The Identification of Two JWST/NIRCam-dark Starburst Galaxies at z = 6.6 with ALMA
Year: 2026
Type: article
Abstract: We analyze two dusty star-forming galaxies at z = 6.6. These galaxies are selected from the ASPIRE survey, a JWST Cycle 1 medium program, and the Atacama Large Millimeter/submillimeter Array (ALMA) Cycle 9 large program targeting 25 quasars and their environments at z ≃ 6.5–6.8. These galaxies are identified as companions to UV-luminous quasars and robustly detected in ALMA continuum and [C ii ] emission, yet they are extraordinarily faint at the NIRCam wavelengths (down to >28.0 AB mag in the F356W band). They are more obscured than galaxies like Arp220 ( A V up to ∼7.5 mag), and thus we refer to them as “NIRCam-dark” starburst galaxies (star formation rate ≃80–250 M ⊙ yr −1 ). Such galaxies are typically missed by (sub)-millimeter blank-field surveys. From the star formation history (SFH), we show that the NIRCam-dark galaxies are viable progenitors of massive quiescent galaxies at z ≳ 4 and descendants of UV-luminous galaxies at z > 10. Although it is hard to constrain their number density from a quasar survey, we conclude that NIRCam-dark galaxies can be as abundant as n ∼ 10 −5.5 Mpc −3 assuming a light halo occupation model. If true, this would equal to ∼30% of the number densities of both the quiescent galaxies at z ≳ 4 and UV-luminous galaxies at z > 10. We further predict that analogs at z ∼ 8 should exist according to the SFH of early massive quiescent galaxies. However, they may fall below the current detection limits of wide JWST and ALMA surveys, and thus remain “JWST-dark.” To fully trace the evolution of massive galaxies and dust-obscured cosmic star formation at z ≳ 8, wide-field JWST/NIRCam imaging and slitless spectroscopic surveys of early protoclusters are essential.
Source: The Astrophysical Journal
Authors: Fengwu Sun, Jinyi Yang, Feige Wang, Daniel J. Eisenstein, Roberto Decarli, Xiaohui Fan, George H. Rieke, Eduardo Bañados, Sarah E. I. Bosman, Zheng Cai, Jaclyn B. Champagne, Luis Colina, Francesco D’Eugenio, Yoshinobu Fudamoto, Mingyu Li, Xiaojing Lin, Weizhe Liu, Jianwei Lyu, Chiara Mazzucchelli, Xiangyu Jin, Hyunsung D. Jun, Wei Leong Tee, Yunjing Wu, Huanian Zhang
Institutions: Center for Astrophysics Harvard & Smithsonian, University of Michigan, Osservatorio di Astrofisica e Scienza dello Spazio, National Institute for Astrophysics, University of Arizona, Max Planck Institute for Astronomy, Heidelberg University, Tsinghua University, Space Telescope Science Institute, Centro de Astrobiología, University of Cambridge, Chiba University, Universidad Diego Portales, Pennsylvania State University, Huazhong University of Science and Technology
Language: English
Subfield: Astronomy and Astrophysics
Field: Physics and Astronomy
Domain: Physical Sciences
Open Access status: gold
Estimated APC paid: $4,499
Funders: National Science Foundation, National Aeronautics and Space Administration, Space Telescope Science Institute, National Radio Astronomy Observatory, Deutsche Forschungsgemeinschaft, Korea Astronomy and Space Science Institute, Ministerio de Ciencia e Innovación, National Astronomical Observatory of Japan, Agencia Nacional de Investigación y Desarrollo, National Institutes of Natural Sciences, European Regional Development Fund, Agencia Estatal de Investigación
Awards: G103270039, G1166668239, G1199145202, G121809054, G1622782223, G1824424381, ASPIRE - A Legacy Survey of Quasars in the Epoch of Reionization, G2309174360, G256731684, G2660406951, G3010137097, G3340416472, G3457489054, G3518538256, A PANCHROMATIC VIEW OF RADIO-LOUD QUASARS IN THE EARLY UNIVERSE, G5568641063, CENTRO DE ASTROFISICA Y TECNOLOGIAS AFINES (CATA), G897484643
OpenAlex ID: W7162408075