Are JWST/NIRCam Color Gradients in the Lensed z = 2.3 Dusty Star-forming Galaxy El Anzuelo Due to Central Dust Attenuation or Inside-out Galaxy Growth?

Patrick S. Kamieneski, Brenda L. Frye, Massimo Pascale, Seth H. Cohen, Rogier A. Windhorst, Rolf A. Jansen, Min S. Yun, Cheng Cheng, Jake S. Summers, Timothy Carleton, Kevin C. Harrington, Jose M. Diego, Haojing Yan, Anton M. Koekemoer, Christopher N.A. Willmer, Andreea Petric, Lukas J. Furtak, Nicholas Foo, Christopher J. Conselice, Dan CoeSimon P. Driver, Norman A. Grogin, Madeline A. Marshall, Mario Nonino, Nor Pirzkal, Aaron S.G. Robotham, Russell E. Ryan, Scott Tompkins

Research output: Contribution to journalArticlepeer-review

1 Scopus citations


Gradients in the mass-to-light ratio of distant galaxies impede our ability to characterize their size and compactness. The long-wavelength filters of JWST’s NIRCam offer a significant step forward. For galaxies at Cosmic Noon (z ∼ 2), this regime corresponds to the rest-frame near-infrared, which is less biased toward young stars and captures emission from the bulk of a galaxy’s stellar population. We present an initial analysis of an extraordinary lensed dusty star-forming galaxy at z = 2.3 behind the El Gordo cluster (z = 0.87), named El Anzuelo (“The Fishhook”) after its partial Einstein-ring morphology. The far-UV to near-IR spectral energy distribution suggests an intrinsic star formation rate of 81 − 2 + 7 M ⊙ yr − 1 and dust attenuation A V ≈ 1.6, in line with other DSFGs on the star-forming main sequence. We develop a parametric lens model to reconstruct the source-plane structure of dust imaged by the Atacama Large Millimeter/submillimeter Array, far-UV to optical light from Hubble, and near-IR imaging with 8 filters of JWST/NIRCam, as part of the Prime Extragalactic Areas for Reionization and Lensing Science program. The source-plane half-light radius is remarkably consistent from ∼1 to 4.5 μm, despite a clear color gradient where the inferred galaxy center is redder than the outskirts. We interpret this to be the result of both a radially decreasing gradient in attenuation and substantial spatial offsets between UV- and IR-emitting components. A spatial decomposition of the SED reveals modestly suppressed star formation in the inner kiloparsec, which suggests that we are witnessing the early stages of inside-out quenching.

Original languageEnglish (US)
Article number91
JournalAstrophysical Journal
Issue number2
StatePublished - Oct 1 2023

ASJC Scopus subject areas

  • Astronomy and Astrophysics
  • Space and Planetary Science


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