Black Brane Research Articles

Stabilizing homogeneous black strings in AdS

It is known that homogenous black strings in flat spacetime are unstable under long wavelength perturbations. Recently, by including scalar fields that depend on the extended coordinates only, homogenous black strings have been constructed in the presence of a negative cosmological constant, therefore implying that generic perturbations will contain both metric and scalar fluctuations. Here we show that for such generic perturbations homogeneous black strings with a negative cosmological constant are perturbatively stable at linear level, regardless the size of the Schwarzschild-AdS black hole located on the brane.

Rotating black string in Born–Infeld gravity’s rainbow

Compact objects endowed with rotation and charge are interesting both from physical and mathematical points of view. Motivated by the recent interesting consequences of gravity’s rainbow, in this paper we introduce energy-dependent asymptotically anti-de Sitter black string solutions of Einstein–Born–Infeld gravity. We report the geometric properties of the solutions and generalize them to rotating black string solutions through an improper local transformation. We calculate the conserved and thermodynamic quantities of rotating black strings and examine the validity of the first law of thermodynamics. In addition, the effects of both rainbow functions and nonlinear electrodynamics on the thermodynamic behavior of the solutions will be studied. Finally, we investigate the thermal stability of the solutions using different methods.

Gluing gravitational blocks for AdS black holes

We provide a unifying entropy functional and an extremization principle for black holes and black strings in AdS4 × S7 and AdS5 × S5 with arbitrary rotation and generic electric and magnetic charges. This is done by gluing gravitational blocks, basic building blocks that are directly inspired by the holomorphic blocks appearing in the factorization of supersymmetric partition functions in three and four dimensions. We also provide an explicit realization of the attractor mechanism by identifying the values of the scalar fields at the horizon with the critical points of the entropy functional. We give examples based on dyonic rotating black holes with a twist in AdS4 × S7, rotating black strings in AdS5 × S5, dyonic Kerr-Newman black holes in AdS4 × S7 and Kerr-Newman black holes in AdS5 × S5. In particular, our entropy functional extends existing results by adding rotation to the twisted black holes in AdS4 and by adding flavor magnetic charges for the Kerr-Newman black holes in AdS4. We also discuss generalizations to higher-dimensional black objects.

Orbits in nonsupersymmetric magic theories

We determine and classify the electric-magnetic duality orbits of fluxes supporting asymptotically flat, extremal black branes in [Formula: see text] space–time dimensions in the so-called nonsupersymmetric magic Maxwell–Einstein theories, which are consistent truncations of maximal supergravity and which can be related to Jordan algebras (and related Freudenthal triple systems) over the split complex numbers [Formula: see text] and the split quaternions [Formula: see text]. By studying the stabilizing subalgebras of suitable representatives, realized as bound states of specific weight vectors of the corresponding representation of the electric-magnetic duality symmetry group, we obtain that, as for the case of maximal supergravity, in magic nonsupersymmetric Maxwell–Einstein theories there is no splitting of orbits, namely there is only one orbit for each nonmaximal rank element of the relevant Jordan algebra (in [Formula: see text] and 6) or of the relevant Freudenthal triple system (in [Formula: see text]).

Black string surrounded by a static anisotropic quintessence fluid

A black string is a solution of the four-dimensional general relativity in cylindrical symmetric anti-de Sitter (AdS) spacetime pioneered by Lemos (1999). We obtain an exact rotating black string surrounded by quintessence matter in anti-de Sitter (AdS) spacetime and analyse its properties. The solution has an additional parameter Nq due to background quintessence matter and it also depends on quintessence state parameter wq. Our rotating solution encompasses the Lemos black string Lemos (1999), which can be recovered in the absence of background matter (Nq=0). The special case of rotating charged black string (wq=1∕3) has both Cauchy and event horizons. We find that thermodynamic quantities mass, temperature, entropy and heat capacity get corrected due to quintessence background. The counterterm method is utilized to calculate the associated conserved quantities to conclude that the first law of thermodynamics is satisfied. The cloud of strings background (wq=−1∕3) has been included as a special case.

Linearized Einstein’s equation around pure BTZ from entanglement thermodynamics

It is known that the linearized Einstein's equation around the pure $AdS$ can be obtained from the constraint $ \Delta S = \Delta\left< H \right> $, known as the first law of entanglement, on the boundary $CFT$. The corresponding dual state in the boundary $CFT$ is the vacuum state around which the linear perturbation is taken. In this paper we revisit this question, in the context of $ {AdS}_3/{CFT}_2 $, with the state of the boundary ${CFT}_2$ as a thermal state. The corresponding dual geometry is a planar BTZ black hole. By considering the linearized perturbation around this black brane we show that Einstein's equation follows from the first law of entanglement. The modular Hamiltonian in a thermal state of the ${CFT}_2$ that we have used has been recently found in arXiv:1608.01283 [cond-mat.stat-mech].

