Evolution characteristics of the central black hole of a magnetized accretion disc

Wang, D. X.; Xiao, Keke; Lei, Wei‐Hua

doi:10.1046/j.1365-8711.2002.05652.x

Cited by 127 publications

(138 citation statements)

References 21 publications

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“…In addition, the Blandford-Znajek process [18], Blandford-Payne process [19] and magnetic coupling process [20,21] can be incorporated with NDAF based on this model. The large-scale magnetic field of required in these processes could be realized, provided that the Parker instability or buoyant rise convert 15 …”

Section: Conclusion and Discussionmentioning

confidence: 99%

A toy model for magnetized neutrino-dominated accretion flows

Lei

Wang

Zhang

et al. 2010

Sci. China Phys. Mech. Astron.

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In this paper, we present a simplified model for magnetized neutrino-dominated accretion flow (NDAF) in which effect of black hole (BH) spin is taken into account by adopting a set of relativistic correction factor, and the magnetic field is parameterized as β , the ratio of the magnetic pressure to the total pressure. It is found that the disc properties are sensitive to the values of the BH spin and β , and more energy can be extracted from NDAF for the faster spin and lower β .black hole, gamma-ray bursts, accretion disc, magnetic fieldThe nature of the central engine of gamma-ray bursts (GRBs) remains unclear, and the favoured models invoke binary merger or collapse of compact objects. These models lead to the formation of a transient hot and dense accretion torus/disc around a black hole (BH) of a few solar masses. If an accretion disc is cooled mainly via the neutrino loss, it is referred to as neutrino-dominated accretion flow (NDAF) [1].NDAF has been extensively discussed by many authors [2][3][4][5]. However, the effects of the magnetic fields are usually neglected in NDAF due to the intrinsic complexity.Magnetic fields could play an important role in the central engine in some aspects [10], e.g., a bold gamma-ray polarization [6], a higher magnetic energy density required by the reverse shock [7,8], and the energy argument for X-ray flares [9]. These considerations stimulate us to discuss a model of magnetized NDAF.Recently, Chen & Beloborodov [4], Gu et al.[5] and Shibata et al. [11] argued that the general relativistic (GR) effects are important for NDAF, and we introduce GR correction factors in our model. This paper is organized as follows. In Sect. 1 we describe the magnetized NDAF in the frame of a relativistic thin disc of steady state, and the effects of MHD stress are described. The main equations are based on refs.[2] and [3], but corrected with GR factors. We solve the set of equations for the solutions of NDAF in Sect. 2, and compute disc temperature, density and neutrino luminosities. The effects of the free parameters are also discussed. Finally, we summarize our results and discuss some related issues in Sect. 3. Magnetized Neutrino-Dominated Accretion FlowsAs is well known, the magneto-rotational instability (MRI) plays an important role in angular momentum transportation of accretion disc [11,12]. Currently, it is widely believed that the viscosity in accretion flows is effectively determined by the turbulent motion of fluid, being related to the magnetic stress. Therefore, we consider only the magnetic viscosity in this model.The magnetic viscous shear r t ϕ can be expressed as where B ϕ is given byThe parameter β is the ratio of the magnetic pressure to the total pressure. A roughly steady state is reached when the growing rate of B ϕ generated by differential rotation of the radial field is equal to its loss rate due to buoyancy effect, and B ϕ can be estimated as [13]

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Section: Conclusion and Discussionmentioning

confidence: 99%

A toy model for magnetized neutrino-dominated accretion flows

Lei

Wang

Zhang

et al. 2010

Sci. China Phys. Mech. Astron.

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“…The quantities rH and rout are the radii corresponding to the BH horizon and the outer boundary of the MCHD region, and we take rout equal to 100 gravitational radius in this paper. The electromotive forces in the MC process due to the rotation of the BH, the plunging region and the disc are given as follows (Li 2000;Wang, Xiao and Lei 2002),…”

Section: Transfer Of Energy and Angular Momentum In MC Processmentioning

confidence: 99%

A model for 3:2 HFQPO pairs in black hole binaries based on cosmic battery

Huang¹,

Ye²,

Wang³

et al. 2016

Mon. Not. R. Astron. Soc.

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A model for 3:2 high-frequency quasi-periodic oscillations (HFQPOs) with 3:2 pairs observed in four black hole X-ray binaries (BHXBs) is proposed by invoking the epicyclic resonances with the magnetic connection (MC) between a spinning black hole (BH) with a relativistic accretion disc. It turns out that the MC can be worked out due to Poynting-Robertson cosmic battery (PRCB), and the 3:2 HFQPO pairs associated with the steep power-law states can be fitted in this model. Furthermore, the severe damping problem in the epicyclic resonance model can be overcome by transferring energy from the BH to the inner disc via the MC process for emitting X-rays with sufficient amplitude and coherence to produce the HFQPOs. In addition, we discuss the important role of the magnetic field in state transition of BHXBs.

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“…This suggests a link between ∆ǫ (as well as η) and BH spin. As we known, spin energy and angular momentum can be transferred from the BH to the disk via a large-scale closed magnetic field (Blandford 1999;van Putten 1999;Li & Paczynski 2000;Li 2000Li , 2002Wang et al 2002Wang et al , 2003Gan et al 2007;Lei et al 2007Lei et al , 2009). This mechanism is called magnetic coupling process (MC).…”

Section: Introductionmentioning

confidence: 99%

Numerical and Analytical Solutions of Neutrino-Dominated Accretion Flows With a Non-Zero Torque Boundary Condition and Its Applications in Gamma-Ray Bursts

Xie

Lei

Wang

2016

ApJ

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A stellar mass black hole (BH) surrounded by a neutrino-dominated accretion flow (NDAF) has been discussed in a number of works as the central engine of gamma-ray bursts (GRBs). It is widely believed that NDAF cannot liberate enough energy for bright GRBs. However, these works have been based on the assumption of "no torque" boundary condition, which is invalid when the disk is magnetized. In this paper, we present both numerical and analytical solutions for NDAFs with non-zero boundary stresses, and reexamine their properties. We find that NDAF with such boundary torque can be powerful enough to account for those bright short GRBs, energetic long GRBs and ultra-long GRBs. The disk becomes viscously unstable, which makes it possible to interpret the variability of GRB prompt emission and the steep decay phase in the early X-ray afterglow. Finally, we study the gravitational waves radiated from a processing BH-NDAF. We find that the effects of the boundary torque on the strength of the gravitational waves can be ignored.

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Evolution characteristics of the central black hole of a magnetized accretion disc

Cited by 127 publications

References 21 publications

A toy model for magnetized neutrino-dominated accretion flows

A toy model for magnetized neutrino-dominated accretion flows

A model for 3:2 HFQPO pairs in black hole binaries based on cosmic battery

Numerical and Analytical Solutions of Neutrino-Dominated Accretion Flows With a Non-Zero Torque Boundary Condition and Its Applications in Gamma-Ray Bursts

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