GA-NIFS: A massive black hole in a low-metallicity AGN at z ∼ 5.55 revealed by JWST/NIRSpec IFS

Hannah Übler, Roberto Maiolino, Emma Curtis-Lake, Pablo G. Pérez-González, Mirko Curti, Michele Perna, Santiago Arribas, Stéphane Charlot, Madeline A. Marshall, Francesco D'Eugenio, Jan Scholtz, Andrew Bunker, Stefano Carniani, Pierre Ferruit, Peter Jakobsen, Hans-Walter Rix, Bruno Rodríguez Del Pino, Chris J. Willott, Torsten Böker, Giovanni CresciGareth C. Jones, Nimisha Kumari, Tim Rawle

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We present rest-frame optical data of the compact z=5.55 galaxy GS_3073 obtained using the integral field spectroscopy mode of the Near-InfraRed Spectrograph on board the James Webb Space Telescope. The galaxybs prominent broad components in several hydrogen and helium lines (though absent in the forbidden lines) and v detection of a large equivalent width of HeIIλ4686, EW(He II) 20 ÅB, unambiguously identify it as an active galactic nucleus (AGN). We measured a gas phase metallicity of Zgas/Z0.210.04+0.08, which is lower than what has been inferred for both more luminous AGN at a similar redshift and lower redshift AGN. We empirically show that classical emission line ratio diagnostic diagrams cannot be used to distinguish between the primary ionisation source (AGN or star formation) for systems with such low metallicity, though different diagnostic diagrams involving HēIIλ4686 prove very useful, independent of metallicity. We measured the central black hole mass to be log(MBH/M)8.2 ±â 0.4 based on the luminosity and width of the broad line region of the Hα emission. While this places GS_3073 at the lower end of known high-redshift black hole masses, it still appears to be overly massive when compared to its host galaxybs mass properties. We detected an outflow with a projected velocity ⊃700 kms1 and inferred an ionised gas mass outflow rate of about 100M⊙ yr 1, suggesting that one billion years after the Big Bang, GS_3073 is able to enrich the intergalactic medium with metals.

Original languageEnglish
Article numberA145
Pages (from-to)1-17
Number of pages17
JournalAstronomy & Astrophysics
Issue numberSeptember 2023
Early online date18 Sept 2023
Publication statusE-pub ahead of print - 18 Sept 2023


  • astro-ph.GA
  • ISM: abundances
  • Galaxies: active
  • Galaxies: high-redshift
  • Quasars: supermassive black holes


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