Galaxy Zoo <i>JWST</i>: up to 75 per cent of discs are featureless at 3 &amp;lt; <i>z</i> &amp;lt; 7

ABSTRACT We have not yet observed the epoch at which disc galaxies emerge in the Universe. While high-z measurements of large-scale features such as bars and spiral arms trace the evolution of disc galaxies, such methods cannot directly quantify featureless discs in the early Universe. Here, we identify a substantial population of apparently featureless disc galaxies in the Cosmic Evolution Early Release Science (CEERS) survey by combining quantitative visual morphologies of ${\sim} 7000$ galaxies from the Galaxy Zoo JWST CEERS project with a public catalogue of expert visual and parametric morphologies. While the highest redshift featured disc we identify is at $z_{\rm {phot}}=5.5$, the highest redshift featureless disc we identify is at $z_{\rm {phot}}=7.4$. The distribution of Sérsic indices for these featureless systems suggests that they truly are dynamically cold: disc-dominated systems have existed since at least $z\sim 7.4$. We place upper limits on the featureless disc fraction as a function of redshift, and show that up to 75 per cent of discs are featureless at $3.0&amp;lt; z&amp;lt; 7.4$. This is a conservative limit assuming all galaxies in the sample truly lack features. With further consideration of redshift effects and observational constraints, we find the featureless disc fraction in CEERS imaging at these redshifts is more likely ${\sim} 29{\!-\!}38~{{\ \rm per\ cent}}$. We hypothesize that the apparent lack of features in a third of high-redshift discs is due to a higher gas fraction in the early Universe, which allows the discs to be resistant to buckling and instabilities.

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Publication Details

Journal
Monthly Notices of the Royal Astronomical Society
Published
2025-03-28
DOI
https://doi.org/10.1093/mnras/staf506
Citations
6
Primary Topic
Astronomy and Astrophysical Research
Type
article
Field-Weighted Citation Impact
7.15

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article

Galaxy Zoo JWST: up to 75 per cent of discs are featureless at 3 &lt; z &lt; 7

Ray A. Lucas, H. L. Roberts, Tobias Géron, Fabio Pacucci et al.
6 citations
Monthly Notices of the Royal Astronomical Society
Astronomy and Astrophysical Research
7.15
article

Galaxy Zoo JWST: up to 75 per cent of discs are featureless at 3 &lt; z &lt; 7

Ray A. Lucas, H. L. Roberts, Tobias Géron, Fabio Pacucci, Kameswara Bharadwaj Mantha, L. Fortson, M. Calabro, Anton M. Koekemoer, Sandor Kruk, Brooke Simmons, Benne W. Holwerda, Chris Lintott, H. J. Dickinson, Rebecca Smethurst, Izzy L. Garland, Mike Walmsley, Maxime Tarrasse, Karen L. Masters, Matthew R. Thorne, S M Jewell, Y. Lyu, Jason Shingirai Makechemu, Jeyhan S. Kartaltepe, D O’Ryan
article en
6 citations

Abstract

ABSTRACT We have not yet observed the epoch at which disc galaxies emerge in the Universe. While high-z measurements of large-scale features such as bars and spiral arms trace the evolution of disc galaxies, such methods cannot directly quantify featureless discs in the early Universe. Here, we identify a substantial population of apparently featureless disc galaxies in the Cosmic Evolution Early Release Science (CEERS) survey by combining quantitative visual morphologies of ${\sim} 7000$ galaxies from the Galaxy Zoo JWST CEERS project with a public catalogue of expert visual and parametric morphologies. While the highest redshift featured disc we identify is at $z_{\rm {phot}}=5.5$, the highest redshift featureless disc we identify is at $z_{\rm {phot}}=7.4$. The distribution of Sérsic indices for these featureless systems suggests that they truly are dynamically cold: disc-dominated systems have existed since at least $z\sim 7.4$. We place upper limits on the featureless disc fraction as a function of redshift, and show that up to 75 per cent of discs are featureless at $3.0&amp;lt; z&amp;lt; 7.4$. This is a conservative limit assuming all galaxies in the sample truly lack features. With further consideration of redshift effects and observational constraints, we find the featureless disc fraction in CEERS imaging at these redshifts is more likely ${\sim} 29{\!-\!}38~{{\ \rm per\ cent}}$. We hypothesize that the apparent lack of features in a third of high-redshift discs is due to a higher gas fraction in the early Universe, which allows the discs to be resistant to buckling and instabilities.

Monthly Notices of the Royal Astronomical SocietyVol. 539(2)
Centre National de la Recherche Scientifique (FR), Space Telescope Science Institute (US), University of Minnesota (US), Woodwell Climate Research Center (US), Harvard University (US), University of Louisville (US), Rochester Institute of Technology (US), Haverford College (US), University of Toronto (CA), The Open University (GB), Université Paris Cité (FR), Masaryk University (CZ), Commissariat à l'Énergie Atomique et aux Énergies Alternatives (FR), Université Paris-Saclay (FR), Astronomical Observatory of Rome (IT), European Space Agency (FR), University of Oxford (GB), Astrophysique, Instrumentation et Modélisation (FR), European Space Astronomy Centre (ES), Canadian Institute for Theoretical Astrophysics (CA), Université Bourgogne Franche-Comté (FR), Center for Astrophysics Harvard & Smithsonian (US), CEA Paris-Saclay (FR), Centro de Astrobiología (ES), Lancaster University (GB)
National Science Foundation, National Aeronautics and Space Administration, Space Telescope Science Institute, Grantová Agentura České Republiky, Nuclear Safety and Security Commission
Openalex Percentile: Top 3%
Astronomy and Astrophysical Research
7.15
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