TY - JOUR
T1 - JADES: 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, Stephane
AU - Eisenstein, Daniel J.
AU - Ji, Zhiyuan
AU - Johnson, Benjamin D.
AU - Kumari, Nimisha
AU - Maseda, Michael V.
AU - Robertson, Brant
AU - Silcock, Maddie S.
AU - Tacchella, Sandro
AU - Ubler, Hannah
AU - Venturi, Giacomo
AU - Willmer, Christopher N. A.
AU - Willott, Chris
N1 - Accepted for publication on A&A
PY - 2025/2/13
Y1 - 2025/2/13
N2 - We analyse ultra-deep JWST observations of the galaxy JADES-GS-z9-0 at z = 9.4327, and derive detailed stellar and interstellar medium (ISM) properties of this luminous (MUV=-20.43) high-redshift system. Complementary information from NIRCam imaging and NIRSpec (both low- and medium-resolution) spectroscopy 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 ({\Sigma}SFR ~ 72 M yr-1 kpc-2), high ionisation parameter (log(U) ~ -1.5), low metallicity (12+log(O/H) ~ 7.5), and low carbon-over-oxygen abundance ([C/O] = -0.64). Leveraging the detection of N iii]1750 we derive nitrogen-over-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]{\lambda}3426 emission line possibly hints at additional ionization from an AGN. We also report the tentative detection of Ly{\alpha} emission in the G140M spectrum, shifted by ~450 km/s redward of the systemic redshift. Combined with a modelling of the Ly{\alpha} 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 bubble, suggesting that JADES-GS-z9-0 has not yet significantly contributed to cosmic Reionization.
AB - We analyse ultra-deep JWST observations of the galaxy JADES-GS-z9-0 at z = 9.4327, and derive detailed stellar and interstellar medium (ISM) properties of this luminous (MUV=-20.43) high-redshift system. Complementary information from NIRCam imaging and NIRSpec (both low- and medium-resolution) spectroscopy 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 ({\Sigma}SFR ~ 72 M yr-1 kpc-2), high ionisation parameter (log(U) ~ -1.5), low metallicity (12+log(O/H) ~ 7.5), and low carbon-over-oxygen abundance ([C/O] = -0.64). Leveraging the detection of N iii]1750 we derive nitrogen-over-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]{\lambda}3426 emission line possibly hints at additional ionization from an AGN. We also report the tentative detection of Ly{\alpha} emission in the G140M spectrum, shifted by ~450 km/s redward of the systemic redshift. Combined with a modelling of the Ly{\alpha} 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 bubble, suggesting that JADES-GS-z9-0 has not yet significantly contributed to cosmic Reionization.
KW - astro-ph.GA
U2 - 10.1051/0004-6361/202451410
DO - 10.1051/0004-6361/202451410
M3 - Article
SN - 0004-6361
JO - Astronomy & Astrophysics
JF - Astronomy & Astrophysics
ER -