The Identification of Two JWST/NIRCam-dark Starburst Galaxies at z = 6.6 with ALMA

@article{sun2026identification,
  title = {{The Identification of Two JWST/NIRCam-dark Starburst Galaxies at z = 6.6 with ALMA}},
  author = {Fengwu Sun and Jie Yang and Feige Wang and Daniel J. Eisenstein and Roberto Decarli and Xiaohui Fan and George H. Rieke and Eduardo Bañados and Sarah E. I. Bosman and Zheng Cai and Jaclyn B. Champagne and Luis Colina and Francesco D’Eugenio and Yoshinobu Fudamoto and Mingyu Li and Xiaojing Lin and Weizhe Liu and Jianwei Lyu and Chiara Mazzucchelli and Xiangyu Jin and Hyunsung D. Jun and Wei Leong Tee and Y N Wu and Huanian Zhang},
  journal = {The Astrophysical Journal},
  year = {2026},
  month = may,
  doi = {10.3847/1538-4357/ae66e3},
  url = {https://doi.org/10.3847/1538-4357/ae66e3},
  note = {CC BY},
}

TY  - JOUR
TI  - The Identification of Two JWST/NIRCam-dark Starburst Galaxies at z = 6.6 with ALMA
AU  - Fengwu Sun
AU  - Jie Yang
AU  - Feige Wang
AU  - Daniel J. Eisenstein
AU  - Roberto Decarli
AU  - Xiaohui Fan
AU  - George H. Rieke
AU  - Eduardo Bañados
AU  - Sarah E. I. Bosman
AU  - Zheng Cai
AU  - Jaclyn B. Champagne
AU  - Luis Colina
AU  - Francesco D’Eugenio
AU  - Yoshinobu Fudamoto
AU  - Mingyu Li
AU  - Xiaojing Lin
AU  - Weizhe Liu
AU  - Jianwei Lyu
AU  - Chiara Mazzucchelli
AU  - Xiangyu Jin
AU  - Hyunsung D. Jun
AU  - Wei Leong Tee
AU  - Y N Wu
AU  - Huanian Zhang
PY  - 2026
DA  - 2026/05/26
JO  - The Astrophysical Journal
DO  - 10.3847/1538-4357/ae66e3
UR  - https://doi.org/10.3847/1538-4357/ae66e3
AB  - 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.
SN  - 0004-637X
SN  - 1538-4357
ER  -