Illuminating the Dark Side of Cosmic Star Formation Two Billion Years after the Big Bang

Scientific paper - Original scientific paper

• Author: Margherita Talia
• Author: Andrea Cimatti
• Author: Marika Giulietti
• Author: Gianni Zamorani
• Author: Matthieu Bethermin
• Author: Andreas Faisst
• Author: Olivier Le Fèvre
• Author: Vernesa Smolčić
• Author's institution: University of Zagreb; Faculty of Science; (Department of Physics)
• Scientific / art field, discipline and subdiscipline: NATURAL SCIENCES; Physics

Abstract (english)

How and when did galaxies form and assemble their stars and stellar mass? The answer to these questions, so crucial to astrophysics and cosmology, requires the full reconstruction of the so-called cosmic star formation rate density (SFRD), i.e., the evolution of the average star formation rate per unit volume of the universe. While the SFRD has been reliably traced back to 10-11 billion years ago, its evolution is still poorly constrained at earlier cosmic epochs, and its estimate is mainly based on galaxies luminous in the ultraviolet and with low obscuration by dust. This limited knowledge is largely due to the lack of an unbiased census of all types of star- forming galaxies in the early universe. We present a new approach to finding dust-obscured star- forming galaxies based on their emission at radio wavelengths coupled with the lack of optical counterparts. Here, we present a sample of 197 galaxies selected with this method. These systems were missed by previous surveys at optical and near-infrared wavelengths, and 22 of them are at very high redshift (i.e., z > 4.5). The contribution of these elusive systems to the SFRD is substantial and can be as high as 40% of the previously known SFRD based on UV-luminous galaxies. The mere existence of such heavily obscured galaxies in the first two billion years after the Big Bang opens new avenues to investigate the early phases of galaxy formation and evolution, and to understand the links between these systems and the massive galaxies that ceased their star formation at later cosmic times.

• Keywords (english): Galaxy evolution; Galaxy formation; High-redshift galaxies; Star formation; Astrophysics - Cosmology and Nongalactic Astrophysics; Astrophysics - Astrophysics of Galaxies
• Language: english
• Publication type: Scientific paper - Original scientific paper
• Publication status: Published
• Peer review: Peer review - international
• Publication version: Published version
• Journal title: The Astrophysical Journal
• Numbering: vol. 909, no. 1, 23
• p-ISSN: 0004-637X
• e-ISSN: 1538-4357
• DOI: https://doi.org/10.3847/1538-4357/abd6e3
• URN:NBN: urn:nbn:hr:217:868118
• Publication: 2021-03-02
• Document URL: https://iopscience.iop.org/article/10.3847/1538-4357/abd6e3
• Type of resource: Text
• Access conditions: Open access
• Public note: © 2021. The American Astronomical Society. All rights reserved. Received 2020 August 7; revised 2020 December 22; accepted 2020 December 24; published 2021 March 2.
• Created on: 2024-09-14 20:00:34