JWST/CEERS sheds light on dusty star-forming galaxies: Forming bulges, lopsidedness, and outside-in quenching at cosmic noon

¹ Université Paris-Saclay, Université Paris Cité, CEA, CNRS, AIM, 91191 Gif-sur-Yvette, France
e-mail: alebail@ucmerced.edu
² NSF’s National Optical-Infrared Astronomy Research Laboratory, 950 N. Cherry Ave., Tucson, AZ 85719, USA
³ University of Massachusetts Amherst, 710 North Pleasant Street, Amherst, MA 01003-9305, USA
⁴ Kavli Institute for the Physics and Mathematics of the Universe, The University of Tokyo, Kashiwa 277-8583, Japan
⁵ Kavli Institute for Astronomy and Astrophysics, Peking University, Beijing 100871, PR China
⁶ Center for Data-Driven Discovery, Kavli IPMU (WPI), UTIAS, The University of Tokyo, Kashiwa, Chiba 277-8583, Japan
⁷ Space Telescope Science Institute, 3700 San Martin Drive, Baltimore, MD 21218, USA
⁸ Physics & Astronomy Department, University of Louisville, 40292 KY, Louisville, USA
⁹ Department of Physics and Astronomy, University of California, 900 University Ave, Riverside, CA 92521, USA
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 Dipartimento di Fisica e Astronomia “G.Galilei”, Universitá di Padova, Via Marzolo 8, 35131 Padova, Italy
¹³ INAF – Osservatorio Astronomico di Padova, Vicolo dell’Osservatorio 5, 35122 Padova, Italy
¹⁴ Department of Astronomy, The University of Texas at Austin, Austin, TX, USA
¹⁵ Centro de Astrobiología (CAB), CSIC-INTA, Ctra. de Ajalvir km 4, Torrejón de Ardoz, 28850 Madrid, Spain
¹⁶ School of Astronomy and Space Science, Nanjing University, Nanjing 210093, PR China
¹⁷ Key Laboratory of Modern Astronomy and Astrophysics (Nanjing University), Ministry of Education, Nanjing 210093, PR China
¹⁸ Astronomy Centre, University of Sussex, Falmer, Brighton BN1 9QH, UK
¹⁹ Institute of Space Sciences and Astronomy, University of Malta, Msida, MSD 2080, Malta
²⁰ Laboratory for Multiwavelength Astrophysics, School of Physics and Astronomy, Rochester Institute of Technology, 84 Lomb Memorial Drive, Rochester, NY 14623, USA
²¹ Department of Physics and Astronomy, Texas A&M University, College Station, TX 77843-4242, USA
²² George P. and Cynthia Woods Mitchell Institute for Fundamental Physics and Astronomy, Texas A&M University, College Station, TX 77843-4242, USA
²³ ESA/AURA Space Telescope Science Institute, USA
²⁴ ESA/AURA Space Telescope Science Institute and Astrophysics Science Division, NASA Goddard Space Flight Center, 8800 Greenbelt Rd, Greenbelt, MD 20771, USA

Received: 14 July 2023
Accepted: 30 April 2024

Abstract

Context. We investigate the morphology and resolved physical properties of a sample of 22 IR-selected dusty star-forming galaxies at cosmic noon using the James Webb Space Telescope NIRCam images obtained in the EGS field for the CEERS survey. The exceptional resolution of the NIRCam images allowed us to spatially resolve these galaxies up to 4.4 μm and identify their bulge or core even when very extinguished by dust.

Aims. The goal of this study is to obtain a better understanding of the formation and evolution of FIR-bright galaxies by spatially resolving their properties using JWST in order to look through the dust and bridge the gap between the compact FIR sources and the larger optical star-forming galaxies.

Methods. Based on red-green-blue images from the F115W, F200W, and F444W filters, we divided each galaxy into several uniformly colored regions, fit their respective SEDs, and measured physical properties. After classifying each region as star forming or quiescent, we assigned galaxies to three classes depending on whether active star formation is located in the core, in the disk, or in both.

Results. (i) We find that the galaxies at a higher redshift tend to have a fragmented disk with a low core mass fraction. They are at an early stage of bulge formation. When moving toward a lower redshift, the core mass fraction increases, and the bulge growth is associated with a stabilization of the disk, which translates into less patches and clumps. The NIRCam data clearly point toward bulge formation in preexisting disks. (ii) Lopsidedness is a very common feature of DSFGs. It has been wrongly overlooked for a long time and could have a major impact on the evolution of DSFGs. (iii) Twenty-three percent of the galaxies have a star-forming core embedded in a quiescent disk. They seem to be undergoing outside-in quenching, often facilitated by their strong lopsidedness inducing instabilities. (iv) We show that half of our galaxies with star formation concentrated in their core are good sub-millimeter galaxy near-IR counterpart candidates, demonstrating that compact SMGs are usually surrounded by a larger, less obscured disk. (v) Finally, we found surprising evidence for clump-like substructures being quiescent or residing in quiescent regions.

Conclusions. This work demonstrates the major impact JWST/NIRCam has on understanding the complexity of the evolution of distant massive galaxies regarding bulge formation and quenching mechanisms.