A Caltech Library Service

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

Talia, Margherita and Cimatti, Andrea and Giulietti, Marika and Zamorani, Gianni and Béthermin, Matthieu and Faisst, Andreas and Le Fèvre, Olivier and Smolčić, Vernesa (2021) Illuminating the Dark Side of Cosmic Star Formation Two Billion Years after the Big Bang. Astrophysical Journal, 909 (1). Art. No. 23. ISSN 0004-637X. doi:10.3847/1538-4357/abd6e3.

[img] PDF - Published Version
See Usage Policy.

[img] PDF - Accepted Version
See Usage Policy.


Use this Persistent URL to link to this item:


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.

Item Type:Article
Related URLs:
URLURL TypeDescription Paper
Talia, Margherita0000-0003-4352-2063
Cimatti, Andrea0000-0002-4409-5633
Giulietti, Marika0000-0002-1847-4496
Zamorani, Gianni0000-0002-2318-301X
Béthermin, Matthieu0000-0002-3915-2015
Faisst, Andreas0000-0002-9382-9832
Le Fèvre, Olivier0000-0001-5891-2596
Smolčić, Vernesa0000-0002-3893-8614
Additional Information:© 2021 The American Astronomical Society. Received 2020 August 7; revised 2020 December 22; accepted 2020 December 24; published 2021 March 2. This paper is dedicated to the memory of Olivier Le Fèvre. We thank the anonymous referee for useful suggestions to improve the paper. M.T. thanks Francesca Pozzi for useful discussions on dust temperature. M.T., A.C., and M.G. acknowledge the support from grant PRIN MIUR 2017 20173ML3WW_001. We acknowledge the use of Python (v.2.7) libraries in the analysis. This work is partly based on data products from observations made with ESO Telescopes at the La Silla Paranal Observatory under ESO program ID 179.A-2005 and on data products produced by CALET and the Cambridge Astronomy Survey Unit on behalf of the UltraVISTA consortium.
Group:Infrared Processing and Analysis Center (IPAC)
Funding AgencyGrant Number
Ministero dell'Istruzione, dell'Universita e della Ricerca (MIUR)20173ML3WW_001
Subject Keywords:Galaxy evolution; Galaxy formation; High-redshift galaxies; Star formation
Issue or Number:1
Classification Code:Unified Astronomy Thesaurus concepts: Galaxy evolution (594); Galaxy formation (595); High-redshift galaxies (734); Star formation (1569)
Record Number:CaltechAUTHORS:20210303-074449231
Persistent URL:
Usage Policy:No commercial reproduction, distribution, display or performance rights in this work are provided.
ID Code:108284
Deposited By: Tony Diaz
Deposited On:03 Mar 2021 18:22
Last Modified:16 Nov 2021 19:10

Repository Staff Only: item control page