Has JWST Seen Everything? Hunting for "NIRCam-dark" Dusty Star-Forming Galaxies at z ≃ 6 − 9 with ALMA2040

@misc{sun2026jwst,
  title = {{Has JWST Seen Everything? Hunting for "NIRCam-dark" Dusty Star-Forming Galaxies at $z \simeq 6 - 9$ with ALMA2040}},
  author = {Fengwu Sun and Belén Alcalde Pampliega and Hiddo Algera and Manuel Aravena and Tom Bakx and Karina I. Caputi and Pierre Cox and Elisabete da Cunha and Andreas Faisst and Yoshinobu Fudamoto and Carlotta Gruppioni and Mahmoud Hamed and Jacqueline Hodge and Patrick S. Kamieneski and Adarsh Kumar and Ivanna Langan and Andrea Lapi and Umberto Maio and Chiara Mazzucchelli and Dieu D. Nguyen and Mamta Pandey-Pommier and Dominik A. Riechers and Irene Shivaei and Sabine Thater},
  howpublished = {arXiv},
  year = {2026},
  month = oct,
  doi = {10.48550/arxiv.2610.20727},
  eprint = {2610.20727},
  archivePrefix = {arXiv},
  url = {https://arxiv.org/abs/2610.20727},
  note = {CC BY 4.0},
}

TY  - UNPB
TI  - Has JWST Seen Everything? Hunting for "NIRCam-dark" Dusty Star-Forming Galaxies at z ≃ 6 − 9 with ALMA2040
AU  - Fengwu Sun
AU  - Belén Alcalde Pampliega
AU  - Hiddo Algera
AU  - Manuel Aravena
AU  - Tom Bakx
AU  - Karina I. Caputi
AU  - Pierre Cox
AU  - Elisabete da Cunha
AU  - Andreas Faisst
AU  - Yoshinobu Fudamoto
AU  - Carlotta Gruppioni
AU  - Mahmoud Hamed
AU  - Jacqueline Hodge
AU  - Patrick S. Kamieneski
AU  - Adarsh Kumar
AU  - Ivanna Langan
AU  - Andrea Lapi
AU  - Umberto Maio
AU  - Chiara Mazzucchelli
AU  - Dieu D. Nguyen
AU  - Mamta Pandey-Pommier
AU  - Dominik A. Riechers
AU  - Irene Shivaei
AU  - Sabine Thater
PY  - 2026
DA  - 2026/10/14
PB  - arXiv
DO  - 10.48550/arxiv.2610.20727
UR  - https://arxiv.org/abs/2610.20727
AB  - JWST/NIRCam has recovered the stellar counterparts of many ALMA-detected, formerly HST-dark galaxies, yet ALMA has started identifying dusty star-forming galaxies (DSFGs) at z>6 that remain extremely faint or undetected even with NIRCam. These "NIRCam-dark" DSFGs may trace a missing rapid-growth phase connecting UV-luminous galaxies at z>10 to massive quiescent galaxies at z≳4. So far, the small, heterogeneously selected NIRCam-dark sample is insufficient to determine their abundance or role in the evolution of massive galaxies. We show that a blind 1.3-mm continuum survey with ALMA2040 can provide the first high-significance census of this elusive NIRCam-dark DSFG population across z≃ 6 − 9. We conduct sensitivity and survey-speed calculations requiring a 10σ detection of a NIRCam-dark DSFG with a dust-obscured star-formation rate of 60 M_⊙ yr^−1 at z = 8. At a like-for-like 7.5-GHz normalization, ALMA2040 will reach the required 1.3-mm RMS of 21 μJy beam^−1 about 90 times faster than current ALMA. With 100 hr on-source, ALMA2040 can cover an area of ∼0.5 deg^2 and detect ⟨ N ⟩∼16 NIRCam-dark DSFGs over 7.5<z<9, assuming a fiducial number density n=3×10^−6 cMpc^−3. Dividing the survey among independent fields with deep JWST coverage would mitigate cosmic variance and enable immediate NIRCam, MIRI, and spectroscopic characterization of their environments. The ≥512-GHz instantaneous bandwidth expected for ALMA2040 will also detect [C II] line at a wide redshift range, supplementing the continuum discovery with redshift confirmation. Such a survey will test whether NIRCam-dark DSFGs trace a missing rapid-growth phase between the earliest UV-luminous galaxies at z>10 and the rapid emergence of massive quiescent systems at z≳ 4.
ER  -