Hawking emission from quantum gravity black holes
Nicolini, Piero; Winstanley, Elizabeth(Consortium for Fundamental Physics, School of Mathematics and Statistics, University of Sheffield, Hicks Building, Hounsfield Road, Sheffield, S3 7RH, United Kingdom)
2011-01-01
We address the issue of modelling quantum gravity effects in the evaporation of higher dimensional black holes in order to go beyond the usual semi-classical approximation. After reviewing the existing six families of quantum gravity corrected black hole geometries, we focus our work on non-commutative geometry inspired black holes, which encode model independent characteristics, are unaffected by the quantum back reaction and have an analytical form compact enough for numerical simulations. ...
Topological Black Holes in Weyl Conformal Gravity
Klemm, Dietmar
1998-01-01
We present a class of exact solutions of Weyl conformal gravity, which have an interpretation as topological black holes. Solutions with negative, zero or positive scalar curvature at infinity are found, the former generalizing the well-known topological black holes in anti-de Sitter gravity. The rather delicate question of thermodynamic properties of such objects in Weyl conformal gravity is discussed; suggesting that the thermodynamics of the found solutions should be treated within the fra...
Black Hole Interior in Quantum Gravity.
Nomura, Yasunori; Sanches, Fabio; Weinberg, Sean J
2015-05-22
We discuss the interior of a black hole in quantum gravity, in which black holes form and evaporate unitarily. The interior spacetime appears in the sense of complementarity because of special features revealed by the microscopic degrees of freedom when viewed from a semiclassical standpoint. The relation between quantum mechanics and the equivalence principle is subtle, but they are still consistent. PMID:26047218
Black Hole Phase Transition in Massive Gravity
Ning, Shou-Li; Liu, Wen-Biao
2016-07-01
In massive gravity, some new phenomena of black hole phase transition are found. There are more than one critical points under appropriate parameter values and the Gibbs free energy near critical points also has some new properties. Moreover, the Maxwell equal area rule is also investigated and the coexistence curve of the black hole is given.
Black holes and asymptotically safe gravity
Falls, Kevin; Raghuraman, Aarti
2010-01-01
Quantum gravitational corrections to black holes are studied in four and higher dimensions using a renormalisation group improvement of the metric. The quantum effects are worked out in detail for asymptotically safe gravity, where the short distance physics is characterized by a non-trivial fixed point of the gravitational coupling. We find that a weakening of gravity implies a decrease of the event horizon, and the existence of a Planck-size black hole remnant with vanishing temperature and vanishing heat capacity. The absence of curvature singularities is generic and discussed together with the conformal structure and the Penrose diagram of asymptotically safe black holes. The production cross section of mini-black holes in energetic particle collisions, such as those at the Large Hadron Collider, is analysed within low-scale quantum gravity models. Quantum gravity corrections imply that cross sections display a threshold, are suppressed in the Planckian, and reproduce the semi-classical result in the deep...
Evaporation Time of Horava Gravity Black Holes
International Nuclear Information System (INIS)
Recently it has been a lot of interest in the theory proposed by Horava because is a remormalizable theory of gravity and may be a candidate for the UV completion of Einstein gravity. In the present work we study thermodynamical properties of black hole type solutions in this setup. In particular we are able to obtain times of evaporation for black hole solution in this formalism.
Charged Dilatonic Black Holes in Gravity's Rainbow
Hendi, S H; Panah, B Eslam; Panahiyan, S
2015-01-01
In this paper, we analyze charged dilatonic black holes in gravity's rainbow. We obtain metric functions and different thermodynamic quantities for these charged black holes in dilatonic gravity's rainbow. We demonstrate that first law of thermodynamics is valid for these solutions. We also investigate thermal stability of these solutions using canonical ensemble. Finally, we analyze the effect that the variation of different parameters has on the stability of these solutions.
Black hole thermodynamics in MOdified Gravity (MOG)
Mureika, Jonas R.; Moffat, John W.; Faizal, Mir
2016-06-01
We analyze the thermodynamical properties of black holes in a modified theory of gravity, which was initially proposed to obtain correct dynamics of galaxies and galaxy clusters without dark matter. The thermodynamics of non-rotating and rotating black hole solutions resembles similar solutions in Einstein-Maxwell theory with the electric charge being replaced by a new mass dependent gravitational charge Q =√{ αGN } M. This new mass dependent charge modifies the effective Newtonian constant from GN to G =GN (1 + α), and this in turn critically affects the thermodynamics of the black holes. We also investigate the thermodynamics of regular solutions, and explore the limiting case when no horizons forms. So, it is possible that the modified gravity can lead to the absence of black hole horizons in our universe. Finally, we analyze corrections to the thermodynamics of a non-rotating black hole and obtain the usual logarithmic correction term.
Black holes in Asymptotically Safe Gravity
Saueressig, Frank; D'Odorico, Giulio; Vidotto, Francesca
2015-01-01
Black holes are among the most fascinating objects populating our universe. Their characteristic features, encompassing spacetime singularities, event horizons, and black hole thermodynamics, provide a rich testing ground for quantum gravity ideas. In this note we observe that the renormalization group improved Schwarzschild black holes constructed by Bonanno and Reuter within Weinberg's asymptotic safety program constitute a prototypical example of a Hayward geometry used to model non-singular black holes within quantum gravity phenomenology. Moreover, they share many features of a Planck star: their effective geometry naturally incorporates the one-loop corrections found in the effective field theory framework, their Kretschmann scalar is bounded, and the black hole singularity is replaced by a regular de Sitter patch. The role of the cosmological constant in the renormalization group improvement process is briefly discussed.
