Delving deep: A population of extremely dusty dwarfs observed by JWST

¹ Dipartimento di Fisica e Astronomia, Università di Padova, Vicolo dell’Osservatorio, 3, 35122 Padova, Italy
e-mail: laura.bisigello@unipd.it
² INAF – Osservatorio Astronomico di Padova, Vicolo dell’Osservatorio 5, 35122 Padova, Italy
³ Scuola Internazionale Superiore Studi Avanzati (SISSA), Physics Area, Via Bonomea 265, 34136 Trieste, Italy
⁴ Institute for Fundamental Physics of the Universe (IFPU), Via Beirut 2, 34014 Trieste, Italy
⁵ Istituto Nazionale Fisica Nucleare (INFN), Sezione di Trieste, Via Valerio 2, 34127 Trieste, Italy
⁶ Centro de Astrobiología (CAB), CSIC-INTA, Ctra de Ajalvir km 4, Torrejón de Ardoz, 28850 Madrid, Spain
⁷ Department of Physics & Astronomy, University of California, Irvine, 4129 Reines Hall, Irvine, CA 92697, USA
⁸ INAF – Osservatorio di Astrofisica e Scienza dello Spazio, Via Gobetti 93/3, 40129 Bologna, Italy
⁹ Space Telescope Science Institute, 3700 San Martin Dr., Baltimore, MD 21218, USA
¹⁰ Physics & Astronomy Department, University of Louisville, Louisville, 40292 KY, USA
¹¹ Department of Physics and Astronomy and PITT PACC, University of Pittsburgh, Pittsburgh, PA 15260, USA
¹² Astrophysics Science Division, NASA Goddard Space Flight Center, 8800 Greenbelt Rd, Greenbelt, MD 20771, USA
¹³ Department of Physics and Astronomy, University of California, 900 University Ave., Riverside, CA 92521, USA
¹⁴ NSF’s National Optical-Infrared Astronomy Research Laboratory, 950 N. Cherry Ave., Tucson, AZ 85719, USA
¹⁵ Department of Astronomy, The University of Texas at Austin, Austin, TX, USA
¹⁶ Laboratory for Multiwavelength Astrophysics, School of Physics and Astronomy, Rochester Institute of Technology, 84 Lomb Memorial Drive, Rochester, NY 14623, USA
¹⁷ Department of Physics and Astronomy, Texas A&M University, College Station, TX 77843-4242, USA
¹⁸ George P. and Cynthia Woods Mitchell Institute for Fundamental Physics and Astronomy, Texas A&M University, College Station, TX 77843-4242, USA
¹⁹ ESA/AURA Space Telescope Science Institute, USA
²⁰ Astronomy Centre, University of Sussex, Falmer, Brighton BN1 9QH, UK
²¹ Institute of Space Sciences and Astronomy, University of Malta, Msida, MSD 2080, Malta

Received: 22 February 2023
Accepted: 22 May 2023

Abstract

Aims. We take advantage of the NIRCam photometric observations available as part of the Cosmic Evolution Early Release Science survey (CEERS) to identify and analyse very red sources in an effort to discover very dusty star forming galaxies.

Methods. We select red galaxies as objects with a S/N > 3 at 4.4 μm and a S/N < 2 in all JWST and HST filters at λ ≤ 2 μm, which corresponds to [F200W]−[F444W]> 1.2 considering CEERS depths. This selection is ideal to identify very dusty (A_V > 1 mag) galaxies with stellar masses between 10⁶ and 10¹⁰ M_⊙ at z < 5, more massive dusty galaxies at z = 5 − 18 and galaxies at z > 18 due to the Lyman absorption, independently of their dust extinction.

Results. Our sample of F200W-dropouts contains no strong candidates at z > 6.5, instead it consists almost completely (∼81%) of z < 2 low-mass galaxies, with a median stellar mass of 10^7.3 M_⊙. These galaxies show an exceptional dust extinction with median value of A_V = 4.9 mag, completely unexpected given their low stellar mass. The remaining galaxies, which are at z < 6.5, show similar large dust extinction (A_V > 1), but they are generally more massive > 10^7.5 M_⊙.