Microstates of rotating AdS5 strings

We provide a general formula for the refined topologically twisted index of mathcal{N} = 1 gauge theories living on the world-volume of D3-branes at conical Calabi-Yau singularities in the Cardy limit. The index is defined as the partition function on T2× {S}_{omega}^2 , with a partial topological twist and a Ω-deformation along S , in the presence of background magnetic fluxes and fugacities for the global symmetries and can be used to study the properties of a class of BPS black strings. To this purpose, we find rotating domain- wall solutions of five-dimensional gauged supergravity interpolating between AdS5 and a near horizon region consisting of a warped fibration of BTZ over a sphere. We explicitly construct rotating domain-walls that can be embedded in AdS5× S5 by uplifting a class of four-dimensional rotating black holes. We then provide a microscopic explanation of the entropy of such black holes by using the refined topologically twisted index of mathcal{N} = 4 super Yang-Mills.

Holographic entanglement entropy, subregion complexity and Fisher information metric of ‘black’ non-susy D3 brane

The BPS D3 brane has a non-supersymmetric cousin, called the non-susy D3 brane, which is also a solution of type IIB string theory. The corresponding counterpart of black D3 brane is the ‘black’ non-susy D3 brane and like the BPS D3 brane, it also has a decoupling limit, where the decoupled geometry (in the case we are interested, this is asymptotically AdS5 × S5) is the holographic dual of a non-conformal, non-supersymmetric QFT in (3+1)-dimensions. In this QFT we compute the entanglement entropy (EE), the complexity and the Fisher information metric holographically using the above mentioned geometry for spherical subsystems. The fidelity and the Fisher information metric have been calculated from the regularized extremal volume of the codimension one time slice of the bulk geometry using two different proposals in the literature. Although for AdS black hole both the proposals give identical results, the results differ for the non-supersymmetric background.

Shadow of a rotating squashed Kaluza-Klein black hole

We study the shadow of a rotating squashed Kaluza-Klein (KK) black hole and the shadow is found to possess distinct properties from those of usual rotating black holes. It is shown that the shadow for a rotating squashed KK black hole is heavily influenced by the specific angular momentum of photon from the fifth dimension. Especially, as the parameters lie in a certain special range, there is no any shadow for a black hole, which does not emerge for the usual black holes. In the case where the black hole shadow exists, the shadow shape is a perfect black disk and its radius decreases with the rotation parameter of the black hole. Moreover, the change of the shadow radius with extra dimension parameter also depends on the rotation parameter of black hole. Finally, with the latest observation data, we estimate the angular radius of the shadow for the supermassive black hole Sgr A∗ at the centre of the Milky Way galaxy and the supermassive black hole in M 87.

Dispersion relations in non-relativistic two-dimensional materials from quasinormal modes in H\u01d2rava Gravity

We compute dispersion relations of non-hydrodynamic and hydrodynamic modes in a non-relativistic strongly coupled two-dimensional quantum field theory. This is achieved by numerically computing quasinormal modes (QNMs) of a particular analytically known black brane solution to 3+1-dimensional Hǒrava Gravity. Hǒrava Gravity is distinguished from Einstein Gravity by the presence of a scalar field, termed the khronon, defining a preferred time-foliation. Surprisingly, for this black brane solution, the khronon fluctuation numerically decouples from all others, having its own set of purely imaginary eigenfrequencies, for which we provide an analytic expression. All other Hǒrava Gravity QNMs are expressed analytically in terms of QNMs of Einstein Gravity, in units involving the khronon coupling constants and various horizons. Our numerical computation reproduces the analytically known momentum diffusion mode, and extends the analytic expression for the sound modes to a wide range of khronon coupling values. In the eikonal limit (large momentum limit), the analytically known dispersion of QNM frequencies with the momentum is reproduced by our numerics. We provide a parametrization of all QNM frequencies to fourth order in the momentum. We demonstrate perturbative stability in a wide range of coupling constants and momenta.

Cylindrical asymmetric thin-shell wormholes

By employing certain cylindrically symmetric spacetimes we construct traversable, asymmetric thin-shell wormholes. Specifically, these spacetimes consist of the cosmic string and the 4-dimensional black string metrics. The corresponding thin-shell wormholes are analyzed within the context of linear stability by suppressing the axial perturbations which result in stable asymmetric thin-shell wormholes. Next, we look for a correlation between the stability and the symmetry of the spacetime under investigation which certifies the previous results for spherical thin-shell wormholes, in the sense that the more symmetric a thin-shell wormhole, the more probable to find it in a stable state. However, there is an exceptional case in cosmic strings which is discussed in detail. Furthermore, it is shown that cylindrically symmetric cosmic string wormholes cannot be supported by a barotropic equation of state.

