The Physical Conditions of Emission-line Galaxies at Cosmic Dawn from JWST/NIRSpec Spectroscopy in the SMACS 0723 Early Release Observations
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Published:2023-03-01
Issue:1
Volume:945
Page:35
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ISSN:0004-637X
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Container-title:The Astrophysical Journal
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language:
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Short-container-title:ApJ
Author:
Trump Jonathan R.ORCID, Arrabal Haro PabloORCID, Simons Raymond C.ORCID, Backhaus Bren E.ORCID, Amorín Ricardo O.ORCID, Dickinson MarkORCID, Fernández VitalORCID, Papovich CaseyORCID, Nicholls David C.ORCID, Kewley Lisa J.ORCID, Brunker Samantha W.ORCID, Salzer John J.ORCID, Wilkins Stephen M.ORCID, Almaini OmarORCID, Bagley Micaela B.ORCID, Berg Danielle A.ORCID, Bhatawdekar RachanaORCID, Bisigello LauraORCID, Buat VéroniqueORCID, Burgarella DenisORCID, Calabrò AntonelloORCID, Casey Caitlin M.ORCID, Ciesla LaureORCID, Cleri Nikko J.ORCID, Cole Justin W.ORCID, Cooper M. C.ORCID, Cooray Asantha R.ORCID, Costantin LucaORCID, Croton DarrenORCID, Ferguson Henry C.ORCID, Finkelstein Steven L.ORCID, Fujimoto SeijiORCID, Gardner Jonathan P.ORCID, Gawiser EricORCID, Giavalisco MauroORCID, Grazian AndreaORCID, Grogin Norman A.ORCID, Hathi Nimish P.ORCID, Hirschmann MichaelaORCID, Holwerda Benne W.ORCID, Huertas-Company MarcORCID, Hutchison Taylor A.ORCID, Jogee ShardhaORCID, Juneau StéphanieORCID, Jung IntaeORCID, Kartaltepe Jeyhan S.ORCID, Kirkpatrick AllisonORCID, Kocevski Dale D.ORCID, Koekemoer Anton M.ORCID, Lotz Jennifer M.ORCID, Lucas Ray A.ORCID, Magnelli BenjaminORCID, Matharu JasleenORCID, Pérez-González Pablo G.ORCID, Pirzkal NorORCID, Rafelski MarcORCID, Rose CaitlinORCID, Seillé Lise-MarieORCID, Somerville Rachel S.ORCID, Straughn Amber N.ORCID, Tacchella SandroORCID, Vanderhoof Brittany N.ORCID, Weiner Benjamin J.ORCID, Wuyts StijnORCID, Yung L. Y. AaronORCID, Zavala Jorge A.ORCID
Abstract
Abstract
We present rest-frame optical emission-line flux ratio measurements for five z > 5 galaxies observed by the James Webb Space Telescope Near-Infared Spectrograph (NIRSpec) in the SMACS 0723 Early Release Observations. We add several quality-control and post-processing steps to the NIRSpec pipeline reduction products in order to ensure reliable relative flux calibration of emission lines that are closely separated in wavelength, despite the uncertain absolute spectrophotometry of the current version of the reductions. Compared to z ∼ 3 galaxies in the literature, the z > 5 galaxies have similar [O iii]λ5008/Hβ ratios, similar [O iii]λ4364/Hγ ratios, and higher (∼0.5 dex) [Ne III]λ3870/[O II]λ3728 ratios. We compare the observations to MAPPINGS V photoionization models and find that the measured [Ne III]λ3870/[O II]λ3728, [O iii]λ4364/Hγ, and [O iii]λ5008/Hβ emission-line ratios are consistent with an interstellar medium (ISM) that has very high ionization (
log
(
Q
)
≃
8
−
9
, units of cm s−1), low metallicity (Z/Z
⊙ ≲ 0.2), and very high pressure (
log
(
P
/
k
)
≃
8
−
9
, units of cm−3). The combination of [O iii]λ4364/Hγ and [O iii]λ(4960 + 5008)/Hβ line ratios indicate very high electron temperatures of
4.1
<
log
(
T
e
/
K
)
<
4.4
, further implying metallicities of Z/Z
⊙ ≲ 0.2 with the application of low-redshift calibrations for “T
e
-based” metallicities. These observations represent a tantalizing new view of the physical conditions of the ISM in galaxies at cosmic dawn.
Funder
NASA ∣ SMD ∣ Astrophysics Division NSF ∣ MPS ∣ Division of Astronomical Sciences
Publisher
American Astronomical Society
Subject
Space and Planetary Science,Astronomy and Astrophysics
Cited by
47 articles.
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