Normal, dust-obscured galaxies in the epoch of reionization

Y. Fudamoto, P. A. Oesch, S. Schouws, M. Stefanon, R. Smit, R. J. Bouwens, R. A.A. Bowler, R. Endsley, V. Gonzalez, H. Inami, I. Labbe, D. Stark, M. Aravena, L. Barrufet, E. da Cunha, P. Dayal, A. Ferrara, L. Graziani, J. Hodge, A. HutterY. Li, I. De Looze, T. Nanayakkara, A. Pallottini, D. Riechers, R. Schneider, G. Ucci, P. van der Werf, C. White

Research output: Contribution to journalArticlepeer-review

78 Scopus citations


Over the past decades, rest-frame ultraviolet (UV) observations have provided large samples of UV luminous galaxies at redshift (z) greater than 6 (refs. 1–3), during the so-called epoch of reionization. While a few of these UV-identified galaxies revealed substantial dust reservoirs4–7, very heavily dust-obscured sources at these early times have remained elusive. They are limited to a rare population of extreme starburst galaxies8–12 and companions of rare quasars13,14. These studies conclude that the contribution of dust-obscured galaxies to the cosmic star formation rate density at z > 6 is sub-dominant. Recent ALMA and Spitzer observations have identified a more abundant, less extreme population of obscured galaxies at z = 3−6 (refs. 15,16). However, this population has not been confirmed in the reionization epoch so far. Here, we report the discovery of two dust-obscured star-forming galaxies at z = 6.6813 ± 0.0005 and z = 7.3521 ± 0.0005. These objects are not detected in existing rest-frame UV data and were discovered only through their far-infrared [C ii] lines and dust continuum emission as companions to typical UV-luminous galaxies at the same redshift. The two galaxies exhibit lower infrared luminosities and star-formation rates than extreme starbursts, in line with typical star-forming galaxies at z ≈ 7. This population of heavily dust-obscured galaxies appears to contribute 10–25% to the z > 6 cosmic star formation rate density.

Original languageEnglish (US)
Pages (from-to)489-492
Number of pages4
Issue number7877
StatePublished - Sep 23 2021

ASJC Scopus subject areas

  • General


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