Charged dilatonic black holes in gravity's rainbow
Hendi, S. H.; Faizal, Mir; Panah, B. Eslam; Panahiyan, S.
2016-05-01
In this paper, we present charged dilatonic black holes in gravity's rainbow. We study the geometric and thermodynamic properties of black hole solutions. We also investigate the effects of rainbow functions on different thermodynamic quantities for these charged black holes in dilatonic gravity's rainbow. Then we demonstrate that the first law of thermodynamics is valid for these solutions. After that, we investigate thermal stability of the solutions using the canonical ensemble and analyze the effects of different rainbow functions on the thermal stability. In addition, we present some arguments regarding the bound and phase transition points in context of geometrical thermodynamics. We also study the phase transition in extended phase space in which the cosmological constant is treated as the thermodynamic pressure. Finally, we use another approach to calculate and demonstrate that the obtained critical points in extended phase space represent a second order phase transition for these black holes.
Exact Black Hole Solutions in Noncommutative Gravity
Schupp, Peter; Solodukhin, Sergey
2009-01-01
An exact spherically symmetric black hole solution of a recently proposed noncommutative gravity theory based on star products and twists is constructed. This is the first nontrivial exact solution of that theory. The resulting noncommutative black hole quite naturally exhibits holographic behavior; outside the horizon it has a fuzzy shell-like structure, inside the horizon it has a noncommutative de Sitter geometry. The star product and twist contain Killing vectors and act non-trivially on ...
Asymptotically hyperbolic black holes in Horava gravity
Janiszewski, Stefan
2014-01-01
Solutions of Hořava gravity that are asymptotically Lifshitz are explored. General near boundary expansions allow the calculation of the mass of these spacetimes via a Hamiltonian method. Both analytic and numeric solutions are studied which exhibit a causal boundary called the universal horizon, and are therefore black holes of the theory. The thermodynamics of an asymptotically Anti-de Sitter Hořava black hole are verified.
Black Holes in Modified Gravity (MOG)
Moffat, J W
2014-01-01
The field equations for Scalar-Tensor-Vector-Gravity (STVG) or modified gravity (MOG) have a static, spherically symmetric black hole solution determined by the mass $M$ with either two horizons or no horizon depending on the strength of the gravitational constant $G=G_N(1+\\alpha)$ where $\\alpha$ is a parameter. A regular singularity-free MOG black hole solution is derived using a nonlinear, repulsive gravitational field dynamics and a reasonable physical energy-momentum tensor. The Kruskal-Szekeres completions of the MOG black hole solutions are obtained. The Kerr-MOG black hole solution is determined by the mass $M$, the parameter $\\alpha$ and the spin angular momentum $J=Ma$. The equations of motion and the stability condition of a test particle orbiting the MOG black hole are derived, and the radius of the black hole photosphere and its shadow cast by the Kerr-MOG black hole are calculated. A traversable wormhole solution is constructed with a throat stabilized by the repulsive gravitational field.
Black holes in higher derivative gravity.
Lü, H; Perkins, A; Pope, C N; Stelle, K S
2015-05-01
Extensions of Einstein gravity with higher-order derivative terms arise in string theory and other effective theories, as well as being of interest in their own right. In this Letter we study static black-hole solutions in the example of Einstein gravity with additional quadratic curvature terms. A Lichnerowicz-type theorem simplifies the analysis by establishing that they must have vanishing Ricci scalar curvature. By numerical methods we then demonstrate the existence of further black-hole solutions over and above the Schwarzschild solution. We discuss some of their thermodynamic properties, and show that they obey the first law of thermodynamics. PMID:25978224
Black Holes in Higher-Derivative Gravity
Lu, H; Pope, C N; Stelle, K S
2015-01-01
Extensions of Einstein gravity with higher-order derivative terms arise in string theory and other effective theories, as well as being of interest in their own right. In this paper we study static black-hole solutions in the example of Einstein gravity with additional quadratic curvature terms. A Lichnerowicz-type theorem simplifies the analysis by establishing that they must have vanishing Ricci scalar curvature. By numerical methods we then demonstrate the existence of further black-hole solutions over and above the Schwarzschild solution. We discuss some of their thermodynamic properties, and show that they obey the first law of thermodynamics.
Black holes in modified gravity (MOG)
Energy Technology Data Exchange (ETDEWEB)
Moffat, J.W. [Perimeter Institute for Theoretical Physics, Waterloo, ON (Canada); University of Waterloo, Department of Physics and Astronomy, Waterloo, ON (Canada)
2015-04-15
The field equations for scalar-tensor-vector gravity (STVG) or modified gravity (MOG) have a static, spherically symmetric black hole solution determined by the mass M with two horizons. The strength of the gravitational constant is G = G{sub N} (1 + α) where α is a parameter. A regular singularity-free MOG solution is derived using a nonlinear field dynamics for the repulsive gravitational field component and a reasonable physical energy-momentum tensor. The Kruskal-Szekeres completion of the MOG black hole solution is obtained. The Kerr-MOG black hole solution is determined by the mass M, the parameter α and the spin angular momentum J = Ma. The equations of motion and the stability condition of a test particle orbiting the MOG black hole are derived, and the radius of the black hole photosphere and the shadows cast by the Schwarzschild-MOG and Kerr-MOG black holes are calculated. A traversable wormhole solution is constructed with a throat stabilized by the repulsive component of the gravitational field. (orig.)
