TY - JOUR
T1 - Jades: Probing interstellar medium conditions at z ∼ 5.5-9.5 with ultra-deep JWST/NIRSpec spectroscopy
AU - Cameron, Alex J.
AU - Saxena, Aayush
AU - Bunker, Andrew J.
AU - D'Eugenio, Francesco
AU - Carniani, Stefano
AU - Maiolino, Roberto
AU - Curtis-Lake, Emma
AU - Ferruit, Pierre
AU - Jakobsen, Peter
AU - Arribas, Santiago
AU - Bonaventura, Nina
AU - Charlot, Stephane
AU - Chevallard, Jacopo
AU - Curti, Mirko
AU - Looser, Tobias J.
AU - Maseda, Michael V.
AU - Rawle, Tim
AU - Pino, Bruno Rodríguez Del
AU - Smit, Renske
AU - Übler, Hannah
AU - Willott, Chris
AU - Witstok, Joris
AU - Egami, Eiichi
AU - Eisenstein, Daniel J.
AU - Johnson, Benjamin D.
AU - Hainline, Kevin
AU - Rieke, Marcia
AU - Robertson, Brant E.
AU - Stark, Daniel P.
AU - Tacchella, Sandro
AU - Williams, Christina C.
AU - Willmer, Christopher N. A.
AU - Bhatawdekar, Rachana
AU - Bowler, Rebecca
AU - Boyett, Kristan
AU - Circosta, Chiara
AU - Helton, Jakob M.
AU - Jones, Gareth C.
AU - Kumari, Nimisha
AU - Ji, Zhiyuan
AU - Nelson, Erica
AU - Parlanti, Eleonora
AU - Sandles, Lester
AU - Scholtz, Jan
AU - Sun, Fengwu
N1 - © 2023 The Author(s). Published by EDP Sciences. This is an open access article distributed under the terms of the Creative Commons Attribution License (CC BY), https://creativecommons.org/licenses/by/4.0/
PY - 2023/9/12
Y1 - 2023/9/12
N2 - We present emission-line ratios from a sample of 27 Lyman-break galaxies from z∼ 5.5-9.5 with-17.0< M1500<-20.4, measured from ultra-deep JWST/NIRSpec multi-object spectroscopy from the JWST Advanced Deep Extragalactic Survey (JADES). We used a combination of 28 h deep PRISM/CLEAR and 7 h deep G395M/F290LP observations to measure, or place strong constraints on, ratios of widely studied rest-frame optical emission lines including Hα, Hβ, [O II] λ3726, 3729, [Ne III] λ3869, [O III] λ4959, [O III] λ5007, [O I] λ6300, [N II] λ6583, and [S II] λ6716, 6731 in individual z> 5.5 spectra. We find that the emission-line ratios exhibited by these z∼ 5.5-9.5 galaxies occupy clearly distinct regions of line-ratio space compared to typical z∼ 0-3 galaxies, instead being more consistent with extreme populations of lower-redshift galaxies. This is best illustrated by the [O III]/[O II] ratio, tracing interstellar medium (ISM) ionisation, in which we observe more than half of our sample to have [O III]/[O II] > 10. Our high signal-to-noise spectra reveal more than an order of magnitude of scatter in line ratios such as [O II]/Hβ and [O III]/[O II], indicating significant diversity in the ISM conditions within the sample. We find no convincing detections of [N II] λ6583 in our sample, either in individual galaxies, or a stack of all G395M/F290LP spectra. The emission-line ratios observed in our sample are generally consistent with galaxies with extremely high ionisation parameters (log U∼-1.5), and a range of metallicities spanning from ∼0.1 × Z⊙ to higher than ∼0.3 × Z⊙, suggesting we are probing low-metallicity systems undergoing periods of rapid star formation, driving strong radiation fields. These results highlight the value of deep observations in constraining the properties of individual galaxies, and hence probing diversity within galaxy population.
AB - We present emission-line ratios from a sample of 27 Lyman-break galaxies from z∼ 5.5-9.5 with-17.0< M1500<-20.4, measured from ultra-deep JWST/NIRSpec multi-object spectroscopy from the JWST Advanced Deep Extragalactic Survey (JADES). We used a combination of 28 h deep PRISM/CLEAR and 7 h deep G395M/F290LP observations to measure, or place strong constraints on, ratios of widely studied rest-frame optical emission lines including Hα, Hβ, [O II] λ3726, 3729, [Ne III] λ3869, [O III] λ4959, [O III] λ5007, [O I] λ6300, [N II] λ6583, and [S II] λ6716, 6731 in individual z> 5.5 spectra. We find that the emission-line ratios exhibited by these z∼ 5.5-9.5 galaxies occupy clearly distinct regions of line-ratio space compared to typical z∼ 0-3 galaxies, instead being more consistent with extreme populations of lower-redshift galaxies. This is best illustrated by the [O III]/[O II] ratio, tracing interstellar medium (ISM) ionisation, in which we observe more than half of our sample to have [O III]/[O II] > 10. Our high signal-to-noise spectra reveal more than an order of magnitude of scatter in line ratios such as [O II]/Hβ and [O III]/[O II], indicating significant diversity in the ISM conditions within the sample. We find no convincing detections of [N II] λ6583 in our sample, either in individual galaxies, or a stack of all G395M/F290LP spectra. The emission-line ratios observed in our sample are generally consistent with galaxies with extremely high ionisation parameters (log U∼-1.5), and a range of metallicities spanning from ∼0.1 × Z⊙ to higher than ∼0.3 × Z⊙, suggesting we are probing low-metallicity systems undergoing periods of rapid star formation, driving strong radiation fields. These results highlight the value of deep observations in constraining the properties of individual galaxies, and hence probing diversity within galaxy population.
KW - astro-ph.GA
KW - Galaxies: ISM
KW - Galaxies: High-redshift
KW - Galaxies: Evolution
UR - http://www.scopus.com/inward/record.url?scp=85172355009&partnerID=8YFLogxK
U2 - 10.1051/0004-6361/202346107
DO - 10.1051/0004-6361/202346107
M3 - Article
SN - 0004-6361
VL - 677
SP - 1
EP - 19
JO - Astronomy & Astrophysics
JF - Astronomy & Astrophysics
IS - September 2023
M1 - A115
ER -