A dusty, normal galaxy in the epoch of reionization

Darach Watson*, Lise Christensen, Kirsten Kraiberg Knudsen, Johan Richard, Anna Gallazzi, Michal Jerzy Michalowski

*Corresponding author for this work

Research output: Contribution to journalArticlepeer-review

Abstract

Candidates for the modest galaxies that formed most of the stars in the early Universe, at redshifts z> 7, have been found in large numbers with extremely deep restframe-ultraviolet imagingl. But it has proved difficult for existing spectrographs to characterize them using their ultraviolet light(2-4). The detailed properties of these galaxies could be measured from dust and cool gas emission at far-infrared wavelengths if the galaxies have become sufficiently enriched in dust and metals. So far, however, the most distant galaxy discovered via its ultraviolet emission and subsequently detected in dust emission is only at z = 3.2 (ref. 5), and recent results have cast doubt on whether dust and molecules can be found in typical galaxies at z >= 7(6-8). Here we report thermal dust emission from an archetypal early Universe star-forming galaxy, A1689-zDI. We detect its stellar continuum in spectroscopy and determine its redshift to be z = 7.5 +/- 0.2 from a spectroscopic detection of the Lyman-a break. A1689-zD1 is representative of the star-forming population during the epoch of reionization(9), with a total star-formation rate of about 12 solar masses per year. The galaxy is highly evolved: it has a large stellar mass and is heavily enriched in dust, with a dust-to-gas ratio close to that of the Milky Way. Dusty, evolved galaxies are thus present among the fainter star-forming population at z> 7.

Original languageEnglish
Pages (from-to)327-+
Number of pages13
JournalNature
Volume519
Issue number7543
DOIs
Publication statusPublished - 19 Mar 2015

Keywords

  • STAR-FORMING GALAXIES
  • SIMILAR-TO 7
  • HIGH-REDSHIFT GALAXIES
  • LYMAN BREAK GALAXIES
  • SUBMILLIMETER GALAXIES
  • PHYSICAL-PROPERTIES
  • STARBURST GALAXY
  • LOCAL UNIVERSE
  • MOLECULAR GAS
  • SIMPLE-MODEL

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