Black holes in full quantum gravity
International Nuclear Information System (INIS)
Quantum black holes have been studied extensively in quantum gravity and string theory, using various semiclassical or background-dependent approaches. We explore the possibility of studying black holes in the full non-perturbative quantum theory, without recurring to semiclassical considerations, and in the context of loop quantum gravity. We propose a definition of a quantum black hole as the collection of the quantum degrees of freedom that do not influence observables at infinity. From this definition, it follows that for an observer at infinity a black hole is described by an SU(2) intertwining operator. The dimension of the Hilbert space of such intertwiners grows exponentially with the horizon area. These considerations shed some light on the physical nature of the microstates contributing to the black hole entropy. In particular, it can be seen that the microstates being counted for the entropy have the interpretation of describing different horizon shapes. The space of black hole microstates described here is related to the one arrived at recently by Engle et al (2009, arXiv:0905.3168) and sometime ago by Smolin (1995, J. Math. Phys. 36 6417), but obtained here directly within the full quantum theory.
Black holes in modified gravity (MOG)
International Nuclear Information System (INIS)
The field equations for scalar-tensor-vector gravity (STVG) or modified gravity (MOG) have a static, spherically symmetric black hole solution determined by the mass M with two horizons. The strength of the gravitational constant is G = GN (1 + α) where α is a parameter. A regular singularity-free MOG solution is derived using a nonlinear field dynamics for the repulsive gravitational field component and a reasonable physical energy-momentum tensor. The Kruskal-Szekeres completion of the MOG black hole solution is obtained. The Kerr-MOG black hole solution is determined by the mass M, the parameter α and the spin angular momentum J = Ma. The equations of motion and the stability condition of a test particle orbiting the MOG black hole are derived, and the radius of the black hole photosphere and the shadows cast by the Schwarzschild-MOG and Kerr-MOG black holes are calculated. A traversable wormhole solution is constructed with a throat stabilized by the repulsive component of the gravitational field. (orig.)
Gravity coupling from micro-black holes
Scardigli, Fabio
1999-01-01
Recently much work has been done in lowering the Planck threshold of quantum gravitational effects (sub-millimeter dimension(s), Horava-Witten fifth dimension, strings or branes low energy effects, etc.). Working in the framework of 4-dim gravity, with semi-classical considerations based on Hawking evaporation of planckian micro-black holes, I shall show here as quantum gravity effects could occur also near GUT energies.
Astrophysical black holes in screened modified gravity
International Nuclear Information System (INIS)
Chameleon, environmentally dependent dilaton, and symmetron gravity are three models of modified gravity in which the effects of the additional scalar degree of freedom are screened in dense environments. They have been extensively studied in laboratory, cosmological, and astrophysical contexts. In this paper, we present a preliminary investigation into whether additional constraints can be provided by studying these scalar fields around black holes. By looking at the properties of a static, spherically symmetric black hole, we find that the presence of a non-uniform matter distribution induces a non-constant scalar profile in chameleon and dilaton, but not necessarily symmetron gravity. An order of magnitude estimate shows that the effects of these profiles on in-falling test particles will be sub-leading compared to gravitational waves and hence observationally challenging to detect
Lifshitz black holes in higher spin gravity
International Nuclear Information System (INIS)
We study asymptotically Lifshitz solutions to three dimensional higher spin gravity in the SL(3,ℝ)×SL(3,ℝ) Chern-Simons formulation. We begin by specifying the most general connections satisfying Lifshitz boundary conditions, and we verify that their algebra of symmetries contains a Lifshitz sub-algebra. We then exhibit connections that can be viewed as higher spin Lifshitz black holes. We show that when suitable holonomy conditions are imposed, these black holes obey sensible thermodynamics and possess a gauge in which the corresponding metric exhibits a regular horizon
Black Hole Formation in Lovelock Gravity
Taves, Tim
2014-01-01
We first derive the Hamiltonian for Lovelock gravity and find that it takes the same form as in general relativity when written in terms of the Misner-Sharp mass function. We then minimally couple the action to matter fields to find Hamilton's equations of motion. These are gauge fixed to be in the Painlev\\'e-Gullstrand co-ordinates and are well suited to numerical studies of black hole formation. We then use these equations of motion for the massless scalar field to study the formation of general relativistic black holes in four to eight dimensions and Einstein-Gauss-Bonnet black holes in five and six dimensions. We study Choptuik scaling, a phenomenon which relates the initial conditions of a matter distribution to the final observables of small black holes. In both higher dimensional general relativity and Einstein-Gauss-Bonnet gravity we confirm the existence of cusps in the mass scaling relation which had previously only been observed in four dimensional general relativity. In the general relativistic ca...
