Enhanced Subkiloparsec-scale Star Formation: Results from a JWST Size Analysis of 341 Galaxies at 5 < z < 14
Articolo
Data di Pubblicazione:
2024
Citazione:
Enhanced Subkiloparsec-scale Star Formation: Results from a JWST Size Analysis of 341 Galaxies at 5 < z < 14 / T. Morishita, M. Stiavelli, R. Chary, M. Trenti, P. Bergamini, M. Chiaberge, N. Leethochawalit, G. Roberts-Borsani, X. Shen, T. Treu. - In: THE ASTROPHYSICAL JOURNAL. - ISSN 0004-637X. - 963:1(2024), pp. 9.1-9.21. [10.3847/1538-4357/ad1404]
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 ~358 arcmin2. Through conservative
(8σ) photometric selection, we identify 341 galaxies at 5 < z < 14, with 109 having spectroscopic redshift
measurements from the literature, including recent JWST NIRSpec observations. Our regression analysis reveals
that the rest-frame UV size–stellar mass relation follows * Reff M
μ 0.190.03, similar to that of star-forming galaxies
at z ∼ 3, but scaled down in size by ∼0.7 dex. We find a much slower rate for the average size evolution over the
redshift range, Reff ∝ (1 + z)−0.4±0.2, than that derived in the literature. A fraction (∼13%) of our sample galaxies
are marginally resolved even in the NIRCam imaging (100 pc), located at 1.5σ below the derived size–mass
slope. These compact sources exhibit a high star formation surface density ΣSFR > 10Me 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
[O III]-to-Hβ ratios could be high shock velocities, likely originating within intense star-forming regions
characterized by high ΣSFR. 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 being yet to exhibit
the strong color gradient seen at lower redshift.
Tipologia IRIS:
01 - Articolo su periodico
Elenco autori:
T. Morishita, M. Stiavelli, R. Chary, M. Trenti, P. Bergamini, M. Chiaberge, N. Leethochawalit, G. Roberts-Borsani, X. Shen, T. Treu
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