Ultrahigh-redshift or closer-by, dust-obscured galaxies?
Year: 2026
Type: article
Abstract: Context. The James Webb Space Telescope (JWST) is revolutionizing our understanding of the Universe by unveiling faint, near-infrared dropouts previously beyond our reach, ranging from exceptionally dusty sources to galaxies up to redshift z ∼ 14. Aims. In this paper, we identify F200W-dropout objects in the Cosmic Evolution Early Release Science (CEERS) survey that are absent from existing catalogs. Our selection method can effectively identify obscured low-mass (logM * /M ⊙ ≤ 9) objects at z ≤ 6, massive dust-rich sources up to z ∼ 12, and ultrahigh-redshift ( z > 15) candidates. Our goal is to uncover promising targets for further studies using deep mid-infrared imaging and/or spectroscopic follow-ups. Methods. We utilize two photometric catalogs optimized for detecting faint, red objects. Primarily relying on NIRCam photometry from the latest CEERS data release and supplementing with mid-infrared/(sub)millimeter data when available, our analysis pipeline combines multiple SED-fitting codes, star formation histories, and the novel CosMix tool for astronomical stacking to maximize available photometric information. Results. Our work highlights three 2 < z < 3 dusty dwarf galaxies that have higher masses compared to the typical dusty dwarfs previously identified in CEERS. Additionally, we reveal five faint sources with a significant probability of lying above z > 15, with best-fit masses compatible with Λ cold dark matter and a standard baryon-to-star conversion efficiency. We exploit these candidates to compute the z ∼ 17 UV luminosity function, finding estimates in good agreement with other similar studies. Their bimodal redshift probability distributions suggest they could also be z < 1.5 dwarf galaxies with extreme dust extinction. We also identify a strong line emitter galaxy at z ∼ 5 mimicking the near-infrared emission of a z ∼ 13 galaxy. Conclusions. Our sample holds promising candidates for future follow-ups. Confirming ultrahigh-redshift galaxies or lower-redshift dusty dwarfs will offer valuable insights into early galaxy formation, evolution with their central black holes and the nature of dark matter, and/or cosmic dust production mechanisms in low-mass galaxies, and will help us to understand degeneracies and contamination in high-redshift object searches.
Source: Astronomy and Astrophysics
Authors: G. Gandolfi, G. Rodighiero, L. Bisigello, A. Grazian, S. L. Finkelstein, M. Dickinson, M. Castellano, E. Merlin, A. Calabrò, C. Papovich, A. Bianchetti, E. Bañados, P. Benotto, M. Catone, F. Buitrago, E. Daddi, G. Girardi, M. Giulietti, M. Hirschmann, B. W. Holwerda, P. Arrabal Haro, A. Lapi, R. A. Lucas, Y. Lyu, M. Massardi, F. Pacucci, P. G. Pérez-González, T. Ronconi, M. Tarrasse, S. Wilkins, B. Vulcani, L. Y. A. Yung, J. A. Zavala, B. Backhaus, M. Bagley, V. Buat, D. Burgarella, J. Kartaltepe, Y. Khusanova, A. Kirkpatrick, D. Kocevski, A. M. Koekemoer, E. Lambrides, N. Pirzkal, G. Yang
Institutions: University of Padua, Osservatorio Astronomico di Padova, National Institute for Astrophysics, The University of Texas at Austin, NSF NOIRLab, Astronomical Observatory of Rome, Texas A&M University, Max Planck Institute for Astronomy, Universidad de Valladolid, University of Lisbon, Institute of Astrophysics and Space Sciences, Centre National de la Recherche Scientifique, Université Paris Cité, Commissariat à l'Énergie Atomique et aux Énergies Alternatives, Université Paris-Saclay, Astrophysique, Instrumentation et Modélisation, Trieste Astronomical Observatory, École Polytechnique Fédérale de Lausanne, University of Louisville, Goddard Space Flight Center, Scuola Internazionale Superiore di Studi Avanzati, Space Telescope Science Institute, Istituto di Radioastronomia di Bologna, Harvard University, Center for Astrophysics Harvard & Smithsonian, Consejo Superior de Investigaciones Científicas, Centro de Astrobiología, University of Sussex, National Astronomical Observatory of Japan, Aix-Marseille Université, Rochester Institute of Technology, University of Kansas, Colby College, University of Groningen, Space Research Organisation Netherlands
Language: English
Subfield: Astronomy and Astrophysics
Field: Physics and Astronomy
Domain: Physical Sciences
Open Access status: gold
Estimated APC paid: $1,865
Funder: Università degli Studi di Padova
OpenAlex ID: W4407208765