Force-free electrodynamics near rotation axis of a Kerr black hole

Grignani, G.; Harmark, Troels; Orselli, Marta

doi:10.1088/1361-6382/ab7ac7

Cited by 11 publications

(26 citation statements)

References 35 publications

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“…(Ref. [11] further demonstrates the need for matched asymptotic expansions.) Our work shows that the monopole flux function is jointly C 3 in (ǫx, 1/x), where x = r/M , 11 with similar statements for the other quantities.…”

Section: Comparison With Previous Workmentioning

confidence: 99%

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Consistent Blandford-Znajek expansion

Armas

Cai

Compère

et al. 2020

J. Cosmol. Astropart. Phys.

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The Blandford-Znajek mechanism is the continuous extraction of energy from a rotating black hole via plasma currents flowing on magnetic field lines threading the horizon. In the discovery paper, Blandford and Znajek demonstrated the mechanism by solving the equations of force-free electrodynamics in a perturbative expansion valid at small black hole spin. Attempts to extend this perturbation analysis to higher order have encountered inconsistencies. We overcome this problem using the method of matched asymptotic expansions, taking care to resolve all of the singular surfaces (light surfaces) in the problem. Working with the monopole field configuration, we show explicitly how the inconsistencies are resolved in this framework and calculate the field configuration to one order higher than previously known. However, there is no correction to the energy extraction rate at this order. These results confirm the basic consistency of the split monopole at small spin and lay a foundation for further perturbative studies of the Blandford-Znajek mechanism. * j.armas@uva.nl †

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Section: Comparison With Previous Workmentioning

confidence: 99%

“…Tanabe and Nagataki [7] computed the subleading correction to the energy extraction rate, but noted the full subleading solution could not be determined from their method. More recently, there have been conflicting claims of a high-order solution [8,9] and that the expansion is inconsistent [10,11].…”

Section: Introductionmentioning

confidence: 99%

Consistent Blandford-Znajek expansion

Armas

Cai

Compère

et al. 2020

J. Cosmol. Astropart. Phys.

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show abstract

“…In recent years, there has been renewed interest in extending these perturbative constructions [14][15][16][17][18][19][20] and exploring other profiles [21][22][23][24][25]. The BZ mechanism has been investigated in the intermediate-spin regime [26][27][28][29][30][31][32] using numerical simulations.…”

Section: Introduction and Summary Of The Resultsmentioning

confidence: 99%

“…Among the static magnetospheres, there are configurations with monopole [1], paraboloidal [1], hyperbolic [23] and vertical [4,21] magnetic field line profiles. We refer the reader to [19] for a classification of the asymptotic behaviour. Typically, in solving Eq.…”

Section: Blandford-znajek Split-monopole In the Slow-spin Regimementioning

confidence: 99%

Blandford--Znajek monopole expansion revisited: novel non-analytic contributions to the power emission

Camilloni¹,

Dias²,

Grignani³

et al. 2022

Preprint

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The Blandford and Znajek (BZ) split-monopole serves as an important theoretical example of the mechanism that can drive the electromagnetic extraction of energy from Kerr black holes. It is constructed as a perturbative low spin solution of Force Free Electrodynamics (FFE). Recently, Armas et al. put this construction on a firmer footing by clearing up issues with apparent divergent asymptotics. This was accomplished by resolving the behavior around the outer light surface, a critical surface of the FFE equations. Building on this, we revisit the BZ perturbative expansion, and extend the perturbative approach to higher orders in the spin parameter of the Kerr black hole. We employ matchedasymptotic-expansions and semi-analytic techniques to extend the split-monopole solution to the sixth-order in perturbation theory. The expansion necessarily includes novel logarithmic contributions in the spin parameter. We show that these higher order terms result in non-analytic contributions to the power and angular momentum output. In particular, we compute for the first time the perturbative contributions to the energy extraction at seventh-and eighth-order in the spin parameter. The resulting formula for the energy extraction improves the agreement with numerical simulations at finite spin. Moreover, we present a novel numerical procedure for resolving the FFE equations across the outer light surface, resulting in significantly faster convergence and greater accuracy, and extend this to higher orders as well. Finally, we include a general discussion of light surfaces as critical surfaces of the FFE equations.

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“…in active galactic nuclei and quasars. For more recent discussions on the consistency of the BZ mechanism, see [2][3][4].…”

Section: Jhep12(2020)018mentioning

confidence: 99%

Electro-magnetic energy extraction from rotating black holes in AdS

Callebaut

Rodríguez

Verlinde

2020

J. High Energ. Phys.

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Force-Free Electrodynamics for black holes in Anti de Sitter is considered. We present new, energy extracting solutions of Force-Free Electrodynamics in Anti de Sitter-Near Horizon Extremal Kerr and Super-Entropic Near Horizon Extremal Kerr geometries. The relevant equations of motion are derived from an action for force-free plasma surrounding spinning black holes with generic asymptotics. We consider the energy flux of electrodynamic fields in rotating frames to argue that the correct measure for energy extraction is the energy flux measured by a rotating observer in the near horizon region. We illustrate this procedure by application to near horizon solutions in Kerr, AdS-Kerr and BTZ.

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Force-free electrodynamics near rotation axis of a Kerr black hole

Cited by 11 publications

References 35 publications

Consistent Blandford-Znajek expansion

Consistent Blandford-Znajek expansion

Blandford--Znajek monopole expansion revisited: novel non-analytic contributions to the power emission

Electro-magnetic energy extraction from rotating black holes in AdS

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