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.

Normal, dust-obscured galaxies in the epoch of reionization / Fudamoto, Y.; Oesch, P. A.; Schouws, S.; Stefanon, M.; Smit, R.; Bouwens, R. J.; Bowler, R. A. A.; Endsley, R.; Gonzalez, V.; Inami, H.; Labbe, I.; Stark, D.; Aravena, M.; Barrufet, L.; da Cunha, E.; Dayal, P.; Ferrara, A.; Graziani, L.; Hodge, J.; Hutter, A.; Li, Y.; De Looze, I.; Nanayakkara, T.; Pallottini, A.; Riechers, D.; Schneider, R.; Ucci, G.; van der Werf, P.; White, C.. - In: NATURE. - ISSN 0028-0836. - 597:7877(2021), pp. 489-492. [10.1038/s41586-021-03846-z]

Normal, dust-obscured galaxies in the epoch of reionization

Dayal P.;Ferrara A.;Graziani L.;Schneider R.;Ucci G.;
2021

Abstract

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.
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Utilizza questo identificativo per citare o creare un link a questo documento: https://hdl.handle.net/11573/1577032
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