scholarly journals The first law of black hole mechanics in the Einstein-Maxwell theory revisited

2020 ◽  
Vol 2020 (9) ◽  
Author(s):  
Zachary Elgood ◽  
Patrick Meessen ◽  
Tomás Ortín
Keyword(s):  
Black Hole ◽  
Maxwell Theory ◽  
Gauge Invariant ◽  
Momentum Maps ◽  
Field Strengths

Abstract We re-derive the first law of black hole mechanics in the context of the Einstein-Maxwell theory in a gauge-invariant way introducing “momentum maps” associated to field strengths and the vectors that generate their symmetries. These objects play the role of generalized thermodynamical potentials in the first law and satisfy generalized zeroth laws, as first observed in the context of principal gauge bundles by Prabhu, but they can be generalized to more complex situations. We test our ideas on the d-dimensional Reissner-Nordström-Tangherlini black hole.

scholarly journals Nonminimal black holes with regular electric field

2015 ◽  
Vol 24 (09) ◽  
pp. 1542009 ◽  
Author(s):  
Alexander B. Balakin ◽  
Alexei E. Zayats
Keyword(s):  
Black Hole ◽  
Electric Field ◽  
Radial Electric Field ◽  
Coupling Constants ◽  
Regular Solutions ◽  
Maxwell Theory ◽  
Spacetime Curvature ◽  
Type Object ◽  
Metric Function

We discuss the problem of identification of coupling constants, which describe interactions between photons and spacetime curvature, using exact regular solutions to the extended equations of the nonminimal Einstein–Maxwell theory. We argue the idea that three nonminimal coupling constants in this theory can be reduced to the single guiding parameter, which plays the role of nonminimal radius. We base our consideration on two examples of exact solutions obtained earlier in our works: the first of them describes a nonminimal spherically symmetric object (star or black hole) with regular radial electric field; the second example represents a nonminimal Dirac-type object (monopole or black hole) with regular metric. We demonstrate that one of the inflexion points of the regular metric function identifies a specific nonminimal radius, thus marking the domain of dominance of nonminimal interactions.

scholarly journals Causality of black holes in 4-dimensional Einstein–Gauss–Bonnet–Maxwell theory

2020 ◽  
Vol 80 (8) ◽  
Author(s):  
Xian-Hui Ge ◽  
Sang-Jin Sin
Keyword(s):  
Black Holes ◽  
Black Hole ◽  
Shear Viscosity ◽  
Upper Bound ◽  
Causal Structure ◽  
Density Ratio ◽  
Entropy Density ◽  
Coupling Constant ◽  
Maxwell Theory ◽  
Black Hole Solutions

Abstract We study charged black hole solutions in 4-dimensional (4D) Einstein–Gauss–Bonnet–Maxwell theory to the linearized perturbation level. We first compute the shear viscosity to entropy density ratio. We then demonstrate how bulk causal structure analysis imposes an upper bound on the Gauss–Bonnet coupling constant in the AdS space. Causality constrains the value of Gauss–Bonnet coupling constant $$\alpha _{GB}$$αGB to be bounded by $$\alpha _{GB}\le 0$$αGB≤0 as $$D\rightarrow 4$$D→4.

scholarly journals Black hole and neutron star mergers in galactic nuclei: the role of triples

2019 ◽  
Vol 488 (2) ◽  
pp. 2825-2835 ◽  
Author(s):  
Giacomo Fragione ◽  
Nathan W C Leigh ◽  
Rosalba Perna
Keyword(s):  
Black Holes ◽  
Black Hole ◽  
Neutron Star ◽  
Massive Stars ◽  
Star Clusters ◽  
Galactic Nuclei ◽  
Compact Objects ◽  
Large Numbers ◽  
Binary Case

ABSTRACT Nuclear star clusters that surround supermassive black holes (SMBHs) in galactic nuclei are thought to contain large numbers of black holes (BHs) and neutron stars (NSs), a fraction of which form binaries and could merge by Kozai–Lidov oscillations (KL). Triple compact objects are likely to be present, given what is known about the multiplicity of massive stars, whose life ends either as an NS or a BH. In this paper, we present a new possible scenario for merging BHs and NSs in galactic nuclei. We study the evolution of a triple black hole (BH) or neutron star (NS) system orbiting an SMBH in a galactic nucleus by means of direct high-precision N-body simulations, including post-Newtonian terms. We find that the four-body dynamical interactions can increase the KL angle window for mergers compared to the binary case and make BH and NS binaries merge on shorter time-scales. We show that the merger fraction can be up to ∼5–8 times higher for triples than for binaries. Therefore, even if the triple fraction is only ∼10–$20\rm{\,per\,cent}$ of the binary fraction, they could contribute to the merger events observed by LIGO/VIRGO in comparable numbers.

scholarly journals Hairy black hole entropy and the role of solitons in three dimensions

2012 ◽  
Vol 2012 (2) ◽  
Author(s):  
Francisco Correa ◽  
Cristián Martínez ◽  
Ricardo Troncoso
Keyword(s):  
Black Hole ◽  
Black Hole Entropy ◽  
Three Dimensions ◽  
Hairy Black Hole

scholarly journals THE PHYSICS OF 2D STRINGY SPACETIMES

1992 ◽  
Vol 01 (02) ◽  
pp. 335-354 ◽  
Author(s):  
G.W. GIBBONS ◽  
MALCOLM J. PERRY
Keyword(s):  
Black Hole ◽  
Scalar Field ◽  
String Theory ◽  
Nontrivial Solution ◽  
Heterotic String ◽  
Two Dimensional ◽  
Dilaton Field ◽  
Black Hole Spacetime ◽  
Canonical Scalar Field

We examine the two-dimensional spacetimes that emerge from string theory. We find all of the solutions with no tachyons, and show that the only nontrivial solution is the black-hole spacetime. We examine the role of duality in this picture. We then explore the thermodynamics of these solutions which is complicated by the fact that only in two spacetime dimensions is it impossible to redefine the dilaton field in terms of a canonical scalar field. Finally, we extend our analysis to the heterotic string, and briefly comment on exact, as opposed to perturbative, solutions.

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