Light, Gravity and Black Holes
Falla, David
2012-01-01
The nature of light and how it is affected by gravity is discussed. Einstein's prediction of the deflection of light as it passes near the Sun was verified by observations made during the solar eclipse of 1919. Another prediction was that of gravitational redshift, which occurs when light emitted by a star loses energy in the gravitational field…
Black Holes and Two-Dimensional Dilaton Gravity
Futamase, T.; Hotta, M; ITOH, Y
1998-01-01
We study the conditions for 2-dimensional dilaton gravity models to have dynamical formation of black holes and construct all such models. Furthermore we present a parametric representation of the general solutions of the black holes.
Black hole evaporation and higher-derivative gravity
International Nuclear Information System (INIS)
The authors examine the role which higher-derivative gravity interactions may play in black hole evaporation. The thermodynamic properties of black holes in Lovelock gravity are described. In certain cases, the specific heat of a black hole becomes positive at a small mass. This results in an infinite lifetime for the black hole (and also allows it to achieve stable equilibrium with a thermal environment). Thus no conflict with unitary time evolution would arise in such theories
Entropy spectrum of BTZ black hole in massive gravity
Suresh, Jishnu
2016-01-01
We study the entropy spectrum of (2+1) BTZ black holes in massive gravity models. We use the formalism proposed by Jiang and Han where black hole property of adiabaticity and the oscillating velocity of the black hole horizon are used to investigate the quantization of the entropy of such systems. We find that the entropy of the BTZ black holes in massive gravity is quantized with equally spaced spectra.
Loop quantum gravity and black hole entropy quantization
Institute of Scientific and Technical Information of China (English)
LI ChuanAn; JIANG JiJian; SU JiuQing
2009-01-01
Using the spin networks and the asymptotic quasinormal mode frequencies of black holes given by loop quantum gravity, the minimum horizon area gap is obtained. Then the quantum area spectrum of black holes is derived and the black hole entropy is a realized quantization. The results show that the black hole entropy given by loop quantum gravity is in full accord with the Bekenstein-Hawking entropy with a suitable Immirzi.
Loop quantum gravity and black hole entropy quantization
Institute of Scientific and Technical Information of China (English)
无
2009-01-01
Using the spin networks and the asymptotic quasinormal mode frequencies of black holes given by loop quantum gravity,the minimum horizon area gap is obtained.Then the quantum area spectrum of black holes is derived and the black hole entropy is a realized quantization.The results show that the black hole entropy given by loop quantum gravity is in full accord with the Bekenstein-Hawking entropy with a suitable Immirzi.
Black holes in modified gravity theories
International Nuclear Information System (INIS)
In the context of f(R) gravity theories, the issue of finding static and spherically symmetric black hole solutions is addressed. Two approaches to study the existence of such solutions are considered: first, constant curvature solutions, and second, the general case (without imposing constant curvature) is also studied. Performing a perturbative expansion around the Einstein-Hilbert action, it is found that only solutions of the Schwarzschild-(Anti-) de Sitter type are present (up to second order in perturbations) and the explicit expressions for these solutions are provided in terms of the f(R) function. Finally we consider the thermodynamics of black holes in Anti-de Sitter space-time and study their local and global stability.
Charged black holes in generalized teleparallel gravity
International Nuclear Information System (INIS)
In this paper we investigate charged static black holes in 4D for generalized teleparallel models of gravity, based on torsion as the geometric object for describing gravity according to the equivalence principle. As a motivated idea, we introduce a set of non-diagonal tetrads and derive the full system of non linear differential equations. We prove that the common Schwarzschild gauge is applicable only when we study linear f(T) case. We reobtain the Reissner-Nordstrom-de Sitter (or RN-AdS) solution for the linear case of f(T) and perform a parametric cosmological reconstruction for two nonlinear models. We also study in detail a type of the no-go theorem in the framework of this modified teleparallel gravity
Charged black holes in generalized teleparallel gravity
Energy Technology Data Exchange (ETDEWEB)
Rodrigues, M.E. [Faculdade de Física, Universidade Federal do Pará, Belém, Pará, 66075–110 (Brazil); Houndjo, M.J.S.; Tossa, J. [Institut de Mathématiques et de Sciences Physiques (IMSP) - Porto-Novo, 01 BP 613 (Benin); Momeni, D.; Myrzakulov, R., E-mail: esialg@gmail.com, E-mail: sthoundjo@yahoo.fr, E-mail: joel.tossa@imsp-uac.org, E-mail: d.momeni@yahoo.com, E-mail: rmyrzakulov@gmail.com [Eurasian International Center for Theoretical Physics - Eurasian National University, Astana, 010008 (Kazakhstan)
2013-11-01
In this paper we investigate charged static black holes in 4D for generalized teleparallel models of gravity, based on torsion as the geometric object for describing gravity according to the equivalence principle. As a motivated idea, we introduce a set of non-diagonal tetrads and derive the full system of non linear differential equations. We prove that the common Schwarzschild gauge is applicable only when we study linear f(T) case. We reobtain the Reissner-Nordstrom-de Sitter (or RN-AdS) solution for the linear case of f(T) and perform a parametric cosmological reconstruction for two nonlinear models. We also study in detail a type of the no-go theorem in the framework of this modified teleparallel gravity.
Asymptotically charged BTZ black holes in gravity's rainbow
Hendi, S. H.
