Issue |
A&A
Volume 681, January 2024
|
|
---|---|---|
Article Number | L3 | |
Number of page(s) | 8 | |
Section | Letters to the Editor | |
DOI | https://doi.org/10.1051/0004-6361/202348306 | |
Published online | 25 December 2023 |
Letter to the Editor
NOEMA reveals the true nature of luminous red JWST z > 10 galaxy candidates
1
Departement d’Astronomie, University of Geneva, Chemin Pegasi 51, 1290 Versoix, Switzerland
e-mail: romain.meyer@unige.ch
2
Max-Planck Institute for Astronomy, Königstuhl 17, 69118 Heidelberg, Germany
3
Center for Astrophysics | Harvard & Smithsonian, 60 Garden Street, Cambridge, MA 02138, USA
4
MIT Kavli Institute for Astrophysics and Space Research, 77 Massachusetts Ave., Cambridge, MA 02139, USA
5
Cosmic Dawn Center (DAWN), Niels Bohr Institute, University of Copenhagen, Jagtvej 128, København N 2200, Denmark
Received:
18
October
2023
Accepted:
1
December
2023
The first year of JWST has revealed a surprisingly large number of luminous galaxy candidates beyond z > 10. While some galaxies have already been spectroscopically confirmed, there is mounting evidence that a subsample of the candidates with particularly red inferred UV colours are, in fact, lower redshift contaminants. These interlopers are often found to be ‘HST-dark’ or ‘optically faint’ galaxies at z ∼ 2 − 6, a population that is key to improving our understanding of dust-obscured star formation throughout cosmic time. This paper demonstrates the complementarity of ground-based mm-interferometry and JWST infrared imaging to unveil the true nature of red 1.5–2.0 μm dropouts that have been selected as ultra-high-redshift galaxy candidates. We present NOEMA Polyfix follow-up observations of four JWST red 1.5–2.0 μm dropouts selected by Yan et al. (ApJ, 942, L8) as ultra-high-redshift candidates in the PEARLS-IDF field. The new NOEMA observations constrain the rest-frame far-infrared continuum emission and efficiently discriminate between intermediate- and high-redshift solutions. We report > 10σ NOEMA continuum detections of all our target galaxies at observed frequencies of ν = 236 and 252 GHz, with FIR slopes indicating a redshift of z < 5. We modelled their optical-to-FIR spectral energy distribution (SED) with multiple SED codes, finding that they are not z > 10 galaxies but dust-obscured, massive star-forming galaxies at z ∼ 2 − 4 instead. The contribution to the cosmic star formation rate density (CSFRD) of such sources is not negligible at z ≃ 3.5 (ϕ ≳ (1.9 − 4.4) × 10−3 cMpc−3; or > 3 − 6% of the total CSFRD), in line with previous studies of optically faint and sub-millimeter galaxies. This work showcases a new way to select intermediate- to high-redshift dust-obscured galaxies in JWST fields with minimal wavelength coverage. This approach opens up a new window onto obscured star formation at intermediate redshifts, whilst removing contaminants with red colours from searches at ultra-high redshifts.
Key words: techniques: interferometric / galaxies: high-redshift / 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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