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 CII, SiIV, NIV], CIV, HeII, OIII], NIII], and CIII]. The prominent rest-frame equivalent widths (EW(CIV) ≃65Å, EW(OIII]) ≃28Å, and EW(CIII]) ≃48Å) 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=0.01–0.1Z⊙), and compact (<106pc), 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 0.5–7keV. 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) × 108M⊙, which is consistent either with Eddington-accretion onto heavy (�106M⊙) BH seeds formed at z=18 or super-Eddington accretion onto a light seed of∼102–104M⊙at z=25. The corresponding BH-to-stellar mass ratio MBH/Mstar=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.