Issue |
A&A
Volume 672, April 2023
|
|
---|---|---|
Article Number | A18 | |
Number of page(s) | 26 | |
Section | Cosmology (including clusters of galaxies) | |
DOI | https://doi.org/10.1051/0004-6361/202245100 | |
Published online | 23 March 2023 |
The hidden side of cosmic star formation at z > 3
Bridging optically dark and Lyman-break galaxies with GOODS-ALMA
1
School of Astronomy and Space Science, Nanjing University, Nanjing 210093, PR China
e-mail: my.xiao@smail.nju.edu.cn
2
AIM, CEA, CNRS, Université Paris-Saclay, Université Paris Diderot, Sorbonne Paris Cité, 91191 Gif-sur-Yvette, France
3
Key Laboratory of Modern Astronomy and Astrophysics (Nanjing University), Ministry of Education, Nanjing 210093, PR China
4
Aix- Marseille Université, CNRS, LAM, Laboratoire d’Astrophysique de Marseille, 13013 Marseille, France
5
Department of Astronomy, The University of Texas at Austin, 2515 Speedway Blvd Stop C1400, Austin, TX 78712, USA
6
Community Science and Data Center/NSF’s NOIRLab., 950 N. Cherry Ave., Tucson, AZ 85719, USA
7
Department of Physics, Faculty of Science, Chulalongkorn University, 254 Phayathai Road, Pathumwan, Bangkok 10330, Thailand
8
National Astronomical Research Institute of Thailand (Public Organization), Don Kaeo, Mae Rim, Chiang Mai 50180, Thailand
9
Kavli IPMU (WPI), UTIAS, The University of Tokyo, Kashiwa, Chiba 277-8583, Japan
10
Cosmic Dawn Center (DAWN), Jagtvej 128, 2200 Copenhagen N, Denmark
11
DTU-Space, Technical University of Denmark, Elektrovej 327, 2800 Kgs. Lyngby, Denmark
12
Niels Bohr Institute, University of Copenhagen, Jagtvej 128, 2200 Copenhagen N, Denmark
13
Instituto de Astrofísica, Facultad de Física, Pontificia Universidad Católica de Chile, Casilla 306, Santiago 22, Chile
14
Hiroshima Astrophysical Science Center, Hiroshima University, 1-3-1 Kagamiyama, Higashi-Hiroshima, Hiroshima 739-8526, Japan
15
Departamento de Astronomía, Facultad de Ciencias Fśicas y Matemáticas, Universidad de Concepción, Concepción, Chile
16
Astronomy Centre, Department of Physics and Astronomy, University of Sussex, Brighton BN1 9QH, UK
17
International Space Science Institute (ISSI), Hallerstrasse 6, CH-3012 Bern, Switzerland
18
Department of Physics, Anhui Normal University, Wuhu, Anhui 241000, PR China
19
Laboratory for Multiwavelength Astrophysics, School of Physics and Astronomy, Rochester Institute of Technology, 84 Lomb Memorial Drive, Rochester, NY 14623, USA
20
Centre for Extragalactic Astronomy, Department of Physics, Durham University, Durham DH1 3LE, UK
21
Space Telescope Science Institute, 3700 San Martin Drive, Baltimore, MD 21218, USA
22
Astronomy Department, University of Massachusetts, Amherst, MA 01003, USA
23
National Astronomical Observatory of Japan, 2-21-1 Osawa, Mitaka, Tokyo 181-8588, Japan
24
Department of Astronomical Science, SOKENDAI (The Graduate University for Advanced Studies), Mitaka, Tokyo 181-8588, Japan
25
Joint ALMA Observatory, Alonso de Córdova 3107, Vitacura, 763-0355 Santiago, Chile
26
European Southern Observatory, Alonso de Córdova 3107, Vitacura, Casilla, 19001 19 Santiago, Chile
27
Institute of Astronomy, Graduate School of Science, The University of Tokyo, 2-21-1 Osawa, Mitaka, Tokyo 181-0015, Japan
28
Department of Physics and Astronomy, University of Sheffield, Sheffield S3 7RH, UK
29
Department of Astronomy, Universidad de Concepción, Casilla 160- C, Concepción, Chile
30
Astronomy Unit, Department of Physics, University of Trieste, via Tiepolo 11, 34131 Trieste, Italy
31
Fakultät für Physik der Ludwig-Maximilians-Universität, 81679 München, Germany
32
Department of Physics and Astronomy, Texas A&M University, College Station, TX 77843-4242, USA
