SILVERRUSH. III. Deep Optical and Near-Infrared Spectroscopy for Lya and UV-Nebular Lines of Bright Lya Emitters at z=6-7
| Autor: | Shibuya, Takatoshi, Ouchi, Masami, Harikane, Yuichi, Rauch, Michael, Ono, Yoshiaki, Mukae, Shiro, Higuchi, Ryo, Kojima, Takashi, Yuma, Suraphong, Lee, Chien-Hsiu, Furusawa, Hisanori, Konno, Akira, Martin, Crystal L., Shimasaku, Kazuhiro, Taniguchi, Yoshiaki, Kobayashi, Masakazu A. R., Kajisawa, Masaru, Nagao, Tohru, Goto, Tomotsugu, Kashikawa, Nobunari, Komiyama, Yutaka, Kusakabe, Haruka, Momose, Rieko, Nakajima, Kimihiko, Tanaka, Masayuki, Wang, Shiang-Yu |
|---|---|
| Rok vydání: | 2017 |
| Předmět: | |
| Druh dokumentu: | Working Paper |
| DOI: | 10.1093/pasj/psx107 |
| Popis: | We present Lya and UV-nebular emission line properties of bright Lya emitters (LAEs) at z=6-7 with a luminosity of log L_Lya/[erg s-1] = 43-44 identified in the 21-deg2 area of the SILVERRUSH early sample developed with the Subaru Hyper Suprime-Cam (HSC) survey data. Our optical spectroscopy newly confirm 21 bright LAEs with clear Lya emission, and contribute to make a spectroscopic sample of 96 LAEs at z=6-7 in SILVERRUSH. From the spectroscopic sample, we select 7 remarkable LAEs as bright as Himiko and CR7 objects, and perform deep Keck/MOSFIRE and Subaru/nuMOIRCS near-infrared spectroscopy reaching the 3sigma-flux limit of ~ 2x10^{-18} erg s-1 for the UV-nebular emission lines of He II1640, C IV1548,1550, and O III]1661,1666. Except for one tentative detection of C IV, we find no strong UV-nebular lines down to the flux limit, placing the upper limits of the rest-frame equivalent widths (EW_0) of ~2-4 A for He II, C IV, and O III] lines. Here we also investigate the VLT/X-SHOOTER spectrum of CR7 whose 6 sigma detection of He II is claimed by Sobral et al. Although two individuals and the ESO-archive service carefully re-analyze the X-SHOOTER data that are used in the study of Sobral et al., no He II signal of CR7 is detected, supportive of weak UV-nebular lines of the bright LAEs even for CR7. Spectral properties of these bright LAEs are thus clearly different from those of faint dropouts at z~7 that have strong UV-nebular lines shown in the various studies. Comparing these bright LAEs and the faint dropouts, we find anti-correlations between the UV-nebular line EW_0 and UV-continuum luminosity, which are similar to those found at z~2-3. Comment: 26 pages, 12 figures. Accepted for publication in PASJ special issue |
| Databáze: | arXiv |
| Externí odkaz: |
|