Nuclear burning in an accretion flow around a stellar-mass black hole embedded within an AGN disc
Nov 11, 20249 pages
Published in:
- Mon.Not.Roy.Astron.Soc. 535 (2024) 4, 3050-3058
- Published: Nov 13, 2024
e-Print:
- 2411.07531 [astro-ph.HE]
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Abstract: (Oxford University Press)
A stellar-mass black hole, embedded within the accretion disc of an active galactic nuclei (AGN), has the potential to accrete gas at a rate that can reach approximately ∼109 times the Eddington limit. This study explores the potential for nuclear burning in the rapidly accreting flow towards this black hole and studies how nucleosynthesis affects metal production. Using numerical methods, we have obtained the disc structure while considering nuclear burning and assessed the stability of the disc. In contrast to gas accretion onto the surface of a neutron star or white dwarf, the disc remains stable against the thermal and secular instabilities because advection cooling offsets the nuclear heating effects. The absence of a solid surface for a black hole prevents excessive mass accumulation in the inner disc region. Notably, nuclear fusion predominantly takes place in the inner disc region, resulting in substantial burning of 12C and 3He, particularly for black holes around M=10M⊙ with accretion rates exceeding approximately ∼107 times the Eddington rate. The ejection of carbon-depleted gas through outflows can lead to an increase in the mass ratio of oxygen or nitrogen to carbon, which may be reflected in observed line ratios such as N v/C iv and O iv/C iv. Consequently, these elevated spectral line ratios could be interpreted as indications of supersolar metallicity in the broad-line region.Note:
- 9 pages, 5 figures, accepted for publication in MNRAS
- accretion, accretion discs
- nuclear reactions, nucleosynthesis, abundances
- methods: analytical
- stars: black holes
- quasars: supermassive black holes
References(256)
Figures(5)