TY - JOUR
T1 - JADES
T2 - The star formation and chemical enrichment history of a luminous galaxy at z ∼ 9.43 probed by ultra-deep JWST/NIRSpec spectroscopy
AU - Curti, Mirko
AU - Witstok, Joris
AU - Jakobsen, Peter
AU - Kobayashi, Chiaki
AU - Curtis-Lake, Emma
AU - Hainline, Kevin
AU - Ji, Xihan
AU - D'Eugenio, Francesco
AU - Chevallard, Jacopo
AU - Maiolino, Roberto
AU - Scholtz, Jan
AU - Carniani, Stefano
AU - Arribas, Santiago
AU - Baker, William M.
AU - Bhatawdekar, Rachana
AU - Boyett, Kristan
AU - Bunker, Andrew J.
AU - Cameron, Alex
AU - Cargile, Phillip A.
AU - Charlot, Stéphane
AU - Eisenstein, Daniel J.
AU - Ji, Zhiyuan
AU - Johnson, Benjamin D.
AU - Kumari, Nimisha
AU - Maseda, Michael V.
AU - Robertson, Brant E
AU - Silcock, Maddie S.
AU - Tacchella, Sandro
AU - Übler, Hannah
AU - Venturi, Giacomo
AU - Williams, Christina C.
AU - Willmer, Christopher N.A.
AU - Willott, Chris
N1 - Publisher Copyright:
© The Authors 2025.
PY - 2025/5/1
Y1 - 2025/5/1
N2 - We analysed ultra-deep JWST observations of the galaxy JADES-GS-z9-0 at z = 9.4327, and derived detailed stellar and interstellar medium (ISM) properties of this luminous (MUV=-20.43) high-redshift system. Complementary information from NIRCam imaging and NIRSpec spectroscopy (both low and medium resolution) reveal a compact system (Re∼110 pc) characterised by a steeply rising star formation history, which is reflected in the inferred young stellar age (t∼3 Myr, light-weighted), high star formation rate surface density (ΣSFR∼72 M⊙ yr-1 kpc-2), high ionisation parameter (log(U) ∼-1.5), low metallicity (12 + log(O/H) ∼7.5), and low carbon-to-oxygen abundance ([C/O] =-0.64). Leveraging the detection of Na III] λ1750 we derived a nitrogen-to-oxygen abundance ([N/O] ∼0) higher than the plateau followed by low-redshift galaxies of similar metallicity, possibly revealing the imprint from (very) massive stars on the ISM enrichment and favouring a top-heavy initial mass function (IMF) scenario. Massive stars powering a hard radiation field are also required to explain the rest-frame UV line ratios, though the presence of the high-excitation [Ne V] λ3426 emission line possibly hints at additional ionisation from an active galactic nucleus (AGN). We also report the tentative detection of Lyα emission in the G140M spectrum, shifted by ∼450 km/s redwards of the systemic redshift. Combined with a modelling of the Lyα spectral break, we rule out the presence of very high column densities of neutral gas pertaining to local absorbers, as well as any extended surrounding ionised bubbles, suggesting that JADES-GS-z9-0 has not yet significantly contributed to cosmic reionisation.
AB - We analysed ultra-deep JWST observations of the galaxy JADES-GS-z9-0 at z = 9.4327, and derived detailed stellar and interstellar medium (ISM) properties of this luminous (MUV=-20.43) high-redshift system. Complementary information from NIRCam imaging and NIRSpec spectroscopy (both low and medium resolution) reveal a compact system (Re∼110 pc) characterised by a steeply rising star formation history, which is reflected in the inferred young stellar age (t∼3 Myr, light-weighted), high star formation rate surface density (ΣSFR∼72 M⊙ yr-1 kpc-2), high ionisation parameter (log(U) ∼-1.5), low metallicity (12 + log(O/H) ∼7.5), and low carbon-to-oxygen abundance ([C/O] =-0.64). Leveraging the detection of Na III] λ1750 we derived a nitrogen-to-oxygen abundance ([N/O] ∼0) higher than the plateau followed by low-redshift galaxies of similar metallicity, possibly revealing the imprint from (very) massive stars on the ISM enrichment and favouring a top-heavy initial mass function (IMF) scenario. Massive stars powering a hard radiation field are also required to explain the rest-frame UV line ratios, though the presence of the high-excitation [Ne V] λ3426 emission line possibly hints at additional ionisation from an active galactic nucleus (AGN). We also report the tentative detection of Lyα emission in the G140M spectrum, shifted by ∼450 km/s redwards of the systemic redshift. Combined with a modelling of the Lyα spectral break, we rule out the presence of very high column densities of neutral gas pertaining to local absorbers, as well as any extended surrounding ionised bubbles, suggesting that JADES-GS-z9-0 has not yet significantly contributed to cosmic reionisation.
KW - Galaxies: abundances
KW - Galaxies: evolution
KW - Galaxies: high-redshift
KW - Galaxies: ISM
KW - Galaxies: star formation
UR - http://www.scopus.com/inward/record.url?scp=105005261752&partnerID=8YFLogxK
UR - http://www.scopus.com/inward/citedby.url?scp=105005261752&partnerID=8YFLogxK
U2 - 10.1051/0004-6361/202451410
DO - 10.1051/0004-6361/202451410
M3 - Article
AN - SCOPUS:105005261752
SN - 0004-6361
VL - 697
JO - Astronomy and astrophysics
JF - Astronomy and astrophysics
M1 - A89
ER -