RIOJA. Young starburst and ionized gas outflows in a z = 7.212 galaxy uncovered by JWST NIRCam and NIRSpec observations
Journal article, 2025
We present the analysis of James Webb Space Telescope (JWST) NIRCam and NIRSpec observations of the galaxy SXDF-NB1006-2 at $z = 7.212$, as part of the Reionization and the ISM/Stellar Origins with JWST and ALMA project. We derive the physical properties by conducting spectral energy distribution fitting, revealing that our target is a young (age $\sim 2$ Myr) starburst galaxy with intense radiation field. We detect multiple nebular emission lines from NIRSpec integral field spectroscopy data. We identify a robust broad component of [Oiii]$\lambda$5008 emission, indicating the presence of ionized gas outflows. The derived gas depletion time of a few hundred Myr implies that our target could be one of the progenitors of massive quiescent galaxies at $z\sim 4\!-\!5$ identified by recent JWST observations. The spatial distribution of optical and far-infrared [Oiii] emission lines differs in morphology, likely resulting from different critical densities and inhomogeneous density distributions within the galaxy. Potential old stellar populations may be necessary to account for the derived metallicity of $\sim 0.2\, \rm {Z}_\odot$, and their presence can be confirmed by future MIRI observations. Including our target, star-forming galaxies at $z>6$ detected by ALMA are generally very young but more massive and brighter in UV than galaxies identified by only JWST. The ALMA-detected galaxies may also have a steeper mass–metallicity relation. These findings suggest that the ALMA-detected galaxies may have experienced more efficient mass assembly processes in their evolutionary pathways.
galaxies: high-redshift
galaxies: evolution
galaxies: formation
galaxies: starburst
galaxies: ISM
Author
Yi W. Ren
Waseda University
Akio K. Inoue
Waseda University
J. Álvarez-Márquez
Centro de Astrobiologia (CAB)
Takuya Hashimoto
University of Tsukuba
L. Colina
Centro de Astrobiologia (CAB)
Yuma Sugahara
National Astronomical Observatory of Japan
Waseda University
Luca Constantin
Centro de Astrobiologia (CAB)
Ken Mawatari
University of Tsukuba
Waseda University
Yoshinobu Fudamoto
National Astronomical Observatory of Japan
Waseda University
Chiba University
S. Arribas
Centro de Astrobiologia (CAB)
A. Gomez
Space Telescope Science Institute (STScI)
Centro de Astrobiologia (CAB)
Daniel Ceverino
Universidad Autonoma de Madrid (UAM)
Yurina Nakazato
University of Tokyo
Masato Hagimoto
Nagoya University
Mitsutaka Usui
University of Tsukuba
Rui Marques-Chaves
University of Geneva
Hiroshi Matsuo
The Graduate University for Advanced Studies (SOKENDAI)
National Astronomical Observatory of Japan
Takeshi Hashigaya
Kyoto University
Wataru Osone
University of Tsukuba
Carmen Blanco-Prieto
Centro de Astrobiologia (CAB)
Y. Tamura
Nagoya University
Naoki Yoshida
Research Center for the Early Universe
University of Tokyo
Tom Bakx
Chalmers, Space, Earth and Environment, Astronomy and Plasmaphysics
M. Pereira-Santaella
Spanish National Research Council (CSIC)
Monthly Notices of the Royal Astronomical Society
00358711 (ISSN) 13652966 (eISSN)
Vol. 544 4 4722-4743Subject Categories (SSIF 2025)
Atom and Molecular Physics and Optics
Astronomy, Astrophysics, and Cosmology
DOI
10.1093/mnras/staf1886