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

¹ Université Paris-Saclay, Université Paris Cité, CEA, CNRS, AIM, 91191 Gif-sur-Yvette, France
e-mail: carlos.gomezguijarro@cea.fr
² Department of Physics, University of Bath, Claverton Down, Bath BA2 7AY, UK
³ University of Massachusetts Amherst, 710 North Pleasant Street, Amherst, MA 01003-9305, USA
⁴ NSF’s National Optical-Infrared Astronomy Research Laboratory, 950 N. Cherry Ave., Tucson, AZ 85719, USA
⁵ Centro de Astrobiología (CAB), CSIC-INTA, Ctra. de Ajalvir km 4, Torrejón de Ardoz, 28850 Madrid, Spain
⁶ Department of Astronomy, The University of Texas at Austin, Austin, TX, USA
⁷ INAF–Osservatorio Astronomico di Padova, Vicolo dell’Osservatorio 5, 35122 Padova, Italy
⁸ Dipartimento di Fisica e Astronomia “G.Galilei”, Universitá di Padova, Via Marzolo 8, 35131 Padova, Italy
⁹ Aix Marseille Univ, CNRS, CNES, LAM, Marseille, France
¹⁰ INAF–Osservatorio Astronomico di Roma, via di Frascati 33, 00078 Monte Porzio Catone, Italy
¹¹ Racah Institute of Physics, The Hebrew University of Jerusalem, Jerusalem 91904, Israel
¹² Space Telescope Science Institute, 3700 San Martin Drive, Baltimore, MD 21218, USA
¹³ Physics & Astronomy Department, University of Louisville, 40292 KY, Louisville, USA
¹⁴ Cosmic Dawn Center (DAWN), Copenhagen, Denmark
¹⁵ DTUSpace, Technical University of Denmark, Elektrovej 327, 2800 Kgs. Lyngby, Denmark
¹⁶ Niels Bohr Institute, University of Copenhagen, Jagtvej 128, 2200 Copenhagen, Denmark
¹⁷ Laboratory for Multiwavelength Astrophysics, School of Physics and Astronomy, Rochester Institute of Technology, 84 Lomb Memorial Drive, Rochester, NY 14623, USA
¹⁸ Kapteyn Astronomical Institute, University of Groningen, PO Box 800 9700AV Groningen, The Netherlands
¹⁹ Department of Physics and Astronomy, Texas A&M University, College Station, TX 77843-4242, USA
²⁰ George P. and Cynthia Woods Mitchell Institute for Fundamental Physics and Astronomy, Texas A&M University, College Station, TX 77843-4242, USA
²¹ ESA/AURA Space Telescope Science Institute, 3700 San Martin Drive, Baltimore, MD 21218, USA
²² Kavli Institute for Cosmology, University of Cambridge, Madingley Road, Cambridge CB3 0HA, UK
²³ Cavendish Laboratory, University of Cambridge, 19 JJ Thomson Avenue, Cambridge CB3 0HE, UK
²⁴ European Southern Observatory, Karl-Schwarzschild-Str. 2, 85748 Garching bei Munchen, Germany
²⁵ Department of Physics and Astronomy, University of California, 900 University Ave, Riverside, CA 92521, USA
²⁶ Astronomy Centre, University of Sussex, Falmer, Brighton BN1 9QH, UK
²⁷ Institute of Space Sciences and Astronomy, University of Malta, Msida, MSD 2080, Malta
²⁸ Department of Astronomy, University of Geneva, Chemin Pegasi 51, 1290 Versoix, Switzerland
²⁹ Astrophysics Science Division, NASA Goddard Space Flight Center, 8800 Greenbelt Rd, Greenbelt, MD 20771, USA

Received: 17 April 2023
Accepted: 16 June 2023

Abstract

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.