Alexandra Pope, University of Massachusetts Amherst
Alfredo Montaña, Instituto Nacional de Astrofísica
Andrew Battisti, University of Massachusetts Amherst
Marceau Limousin, Aix Marseille University
Danilo Marchesini, Tufts University
Grant W. Wilson, University of Massachusetts Amherst
Stacy Alberts, University of Arizona
Itziar Aretxaga, Instituto Nacional de Astrofísica
Vladimir Avila-Reese, Universidad Nacional Autónoma de México
José Ramón Bermejo-Climent, Universidad de La Laguna
Gabriel Brammer, Space Telescope Science Institute
Hector Bravo-Alfaro, Universidad de Guanajuato
Daniela Calzetti, University of Massachusetts Amherst
Ranga-Ram Chary, California Institute of Technology
Ryan Cybulski, University of Massachusetts Amherst
Mauro Giavalisco, University of Massachusetts Amherst
David Hughes, Instituto Nacional de Astrofísica
Erin Kado-Fong, Tufts University
Erica Keller, National Radio Astronomy Observatory
Allison Kirkpatrick, University of Massachusetts Amherst
Ivo Labbe, Leiden University
Daniel Lange-Vagle, Tufts University
James Lowenthal, Smith CollegeFollow
Eric Murphy, National Radio Astronomy Observatory
Pascal Oesch, Yale University
Daniel Rosa Gonzalez, Instituto Nacional de Astrofísica
David Sánchez-Argüelles, Instituto Nacional de Astrofísica
Heath Shipley, Tufts University
Mauro Stefanon, Leiden University
Olga Vega, Instituto Nacional de Astrofísica
Katherine Whitaker, University of Massachusetts Amherst
Christina C. Williams, University of Arizona
Min Yun, University of Massachusetts Amherst
Jorge A. Zavala, Instituto Nacional de Astrofísica
Milagros Zeballos, Instituto Nacional de Astrofísica

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The Astrophysical Journal


We directly detect dust emission in an optically detected, multiply imaged galaxy lensed by the Frontier Fields cluster MACSJ0717.5+3745. We detect two images of the same galaxy at 1.1 mm with the AzTEC camera on the Large Millimeter Telescope leaving no ambiguity in the counterpart identification. This galaxy, MACS0717_Az9, is at z > 4 and the strong lensing model (μ=7.5) allows us to calculate an intrinsic IR luminosity of 9.7 × 1010 Le and an obscured star formation rate of 14.6 ± 4.5 Me yr−1. The unobscured star formation rate from the UV is only 4.1 ± 0.3 Me yr−1, which means the total star formation rate (18.7 ± 4.5 Me yr−1) is dominated (75%–80%) by the obscured component. With an intrinsic stellar mass of only 6.9 × 109 Me, MACS0717_Az9 is one of only a handful of z > 4 galaxies at these lower masses that is detected in dust emission. This galaxy lies close to the estimated star formation sequence at this epoch. However, it does not lie on the dust obscuration relation (IRX-β) for local starburst galaxies and is instead consistent with the Small Magellanic Cloud attenuation law. This remarkable lower mass galaxy, showing signs of both low metallicity and high dust content, may challenge our picture of dust production in the early universe.


galaxies: evolution, galaxies: high-redshift, galaxies: star formation, gravitational lensing: strong, infrared: galaxies, dust, extinction







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Creative Commons Attribution 4.0 International License
This work is licensed under a Creative Commons Attribution 4.0 International License.


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