A solar metallicity galaxy at z > 7? Possible detection of the [N II] 122 mu m and [O III] 52 mu m lines
Journal article, 2023
We present the first detection of the [NII] 122 mu m and [O III ] 52 mu m lines for a reionization-epoch galaxy. Based on these lines and previous [C II ] 158 mu m and [O III ] 88 mu m measurements, using two different radiati ve transfer models of the interstellar medium, we estimate an upper limit on electron density of < 500 cm(-3) and an approximate gas-phase metallicity of Z/Z(circle dot) similar to 1.1 +/- 0.2 for A1689-zD1, a gravitationally lensed dusty galaxy at z = 7.133. Other measurements or indicators of metallicity so far in galaxy interstellar media at z greater than or similar to 6 are typically an order of magnitude lower than this. The unusually high metallicity makes A1689-zD1 inconsistent with the fundamental metallicity relation, although there is likely significant dust obscuration of the stellar mass, which may partly resolve the inconsistency. Given a solar metallicity, the dust-to-metals ratio is a factor of several lower than expected, hinting that galaxies be yond z similar to 7 may hav e lower dust formation efficiency . Finally , the inferred nitrogen enrichment compared to oxygen, on which the metallicity measurement depends, indicates that star formation in the system is older than about 250 Myr, pushing the beginnings of this galaxy to z > 10.
galaxies:ISM
submillimetre:galaxies
galaxies:individual:(A1689-zD1)
ISM:abundances
galaxies:high-redshift
Author
Meghana Killi
University of Copenhagen
Darach Watson
University of Copenhagen
Seiji Fujimoto
University of Copenhagen
Hollis Akins
University of Texas
Kirsten Knudsen
Chalmers, Space, Earth and Environment, Astronomy and Plasmaphysics
Johan Richard
Université de Lyon
Yuichi Harikane
University College London (UCL)
University of Tokyo
Dimitra Rigopoulou
European University Cyprus
University of Oxford
Francesca Rizzo
University of Copenhagen
Michele Ginolfi
University of Florence
Gergo Popping
European Southern Observatory Santiago
Vasily Kokorev
University of Copenhagen
Monthly Notices of the Royal Astronomical Society
0035-8711 (ISSN) 1365-2966 (eISSN)
Vol. 521 2 2526-2534Subject Categories (SSIF 2011)
Astronomy, Astrophysics and Cosmology
Probability Theory and Statistics
Fusion, Plasma and Space Physics
DOI
10.1093/mnras/stad687