A Massive Barred Spiral Galaxy at z = 5.102 Discovered by JWST

Abstract We report M1149-BSG-z5, a barred spiral galaxy at z = 5.102, identified in the parallel field of MACS J1149+2223 with JWST and the Hubble Space Telescope. M1149-BSG-z5 is the highest-redshift barred galaxy candidate to date. Both isophote ellipse fitting and structural modeling support a stellar bar of length ≈ 4.5 kpc, and extended spiral arms peaking at r ≈ 5.5 kpc. M1149-BSG-z5 is a massive star-forming main-sequence galaxy, with a stellar mass of 10 10.45 M ⊙ and a star formation rate of 144 M ⊙ yr −1 . A concentrated bulge is embedded in an extended disk with a global Sérsic index n = 2.37. With an effective radius of R e = 2.61 kpc measured from a stacked F277W + F356W + F444W image, M1149-BSG-z5 is larger than typical galaxies at z ∼ 5 and comparable to barred galaxies at 2 < z < 4. M1149-BSG-z5 also hosts a broad-line active galactic nucleus, with a relatively low black hole-to-stellar mass ratio of M BH / M * ∼ 10 −3 . Its metal-enriched emission-line properties indicate that it is already chemically evolved. Taken together, these properties imply that M1149-BSG-z5 assembled early and is already structurally evolved. We also find that M1149-BSG-z5 resides in an overdense region with a nearby companion galaxy, suggesting interaction-driven bar formation. Its concentrated light distribution, early assembly, and location on the star-forming main sequence also suggest baryon-dominated, gas-rich conditions, where gravitational instability may further accelerate bar formation.

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Publication Details

Journal
The Astrophysical Journal
Published
2026-10-27
DOI
https://doi.org/10.3847/1538-4357/aea414
Primary Topic
Galaxies: Formation, Evolution, Phenomena
Type
article
Field-Weighted Citation Impact
0.00

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article

A Massive Barred Spiral Galaxy at z = 5.102 Discovered by JWST

Sijia Cai, Fengwu Sun, Rogier A. Windhorst, Shude Mao et al.
2 links
The Astrophysical Journal
Galaxies: Formation, Evolution, Phenomena
article

A Massive Barred Spiral Galaxy at z = 5.102 Discovered by JWST

Sijia Cai, Fengwu Sun, Rogier A. Windhorst, Shude Mao, Yunjing Wu, D. Espada, Chian-Chou Chen, Christopher J. Conselice, Miroslava Dessauges-Zavadsky, Jean-Baptiste Jolly, Yoshihisa Asada, Brenda Frye, Hideki Umehata, Cheng Cheng, Zheng Cai, Nicholas S. Martis, Adi Zitrin, Kotaro Kohno, Wenlei Chen, Mingyu Li, Weichen Wang, Xiaojing Lin, Xiaohan Wang
article en

Abstract

Abstract We report M1149-BSG-z5, a barred spiral galaxy at z = 5.102, identified in the parallel field of MACS J1149+2223 with JWST and the Hubble Space Telescope. M1149-BSG-z5 is the highest-redshift barred galaxy candidate to date. Both isophote ellipse fitting and structural modeling support a stellar bar of length ≈ 4.5 kpc, and extended spiral arms peaking at r ≈ 5.5 kpc. M1149-BSG-z5 is a massive star-forming main-sequence galaxy, with a stellar mass of 10 10.45 M ⊙ and a star formation rate of 144 M ⊙ yr −1 . A concentrated bulge is embedded in an extended disk with a global Sérsic index n = 2.37. With an effective radius of R e = 2.61 kpc measured from a stacked F277W + F356W + F444W image, M1149-BSG-z5 is larger than typical galaxies at z ∼ 5 and comparable to barred galaxies at 2 < z < 4. M1149-BSG-z5 also hosts a broad-line active galactic nucleus, with a relatively low black hole-to-stellar mass ratio of M BH / M * ∼ 10 −3 . Its metal-enriched emission-line properties indicate that it is already chemically evolved. Taken together, these properties imply that M1149-BSG-z5 assembled early and is already structurally evolved. We also find that M1149-BSG-z5 resides in an overdense region with a nearby companion galaxy, suggesting interaction-driven bar formation. Its concentrated light distribution, early assembly, and location on the star-forming main sequence also suggest baryon-dominated, gas-rich conditions, where gravitational instability may further accelerate bar formation.

The Astrophysical JournalVol. 1011(1)
University of Geneva (CH), Oklahoma State University (US), Ben-Gurion University of the Negev (IL), Institute of Astronomy and Astrophysics, Academia Sinica (TW), Universidad de Granada (ES), Chinese Academy of Sciences (CN), University of Cambridge (GB), University of Manchester (GB), Westlake University (CN), Chinese Academy of Science South America Center for Astronomy (CL), Max Planck Institute for Extraterrestrial Physics (DE), East Asian Observatory (US), Center for Astrophysics Harvard & Smithsonian (US), Arizona State University (US), Nagoya University (JP), University of Milano-Bicocca (IT), The University of Tokyo (JP), Academia Sinica (TW), Tsinghua University (CN)
National Aeronautics and Space Administration, Space Telescope Science Institute, Westlake University, Consejería de Transformación Económica, Industria, Conocimiento y Universidades, National Natural Science Foundation of China, University of Toronto, Israel Science Foundation, Ministerio de Ciencia e Innovación, Junta de Andalucía, Goddard Space Flight Center, Japan Society for the Promotion of Science, Agencia Estatal de Investigación
Openalex Percentile: Top 14%
Galaxies: Formation, Evolution, Phenomena
DOIOpen Access PDFOpenAlex
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