scholarly journals MANIFESTLY O(d,d) INVARIANT APPROACH TO SPACE-TIME DEPENDENT STRING VACUA

1991 ◽  
Vol 06 (37) ◽  
pp. 3397-3404 ◽  
Author(s):  
K. A. MEISSNER ◽  
G. VENEZIANO
Keyword(s):  
Black Hole ◽  
Renormalization Group ◽  
General Solution ◽  
Equations Of Motion ◽  
Space Time ◽  
Low Energy ◽  
Time Dependent ◽  
Energy Equations ◽  
Invariant Approach ◽  
Black Hole Solutions

An O(d,d) symmetry of the manifold of string vacua that do not depend on d (out of D) space-time coordinates has been recently identified. Here we write down, for d=D-1, the low energy equations of motion and their general solution in a manifestly O(d,d)-invariant form, pointing out an amusing similarity with the renormalization group framework. Previously considered cosmological and black hole solutions are reproduced as particular examples.

scholarly journals DUALITIES, COMPOSITENESS AND SPACE–TIME STRUCTURE OF 4D EXTREME STRINGY BLACK HOLES

1999 ◽  
Vol 14 (07) ◽  
pp. 1015-1034 ◽  
Author(s):  
MARIANO CADONI
Keyword(s):  
Black Holes ◽  
Black Hole ◽  
String Theory ◽  
Bound States ◽  
Bound State ◽  
Space Time ◽  
Naked Singularities ◽  
Heterotic String Theory ◽  
Space Time Structure ◽  
Black Hole Solutions

We study the BPS black hole solutions of the (truncated) action for heterotic string theory compactified on a six-torus. The O (3,Z) duality symmetry of the theory, together with the bound state interpretation of extreme black holes, is used to generate the whole spectrum of the solutions. The corresponding space–time structures, written in terms of the string metric, are analyzed in detail. In particular, we show that only the elementary solutions present naked singularities. The bound states have either null singularities (electric solutions) or are regular (magnetic or dyonic solutions) with near-horizon geometries given by the product of two 2d spaces of constant curvature. The behavior of some of these solutions as supersymmetric attractors is discussed. We also show that our approach is very useful to understand some of the puzzling features of charged black hole solutions in string theory.

scholarly journals Non-Rindler horizons and radiating black holes

2021 ◽  
pp. 2150184
Author(s):  
Vaibhav Wasnik
Keyword(s):  
Black Holes ◽  
Black Hole ◽  
Energy Condition ◽  
Null Energy Condition ◽  
Space Time ◽  
Coordinate Transformations ◽  
Spatial Infinity ◽  
Rindler Space ◽  
Black Hole Solutions

In this work we construct metrics corresponding to radiating black holes whose near horizon regions cannot be approximated by Rindler space–time. We first construct infinite parameter coordinate transformations from Minkowski coordinates, such that an observer using these coordinates to describe space–time events measures the Minkowski vacuum to be Planckian. Utilizing these results, we construct a family of black holes that radiate at spatial infinity. As an illustration, we study a subset of the black hole solutions and show that they satisfy the null energy condition.

scholarly journals Exact charged black hole solutions in D-dimensions in f(R) gravity

2021 ◽  
Vol 81 (4) ◽  
Author(s):  
Zi-Yu Tang ◽  
Bin Wang ◽  
Eleftherios Papantonopoulos
Keyword(s):  
Black Holes ◽  
Black Hole ◽  
General Solution ◽  
Constant Curvature ◽  
Black Hole Solution ◽  
Einstein Gravity ◽  
Charged Black Hole ◽  
Spherically Symmetric ◽  
Spherically Symmetric Metric ◽  
Black Hole Solutions

AbstractWe consider Maxwell-f(R) gravity and obtain an exact charged black hole solution with dynamic curvature in D-dimensions. Considering a spherically symmetric metric ansatz and without specifying the form of f(R) we find a general black hole solution in D-dimensions. This general black hole solution can reduce to the Reissner–Nordström (RN) black hole in D-dimensions in Einstein gravity and to the known charged black hole solutions with constant curvature in f(R) gravity. Restricting the parameters of the general solution we get polynomial solutions which reveal novel properties when compared to RN black holes. Specifically we study the solution in $$(3+1)$$ ( 3 + 1 ) -dimensions in which the form of f(R) can be solved explicitly giving a dynamic curvature and compare it with the RN black hole. We also carry out a detailed study of its thermodynamics.

AN ANSWER TO THE MAIN BLACK HOLE PATHOLOGY: FORMING NONSINGULAR BLACK HOLES FROM DUST COLLAPSE

2009 ◽  
Vol 18 (14) ◽  
pp. 2221-2229 ◽  
Author(s):  
R. MAIER ◽  
I. DAMIÃO SOARES
Keyword(s):  
Black Holes ◽  
General Relativity ◽  
Black Hole ◽  
Event Horizon ◽  
Nonlinear Resonance ◽  
Space Time ◽  
Low Energy ◽  
Spherically Symmetric ◽  
Energy Limit ◽  
Exterior Space

The dynamics of gravitational collapse is examined in the realm of string-based formalism of D-branes which encompasses general relativity as a low energy limit. A complete analytical solution is given to the spherically symmetric collapse of a pure dust star, including its matching with a corrected Schwarzschild exterior space–time. The collapse forms a black hole (an exterior event horizon) enclosing not a singularity but perpetually bouncing matter in the infinite chain of space–time maximal analytical extensions inside the outer event horizon. This chain of analytical extensions has a structure analogous to that of the Reissner–Nordstrom solution. The interior trapped bouncing matter has the possibility of being expelled by disruptive nonlinear resonance mechanisms.

