Elsevier

Physics Letters B

Volume 693, Issue 3, 4 October 2010, Pages 399-403
Physics Letters B

On analogues of black brane solutions in the model with multicomponent anisotropic fluid

https://doi.org/10.1016/j.physletb.2010.08.060Get rights and content

Abstract

A family of spherically symmetric solutions with horizon in the model with m-component anisotropic fluid is presented. The metrics are defined on a manifold that contains a product of n1 Ricci-flat “internal” spaces. The equation of state for any s-th component is defined by a vector Us belonging to Rn+1. The solutions are governed by moduli functions Hs obeying non-linear differential equations with certain boundary conditions imposed. A simulation of black brane solutions in the model with antisymmetric forms is considered. An example of solution imitating M2M5 configuration (in D=11 supergravity) corresponding to Lie algebra A2 is presented.

Introduction

In this Letter we continue our investigations of spherically-symmetric solutions with horizon (e.g., black brane ones) defined on product manifolds containing several Ricci-flat factor-spaces (with diverse signatures and dimensions). These solutions appear either in models with antisymmetric forms and scalar fields [1], [2], [3], [4], [5], [6], [7], [8], [9], [10], [11] or in models with (multicomponent) anisotropic fluid [12], [13], [14], [15]. For black brane solutions with 1-dimensional factor-spaces (of Euclidean signatures) see [16], [17], [18] and references therein.

These and more general brane cosmological and spherically symmetric solutions were obtained by reduction of the field equations to the Lagrange equations corresponding to Toda-like systems [2], [19]. An analogous reduction for models with multicomponent anisotropic fluids was performed earlier in [20], [21]. For cosmological-type models with antisymmetric forms without scalar fields any brane is equivalent to an anisotropic fluid with the equations of state:pˆi=ρˆorpˆi=ρˆ, when the manifold Mi belongs or does not belong to the brane worldvolume, respectively (here pˆi is the effective pressure in Mi and ρˆ is the effective density).

In this Letter we present spherically-symmetric solutions with horizon (e.g the analogues of intersecting black brane solutions) in a model with multicomponent anisotropic fluid (MCAF), when certain relations on fluid parameters are imposed. The solutions are governed by a set of moduli functions Hs obeying non-linear differential master equations with certain boundary conditions imposed. These master equations are equivalent to Toda-like equations and depend upon the non-degenerate (m×m) matrix A. It was conjectured earlier that the functions Hs should be polynomials when A is a Cartan matrix for some semisimple finite-dimensional Lie algebra (of rank m) [6]. This conjecture was verified for Lie algebras: Am, Cm+1, m1 [7], [8]. A special case of black hole solutions with MCAF corresponding to semisimple Lie algebra A1A1 was considered earlier in [13] (for m=1 see [12]).

The Letter is organized as follows. In Section 2 the model is formulated. In Section 3 spherically-symmetric MCAF solutions with horizon corresponding to black brane type solutions, are presented. In Section 4 a polynomial structure of moduli functions Hs for semisimple finite-dimensional Lie algebras is discussed. In Section 5 a simulation of intersecting black brane solutions is considered and an analogue of M2M5 dyonic solution is presented.

Section snippets

The model

In this Letter we deal with a family of spherically symmetric solutions to Einstein equations with an anisotropic matter sourceRNM12δNMR=k2TNM, defined on the manifoldM=Rradialvariable×(M0=Sd0)sphericalvariables×(M1=R)time××Mn, with the block-diagonal metricsds2=e2γ(u)du2+i=0ne2βi(u)hmini[i]dymidyni.

Here RR is an open interval. The manifold Mi with the metric h[i], i=1,2,,n, is a Ricci-flat space of dimension di:Rmini[h[i]]=0, and h[0] is the standard metric on the unit sphere Sd0, so

Spherically symmetric solutions with horizon

We will make the following assumptions:1.U0s=0pˆ0s=ρˆs,2.U1s=1pˆ1s=ρˆs,3.(Us,Us)=UisGijUjs>0,4.2(Us,Ul)/(Ul,Ul)=Asl, where A=(Asl) is non-degenerate matrix,Gij=δijdi+12D, are components of the matrix inverse to the matrix of the minisuperspace metric [22](Gij)=(diδijdidj), i,j=0,1,,n, and D=1+i=0ndi is the total dimension.

The conditions 1 and 2 in brane terms mean that brane “lives” in the time manifold M1 and does not “live” in M0. Due to assumptions 1 and 2 and the equations of

Polynomial structure of Hs for Lie algebras

Now we deal with solutions to second order non-linear differential equations (3.12) that may be rewritten as followsddz((12μz)HsddzHs)=B¯sl=1mHlAsl, where Hs(z)>0, z=Rd(0,(2μ)1) (μ>0) and B¯s=Bs/d20. Eqs. (3.13), (3.14) readHs((2μ)10)=Hs0(0,+),Hs(+0)=1, s=1,,m.

The condition (3.15) reads as followsHs(z)>0is smooth in(0,zϵ), s=1,,m, where zϵ=(2μ)1eϵd, ϵ>0.

It was conjectured in [6] that Eqs. (4.1), (4.2), (4.3) have polynomial solutions when (Ass) is a Cartan matrix for some

Analogues of intersecting black brane solutions

The solution from the previous section for MCAF allows one to simulate the intersecting black brane solutions [11] in the model with antisymmetric forms without scalar fields. In this case the parameters Uis and pressures have the following form:Uis={di,pis=ρs,iIs;0,ρs,iIs.

Here Is={i1s,,ikss}{1,,n} is the index set [11] corresponding to brane submanifold Mi1s××Mikss.

The relation 4 (3.1) leads us to the following dimensions of intersections of brane submanifolds (“worldvolumes”) [2], [11]

Conclusions

Here we have presented a family of spherically symmetric solutions with horizon in the model with multicomponent anisotropic fluid with the equations of state (2.8) and the conditions (3.1) imposed. The metric of any solution contains (n1) Ricci-flat “internal” space metrics.

As in [6], [7], [8] the solutions are defined up to solutions of non-linear differential equations (equivalent to Toda-like ones) with certain boundary conditions imposed. These solutions may have a polynomial structure

Acknowledgements

This work was supported in part by grant NPK-MU (PFUR) and Russian Foundation for Basic Research (Grant No. 09-02-00677-a).

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