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?

分类： 天文学 >> 天文学 提交时间： 2023-02-19

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 Coe

摘要： 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 ($z\sim2$), this regime corresponds to the rest-frame near-infrared, which is less biased towards 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 (DSFG) at $z=2.3$ behind the $El~Gordo$ cluster ($z=0.87$), named $El~Anzuelo$ ("The Fishhook") after its partial Einstein-ring morphology. The FUV-NIR SED suggests an intrinsic star formation rate of $81^{+7}_{-2}~M_\odot~{\rm yr}^{-1}$ and dust attenuation $A_V\approx 1.6$, 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 (PEARLS) program. The source-plane half-light radius is remarkably consistent from $\sim 1-4.5~\mu$m, 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.

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