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We explore the possibility of theN-rich young proto-galaxy GN-z11, recently observed atz = 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.
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Supermassive black holes from runaway mergers and accretion in nuclear star clusters
ABSTRACT Rapid formation of supermassive black holes occurs in dense nuclear star clusters that are initially gas-dominated. Stellar-mass black hole remnants of the most massive cluster stars sink into the core, where a massive runaway black hole forms as a consequence of combined effects of repeated mergers and Eddington-limited gas accretion. The associated gravitational wave signals of high-redshift extreme mass-ratio inspirals are a unique signature of the nuclear star cluster scenario.
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- PAR ID:
- 10507036
- Publisher / Repository:
- Oxford University Press
- Date Published:
- Journal Name:
- Monthly Notices of the Royal Astronomical Society
- Volume:
- 531
- Issue:
- 1
- ISSN:
- 0035-8711
- Format(s):
- Medium: X Size: p. 133-136
- Size(s):
- p. 133-136
- Sponsoring Org:
- National Science Foundation
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