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arXiv · 2507.06311

Dating N loud AGNs at high redshift: GS3073 as a snapshot of wCen like evolution of a nuclear star cluster

F. D'Antona·P. Ventura·A. F. Marino·A. P. Milone·E. Vesperini·F. Calura·M. Tailo·R. Valiante·V. Caloi·A. D'Ercole·F. Dell'Agli
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Abstract

In this paper we address two major questions raised by recent James Webb Space Telescope observations of the young Universe, namely: 1) what are the seed initial masses, and how rapidly have supermassive black holes (BHs) with masses of 1e6-1e8Msun grown in active galactic nuclei (AGN) hosted by very young galaxies? 2) What are the plausible explanations for the super solar abundances of nitrogen in a fraction of young galaxies at high redshift, both with and without evidence of a massive central black hole? We focus mainly on the system GS3073. This system shows an exceptionally large log(N/O)=+0.42(+0.13/-0.10) in the gas close to the AGN. We show here that this abundance is consistent with the composition of gas ejected from massive asymptotic giant branch stars. Moreover, this system shows chemical properties matching those expected at a specific point of the evolution of the abundances in the extreme populations of the former nuclear star cluster wCentauri (wCen). This analogy, along with the N/O, C/O and Fe/O abundances in GS3073, lead to an estimate of an age range of 270-440 Myr for this object, much smaller than the redshift (z=5.5) age of about 1 Gyr. We also adopt the same criteria to estimate an age for GNz11. These two determinations constrain the BH mass versus age relation: accretion on the BH must proceed at intermittent superEddington rates in the first phases, and at a much lower rate after the first half gigayear of life of the Universe. The intermittency of accretion is also a fundamental requirement to allow the formation of the extreme (N rich, O depleted, He rich) populations today observed in wCen for a large range of metallicities.

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F. D'Antona, P. Ventura, A. F. Marino, A. P. Milone, E. Vesperini, F. Calura, M. Tailo, R. Valiante, V. Caloi, A. D'Ercole, F. Dell'Agli. 2025-07-08. Dating N loud AGNs at high redshift: GS3073 as a snapshot of wCen like evolution of a nuclear star cluster. https://doi.org/10.1051/0004-6361%2F202554957

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