JWST CEERS probes the role of stellar mass and morphology in obscuring galaxies

Carlos Gómez-Guijarro, Benjamin Magnelli, David Elbaz, Stijn Wuyts, Emanuele Daddi, Aurélien Le bail, Mauro Giavalisco, Mark Dickinson, Pablo G. Pérez-González, Pablo Arrabal haro, Micaela B. Bagley, Laura Bisigello, Véronique Buat, Denis Burgarella, Antonello Calabrò, Caitlin M. Casey, Yingjie Cheng, Laure Ciesla, Avishai Dekel, Henry C. FergusonSteven L. Finkelstein, Maximilien Franco, Norman A. Grogin, Benne W. Holwerda, Shuowen Jin, Jeyhan S. Kartaltepe, Anton M. Koekemoer, Vasily Kokorev, Arianna S. Long, Ray A. Lucas, Georgios E. Magdis, Casey Papovich, Nor Pirzkal, Lise-marie Seillé, Sandro Tacchella, Maxime Tarrasse, Francesco Valentino, Alexander De la vega, Mengyuan Xiao, L. Y. Aaron Yung

Research output: Contribution to journalArticlepeer-review

10 Citations (SciVal)


In recent years, observations have uncovered a population of massive galaxies that are invisible or very faint in deep optical/near-infrared (near-IR) surveys but brighter at longer wavelengths. However, the nature of these optically dark or faint galaxies (OFGs; one of several names given to these objects) is highly uncertain. In this work, we investigate the drivers of dust attenuation in the JWST era. In particular, we study the role of stellar mass, size, and orientation in obscuring star-forming galaxies (SFGs) at 3'., <'., z'., <'., 7.5, focusing on the question of why OFGs and similar galaxies are so faint at optical/near-IR wavelengths. We find that stellar mass is the primary proxy for dust attenuation, among the properties studied. Effective radius and axis ratio do not show a clear link with dust attenuation, with the effect of orientation being close to random. However, there is a subset of highly dust attenuated (A V'., >'., 1, typically) SFGs, of which OFGs are a specific case. For this subset, we find that the key distinctive feature is their compact size (for massive systems with log(M /M ) > 10); OFGs exhibit a 30% smaller effective radius than the average SFG at the same stellar mass and redshift. On the contrary, OFGs do not exhibit a preference for low axis ratios (i.e., edge-on disks). The results in this work show that stellar mass is the primary proxy for dust attenuation and compact stellar light profiles behind the thick dust columns obscuring typical massive SFGs.

Original languageEnglish
Article numberA34
JournalAstronomy & Astrophysics
Early online date29 Aug 2023
Publication statusPublished - 1 Sept 2023

Bibliographical note

Funding Information:
C.G.G. acknowledges support from CNES. PGP-G acknowledges support from Spanish Ministerio de Ciencia e Innovación MCIN/AEI/10.13039/501100011033 through grant PGC2018-093499-B-I00. This work is based on observations made with the NASA/ESA/CSA James Webb Space Telescope. The data were obtained from the Mikulski Archive for Space Telescopes at the Space Telescope Science Institute, which is operated by the Association of Universities for Research in Astronomy, Inc., under NASA contract NAS 5-03127 for JWST. These observations are associated with program #1345. We would acknowledge the following open source software used in the analysis: Astropy (Astropy Collaboration 2013, 2018, 2022), photutils (Bradley et al. 2022), APLpy (Robitaille & Bressert 2012), pandas (The pandas development team 2020), NumPy (Harris et al. 2020). We are grateful to the anonymous referee, whose comments have been very useful to improving our work.


  • Galaxies: evolution
  • Galaxies: high-redshift
  • Galaxies: photometry
  • Galaxies: star formation
  • Galaxies: structure
  • Infrared: galaxies

ASJC Scopus subject areas

  • Astronomy and Astrophysics
  • Space and Planetary Science


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