Two Massive, Compact, and Dust-obscured Candidate z ≃ 8 Galaxies Discovered by JWST

Authors

• Hollis B. Akins, The University of Texas at Austin
• Caitlin M. Casey, The University of Texas at Austin
• Natalie Allen, Cosmic Dawn Center
• Micaela B. Bagley, The University of Texas at Austin
• Mark Dickinson, NOIRLab
• Steven L. Finkelstein, The University of Texas at Austin
• Maximilien Franco, The University of Texas at Austin
• Santosh Harish, Rochester Institute of Technology
• Pablo Arrabal Haro, NOIRLab
• Olivier Ilbert, Laboratoire d'Astrophysique de Marseille
• Jeyhan S. Kartaltepe, Rochester Institute of Technology
• Anton M. Koekemoer, Space Telescope Science Institute
• Daizhong Liu, Max Planck Institute for Extraterrestrial Physics
• Arianna S. Long, The University of Texas at Austin
• Henry Joy McCracken, Institut d’Astrophysique de Paris
• Louise Paquereau, Institut d’Astrophysique de Paris
• Casey Papovich, Texas A&M University
• Nor Pirzkal, ESA/AURA Space Telescope Science Institute
• Jason Rhodes, California Institute of Technology
• Brant E. Robertson, University of California, Santa Cruz
• Marko Shuntov, Cosmic Dawn Center
• Sune Toft, Cosmic Dawn Center

Document Type

Article

Publication Title

Astrophysical Journal

Department

Physics

ISSN

15384357

Volume

956

Issue

1

DOI

10.3847/1538-4357/acef21

First Page

1

Last Page

17

Publication Date

10-6-2023

Abstract

We present a search for extremely red, dust-obscured, z > 7 galaxies with JWST/NIRCam+MIRI imaging over the first 20 arcmin² of publicly available Cycle 1 data from the COSMOS-Web, CEERS, and PRIMER surveys. Based on their red color in F277W−F444W (∼2.5 mag) and detection in MIRI/F770W (∼25 mag), we identify two galaxies, COS-z8M1 and CEERS-z7M1, that have best-fit photometric redshifts of z = 8.4 − 0.4 + 0.3 and 7.6 − 0.1 + 0.1 , respectively. We perform spectral energy distribution fitting with a variety of codes (including bagpipes, prospector, beagle, and cigale) and find a >95% probability that these indeed lie at z > 7. Both sources are compact (R eff ≲ 200 pc) and highly obscured (A V ∼ 1.5-2.5) and, at our best-fit redshift estimates, likely have strong [O iii]+Hβ emission contributing to their 4.4 μm photometry. We estimate stellar masses of ∼10¹⁰ M ⊙ for both sources; by virtue of detection in MIRI at 7.7 μm, these measurements are robust to the inclusion of bright emission lines, for example, from an active galactic nucleus. We identify a marginal (2.9σ) Atacama Large Millimeter/submillimeter Array detection at 2 mm within 0.″5 of COS-z8M1, which, if real, would suggest a remarkably high IR luminosity of ∼10¹² L ⊙. These two galaxies, if confirmed at z ∼ 8, would be extreme in their stellar and dust masses and may be representative of a substantial population of highly dust-obscured galaxies at cosmic dawn.

Creative Commons License

This work is licensed under a Creative Commons Attribution 4.0 International License.

Recommended Citation

Akins, Hollis B.; Casey, Caitlin M.; Allen, Natalie; Bagley, Micaela B.; Dickinson, Mark; Finkelstein, Steven L.; Franco, Maximilien; Harish, Santosh; Arrabal Haro, Pablo; Ilbert, Olivier; Kartaltepe, Jeyhan S.; Koekemoer, Anton M.; Liu, Daizhong; Long, Arianna S.; McCracken, Henry Joy; Paquereau, Louise; Papovich, Casey; Pirzkal, Nor; Rhodes, Jason; Robertson, Brant E.; Shuntov, Marko; and Toft, Sune, "Two Massive, Compact, and Dust-obscured Candidate z ≃ 8 Galaxies Discovered by JWST" (2023). Pacific Faculty Work. 155.
https://scholarlycommons.pacific.edu/all-faculty/155