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SUMMARY:The chemical abundance pattern of a nitrogen-loud AGN in the early
  Universe - Xihan Ji (Cavendish)
DTSTART:20240301T113000Z
DTEND:20240301T123000Z
UID:TALK211612@talks.cam.ac.uk
CONTACT:Sandro Tacchella
DESCRIPTION:Recent JWST/NIRSpec observations have revealed several interes
 ting galaxies with particularly enhanced nitrogen abundances at redshifts 
 of z > 6. These galaxies are featured by strong nitrogen emission lines in
  the rest-frame UV\, similar to the ''nitrogen-loud'' quasars previously o
 bserved at lower redshifts. Among these nitrogen-loud galaxies\, there is 
 an AGN candidate\, GN-z11\, at a redshift of z = 10.6\, also showing poten
 tially exotic abundances of carbon and iron. The chemical enrichment histo
 ry of the high-redshift nitrogen-loud galaxies and their connection with n
 itrogen-loud quasars remain unclear despite that many theories have been p
 roposed. In this talk\, I present our recent analyses on a nitrogen-loud T
 ype-1 AGN at z = 5.55 observed within the JWST/NIRSpec IFS GTO Program\, G
 A-NIFS. By combining the ground-based observations and JWST observations\,
  we confirmed the nitrogen loudness of this AGN and further constrained it
 s carbon abundance and iron abundance. We found evidence of a chemically s
 tratified narrow-line region (NLR) in this AGN\, where the denser and more
  highly ionized part of the NLR is more nitrogen enhanced. Our results sug
 gest the peculiar chemical enrichment in this AGN is confined to the inner
  part of the NLR and potentially traces a specific stage of chemical evolu
 tion in a dense environment.
LOCATION:Ryle seminar room + online
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