Chorus. III. Photometric and spectroscopic properties of Lyα blobs at z = 4.9 − 7.0

Haibin Zhang, Masami Ouchi, Ryohei Itoh, Takatoshi Shibuya, Yoshiaki Ono, Yuichi Harikane, Akio K. Inoue, Michael Rauch, Shotaro Kikuchihara, Kimihiko Nakajima, Hidenobu Yajima, Shohei Arata, Makito Abe, Ikuru Iwata, Nobunari Kashikawa, Satoshi Kawanomoto, Satoshi Kikuta, Masakazu Kobayashi, Haruka Kusakabe, Ken MawatariTohru Nagao, Kazuhiro Shimasaku, Yoshiaki Taniguchi

Research output: Contribution to journalArticlepeer-review

Abstract

We report the Subaru Hyper Suprime-Cam (HSC) discovery of two Lyα blobs (LABs), dubbed z70-1 and z49-1 at z = 6.965 and z = 4.888 respectively, that are Lyα emitters with a bright (log LLyα/[erg s1] > 43.4) and spatially-extended Lyα emission, and present the photometric and spectroscopic properties of a total of seven LABs; the two new LABs and five previously-known LABs at z = 5.7 − 6.6. The z70-1 LAB shows the extended Lyα emission with a scale length of 1.4 ± 0.2 kpc, about three times larger than the UV continuum emission, making z70-1 the most distant LAB identified to date. All of the 7 LABs, except z49-1, exhibit no AGN signatures such as X-ray emission, Nvλ1240 emission, or Lyα line broadening, while z49-1 has a strong Civλ1548 emission line indicating an AGN on the basis of the UV-line ratio diagnostics. We carefully model the point-spread functions of the HSC images, and conduct two-component exponential profile fitting to the extended Lyα emission of the LABs. The Lyα scale lengths of the core (star-forming region) and the halo components are rc = 0.6 − 1.2 kpc and rh = 2.0 − 13.8 kpc, respectively. The average rh of the LABs falls on the extrapolation of the rh-Lyα luminosity relation of the Lyα halos around VLT/MUSE star-forming galaxies at the similar redshifts, suggesting that typical LABs at z ≳ 5 are not special objects, but star-forming galaxies at the bright end.

Original languageEnglish
JournalUnknown Journal
Publication statusPublished - 2019 May 23

Keywords

  • Cosmology: observations
  • Galaxies: evolution
  • Galaxies: formation
  • Galaxies: high-redshift

ASJC Scopus subject areas

  • General

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