Letter to the Editor

GN-z11: Witnessing the formation of second-generation stars and an accreting massive black hole in a massive star cluster

¹ Istituto Nazionale di Astrofisica, Osservatorio Astronomico di Roma, Via Frascati 33, 00077 Monte Porzio Catone, Italy
e-mail: franca.dantona@gmail.com
² Department of Astronomy, Indiana University, Swain West, 727 E. 3rd Street, Bloomington, IN 47405, USA
³ INAF – OAS, Osservatorio di Astrofisica e Scienza dello Spazio di Bologna, via Gobetti 93/3, 40129 Bologna, Italy
⁴ Istituto Nazionale di Astrofisica – Istituto di Astrofisica e Planetologia Spaziali, Via Fosso del Cavaliere 100, 00133 Roma, Italy
⁵ Istituto Nazionale di Astrofisica – Osservatorio Astronomico di Padova, Vicolo dell’Osservatorio 5, 35122 Padova, Italy
⁶ Istituto Nazionale di Astrofisica, Osservatorio Astrofisico di Arcetri, Largo Enrico Fermi, 5, 50125 Firenze, Italy
⁷ Dipartimento di Fisica e Astronomia “Galileo Galilei”, Univ. di Padova, Vicolo dell’Osservatorio 3, 35122 Padova, Italy
⁸ Dipartimento di Fisica e Astronomia Augusto Righi, Università degli Studi di Bologna, Via Gobetti 93/2, 40129 Bologna, Italy

Received: 11 October 2023
Accepted: 23 November 2023

Abstract

We explore the possibility of the N-rich young proto-galaxy GN-z11, recently observed at z = 10.6 by JWST, being the result of the formation of second generation stars from pristine gas and asymptotic giant branch (AGB) ejecta in a massive globular cluster or nuclear star cluster. We show that a second generation forming out of gas polluted by the ejecta of massive AGB stars and mixed with gas of a standard composition accounts for the unusually large N/O in the GN-z11 spectrum. The timing of the evolution of massive (4–7.5 M_⊙) AGBs also provides a favorable environment for the growth of a central stellar mass black hole to the AGN stage observed in GN-z11. According to our model, the progenitor system was born when the age of the Universe was ≃260 − 380 Myr, well within the bounds of the pre-reionization epoch.