Observations of the gas reservoir around a star-forming galaxy in the early universe

Brenda L. Frye, David V. Bowen, Mairead Hurley, Todd M. Tripp, Xiaohui Fan, Bradford Holden, Puragra Guhathakurta, Dan Coe, Tom Broadhurst, Eiichi Egami, G. Meylan

Research output: Contribution to journalArticle

9 Scopus citations

Abstract

We present a high signal-to-noise spectrum of a bright galaxy at z=4.9 in 14 hr of integration on VLT FORS2. This galaxy is extremely bright, i 850 p 23.10 ± 0.01, and is strongly lensed by the foreground massive galaxy cluster A1689 (z=0.18). Stellar continuum is seen longward of the Lyα emission line at-7100 å, while intergalactic H i produces strong absorption shortward of Lyα. Two transmission spikes at-6800 and-7040 å are also visible, along with other structures at shorter wavelengths. Although this star-forming is galaxy fainter than a QSO, the absence of a strong central ultraviolet flux source in it enables a measurement of the H i flux transmission in the intergalactic medium (IGM) in the vicinity of a high-redshift object. We find that the effective H i optical depth of the IGM is remarkably high within a large 14 Mpc (physical) region surrounding the galaxy compared to that seen toward QSOs at similar redshifts. Evidently, this high-redshift galaxy is located in a region of space where the amount of H i is much larger than that seen at similar epochs in the diffuse IGM. We argue that observations of high-redshift galaxies like this one provide unique insights into the nascent stages of baryonic large-scale structures that evolve into the filamentary cosmic web of galaxies and clusters of galaxies observed in the current universe.

Original languageEnglish (US)
Pages (from-to)L5-L8
JournalAstrophysical Journal
Volume685
Issue number1 PART 2
DOIs
StatePublished - 2008

Keywords

  • Clusters
  • Data analysis
  • Galaxies
  • General
  • Gravitational lensing
  • High-redshift
  • Individual (A1689)
  • Methods
  • Spectroscopic
  • Techniques

ASJC Scopus subject areas

  • Astronomy and Astrophysics
  • Space and Planetary Science

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