Galaxy morphology from z ∼ 6 through the lens of JWST^⋆

¹ Instituto de Astrofísica de Canarias (IAC), La Laguna 38205, Spain
e-mail: mhuertas@iac.es
² Observatoire de Paris, LERMA, PSL University, 61 avenue de l’Observatoire, 75014 Paris, France
³ Université Paris-Cité, 5 rue Thomas Mann, 75014 Paris, France
⁴ Universidad de La Laguna, Avda. Astrofísico Fco. Sanchez, La Laguna, Tenerife, Spain
⁵ Columbia Astrophysics Laboratory, Columbia University, 550 West 120th Street, New York, NY 10027, USA
⁶ NSF’s National Optical-Infrared Astronomy Research Laboratory, 950 N. Cherry Ave., Tucson, AZ 85719, USA
⁷ Department of Astronomy, The University of Texas at Austin, Austin, TX, USA
⁸ Department of Astronomy and Steward Observatory, University of Arizona, Tucson, AZ 85721, USA
⁹ Division of Science, National Astronomical Observatory of Japan, 2-21-1 Osawa, Mitaka, Tokyo 181-8588, Japan
¹⁰ Departamento de Física Teórica, Atómica y Óptica, Universidad de Valladolid, 47011 Valladolid, Spain
¹¹ Instituto de Astrofísica e Ciências do Espaço, Universidade de Lisboa, OAL, Tapada da Ajuda, 1349-018 Lisbon, Portugal
¹² University of Massachusetts Amherst, 710 North Pleasant Street, Amherst, MA 01003-9305, USA
¹³ Centro de Astrobiología (CAB), CSIC-INTA, Ctra. de Ajalvir km 4, Torrejón de Ardoz, 28850 Madrid, Spain
¹⁴ Centre for Astrophysics and Planetary Science, Racah Institute of Physics, The Hebrew University, Jerusalem 91904, Israel
¹⁵ Santa Cruz Institute for Particle Physics, University of California, Santa Cruz, CA 95064, USA
¹⁶ Laboratoire AIM-Paris-Saclay, CEA/DRF/Irfu – CNRS – Université Paris Cité, CEA-Saclay, pt courrier 131, 91191 Gif-surYvette, France
¹⁷ Physics & Astronomy Department, University of Louisville, Louisville, KY 40292, USA
¹⁸ Laboratory for Multiwavelength Astrophysics, School of Physics and Astronomy, Rochester Institute of Technology, 84 Lomb Memorial Drive, Rochester, NY 14623, USA
¹⁹ Space Telescope Science Institute, 3700 San Martin Dr., Baltimore, MD 21218, USA
²⁰ Department of Physics and Astronomy, Texas A&M University, College Station, TX 77843-4242, USA
²¹ George P. and Cynthia Woods Mitchell Institute for Fundamental Physics and Astronomy, Texas A&M University, College Station, TX 77843-4242, USA
²² ESA/AURA Space Telescope Science Institute, Baltimore, MD, USA
²³ Aix-Marseille Univ., CNRS, CNES, LAM Marseille, Marseille, France
²⁴ Department of Physics and Astronomy, University of California, 900 University Ave, Riverside, CA 92521, USA
²⁵ Department of Physics, University of Bath, Claverton Down, Bath BA2 7AY, UK
²⁶ Kapteyn Astronomical Institute, University of Groningen, PO Box 800 9700 AV Groningen, The Netherlands
²⁷ SRON Netherlands Institute for Space Research, Postbus 800 9700 AV Groningen, The Netherlands
²⁸ Astrophysics Science Division, NASA Goddard Space Flight Center, 8800 Greenbelt Rd, Greenbelt, MD 20771, USA
²⁹ Department of Physics and Astronomy, Colby College, Waterville, ME 04901, USA
³⁰ Center for Computational Astrophysics, Flatiron Institute, New York, USA

Received: 2 May 2023
Accepted: 8 October 2023

Abstract

Context. The James Webb Space Telescope’s (JWST’s) unprecedented combination of sensitivity, spatial resolution, and infrared coverage has enabled a new era of galaxy morphology exploration across most of cosmic history.

Aims. We analyze the near-infrared (NIR ∼ 0.8 − 1 μm) rest-frame morphologies of galaxies with log M_*/M_⊙ > 9 in the redshift range of 0 < z < 6, compare with previous HST-based results and release the first JWST-based morphological catalog of ∼20 000 galaxies in the CEERS survey.

Methods. We classified the galaxies in our sample into four main broad classes: spheroid, disk+spheroid, disk, and disturbed, based on imaging with four filters: F150W, F200W, F356W, and F444W. We used convolutional neural networks (CNNs) trained on HST/WFC3 labeled images and domain-adapted to JWST/NIRCam.

Results. We find that ∼90% and ∼75% of galaxies at z < 3 have the same early and late and regular and irregular classification, respectively, in JWST and HST imaging when considering similar wavelengths. For small (large) and faint objects, JWST-based classifications tend to systematically present less bulge-dominated systems (peculiar galaxies) than HST-based ones, but the impact on the reported evolution of morphological fractions is less than ∼10%. Using JWST-based morphologies at the same rest-frame wavelength (∼0.8 − 1 μm), we confirm an increase in peculiar galaxies and a decrease in bulge-dominated galaxies with redshift, as reported in previous HST-based works, suggesting that the stellar mass distribution, in addition to light distribution, is more disturbed in the early Universe. However, we find that undisturbed disk-like systems already dominate the high-mass end of the late-type galaxy population (log M_*/M_⊙ > 10.5) at z ∼ 5, and bulge-dominated galaxies also exist at these early epochs, confirming a rich and evolved morphological diversity of galaxies ∼1 Gyr after the Big Bang. Finally, we find that the morphology-quenching relation is already in place for massive galaxies at z > 3, with massive quiescent galaxies (log M_*/M_⊙ > 10.5) being predominantly bulge-dominated.