Enhanced Sub-kpc Scale Star-formation: Results From A JWST Size Analysis of 341 Galaxies At 5<z<14

Takahiro Morishita; Massimo Stiavelli; Ranga-Ram Chary; Michele Trenti; Pietro Bergamini; Marco Chiaberge; Nicha Leethochawalit; Guido Roberts-Borsani; Xuejian Shen; Tommaso Treu

arXiv · 2308.05018

Enhanced Sub-kpc Scale Star-formation: Results From A JWST Size Analysis of 341 Galaxies At 5<z<14

Takahiro Morishita·Massimo Stiavelli·Ranga-Ram Chary·Michele Trenti·Pietro Bergamini·Marco Chiaberge·Nicha Leethochawalit·Guido Roberts-Borsani·Xuejian Shen·Tommaso Treu

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Abstract

We present a comprehensive search and analysis of high-redshift galaxies in a suite of nine public JWST extragalactic fields taken in Cycle 1, covering a total effective search area of $\sim358{\rm arcmin^2}$. Through conservative ($8\sigma$) photometric selection, we identify 341 galaxies at $5 1.5\,\sigma$ below the derived size-mass slope. These compact sources exhibit a high star formation surface density $\Sigma_{\rm SFR}>10\,M_\odot\,{\rm yr^{-1}\,kpc^{-2}}$, a range in which only $<0.01\,\%$ of the local star-forming galaxy sample is found. For those with available NIRSpec data, no evidence of ongoing supermassive black hole accretion is observed. A potential explanation for the observed high [OIII]-to-Hbeta ratios could be high shock velocities, likely originating within intense star-forming regions characterized by high $\Sigma_{\rm SFR}$. Lastly, we find that the rest-frame UV and optical sizes of our sample are comparable. Our results are consistent with these early galaxies building up their structures inside-out and yet to exhibit the strong color gradient seen at lower redshift.

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Takahiro Morishita, Massimo Stiavelli, Ranga-Ram Chary, Michele Trenti, Pietro Bergamini, Marco Chiaberge, Nicha Leethochawalit, Guido Roberts-Borsani, Xuejian Shen, Tommaso Treu. 2023-08-09. Enhanced Sub-kpc Scale Star-formation: Results From A JWST Size Analysis of 341 Galaxies At 5<z<14. https://arxiv.org/abs/2308.05018

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