scholarly journals DUALITY IN EQUATIONS OF MOTION FROM SPACE–TIME DEPENDENT LAGRANGIANS

2000 ◽  
Vol 15 (14) ◽  
pp. 901-911 ◽  
Author(s):  
RAJSEKHAR BHATTACHARYYA ◽  
DEBASHIS GANGOPADHYAY
Keyword(s):  
Equations Of Motion ◽  
Space Time ◽  
Quantization Condition ◽  
Time Dependent ◽  
Classical Solutions ◽  
String Solution ◽  
Yang Mills ◽  
Dirac Quantization ◽  
Lagrangian Field Theory ◽  
Condition C

Starting from Lagrangian field theory and the variational principle, we show that duality in equations of motion can also be obtained by introducing explicit space–time dependence of the Lagrangian. Poincaré invariance is achieved precisely when the duality conditions are satisfied in a particular way. The same analysis and criteria are valid for both Abelian and non-Abelian dualities. We illustrate how (a) Dirac string solution, (b) Dirac quantization condition, (c) 't Hooft–Polyakov monopole solutions and (d) a procedure emerges for obtaining new classical solutions of Yang–Mills (YM) theory. Moreover, these results occur in a way that is strongly reminiscent of the holographic principle.

scholarly journals Generalized Robertson-Walker Space-Time Admitting Evolving Null Horizons Related to a Black Hole Event Horizon

2016 ◽  
Vol 2016 ◽  
pp. 1-6
Author(s):  
K. L. Duggal
Keyword(s):  
Black Hole ◽  
Event Horizon ◽  
Space Time ◽  
Time Dependent ◽  
New Technique ◽  
Open Problems ◽  
Totally Umbilical ◽  
Kinematic Condition ◽  
A New Technique

A new technique is used to study a family of time-dependent null horizons, called “Evolving Null Horizons” (ENHs), of generalized Robertson-Walker (GRW) space-time (M¯,g¯) such that the metric g¯ satisfies a kinematic condition. This work is different from our early papers on the same issue where we used (1+n)-splitting space-time but only some special subcases of GRW space-time have this formalism. Also, in contrast to previous work, we have proved that each member of ENHs is totally umbilical in (M¯,g¯). Finally, we show that there exists an ENH which is always a null horizon evolving into a black hole event horizon and suggest some open problems.

PROBING THE QUANTUM MICROSTRUCTURE OF SPACE–TIME

1999 ◽  
Vol 14 (24) ◽  
pp. 1667-1672 ◽  
Author(s):  
T. PADMANABHAN
Keyword(s):  
Black Hole ◽  
Quantum Gravity ◽  
Degrees Of Freedom ◽  
Microscopic Theory ◽  
High Energy ◽  
Space Time ◽  
Low Energy ◽  
Fundamental Theory ◽  
Microscopic Description ◽  
Physical Reasons

The question of how tightly one can constrain the microscopic theory of quantum gravity from the known features of low energy gravity is addressed. To begin with, from the very fact that our universe made a transition from a quantum regime to classical one, it is possible to conclude that infinite number of degrees of freedom had to be integrated out from the fundamental theory to obtain the low energy Einstein Lagrangian. Further constraints can be imposed from the fact that the quantum state describing a black hole has to possess certain universal form of density of states, in any microscopic description of space–time, which can be ascertained from general considerations. Since a black hole can be formed from the collapse of any physical system with a low energy (E ≪ Ep) Hamiltonian H, it is possible to obtain the form the effective high energy (E ≫ Ep) Hamiltonian from general consideration. These results provide the physical reasons for some of the mathematical features underlying string theories and other models for quantum gravity.

Classical strings in ten dimensions

1987 ◽  
Vol 414 (1847) ◽  
pp. 423-431 ◽  
Keyword(s):  
General Solution ◽  
Linear Space ◽  
Significant Role ◽  
Algebraic Variety ◽  
Dimensional Space ◽  
Equations Of Motion ◽  
Space Time ◽  
Relativistic String ◽  
Dimensional Space Time ◽  
The Given

This article analyses the motion of a classical relativistic string in flat complex ten-dimensional space-time. A general solution is presented for the equations of motion. The solution is given in terms of essentially freely specifiable functions. In deriving these results extensive use is made of spinors for ten dimensions, the basic properties of which are described in some detail. In particular, a significant role is played by those spinors in ten dimensions that satisfy the ‘purity’ property of E. Cartan. These constitute an eleven-dimensional algebraic variety V in the sixteen-dimensional linear space of reduced (Weyl) spinors for the group SO(10). A general classical relativistic string in ten dimensions can be represented by means of a set of arbitrarily specifiable twice-differentiable curves in V . As a by-product of the investigation a general solution is also given for the equations of motion of a classical relativistic string in eight­-dimensional space-time. Seldom have thinkers become so absorbed in revery, or so far estranged from reality, as to imagine for our space a number of dimensions exceeding the three of the given space of sense ...(Ernst Mach, 1906)

scholarly journals ON ELECTROGRAVITY DUALITY

1999 ◽  
Vol 14 (05) ◽  
pp. 337-342 ◽  
Author(s):  
NARESH DADHICH
Keyword(s):  
Black Hole ◽  
Gravitational Field ◽  
Topological Defect ◽  
Flat Space ◽  
Interesting Property ◽  
Space Time ◽  
Global Monopole ◽  
Duality Transformation ◽  
Original Space ◽  
Black Hole Solutions

By resolving the gravitational field into electric and magnetic parts, we define an electrogravity duality transformation and discover an interesting property of the field. Under the duality transformation, a vacuum/flat space–time maps into the original space–time with a topological defect of global monopole/texture. The electrogravity-duality is thus a topological defect generating process. It turns out that all black hole solutions possess dual solutions that imbibe a global monopole.

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