Is the energy generation rate of nuclear reactions  in hot
 accretion flows important?

Zhang, H.; Wang, Y.; Yuan, Feng; Ding, Fenglin; Luo, Xiaochun; Peng, Qiu‐He

doi:10.1051/0004-6361/200912005

Cited by 2 publications

(3 citation statements)

References 20 publications

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“…It is well known that self-similar solutions of ADAF would lead to a significant uncertainty in the hot accretion disks and outflow regions. [18] Therefore, based on the global solution of ADAFs, we revisit nucleosynthesis mechanism in accretion disks around black holes. It is found that our simulation results show a predicted isotopic abundance to the observations from high-resolution spectroscopic data.…”

Section: -3mentioning

confidence: 99%

Nucleosynthesis in Advection-Dominated Accretion Flow onto a Black Hole

Zhang

et al. 2017

Chinese Phys. Lett.

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Nucleosynthesis in advection-dominated accretion flow (ADAF) onto a black hole is proposed to be an important role in chemical evolution around compact stars. We investigate the nucleosynthesis in ADAF relevant for a black hole of low mass, different from that of the self-similar solution. In particular, the presence of supersolar metal mass fractions of some isotopes seems to be associated with the known black hole nucleosynthesis in ADAF, which offers further evidence of diversity of the chemical enrichment.

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Section: -3mentioning

confidence: 99%

Nucleosynthesis in Advection-Dominated Accretion Flow onto a Black Hole

Zhang

et al. 2017

Chinese Phys. Lett.

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“…We can rewrite it as It was shown earlier that the nuclear energy released/absorbed in a hot accretion disk need not be negligible [10,11,14,28] and the thermonuclear reactions therein could produce over-abundant metals [10,[29][30][31] which are observed in galaxies. However, the value of α viscosity determines whether the energy due to nuclear reactions is comparable to that due to the viscous effects [10,28] and Ohmic dissipation or not. From equation (4) we can write down the entropy per unit volume, namely the entropy density, of the flow as…”

Section: Advective Accretion Flows Around Black Holesmentioning

confidence: 99%

“…We have recalled the previous work discussing possible nuclear burning in accretion flows and its observational evidences/consequences [10,11,[28][29][30][31].…”

Section: −4ṁmentioning

confidence: 99%

Can the viscosity in astrophysical black hole accretion disks be close to its string theory bound?

Mukhopadhyay

2013

Physics Letters B

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String theory and gauge/gravity duality suggest the lower bound of shear viscosity (η) to entropy density (s) for any matter to be ∼ µ /4πk B , when and k B are reduced Planck and Boltzmann constants respectively and µ ≤ 1. Motivated by this, we explore η/s in black hole accretion flows, in order to understand if such exotic flows could be a natural site for the lowest η/s. Accretion flow plays an important role in black hole physics in identifying the existence of the underlying black hole. This is a rotating shear flow with insignificant molecular viscosity, which could however have a significant turbulent viscosity, generating transport, heat and hence entropy in the flow. However, in presence of strong magnetic field, magnetic stresses can help in transporting matter independent of viscosity, via celebrated Blandford-Payne mechanism. In such cases, energy and then entropy produces via Ohmic dissipation.In addition, certain optically thin, hot, accretion flows, of temperature > ∼ 10 9 K, may be favourable for nuclear burning which could generate/absorb huge energy, much higher than that in a star. We find that η/s in accretion flows appears to be close to the lower bound suggested by theory, if they are embedded by strong magnetic field or producing nuclear energy, when the source of energy is not viscous effects.A lower bound on η/s also leads to an upper bound on the Reynolds number of the flow.

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Is the energy generation rate of nuclear reactions in hot accretion flows important?

Cited by 2 publications

References 20 publications

Nucleosynthesis in Advection-Dominated Accretion Flow onto a Black Hole

Nucleosynthesis in Advection-Dominated Accretion Flow onto a Black Hole

Can the viscosity in astrophysical black hole accretion disks be close to its string theory bound?

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