G. Gandolfi, G. Rodighiero, L. Bisigello, A. Grazian, S. L. Finkelstein, M. E. Dickinson, M. Castellano, E. Merlin, A. Calabro, 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, Pablo G. Perez-Gonzalez, T. Ronconi, M. Tarrasse, S. M. Wilkins, B. Vulcani, L. Y. A. Yung, J. A. Zavala, B. E. Backhaus, M. B. Bagley, V. Buat, D. Burgarella, J. S. Kartaltepe, Y. Khusanova, A. Kirkpatrick, D. D. Kocevski, A. M. Koekemoer, E. Lambrides, N. Pirzkal, G. Yang
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.
Keywords
galaxies: dwarf / galaxies: high-redshift / galaxies: photometry
Astronomy & Astrophysics
Volume 708, Article Number A195, Number of pages 29
2026 April
