CEERS Key Paper. IV. A Triality in the Nature of HST-dark Galaxies


Change log
Abstract

jats:titleAbstract</jats:title> jats:pThe 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 < jats:italicz</jats:italic> < 6 with jats:inline-formula jats:tex-math

</jats:tex-math> <mml:math xmlns:mml="http://www.w3.org/1998/Math/MathML" overflow="scroll"> mml:mn9</mml:mn> mml:mo<</mml:mo> mml:milog</mml:mi> mml:msub mml:mrow mml:miM</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:miM</mml:mi> </mml:mrow> mml:mrow mml:mo⊙</mml:mo> </mml:mrow> </mml:msub> mml:mo<</mml:mo> mml:mn11</mml:mn> </mml:math> <jats:inline-graphic xmlns:xlink="http://www.w3.org/1999/xlink" xlink:href="apjlacb3a5ieqn1.gif" xlink:type="simple" /> </jats:inline-formula> and a variety of specific SFRs (<1 to >100 Gyrjats:sup−1</jats:sup>); (2) 18% are quiescent/dormant (i.e., subject to reignition/rejuvenation) galaxies (QGs) at 3 < jats:italicz</jats:italic> < 5, with jats:inline-formula jats:tex-math

</jats:tex-math> <mml:math xmlns:mml="http://www.w3.org/1998/Math/MathML" overflow="scroll"> mml:milog</mml:mi> mml:msub mml:mrow mml:miM</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:miM</mml:mi> </mml:mrow> mml:mrow mml:mo⊙</mml:mo> </mml:mrow> </mml:msub> mml:mo∼</mml:mo> mml:mn10</mml:mn> </mml:math> <jats:inline-graphic xmlns:xlink="http://www.w3.org/1999/xlink" xlink:href="apjlacb3a5ieqn2.gif" xlink:type="simple" /> </jats:inline-formula> 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 jats:sciii</jats:sc>]+Hjats:italicβ</jats:italic>) at 6 < jats:italicz</jats:italic> < 7 (XELG-jats:italicz</jats:italic>6) and jats:inline-formula jats:tex-math

</jats:tex-math> <mml:math xmlns:mml="http://www.w3.org/1998/Math/MathML" overflow="scroll"> mml:milog</mml:mi> mml:msub mml:mrow mml:miM</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:miM</mml:mi> </mml:mrow> mml:mrow mml:mo⊙</mml:mo> </mml:mrow> </mml:msub> mml:mo∼</mml:mo> mml:mn9.5</mml:mn> </mml:math> <jats:inline-graphic xmlns:xlink="http://www.w3.org/1999/xlink" xlink:href="apjlacb3a5ieqn3.gif" xlink:type="simple" /> </jats:inline-formula>. The sample is dominated by disk-like galaxies with remarkable compactness for XELG-jats:italicz</jats:italic>6 (effective radii smaller than 0.4 kpc). Large attenuations in SFGs, 2 < jats:italicA</jats:italic>(jats:italicV</jats:italic>) < 5 mag, are found within 1.5 times the effective radius, approximately 2 kpc, while QGs present jats:italicA</jats:italic>(jats:italicV</jats:italic>) ∼ 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 jats:italicz</jats:italic> ∼ 20 and jats:italicz</jats:italic> ∼ 10, where virtually 100% of our galaxies had already formed 10jats:sup8</jats:sup> jats:italicM</jats:italic> jats:sub⊙</jats:sub>, 60% had assembled 10jats:sup9</jats:sup> jats:italicM</jats:italic> jats:sub⊙</jats:sub>, and 10% up to 10jats:sup10</jats:sup> jats:italicM</jats:italic> jats:sub⊙</jats:sub> (in situ or ex situ).</jats:p>

Description
Keywords
5109 Space Sciences, 51 Physical Sciences
Journal Title
Astrophysical Journal Letters
Conference Name
Journal ISSN
2041-8205
2041-8213
Volume Title
Publisher
American Astronomical Society