The Dual Nature of GHZ9: Coexisting Active Galactic Nuclei and Star Formation Activity in a Remote X-Ray Source at z = 10.145

The Dual Nature of GHZ9: Coexisting Active Galactic Nuclei and Star Formation Activity in a Remote X-Ray Source at z = 10.145

We present James Webb Space Telescope (JWST)/NIRSpec PRISM spectroscopic characterization of GHZ9 at z = 10.145 ± 0.010, currently the most distant source detected by the Chandra X-ray Observatory. The spectrum reveals several UV high-ionization lines, including C II , Si IV , N IV ], C IV , He II ,...

Full description

Saved in:
Bibliographic Details
Main Authors: Lorenzo Napolitano, Marco Castellano, Laura Pentericci, Cristian Vignali, Roberto Gilli, Adriano Fontana, Paola Santini, Tommaso Treu, Antonello Calabrò, Mario Llerena, Enrico Piconcelli, Luca Zappacosta, Sara Mascia, Roberta Tripodi, Pablo Arrabal Haro, Pietro Bergamini, Tom J. L. C. Bakx, Mark Dickinson, Karl Glazebrook, Alaina Henry, Nicha Leethochawalit, Giovanni Mazzolari, Emiliano Merlin, Takahiro Morishita, Themiya Nanayakkara, Diego Paris, Simonetta Puccetti, Guido Roberts-Borsani, Sofia Rojas Ruiz, Piero Rosati, Eros Vanzella, Fabio Vito, Benedetta Vulcani, Xin Wang, Ilsang Yoon, Jorge A. Zavala
Format: Article
Language:English
Published: IOP Publishing 2025-01-01
Series:The Astrophysical Journal
Subjects:
High-redshift galaxies
Primordial galaxies
Active galactic nuclei
X-ray active galactic nuclei
Online Access:https://doi.org/10.3847/1538-4357/ade706
Tags: Add Tag
No Tags, Be the first to tag this record!
Description
Summary:We present James Webb Space Telescope (JWST)/NIRSpec PRISM spectroscopic characterization of GHZ9 at z = 10.145 ± 0.010, currently the most distant source detected by the Chandra X-ray Observatory. The spectrum reveals several UV high-ionization lines, including C II , Si IV , N IV ], C IV , He II , O III ], N III ], and C III ]. The prominent rest-frame equivalent widths (EW(C IV ) ≃ 65 Å, EW(O III ]) ≃ 28 Å, and EW(C III ]) ≃ 48 Å) show the presence of a hard active galactic nucleus (AGN) radiation field, while line ratio diagnostics are consistent with either AGN or star formation as the dominant ionizing source. GHZ9 is nitrogen-enriched (6–9.5 (N/O) _⊙ ), carbon-poor (0.2–0.65 (C/O) _⊙ ), metal-poor ( Z = 0.01–0.1 Z _⊙ ), and compact (<106 pc), similarly to GN-z11, GHZ2, and recently discovered N-enhanced high redshift objects. We exploited the newly available JWST/NIRSpec and NIRCam data set to perform an independent analysis of the Chandra data confirming that GHZ9 is the most likely JWST source associated with X-ray emission at 0.5–7 keV. Assuming a spectral index Γ = 2.3 (1.8), we estimate a black hole (BH) mass of 1.60 ± 0.31 (0.48 ± 0.09) × 10 ^8 M _⊙ , which is consistent either with Eddington-accretion onto heavy (≥10 ^6 M _⊙ ) BH seeds formed at z = 18 or super-Eddington accretion onto a light seed of ∼10 ^2 –10 ^4 M _⊙ at z = 25. The corresponding BH-to-stellar mass ratio M _BH / M _star = 0.33 ± 0.22 (0.10 ± 0.07), with a stringent limit >0.02, implies an accelerated growth of the BH mass with respect to the stellar mass. GHZ9 is the ideal target to constrain the early phases of AGN–galaxy coevolution with future multifrequency observations.
ISSN:1538-4357

Similar Items