star-formation rate ratio (L_[CII]/SFR) and EW^0_Lya at the >99% confidence level. We carefully investigate physical origins of the correlations with stellar-synthesis and photoionization models, and find that a simple anti-correlation between EW_Lya^0 and metallicity explains self-consistently all of the correlations of Lya, Ha, [OIII]/Ha, and [CII] identified in our study, indicating detections of metal-poor (~0.03 Zo) galaxies with EW^0_Lya~200 A.

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Yuichi Harikane, Masami Ouchi, Takatoshi Shibuya, Takashi Kojima, Haibin Zhang, Ryohei Itoh, Yoshiaki Ono, Ryo Higuchi, Akio K. Inoue, Jacopo Chevallard, Peter L. Capak, Tohru Nagao, Masato Onodera, Andreas L. Faisst, Crystal L. Martin, Michael Rauch, Gustavo A. Bruzual, Stephane Charlot, Iary Davidzon, Seiji Fujimoto, Miftahul Hilmi, Olivier Ilbert, Chien-Hsiu Lee, Yoshiki Matsuoka, John D. Silverman, Sune Toft. 2018-05-09. SILVERRUSH. V. Census of Lya, [OIII]5007, Ha, and [CII]158um Line Emission with ~1000 LAEs at z=4.9-7.0 Revealed with Subaru/HSC. https://doi.org/10.3847/1538-4357%2Faabd80

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