CHORUS. III. Photometric and Spectroscopic Properties of Ly 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 A.R. Kobayashi, Haruka Kusakabe, Ken MawatariTohru Nagao, Kazuhiro Shimasaku, Yoshiaki Taniguchi

*Corresponding author for this work

Research output: Contribution to journalArticlepeer-review

10 Citations (Scopus)


We report the Subaru Hyper Suprime-Cam (HSC) discovery of two Ly blobs (LABs), dubbed z70-1 and z49-1 at z = 6.965 and z = 4.888, respectively, that are Ly emitters with a bright () and spatially extended Ly 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 extended Ly 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 seven LABs, except z49-1, exhibit no active galactic nucleus (AGN) signatures such as X-ray emission, N v λ1240 emission, or Ly line broadening, while z49-1 has a strong C iv λ1548 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 Ly emission of the LABs. The Ly scale lengths of the core (star-forming region) and halo components are r c = 0.6-1.2 kpc and r h = 2.0-13.8 kpc, respectively. The relations between the scale lengths and galaxy properties (Ly luminosity L Ly, Ly rest-frame equivalent width EW0, and UV continuum magnitude M UV) of our LABs are similar to those of Ly halos (LAHs) identified around star-forming galaxies found previously by the Very Large Telescope/MUSE at similar redshifts, suggesting that our LABs are likely the bright version of high-z LAHs.

Original languageEnglish
Article number177
JournalAstrophysical Journal
Issue number2
Publication statusPublished - 2020 Mar 10

ASJC Scopus subject areas

  • Astronomy and Astrophysics
  • Space and Planetary Science


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