Physical and thermodynamic properties of quartic quasitopological black holes and rotating black branes with a nonlinear source

In this paper, we find the solutions of quartic quasitopological black holes and branes coupled to logarithmic and exponential forms of nonlinear electrodynamics. These solutions have an essential singularity at $r=0$. Depending on the value of charge parameter $q$, we have an extreme black hole/brane, a black hole/brane with two horizons or a naked singularity. For small values of parameter $q$, the solutions lead to a black hole/brane with two horizons. The values of the horizons are independent of the values of quasitopological parameters and depend only on the values of $q$, dimensions $n$, nonlinear parameter $\beta$ and mass parameter. Also, the solutions are not thermally stable for dS and flat spacetimes. However, AdS solutions are stable for $r_{+}>{r_{+}}_{\rm{ext}}$ which the temperature is zero for $r_{+}={r_{+}}_{\rm{ext}}$. The value of ${r_{+}}_{\rm{ext}}$ also depends on the values of parameters $q$, $\beta$, $n$ and $m$. As the value of ${r_{+}}_{\rm{ext}}$ decreases, the region of stability becomes larger. We also use HPEM metric to probe GTD formalism for our solutions. This metric is successful to predict the divergences of the scalar curvature exactly at the phase transition points. For large values of parameter $\Xi$, the black hole/brane has a transition to a stable state and stays stable.

Does a cloud of strings affect shear viscosity bound?

The Einstein AdS black brane with a cloud of strings background in context of massive gravity is introduced. There is a momentum dissipation on the boundary because of graviton mass on the bulk. The ratio of shear viscosity to entropy density is calculated for this solution. This value violates the KSS bound if we apply the Dirichlet boundary and regularity on the horizon conditions. Our result shows that this value is independent of the cloud of strings.

New results on the physical interpretation of black-brane gravitational perturbations

The linear perturbation theory applied to the study of black holes is a traditional and powerful tool to investigate some of the basic properties of these objects, such as the stability of the event horizon, the spectra of quasinormal modes, the scattering and the production of waves in a process of gravitational collapse. Since long ago, the physical interpretation of the linear fluctuations in the metric of spherically symmetric black holes has been established. In a multipolar expansion, it is known that polar perturbations of a monopole type ($l=0$) can only increase the black-hole mass, axial perturbations of a dipole type ($l=1$) induce a slow rotation in the system, and perturbations with $l\geq 2$ always lead to the production of gravitational waves. However, in relation to the planar Schwarzschild anti--de Sitter black holes (or black branes, for short), there is still no conclusive study on some aspects of the physical meaning of these perturbations. In particular, there is some controversy concerning the polar sector of fluctuations with zero wave number $(k=0)$. Some authors claim that this kind of perturbations causes only a variation in the black-brane mass parameter, while others obtained also evidence for the existence of gravitational waves associated to such modes. The present study aims to contribute to the resolution of this controversy by revealing the physical meaning of the gravitational perturbations of anti--de Sitter black branes. In this work we use the Chandrasekhar's gauge formalism to evaluate the linear variations in the complex Weyl scalars in terms of the Regge-Wheeler-Zerilli gauge-invariant quantities. Then we use the Szekeres' proposal for the meaning of the Weyl scalars and the Pirani's criterion for the existence of gravitational radiation in order to give a physical interpretation of the black-brane perturbations with arbitrary wave number value.

Strongly coupled N=4 supersymmetric Yang-Mills plasma on the Coulomb branch. II. Transport coefficients and hard probe parameters

We study $\mathcal{N} = 4$ super Yang-Mills theory on the Coulomb branch (cSYM) by using its Type IIB supergravity dual. We compute the transport coefficients, and hard probe parameters of $\mathcal{N} = 4$ cSYM at finite temperature $T$. We use the rotating black 3-brane solution of Type IIB supergravity with a single non-zero rotation parameter $r_{0}$ after analytically continuing $r_{0}\rightarrow -ir_{0}$, and in an ensemble where the Hawking temperature $T$ and a scalar condensate $<\mathcal{O}>\sim r_{0}^4$ are held fixed. We find that the bulk viscosity to entropy density ratio of the large black hole branch decreases with temperature and has a maxima around the critical temperature $T_{c}$ while, for the small black hole branch, it increases with temperature. The other transport coefficients and parameters of hard probes, such as the conductivity, jet quenching parameter, drag force, and momentum diffusion coefficients of the large black hole branch increase with temperature and asymptote to their conformal value while, for the small black hole branch, they decrease with temperature.