33
George P. and Cynthia Woods Mitchell Institute for Fundamental Physics and Astronomy, Texas A&M University, College Station, TX 77843-4242, USA
34
Astrophysics, Department of Physics, Keble Road, Oxford OX1 3RH, UK
Received:
30
September
2022
Accepted:
1
February
2023
Our current understanding of the cosmic star formation history at z > 3 is primarily based on UV-selected galaxies (Lyman-break galaxies, i.e., LBGs). Recent studies of H-dropouts (HST-dark galaxies) have revealed that we may be missing a large proportion of star formation that is taking place in massive galaxies at z > 3. In this work, we extend the H-dropout criterion to lower masses to select optically dark or faint galaxies (OFGs) at high redshifts in order to complete the census between LBGs and H-dropouts. Our criterion (H > 26.5 mag & [4.5] < 25 mag) combined with a de-blending technique is designed to select not only extremely dust-obscured massive galaxies but also normal star-forming galaxies (typically E(B − V) > 0.4) with lower stellar masses at high redshifts. In addition, with this criterion, our sample is not contaminated by massive passive or old galaxies. In total, we identified 27 OFGs at zphot > 3 (with a median of zmed = 4.1) in the GOODS-ALMA field, covering a wide distribution of stellar masses with log(M⋆/M⊙) = 9.4 − 11.1 (with a median of log(M⋆med/M⊙) = 10.3). We find that up to 75% of the OFGs with log(M⋆/M⊙) = 9.5 − 10.5 were neglected by previous LBGs and H-dropout selection techniques. After performing an optical-to-millimeter stacking analysis of the OFGs, we find that rather than being limited to a rare population of extreme starbursts, these OFGs represent a normal population of dusty star-forming galaxies at z > 3. The OFGs exhibit shorter gas depletion timescales, slightly lower gas fractions, and lower dust temperatures than the scaling relation of typical star-forming galaxies. Additionally, the total star formation rate (SFRtot = SFRIR + SFRUV) of the stacked OFGs is much higher than the SFRUVcorr (SFRUV corrected for dust extinction), with an average SFRtot/SFRUVcorr = 8 ± 1, which lies above (∼0.3 dex) the 16–84th percentile range of typical star-forming galaxies at 3 ≤ z ≤ 6. All of the above suggests the presence of hidden dust regions in the OFGs that absorb all UV photons, which cannot be reproduced with dust extinction corrections. The effective radius of the average dust size measured by a circular Gaussian model fit in the uv plane is Re(1.13 mm) = 1.01 ± 0.05 kpc. After excluding the five LBGs in the OFG sample, we investigated their contributions to the cosmic star formation rate density (SFRD). We found that the SFRD at z > 3 contributed by massive OFGs (log(M⋆/M⊙) > 10.3) is at least two orders of magnitude higher than the one contributed by equivalently massive LBGs. Finally, we calculated the combined contribution of OFGs and LBGs to the cosmic SFRD at z = 4 − 5 to be 4 × 10−2 M⊙ yr−1 Mpc−3, which is about 0.15 dex (43%) higher than the SFRD derived from UV-selected samples alone at the same redshift. This value could be even larger, as our calculations were performed in a very conservative way.
Key words: galaxies: high-redshift / galaxies: evolution / galaxies: star formation / galaxies: photometry / submillimeter: galaxies
© The Authors 2023
Open Access article, published by EDP Sciences, under the terms of the Creative Commons Attribution License (https://creativecommons.org/licenses/by/4.0), which permits unrestricted use, distribution, and reproduction in any medium, provided the original work is properly cited.
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