CEERS Key Paper. IV. A Triality in the Nature of HST-dark Galaxies
Pablo G. Pérez‐González, Guillermo Barro, Marianna Annunziatella, Luca Costantin, Ángela García-Argumánez, Elizabeth J. McGrath, Rosa M. Mérida, Jorge A. Zavala, Pablo Arrabal Haro, Micaela B. Bagley, Bren E. Backhaus, Peter Behroozi, Eric F. Bell, Laura Bisigello, V. Buat, Antonello Calabrò, Caitlin M. Casey, Nikko J. Cleri, R. T. Coogan, Michael C. Cooper, Asantha Cooray, Avishai Dekel, Mark Dickinson, D. Elbaz, Henry C. Ferguson, Steven L. Finkelstein, A. Fontana, Maximilien Franco, Jonathan P. Gardner, Mauro Giavalisco, Carlos Gómez-Guijarro, A. Grazian, Norman A. Grogin, Yuchen Guo, Shardha Jogee, Jeyhan S. Kartaltepe, Lisa J. Kewley, Allison Kirkpatrick, Dale D. Kocevski, Anton M. Koekemoer, Arianna S. Long, Jennifer M. Lotz, Ray A. Lucas, Casey Papovich, Nor Pirzkal, Swara Ravindranath, Rachel S. Somerville, Sandro Tacchella, Jonathan R. Trump, Weichen Wang, Stephen M. Wilkins, Stijn Wuyts, Guang Yang, L. Y. Aaron Yung
Abstract
Abstract The new capabilities that JWST offers in the near- and mid-infrared (IR) are used to investigate in unprecedented detail the nature of optical/near-IR-faint, mid-IR-bright sources, with HST-dark galaxies among them. We gather JWST data from the CEERS survey in the Extended Groth Strip, jointly with HST data, and analyze spatially resolved optical-to-mid-IR spectral energy distributions to estimate photometric redshifts in two dimensions and stellar population properties on a pixel-by-pixel basis for red galaxies detected by NIRCam. We select 138 galaxies with F150W − F356W > 1.5 mag and F356W < 27.5 mag. The nature of these sources is threefold: (1) 71% are dusty star-forming galaxies (SFGs) at 2 < z < 6 with <mml:math xmlns:mml="http://www.w3.org/1998/Math/MathML" overflow="scroll"> <mml:mn>9</mml:mn> <mml:mo><</mml:mo> <mml:mi>log</mml:mi> <mml:msub> <mml:mrow> <mml:mi>M</mml:mi> </mml:mrow> <mml:mrow> <mml:mo>⋆</mml:mo> </mml:mrow> </mml:msub> <mml:mrow> <mml:mo stretchy="true">/</mml:mo> </mml:mrow> <mml:msub> <mml:mrow> <mml:mi>M</mml:mi> </mml:mrow> <mml:mrow> <mml:mo>⊙</mml:mo> </mml:mrow> </mml:msub> <mml:mo><</mml:mo> <mml:mn>11</mml:mn> </mml:math> and a variety of specific SFRs (<1 to >100 Gyr −1 ); (2) 18% are quiescent/dormant (i.e., subject to reignition/rejuvenation) galaxies (QGs) at 3 < z < 5, with <mml:math xmlns:mml="http://www.w3.org/1998/Math/MathML" overflow="scroll"> <mml:mi>log</mml:mi> <mml:msub> <mml:mrow> <mml:mi>M</mml:mi> </mml:mrow> <mml:mrow> <mml:mo>⋆</mml:mo> </mml:mrow> </mml:msub> <mml:mrow> <mml:mo stretchy="true">/</mml:mo> </mml:mrow> <mml:msub> <mml:mrow> <mml:mi>M</mml:mi> </mml:mrow> <mml:mrow> <mml:mo>⊙</mml:mo> </mml:mrow> </mml:msub> <mml:mo>∼</mml:mo> <mml:mn>10</mml:mn> </mml:math> and poststarburst mass-weighted ages (0.5–1.0 Gyr); and (3) 11% are strong young starbursts with indications of high equivalent width emission lines (typically, [O iii ]+H β ) at 6 < z < 7 (XELG- z 6) and <mml:math xmlns:mml="http://www.w3.org/1998/Math/MathML" overflow="scroll"> <mml:mi>log</mml:mi> <mml:msub> <mml:mrow> <mml:mi>M</mml:mi> </mml:mrow> <mml:mrow> <mml:mo>⋆</mml:mo> </mml:mrow> </mml:msub> <mml:mrow> <mml:mo stretchy="true">/</mml:mo> </mml:mrow> <mml:msub> <mml:mrow> <mml:mi>M</mml:mi> </mml:mrow> <mml:mrow> <mml:mo>⊙</mml:mo> </mml:mrow> </mml:msub> <mml:mo>∼</mml:mo> <mml:mn>9.5</mml:mn> </mml:math> . The sample is dominated by disk-like galaxies with remarkable compactness for XELG- z 6 (effective radii smaller than 0.4 kpc). Large attenuations in SFGs, 2 < A ( V ) < 5 mag, are found within 1.5 times the effective radius, approximately 2 kpc, while QGs present A ( V ) ∼ 0.2 mag. Our SED-fitting technique reproduces the expected dust emission luminosities of IR-bright and submillimeter galaxies. This study implies high levels of star formation activity between z ∼ 20 and z ∼ 10, where virtually 100% of our galaxies had already formed 10 8 M ⊙ , 60% had assembled 10 9 M ⊙ , and 10% up to 10 10 M ⊙ (in situ or ex situ).