Multiline Assessment of Narrow-line Regions in z similar to 3 Radio Galaxies
Artikel i vetenskaplig tidskrift, 2022

In this paper, we use high-quality rest-UV spectra of three radio galaxies at z similar to 3 observed with the FORS2 camera on the Very Large Telescope to measure the flux of several emission lines, including relatively faint ones, such as N iv]lambda 1486, O iii]lambda 1663, and [Ne iv]lambda 2424. Additionally, we collect fluxes of faint rest-UV emission lines in 12 z similar to 3 radio galaxies from the literature. Previously, physical and chemical properties of narrow-line regions (NLRs) in high-z active galactic nuclei (AGNs) have been investigated mostly by using only strong rest-UV emission lines (e.g., N v lambda 1240, C iv lambda 1549, He ii lambda 1640, and C iii]lambda 1909). Such strong-line diagnostics are based on various assumptions due to the limitation in the number of available emission-line constraints. In this work, both physical and chemical properties of NLR clouds in each object are estimated by fitting detailed photoionization models to the measured emission-line fluxes. We confirm that the metallicity of NLRs in AGNs at z similar to 3 is solar or supersolar, without assumptions about the gas density and ionization parameter thanks to the constraints from the faint emission lines. This result suggests that high-z radio galaxies are already chemically mature at z similar to 3.


Koki Terao

Tohoku University

Tohru Nagao

Ehime University

Kyoko Onishi

Chalmers, Rymd-, geo- och miljövetenskap, Astronomi och plasmafysik, Astronomi och plasmafysik 2

Kenta Matsuoka

Utena Meishu Company Ltd

Masayuki Akiyama

Tohoku University

Yoshiki Matsuoka

Ehime University

Takuji Yamashita

Ehime University

National Astronomical Observatory of Japan

Astrophysical Journal

0004-637X (ISSN) 1538-4357 (eISSN)

Vol. 929 1 51


Meteorologi och atmosfärforskning

Astronomi, astrofysik och kosmologi




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