Extensions of the generalized hedgehog ansatz for the Einstein-nonlinear \u03c3-model system: black holes with NUT, black strings and time-dependent solutions

We consider a class of ansätze for the construction of exact solutions of the Einstein-nonlinear σ-model system with an arbitrary cosmological constant in (3+1) dimensions. Exploiting a geometric interplay between the SU(2) field and Killing vectors of the spacetime reduces the matter field equations to a single scalar equation (identically satisfied in some cases) and simultaneously simplifies Einstein’s equations. This is then exemplified over various classes of spacetimes, which allows us to construct stationary black holes with a NUT parameter and uniform black strings, as well as time-dependent solutions such as Robinson-Trautman and Kundt spacetimes, Vaidya-type radiating black holes and certain Bianchi IX cosmologies. In addition to new solutions, some previously known ones are rederived in a more systematic way.

Black hole collisions, instabilities, and cosmic censorship violation at large D

We study the evolution of black hole collisions and ultraspinning black hole instabilities in higher dimensions. These processes can be efficiently solved numerically in an effective theory in the limit of large number of dimensions D. We present evidence that they lead to violations of cosmic censorship. The post-merger evolution of the collision of two black holes with total angular momentum above a certain value is governed by the properties of a resonance-like intermediate state: a long-lived, rotating black bar, which pinches off towards a naked singularity due to an instability akin to that of black strings. We compute the radiative loss of spin for a rotating bar using the quadrupole formula at finite D, and argue that at large enough D — very likely for D ≳ 8, but possibly down to D = 6 — the spin-down is too inefficient to quench this instability. We also study the instabilities of ultraspinning black holes by solving numerically the time evolution of axisymmetric and non-axisymmetric perturbations. We demonstrate the development of transient black rings in the former case, and of multi-pronged horizons in the latter, which then proceed to pinch and, arguably, fragment into smaller black holes.

D1-D5-P superstrata in 5 and 6 dimensions: separable wave equations and prepotentials

We construct the most general single-mode superstrata in 5 dimensions with ambipolar, two centered Gibbons Hawking bases, via dimensional reduction of superstrata in 6 dimensions. Previously, asymptotically AdS3 × \U0001d54a2 5-dimensional superstrata have been produced, giving microstate geometries of black strings in 5 dimensions. Our construction produces asymptotically AdS2 × \U0001d54a3 geometries as well, the first instances of superstrata describing the microstate geometries of black holes in 5 dimensions. New examples of superstrata with separable massless wave equations in both 5 and 6 dimensions are uncovered. A ℤ2 symmetry which identifies distinct 6-dimensional superstrata when reduced to 5 dimensions is found. Finally we use the mathematical structure of the underlying hyper-Kähler bases to produce prepotentials for the superstrata fluxes in 5 dimensions and uplift them to apply in 6 dimensions as well.

A Black Hole at the Center of Earth Plays the Role of the Biggest System of Telecommunication for Connecting DNAs, Dark DNAs and Molecules of Water on 4+N- Dimensional Manifold.

Recently, some scientists from NASA have claimed that there may be a black hole like structure at the centre of the earth. We show that the existence of life on the earth may be a reason that this black hole like object is a black brane that has been formed from biological materials like DNA. Size of this DNA black brane is 109 times longer than the size of the earth’s core and compacted interior it. By compacting this long object, a curved space-time emerges, and some properties of black holes emerge. This structure is the main cause of the emergence of the large temperature of the core, magnetic field around the earth and gravitational field for moving around the sun. Also, this structure produces some waves which act like topoisomerase in biology and read the information on DNAs. However, on the four-dimensional manifold, DNAs are contracted at least four times around various axis’s and waves of earth couldn’t read their information. While, by adding extra dimensions on 4 +n-dimensional manifold, the separation distance between particles increases and all of the information could be recovered by waves. For this reason, each DNA has two parts which one can be seen on the four-dimensional universe, and another one has existed in extra dimensions, and only it’s e_ects is observed. This dark part of DNA called as a dark DNA in an extra dimension. These dark DNAs not only exchange information with DNAs but also are connected with some of the molecules of water and helps them to store information and have memory. Thus, the earth is the biggest system of telecommunication which connects DNAs, dark DNAs and molecules of water.

More on complexity in finite cut off geometry

It has been recently proposed that late time behavior of holographic complexity in a uncharged black brane solution of Einstein-Hilbert theory with boundary cut off is consistent with Lloyd's bound if we have a cut off behind the horizon. Interestingly, the value of this new cut off is fixed by the boundary cut off. In this paper, we extend this analysis to the charged black holes. Concretely, we find the value of this new cut off for charged small black hole solutions of Einstein-Hilbert-Maxwell theory, in which the proposed bound on the complexification is saturated. We also explore this new cut off in Gauss-Bonnet-Maxwell theory.