scholarly journals Charged anti-de Sitter BTZ black holes in Maxwell-f(T) gravity

2018 ◽  
Vol 33 (13) ◽  
pp. 1850076 ◽  
Author(s):  
G. G. L. Nashed ◽  
S. Capozziello
Keyword(s):  
Black Holes ◽  
Special Form ◽  
Energy Content ◽  
Equations Of Motion ◽  
Main Task ◽  
Cauchy Horizon ◽  
De Sitter ◽  
Vector Form ◽  
Charged Case ◽  
General Vector

Inspired by the Bañados, Teitelboim and Zanelli (BTZ) formalism, we discuss the Maxwell-[Formula: see text] gravity in [Formula: see text] dimensions. The main task is to derive exact solutions for a special form of [Formula: see text], with [Formula: see text] being the torsion scalar of Weitzenböck geometry. To this end, a triad field is applied to the equations of motion of charged [Formula: see text] and sets of circularly symmetric noncharged and charged solutions have been derived. We show that, in the charged case, the monopole-like and the [Formula: see text] terms are linked by a correlative constant despite the known results in teleparallel geometry and its extensions.[Formula: see text] Furthermore, it is possible to show that the event horizon is not identical with the Cauchy horizon due to such a constant. The singularities and the horizons of these black holes are examined: they are new and have no analogue in the literature due to the fact that their curvature singularities are soft. We calculate the energy content of these solutions by using the general vector form of the energy–momentum within the framework of [Formula: see text] gravity. Finally, some thermodynamical quantities, like entropy and Hawking temperature, are derived.

scholarly journals Higher-derivative corrections to entropy and the weak gravity conjecture in Anti-de Sitter space

2020 ◽  
Vol 2020 (9) ◽  
Author(s):  
Sera Cremonini ◽  
Callum R.T. Jones ◽  
James T. Liu ◽  
Brian McPeak
Keyword(s):  
Black Holes ◽  
Equations Of Motion ◽  
Casimir Energy ◽  
Thermodynamic Quantities ◽  
Leading Order ◽  
De Sitter ◽  
Higher Derivative ◽  
Positive Meaning ◽  
Universal Relationship ◽  
Weak Gravity

Abstract We compute the four-derivative corrections to the geometry, extremality bound, and thermodynamic quantities of AdS-Reissner-Nordström black holes for general dimensions and horizon geometries. We confirm the universal relationship between the extremality shift at fixed charge and the shift of the microcanonical entropy, and discuss the consequences of this relation for the Weak Gravity Conjecture in AdS. The thermodynamic corrections are calculated using two different methods: first by explicitly solving the higher-derivative equations of motion and second, by evaluating the higher-derivative Euclidean on-shell action on the leading-order solution. In both cases we find agreement, up to the addition of a Casimir energy in odd dimensions. We derive the bounds on the four-derivative Wilson coefficients implied by the conjectured positivity of the leading corrections to the microcanonical entropy of thermodynamically stable black holes. These include the requirement that the coefficient of Riemann-squared is positive, meaning that the positivity of the entropy shift is related to the condition that c − a is positive in the dual CFT. We discuss implications for the deviation of η/s from its universal value and a potential lower bound.

Rotating charged black hole spacetimes in quadratic f(R) gravitational theories

2018 ◽  
Vol 27 (07) ◽  
pp. 1850074 ◽  
Author(s):  
G. G. L. Nashed
Keyword(s):  
Black Holes ◽  
Energy Condition ◽  
Energy Conditions ◽  
Conserved Quantities ◽  
De Sitter ◽  
Black Hole Spacetimes ◽  
Symmetric Spacetimes ◽  
Gravitational Theories ◽  
Sitter Spacetime ◽  
General Vector

Motivated by the substantial modifications of gravitational theories and by the models that come out of [Formula: see text], we apply the field equation of the charged [Formula: see text] as well as a general vector potential containing three unknown functions to two spherically symmetric spacetimes. We solve the output of the differential equations and derive a class of black holes that are electrically and magnetically rotating spacetimes. The asymptotic behavior of these black holes acts as anti-de Sitter spacetime. Moreover, these solutions have asymptotic curvature singularities as those of General Relativity. We investigate this by calculating the invariants of curvature. Also, we address the issue of the energy conditions and show that the strong energy condition is satisfied provided [Formula: see text]. Finally, we compute the conserved quantities like mass and angular momentum.

scholarly journals Strong cosmic censorship in near-extremal Kerr-Sen-de Sitter spacetime

2021 ◽  
Vol 81 (11) ◽  
Author(s):  
Ming Zhang ◽  
Jie Jiang
Keyword(s):  
Black Hole ◽  
Scalar Field ◽  
Equations Of Motion ◽  
Cosmic Censorship ◽  
Cauchy Horizon ◽  
De Sitter ◽  
Sitter Spacetime ◽  
Resonant Modes ◽  
Strong Cosmic Censorship ◽  
Black Hole Spacetime