2016-04-01
Motivated by the wide applications of BTZ black holes and interesting results of gravity's rainbow, we consider three dimensional rainbow solutions and investigate their thermodynamic properties. In addition to investigate black holes thermodynamics related to AdS/CFT correspondence, one may regard gravity's rainbow to encode quantum gravity effects into the black hole solutions. We take into account the various models of linear and nonlinear electrodynamics and study their effects on the gravity's rainbow spacetime. We also examine thermal stability and find that obtained three dimensional rainbow black holes are thermally stable.
Quantum-gravity phenomenology with primordial black holes
Vidotto, Francesca; Bolliet, Boris; Shutten, Marrit; Weimer, Celine
2016-01-01
Quantum gravity may allow black holes to tunnel into white holes. If so, the lifetime of a black hole could be shorter than the one given by Hawking evaporation, solving the information paradox. More interestingly, this could open to a new window for quantum-gravity phenomenology, in connection with the existence of primordial black holes. We discuss in particular the power of the associated explosion and the possibility to observe an astrophysical signal in the radio and in the gamma wavelengths.
Black holes in Born-Infeld extended new massive gravity
International Nuclear Information System (INIS)
In this paper we find different types of black holes for the Born-Infeld extended new massive gravity. Our solutions include (un)charged warped (anti-)de Sitter black holes for four and six derivative expanded action. We also look at the black holes in unexpanded Born-Infeld action. In each case we calculate the entropy, angular momentum and mass of the black holes. We also find the central charges for the conformal field theory duals.
Entropy of a Black Hole with Distinct Surface Gravities
Wu Zhong Chao
2000-01-01
In gravitational thermodynamics, the entropy of a black hole with distinct surface gravities can be evaluated on a microcanonical ensemble. At the WKB level, the entropy becomes the negative of the Euclidean action of the constrained instanton, which is the seed for the black hole creation in the no-boundary universe. Using the Gauss-Bonnet theorem, we prove the quite universal formula in Euclidean quantum gravity that the entropy of a nonrotating black hole is one quarter the sum of the products of the Euler characteristics and the areas of the horizons. For Lovelock gravity, the entropy and quantum creation of a black hole are also studied.
Black holes, strings and quantum gravity
International Nuclear Information System (INIS)
Most physical phenomena can be explained by 'Quantum Mechanics' and 'Einstein Theory of Gravity'. Quantum mechanics is needed for descriptions involving small objects (atoms, nuclei, molecules, etc.) whereas gravity is required for understanding big objects (planets, galaxies). Since, usually small objects are light while big ones are heavy, when one theory is called for, the other is not relevant. Interestingly enough, if we pretend to use both theories simultaneously, for instance when small and very heavy objects are considered (as those in the beginning of our universe), we find that they are mutually inconsistent. Thus, a new theory, so called 'Quantum Gravity', is needed. This works comments on above inconsistencies and indicates how the string theory, rather than a pointlike particle theory, could provide us with a quantum theory of gravity. Though a discussion of black holes it shows us how a string theory on certain space, ca be equivalently described by a particle theory on its boundary, like a sort of hologram. (author)
Black Hole Solutions in $R^2$ Gravity
Kehagias, Alex; Lust, Dieter; Riotto, Antonio
2015-01-01
We find static spherically symmetric solutions of scale invariant $R^2$ gravity. The latter has been shown to be equivalent to General Relativity with a positive cosmological constant and a scalar mode. Therefore, one expects that solutions of the $R^2$ theory will be identical to that of Einstein theory. Indeed, we find that the solutions of $R^2$ gravity are in one-to-one correspondence with solutions of General Relativity in the case of non-vanishing Ricci scalar. However, scalar-flat $R=0$ solutions are global minima of the $R^2$ action and they cannot in general be mapped to solutions of the Einstein theory. As we will discuss, the $R=0$ solutions arise in Einstein gravity as solutions in the tensionless, strong coupling limit $M_P\\rightarrow 0$. As a further result, there is no corresponding Birkhoff theorem and the Schwarzschild black hole is by no means unique in this framework. In fact, $R^2$ gravity has a rich structure of vacuum static spherically symmetric solutions partially uncovered here. We al...
Scale-Invariant Rotating Black Holes in Quadratic Gravity
Directory of Open Access Journals (Sweden)
Guido Cognola
2015-07-01
Full Text Available Black hole solutions in pure quadratic theories of gravity are interesting since they allow the formulation of a set of scale-invariant thermodynamics laws. Recently, we have proven that static scale-invariant black holes have a well-defined entropy, which characterizes equivalent classes of solutions. In this paper, we generalize these results and explore the thermodynamics of rotating black holes in pure quadratic gravity.
Phase transitions of black holes in massive gravity
Fernando, Sharmanthie
2016-01-01
In this paper we have studied thermodynamics of a black hole in massive gravity in the canonical ensemble. The massive gravity theory in consideration here has a massive graviton due to Lorentz symmetry breaking. The black hole studied here has a scalar charge due to the massive graviton and is asymptotically anti-de Sitter. We have computed various thermodynamical quantities such as temperature, specific heat and free energy. Both the local and global stability of the black hole are studied ...
