EPOCHS. XI. The Structure and Morphology of Galaxies in the Epoch of Reionization to z ∼ 12.5

EPOCHS. XI. The Structure and Morphology of Galaxies in the Epoch of Reionization to z ∼ 12.5

We present a structural analysis of 520 galaxy candidates at 6.5 < z < 12.5 with a signal-to-noise ratio of >10 σ in the F444W filter taken from the EPOCHS v1 sample, consisting of uniformly reduced deep JWST NIRCam data covering the CEERS, JADES GOODS-S, NGDEEP, SMACS-0723, GLASS, and PEAR...

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Main Authors: Lewi Westcott, Christopher J. Conselice, Thomas Harvey, Duncan Austin, Nathan Adams, Fabricio Ferrari, Leonardo Ferreira, James Trussler, Qiong Li, Vadim Rusakov, Qiao Duan, Honor Harris, Caio Goolsby, Thomas J. Broadhurst, Dan Coe, Seth H. Cohen, Simon P. Driver, Jordan C. J. D’Silva, Brenda Frye, Norman A. Grogin, Nimish P. Hathi, Rolf A. Jansen, Anton M. Koekemoer, Madeline A. Marshall, Rafael Ortiz III, Nor Pirzkal, Aaron Robotham, Russell E. Ryan Jr, Jake Summers, Christopher N. A. Willmer, Rogier A. Windhorst, Haojing Yan
Format: Article
Language:English
Published: IOP Publishing 2025-01-01
Series:The Astrophysical Journal
Subjects:
High-redshift galaxies
Galaxies
Galaxy structure
Online Access:https://doi.org/10.3847/1538-4357/adb968
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Summary:We present a structural analysis of 520 galaxy candidates at 6.5 < z < 12.5 with a signal-to-noise ratio of >10 σ in the F444W filter taken from the EPOCHS v1 sample, consisting of uniformly reduced deep JWST NIRCam data covering the CEERS, JADES GOODS-S, NGDEEP, SMACS-0723, GLASS, and PEARLS surveys. We use standard software to fit single Sérsic models to each galaxy in the rest-frame optical and extract their parametric structural parameters (Sérsic index, half-light radius, and axis ratio) and Morfometryka to measure their nonparametric concentration and asymmetry parameters. We find a wide range of sizes for these early galaxies, with galaxy sizes overall continuing to become progressively smaller in the high-redshift regime, following ${R}_{e}=\left(2.12\pm 0.28\right){\left(1+z\right)}^{-0.67\pm 0.06}$ kpc. We further find a galaxy size–mass correlation up to z ∼ 12, with galaxies of a given mass also becoming smaller. Using nonparametric methods, we find that galaxy merger fractions, classified through asymmetry parameters, at these redshifts remain consistent with those in the literature, maintaining a value of f _m ∼ 0.12 ± 0.07 showing little dependence with redshift when combined with the literature at z > 4. We find that galaxies that are smaller in size also appear rounder, with an excess of high axis ratio objects. Finally, we artificially redshift a subsample of our objects to determine how robust the observational trends we see are, determining that the observed trends are due to real evolutionary effects, rather than being a consequence of redshift effects.
ISSN:1538-4357

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