AbstractIn this work, we first calculate equations of motion for particles in the Kerr-Sen-de Sitter black hole spacetime. Then, in the eikonal regime, we analytically obtain the quasi-normal resonant modes of massless neutral scalar field perturbation and find its imaginary part to be characterized by the surface gravity of a near-extremal Kerr-Sen-de Sitter black hole with the Cauchy horizon approaching the event horizon. We further show that the Penrose strong cosmic censorship conjecture is thus respected in this spacetime with dilaton scalar field and axion pseudoscalar field.

scholarly journals Electro-magnetic energy extraction from rotating black holes in AdS

2020 ◽  
Vol 2020 (12) ◽  
Author(s):  
Nele Callebaut ◽  
Maria J. Rodriguez ◽  
Herman Verlinde
Keyword(s):  
Black Holes ◽  
Energy Flux ◽  
Magnetic Energy ◽  
Equations Of Motion ◽  
Energy Extraction ◽  
De Sitter ◽  
New Energy ◽  
Rotating Frames ◽  
Electro Magnetic ◽  
Correct Measure

Abstract 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.

scholarly journals Massive Dirac quasinormal modes in Schwarzschild–de Sitter black holes: Anomalous decay rate and fine structure

2021 ◽  
Vol 103 (6) ◽  
Author(s):  
Almendra Aragón ◽  
Ramón Bécar ◽  
P. A. González ◽  
Yerko Vásquez
Keyword(s):  
Black Holes ◽  
Fine Structure ◽  
Decay Rate ◽  
Quasinormal Modes ◽  
De Sitter

scholarly journals Bifurcation of the Maxwell quasinormal spectrum on asymptotically anti–de Sitter black holes

2021 ◽  
Vol 103 (6) ◽  
Author(s):  
Mengjie Wang ◽  
Zhou Chen ◽  
Xin Tong ◽  
Qiyuan Pan ◽  
Jiliang Jing
Keyword(s):  
Black Holes ◽  
De Sitter

scholarly journals Driven black holes: from Kolmogorov scaling to turbulent wakes

2021 ◽  
Vol 2021 (7) ◽  
Author(s):  
Tomas Andrade ◽  
Christiana Pantelidou ◽  
Julian Sonner ◽  
Benjamin Withers
Keyword(s):  
Nonlinear Dynamics ◽  
Black Holes ◽  
General Relativity ◽  
Black Hole ◽  
Strong Field ◽  
De Sitter ◽  
Event Horizons ◽  
Binary Mergers ◽  
Tidal Deformations ◽  
Proof Of Principle

Abstract General relativity governs the nonlinear dynamics of spacetime, including black holes and their event horizons. We demonstrate that forced black hole horizons exhibit statistically steady turbulent spacetime dynamics consistent with Kolmogorov’s theory of 1941. As a proof of principle we focus on black holes in asymptotically anti-de Sitter spacetimes in a large number of dimensions, where greater analytic control is gained. We focus on cases where the effective horizon dynamics is restricted to 2+1 dimensions. We also demonstrate that tidal deformations of the horizon induce turbulent dynamics. When set in motion relative to the horizon a deformation develops a turbulent spacetime wake, indicating that turbulent spacetime dynamics may play a role in binary mergers and other strong-field phenomena.

scholarly journals Weak gravity bounds in asymptotic string compactifications

2021 ◽  
Vol 2021 (6) ◽  
Author(s):  
Brice Bastian ◽  
Thomas W. Grimm ◽  
Damian van de Heisteeg
Keyword(s):  
Black Holes ◽  
Moduli Space ◽  
Mass Formula ◽  
Complex Structure ◽  
Mass Ratio ◽  
De Sitter ◽  
String Compactifications ◽  
Type Iib String Theory ◽  
Bps States ◽  
Weak Gravity

Abstract We study the charge-to-mass ratios of BPS states in four-dimensional $$ \mathcal{N} $$ N = 2 supergravities arising from Calabi-Yau threefold compactifications of Type IIB string theory. We present a formula for the asymptotic charge-to-mass ratio valid for all limits in complex structure moduli space. This is achieved by using the sl(2)-structure that emerges in any such limit as described by asymptotic Hodge theory. The asymptotic charge-to-mass formula applies for sl(2)-elementary states that couple to the graviphoton asymptotically. Using this formula, we determine the radii of the ellipsoid that forms the extremality region of electric BPS black holes, which provides us with a general asymptotic bound on the charge-to-mass ratio for these theories. Finally, we comment on how these bounds for the Weak Gravity Conjecture relate to their counterparts in the asymptotic de Sitter Conjecture and Swampland Distance Conjecture.

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