The discovery of a very narrow line star-forming object at a redshift of 5.66

Yoshiaki Taniguchi, Masaru Ajiki, Takashi Murayama, Tohru Nagao, Sylvain Veilleux, David B. Sanders, Yutaka Komiyama, Yasuhiro Shioya, Shinobu S. Fujita, Yuko Kakazu, Sadanori Okamura, Hiroyasu Ando, Tetsuo Nishimura, Masahiko Hayashi, Ryusuke Ogasawara, Shin Ichi Ichikawa

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28 Citations (Scopus)


We report on the discovery of a very narrow line star-forming object beyond a redshift of 5. Using the prime-focus camera, Suprime-Cam, on the 8.2 m Subaru Telescope together with a narrow-passband filter centered at λc = 8150 Å with a passband of Δλ = 120 Å, we have obtained a very deep image of the field surrounding the quasar SDSSp J104433.04-012502.2 at a redshift of 5.74. Comparing this image with optical broadband images, we have found an object with a very strong emission line. Our follow-up optical spectroscopy has revealed that this source is at a redshift of z = 5.655 ± 0.002, forming stars at a rate ∼ 13 h 0.7-2 M yr-1. Remarkably, the velocity dispersion of Lyα-emitting gas is only 22 km s-1. Since the blue half of the Lyα emission could be absorbed by neutral hydrogen gas, perhaps in the system, a modest estimate of the velocity dispersion may be ≳44 km s-1. Together with a linear size of 7. 7 h0.7-1 kpc, we estimate a lower limit of the dynamical mass of this object to be ∼2 × 109 M. It is thus suggested that LAE J1044-0123 is a star-forming dwarf galaxy (i.e., a subgalactic object or a building block) beyond redshift 5, although we cannot exclude the possibility that most Lyα emission is absorbed by the red damping wing of neutral intergalactic matter.

Original languageEnglish
Pages (from-to)L97-L100
JournalAstrophysical Journal
Issue number2 II
Publication statusPublished - 2003 Mar 10


  • Galaxies: formation
  • Galaxies: individual (LAE J1044-0123)
  • Galaxies: starburst


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