Black hole spectroscopy from Loop Quantum Gravity models
Barrau, A.; Cao, Xiangyu; Noui, Karim; Perez, Alejandro
2015-01-01
Using Monte Carlo simulations, we compute the integrated emission spectra of black holes in the framework of Loop Quantum Gravity (LQG). The black hole emission rates are governed by the entropy whose value, in recent holographic loop quantum gravity models, was shown to agree at leading order with the Bekenstein-Hawking entropy. Quantum corrections depend on the Barbero-Immirzi parameter $\\gamma$. Starting with black holes of initial horizon area $A \\sim 10^2$ in Planck units, we present the...
Quantum-gravity fluctuations and the black-hole temperature
Hod, Shahar
2015-05-01
Bekenstein has put forward the idea that, in a quantum theory of gravity, a black hole should have a discrete energy spectrum with concomitant discrete line emission. The quantized black-hole radiation spectrum is expected to be very different from Hawking's semi-classical prediction of a thermal black-hole radiation spectrum. One naturally wonders: Is it possible to reconcile the discrete quantum spectrum suggested by Bekenstein with the continuous semi-classical spectrum suggested by Hawking? In order to address this fundamental question, in this essay we shall consider the zero-point quantum-gravity fluctuations of the black-hole spacetime. In a quantum theory of gravity, these spacetime fluctuations are closely related to the characteristic gravitational resonances of the corresponding black-hole spacetime. Assuming that the energy of the black-hole radiation stems from these zero-point quantum-gravity fluctuations of the black-hole spacetime, we derive the effective temperature of the quantized black-hole radiation spectrum. Remarkably, it is shown that this characteristic temperature of the discrete (quantized) black-hole radiation agrees with the well-known Hawking temperature of the continuous (semi-classical) black-hole spectrum.
Quantum-gravity fluctuations and the black-hole temperature
International Nuclear Information System (INIS)
Bekenstein has put forward the idea that, in a quantum theory of gravity, a black hole should have a discrete energy spectrum with concomitant discrete line emission. The quantized black-hole radiation spectrum is expected to be very different from Hawking's semi-classical prediction of a thermal black-hole radiation spectrum. One naturally wonders: Is it possible to reconcile the discrete quantum spectrum suggested by Bekenstein with the continuous semi-classical spectrum suggested by Hawking? In order to address this fundamental question, in this essay we shall consider the zero-point quantum-gravity fluctuations of the black-hole spacetime. In a quantum theory of gravity, these spacetime fluctuations are closely related to the characteristic gravitational resonances of the corresponding black-hole spacetime. Assuming that the energy of the black-hole radiation stems from these zero-point quantum-gravity fluctuations of the black-hole spacetime, we derive the effective temperature of the quantized black-hole radiation spectrum. Remarkably, it is shown that this characteristic temperature of the discrete (quantized) black-hole radiation agrees with the well-known Hawking temperature of the continuous (semi-classical) black-hole spectrum. (orig.)
Quantum-gravity fluctuations and the black-hole temperature
Energy Technology Data Exchange (ETDEWEB)
Hod, Shahar [The Ruppin Academic Center, Emeq Hefer (Israel); The Hadassah Institute, Jerusalem (Israel)
2015-05-15
Bekenstein has put forward the idea that, in a quantum theory of gravity, a black hole should have a discrete energy spectrum with concomitant discrete line emission. The quantized black-hole radiation spectrum is expected to be very different from Hawking's semi-classical prediction of a thermal black-hole radiation spectrum. One naturally wonders: Is it possible to reconcile the discrete quantum spectrum suggested by Bekenstein with the continuous semi-classical spectrum suggested by Hawking? In order to address this fundamental question, in this essay we shall consider the zero-point quantum-gravity fluctuations of the black-hole spacetime. In a quantum theory of gravity, these spacetime fluctuations are closely related to the characteristic gravitational resonances of the corresponding black-hole spacetime. Assuming that the energy of the black-hole radiation stems from these zero-point quantum-gravity fluctuations of the black-hole spacetime, we derive the effective temperature of the quantized black-hole radiation spectrum. Remarkably, it is shown that this characteristic temperature of the discrete (quantized) black-hole radiation agrees with the well-known Hawking temperature of the continuous (semi-classical) black-hole spectrum. (orig.)
Quantum black holes in loop quantum gravity
International Nuclear Information System (INIS)
We study the quantization of spherically symmetric vacuum spacetimes within loop quantum gravity. In particular, we give additional details about our previous work in which we showed that one could complete the quantization of the model and that the singularity inside black holes is resolved. Moreover, we consider an alternative quantization based on a slightly different kinematical Hilbert space. The ambiguity in kinematical spaces stems from how one treats the periodicity of one of the classical variables in these models. The corresponding physical Hilbert spaces solve the diffeomorphism and Hamiltonian constraint but their intrinsic structure is radically different depending on the kinematical Hilbert space one started from. In both cases there are quantum observables that do not have a classical counterpart. However, one can show that at the end of the day, by examining Dirac observables, both quantizations lead to the same physical predictions. (paper)
Black hole conserved charges in Generalized Minimal Massive Gravity
Directory of Open Access Journals (Sweden)
M.R. Setare
2015-05-01
Full Text Available In this paper we construct mass, angular momentum and entropy of black hole solution of Generalized Minimal Massive Gravity (GMMG in asymptotically Anti-de Sitter (AdS spacetimes. The Generalized Minimal Massive Gravity theory is realized by adding the CS deformation term, the higher derivative deformation term, and an extra term to pure Einstein gravity with a negative cosmological constant. We apply our result for conserved charge Qμ(ξ¯ to the rotating BTZ black hole solution of GMMG, and find energy, angular momentum and entropy. Then we show that our results for these quantities are consistent with the first law of black hole thermodynamics.
