Deep LBT/LUCI spectroscopy of an Lyα emitter candidate at z ≃ 7.7

Linhua Jiang, Fuyan Bian, Xiaohui Fan, Hannah B. Krug, Ian D. McGreer, Daniel P Stark, Benjamin Clément, Eiichi Egami

Research output: Contribution to journalArticle

13 Citations (Scopus)

Abstract

We present deep spectroscopic observations of an Lyα emitter (LAE) candidate at z ≃ 7.7 using the infrared spectrograph LUCI on the 2 × 8.4 m Large Binocular Telescope (LBT). The candidate is the brightest among the four z ≃ 7.7 LAE candidates found in a narrowband imaging survey by Krug et al. Our spectroscopic data include a total of 7.5 hr of integration with LBT/LUCI and are deep enough to significantly (3.2σ-4.9σ) detect the Lyα emission line of this candidate based on its Lyα flux 1.2 × 10-17 erg s-1 cm-2 estimated from the narrowband photometry. However, we do not find any convincing signal at the expected position of its Lyα emission line, suggesting that this source is not an LAE at z ≃ 7.7. The non-detection in this work, together with the previous studies of z ≃ 7.7 LAEs, puts a strong constraint on the bright-end Lyα luminosity function (LF) at z ≃ 7.7. We find a rapid evolution of the Lyα LF from z ≃ 6.5 to 7.7: the upper limit of the z ≃ 7.7 LF is more than five times lower than the z ≃ 6.5 LF at the bright end (f≥ 1.0 × 10-17 erg s-1 cm -2 or L≥ 6.9 × 1042 erg s-1). This is likely caused by an increasing neutral fraction in the intergalactic medium that substantially attenuates Lyα emission at z ≃ 7.7.

Original languageEnglish (US)
Article numberL6
JournalAstrophysical Journal Letters
Volume771
Issue number1
DOIs
StatePublished - Jul 1 2013

Fingerprint

emitters
spectroscopy
luminosity
telescopes
erg
narrowband
intergalactic media
spectrographs
photometry

Keywords

  • cosmology: observations
  • galaxies: evolution
  • galaxies: high-redshift

ASJC Scopus subject areas

  • Space and Planetary Science
  • Astronomy and Astrophysics

Cite this

Deep LBT/LUCI spectroscopy of an Lyα emitter candidate at z ≃ 7.7. / Jiang, Linhua; Bian, Fuyan; Fan, Xiaohui; Krug, Hannah B.; McGreer, Ian D.; Stark, Daniel P; Clément, Benjamin; Egami, Eiichi.

In: Astrophysical Journal Letters, Vol. 771, No. 1, L6, 01.07.2013.

Research output: Contribution to journalArticle

Jiang, Linhua ; Bian, Fuyan ; Fan, Xiaohui ; Krug, Hannah B. ; McGreer, Ian D. ; Stark, Daniel P ; Clément, Benjamin ; Egami, Eiichi. / Deep LBT/LUCI spectroscopy of an Lyα emitter candidate at z ≃ 7.7. In: Astrophysical Journal Letters. 2013 ; Vol. 771, No. 1.
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abstract = "We present deep spectroscopic observations of an Lyα emitter (LAE) candidate at z ≃ 7.7 using the infrared spectrograph LUCI on the 2 × 8.4 m Large Binocular Telescope (LBT). The candidate is the brightest among the four z ≃ 7.7 LAE candidates found in a narrowband imaging survey by Krug et al. Our spectroscopic data include a total of 7.5 hr of integration with LBT/LUCI and are deep enough to significantly (3.2σ-4.9σ) detect the Lyα emission line of this candidate based on its Lyα flux 1.2 × 10-17 erg s-1 cm-2 estimated from the narrowband photometry. However, we do not find any convincing signal at the expected position of its Lyα emission line, suggesting that this source is not an LAE at z ≃ 7.7. The non-detection in this work, together with the previous studies of z ≃ 7.7 LAEs, puts a strong constraint on the bright-end Lyα luminosity function (LF) at z ≃ 7.7. We find a rapid evolution of the Lyα LF from z ≃ 6.5 to 7.7: the upper limit of the z ≃ 7.7 LF is more than five times lower than the z ≃ 6.5 LF at the bright end (f≥ 1.0 × 10-17 erg s-1 cm -2 or L≥ 6.9 × 1042 erg s-1). This is likely caused by an increasing neutral fraction in the intergalactic medium that substantially attenuates Lyα emission at z ≃ 7.7.",
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