GA-NIFS: A massive black hole in a low-metallicity AGN at z ~ 5:55 revealed by JWST/NIRSpec IFS

By H. Ubler, R. Maiolino, E. Curtis-Lake, P. Pérez-González, M. Curti, S. Arribas, S. Charlot, Michele Perna, M. Marshall, F. D’Eugenio and 13 more. Astronomy & Astrophysics, 2023

152 citations recorded by the source corpus.

We present JWST/NIRSpec Integral Field Spectrograph rest-frame optical data of the compact $z=5.55$ galaxy GS_3073. Its prominent broad components in several hydrogen and helium lines (while absent in the forbidden lines), and the detection of a large equivalent width of He II$\lambda4686$, EW(He II) ~ 20A, unambiguously identify it as an active galactic nucleus (AGN). We measure a gas-phase metallicity of $Z_{\rm gas}/Z_\odot\sim0.21^{+0.08}_{-0.04}$, lower than what has been inferred for both more luminous AGN at 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 such low-metallicity systems, whereas different diagnostic diagrams involving He II$\lambda4686$ prove very useful, independent of metallicity. We measure the central black hole mass to be $\log(M_{\rm BH}/M_\odot)\sim8.2\pm0.4$ based on the luminosity and width of the broad line region of the H$\alpha$ emission. While this places GS_3073 at the lower end of known high-redshift black hole masses, it still appears to be over-massive compared to its host galaxy properties. We detect an outflow with projected velocity $\gtrsim700$ km/s and infer an ionised gas mass outflow rate of about $100\ M_\odot/$yr, suggesting that GS_3073 is able to enrich the intergalactic medium with metals one billion years after the Big Bang.

Subfields: Astronomy and Astrophysics, Instrumentation

View Paper: https://www.semanticscholar.org/paper/1eb0770ecee4f825aa7320fb78e22e0b63e8b3e3

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In Astronomy and Astrophysics

1. M. Ouchi
2. Yoshiaki Ono
3. K. Nakajima
4. Y. Harikane
5. R. Maiolino
6. Y. Isobe
7. Yechi Zhang
8. Hiroya Umeda

In Instrumentation

1. M. Ouchi
2. Yoshiaki Ono
3. K. Nakajima
4. Y. Harikane
5. Y. Isobe
6. Yechi Zhang
7. Hiroya Umeda
8. P. Dayal

Citations in the corpus

• JWST CEERS and JADES Active Galaxies at z = 4–7 Violate the Local M •–M ⋆ Relation at >3σ: Implications for Low-mass Black Holes and Seeding Models (2023, background): “…come on top of more numerous detections in the redshift range z = 4 − 7 (i.e., where the H α line is effective in measuring masses) that is filling the 10 6 − 10 8 M ⊙ black hole mass range (Harikane et al. 2023a; Kocevski et al. 2023; Onoue et al. 2023; Carnall et al. 2023; ¨Ubler et al. 2023).”
• A JWST/NIRSpec First Census of Broad-line AGNs at z = 4–7: Detection of 10 Faint AGNs with M BH ∼ 106–108 M ⊙ and Their Host Galaxy Properties (2023, background): “55 (¨Ubler et al. 2023), which is interpreted as a type 1.8 AGN with a black hole mass of M BH ∼ 10 8 M ⊙ .”
• A Census of Photometrically Selected Little Red Dots at 4 < z < 9 in JWST Blank Fields (2024, methodology): “…spectra revealed clear evidence for broad H α and/or H β emission indicative of actively accreting supermassive black holes (SMBH; Furtak et al. 2023b; Fujimoto et al. 2023a; Greene et al. 2023; Killi et al. 2023; Kocevski et al. 2023; Kokorev et al. 2023a; Matthee et al. 2023; ¨Ubler et al. 2023).”