Quantum Gravity Effects in Black Holes at the LHC
Alberghi, Gian Luigi; Casadio, Roberto(Dipartimento di Fisica e Astronomia, Università di Bologna, via Irnerio 46, Bologna, 40126, Italy); Tronconi, Alessandro
2006-01-01
We study possible back-reaction and quantum gravity effects in the evaporation of black holes which could be produced at the LHC through a modification of the Hawking emission. The corrections are phenomenologically taken into account by employing a modified relation between the black hole mass and temperature. The usual assumption that black holes explode around $1 $TeV is also released, and the evaporation process is extended to (possibly much) smaller final masses. We show that these effec...
Black hole at Lovelock gravity with anisotropic fluid
Aros, Rodrigo; Estrada, Milko; Montecinos, Alejandra
2016-01-01
In this work a new family of black hole solutions in Lovelock gravity is discussed. These solutions describe anisotropic fluids which extend to the spatial infinity. Though far from the horizon their geometries approach some previously known black holes solutions the location of the horizons differ. Furthemore, although the masses of these solutions match the masses of those previously known black holes, their temperatures and entropies differ.
Black supernovae and black holes in non-local gravity
Bambi, Cosimo; Malafarina, Daniele; Modesto, Leonardo
2016-04-01
In a previous paper, we studied the interior solution of a collapsing body in a non-local theory of gravity super-renormalizable at the quantum level. We found that the classical singularity is replaced by a bounce, after which the body starts expanding. A black hole, strictly speaking, never forms. The gravitational collapse does not create an event horizon but only an apparent one for a finite time. In this paper, we solve the equations of motion assuming that the exterior solution is static. With such an assumption, we are able to reconstruct the solution in the whole spacetime, namely in both the exterior and interior regions. Now the gravitational collapse creates an event horizon in a finite comoving time, but the central singularity is approached in an infinite time. We argue that these black holes should be unstable, providing a link between the scenarios with and without black holes. Indeed, we find a non catastrophic ghost-instability of the metric in the exterior region. Interestingly, under certain conditions, the lifetime of our black holes exactly scales as the Hawking evaporation time.
Black holes and relativitic gravity theories
Fennelly, A. J.; Pavelle, R.
1977-01-01
All presently known relativistic gravitation theories were considered which have a Riemannian background geometry and possess exact static, spherically symmetric solutions which are asymptotically flat. Each theory predicts the existence of trapped surfaces (black holes). For a general static isotropic metric, MACSYMA was used to compute the Newman-Penrose equations, the black hole radius, the impact parameter, and capture radius for photon accretion. These results were then applied to several of the better known gravitation theories.
Black Holes and Quantum Gravity from a Planck Vacuum Perspective
Directory of Open Access Journals (Sweden)
Daywitt W. C.
2009-04-01
Full Text Available This note explores the question of whether or not the Planck vacuum theory can explain black holes and quantum gravity. It is argued that black holes do not physically exist in nature and that the term “quantum gravity” makes no sense. The importance of the Planck vacuum in constraining the n -ratio in the Schwarzschild line element is noted.
Thermodynamic instability of nonlinearly charged black holes in gravity's rainbow
Hendi, S H; Panah, B Eslam; Momennia, M
2015-01-01
Motivated by the violation of Lorentz invariancy in quantum gravity, we study black hole solutions in gravity's rainbow in the context of Einstein gravity coupled with various models of nonlinear electrodynamics. We regard an energy dependent spacetime and obtain related metric functions and electric fields. We show that there is an essential singularity at the origin which is covered with an event horizon. We also compute the conserved and thermodynamical quantities and examine the validity of the first law of thermodynamics in the presence of rainbow functions. Finally we investigate thermal stability conditions for these black hole solutions in context of canonical ensemble. We show that although there is not physical small black hole, large black holes are physical and enjoy thermal stability in gravity's rainbow.
Black holes in an ultraviolet complete quantum gravity
Energy Technology Data Exchange (ETDEWEB)
Modesto, Leonardo, E-mail: lmodesto@perimeterinstitute.c [Perimeter Institute for Theoretical Physics, 31 Caroline Street North, Waterloo, ON N2L 2Y5 (Canada); Moffat, John W., E-mail: john.moffat@utoronto.c [Perimeter Institute for Theoretical Physics, 31 Caroline Street North, Waterloo, ON N2L 2Y5 (Canada); Department of Physics and Astronomy, University of Waterloo, Waterloo, ON N2L 3G1 (Canada); Nicolini, Piero, E-mail: nicolini@th.physik.uni-frankfurt.d [Frankfurt Institute for Advanced Studies (FIAS) and Institut fuer Theoretische Physik, Johann Wolfgang Goethe-Universitaet, Ruth-Moufang-Strasse 1, D-60438 Frankfurt am Main (Germany)
2011-01-10
In this Letter we derive the gravity field equations by varying the action for an ultraviolet complete quantum gravity. Then we consider the case of a static source term and we determine an exact black hole solution. As a result we find a regular spacetime geometry: in place of the conventional curvature singularity extreme energy fluctuations of the gravitational field at small length scales provide an effective cosmological constant in a region locally described in terms of a de Sitter space. We show that the new metric coincides with the noncommutative geometry inspired Schwarzschild black hole. Indeed, we show that the ultraviolet complete quantum gravity, generated by ordinary matter is the dual theory of ordinary Einstein gravity coupled to a noncommutative smeared matter. In other words we obtain further insights about that quantum gravity mechanism which improves Einstein gravity in the vicinity of curvature singularities. This corroborates all the existing literature in the physics and phenomenology of noncommutative black holes.
