A dusty star-forming galaxy at z = 6 revealed by strong gravitational lensing

• Published in: Nature astronomy Vol. 2; no. 1; pp. 56 - 62
• Main Authors: Zavala, Jorge A., Montaña, Alfredo, Hughes, David H., Yun, Min S., Ivison, R. J., Valiante, Elisabetta, Wilner, David, Spilker, Justin, Aretxaga, Itziar, Eales, Stephen, Avila-Reese, Vladimir, Chávez, Miguel, Cooray, Asantha, Dannerbauer, Helmut, Dunlop, James S., Dunne, Loretta, Gómez-Ruiz, Arturo I., Michałowski, Michał J., Narayanan, Gopal, Nayyeri, Hooshang, Oteo, Ivan, Rosa González, Daniel, Sánchez-Argüelles, David, Schloerb, F. Peter, Serjeant, Stephen, Smith, Matthew W. L., Terlevich, Elena, Vega, Olga, Villalba, Alan, van der Werf, Paul, Wilson, Grant W., Zeballos, Milagros
• Format: Journal Article
• Language: English
• Published: London Nature Publishing Group UK 01-01-2018; Nature Publishing Group
• Subjects: 639/33/34/124; 639/33/34/863; Astronomy; Astrophysics and Cosmology; Galaxies; Letter; Physics; Physics and Astronomy; Star & galaxy formation; Stars; Stars & galaxies
• ISSN: 2397-3366; 2397-3366
• DOI: 10.1038/s41550-017-0297-8

Since their discovery, submillimetre-selected galaxies
1
,
2
have revolutionized the field of galaxy formation and evolution. From the hundreds of square degrees mapped at submillimetre wavelengths
3
–
5
, only a handful of sources have been confirmed to lie at
z
 > 5 (refs
6
–
10
) and only two at
z
≥ 6 (refs
11
,
12
). All of these submillimetre galaxies are rare examples of extreme starburst galaxies with star formation rates of ≳1,000 M
⊙
yr
−1
and therefore are not representative of the general population of dusty star-forming galaxies. Consequently, our understanding of the nature of these sources, at the earliest epochs, is still incomplete. Here, we report the spectroscopic identification of a gravitationally amplified (
μ
 = 9.3 ± 1.0) dusty star-forming galaxy at
z
 = 6.027. After correcting for gravitational lensing, we derive an intrinsic less-extreme star formation rate of 380 ± 50 M
⊙
yr
−1
for this source and find that its gas and dust properties are similar to those measured for local ultra luminous infrared galaxies, extending the local trends to a poorly explored territory in the early Universe. The star-formation efficiency of this galaxy is similar to those measured in its local analogues
13
, despite a ~12 Gyr difference in cosmic time.
This paper reports the detection of a high-redshift galaxy that may be more representative of ‘normal’ star-forming galaxies formed in the first billion years of the Universe than the extreme starbursts discovered to date.