Black holes in an ultraviolet complete quantum gravity
International Nuclear Information System (INIS)
In this Letter we derive the gravity field equations by varying the action for an ultraviolet complete quantum gravity. Then we consider the case of a static source term and we determine an exact black hole solution. As a result we find a regular spacetime geometry: in place of the conventional curvature singularity extreme energy fluctuations of the gravitational field at small length scales provide an effective cosmological constant in a region locally described in terms of a de Sitter space. We show that the new metric coincides with the noncommutative geometry inspired Schwarzschild black hole. Indeed, we show that the ultraviolet complete quantum gravity, generated by ordinary matter is the dual theory of ordinary Einstein gravity coupled to a noncommutative smeared matter. In other words we obtain further insights about that quantum gravity mechanism which improves Einstein gravity in the vicinity of curvature singularities. This corroborates all the existing literature in the physics and phenomenology of noncommutative black holes.
Black holes in an ultraviolet complete quantum gravity
Modesto, Leonardo; Moffat, John W.; Nicolini, Piero
2011-01-01
In this Letter we derive the gravity field equations by varying the action for an ultraviolet complete quantum gravity. Then we consider the case of a static source term and we determine an exact black hole solution. As a result we find a regular spacetime geometry: in place of the conventional curvature singularity extreme energy fluctuations of the gravitational field at small length scales provide an effective cosmological constant in a region locally described in terms of a de Sitter space. We show that the new metric coincides with the noncommutative geometry inspired Schwarzschild black hole. Indeed, we show that the ultraviolet complete quantum gravity, generated by ordinary matter is the dual theory of ordinary Einstein gravity coupled to a noncommutative smeared matter. In other words we obtain further insights about that quantum gravity mechanism which improves Einstein gravity in the vicinity of curvature singularities. This corroborates all the existing literature in the physics and phenomenology of noncommutative black holes.
Probing loop quantum gravity with evaporating black holes.
Barrau, A; Cailleteau, T; Cao, X; Diaz-Polo, J; Grain, J
2011-12-16
This Letter aims at showing that the observation of evaporating black holes should allow the usual Hawking behavior to be distinguished from loop quantum gravity (LQG) expectations. We present a full Monte Carlo simulation of the evaporation in LQG and statistical tests that discriminate between competing models. We conclude that contrarily to what was commonly thought, the discreteness of the area in LQG leads to characteristic features that qualify evaporating black holes as objects that could reveal quantum gravity footprints. PMID:22243065
Quantum Gravity Effects On Charged Micro Black Holes Thermodynamics
Abbasvandi, N.; Soleimani, M. J.; Radiman, Shahidan; Abdullah, W. A. T. Wan
2016-01-01
The charged black hole thermodynamics is corrected in terms of the quantum gravity effects. Most of the quantum gravity theories support the idea that near the Planck scale, the standard Heisenberg uncertainty principle should be reformulated by the so-called Generalized Uncertainty Principle (GUP) which provides a perturbation framework to perform required modifications of the black hole quantities. In this paper, we consider the effects of the minimal length and maximal momentum as GUP type...
A rotating charged black hole solution in () gravity
Indian Academy of Sciences (India)
Alexis Larrañaga
2012-05-01
In the context of () theories of gravity, we address the problem of ﬁnding a rotating charged black hole solution in the case of constant curvature. A new metric is obtained by solving the ﬁeld equations and we show that its behaviour is typical of a rotating charged source. In addition, we analyse the thermodynamics of the new black hole. The results ensure that the thermodynamical properties in () gravities are qualitatively similar to those of standard General Relativity.
Detailed black hole state counting in loop quantum gravity
International Nuclear Information System (INIS)
The combinatorial problems associated with the counting of black hole states in loop quantum gravity can be analyzed by using suitable generating functions. These can be used to perform a statistical analysis of the black hole degeneracy spectrum, study the interesting sub-structure found in the entropy of microscopic black holes, and its asymptotic behaviour for large horizon areas. They are also relevant for the discussion of the thermodynamic limit for black holes, and the understanding of sub-leading corrections to the Bekenstein-Hawking law
Black holes and entropy in loop quantum gravity: An overview
Corichi, Alejandro
2009-01-01
Black holes in equilibrium and the counting of their entropy within Loop Quantum Gravity are reviewed. In particular, we focus on the conceptual setting of the formalism, briefly summarizing the main results of the classical formalism and its quantization. We then focus on recent results for small, Planck scale, black holes, where new structures have been shown to arise, in particular an effective quantization of the entropy. We discuss recent results that employ in a very effective manner results from number theory, providing a complete solution to the counting of black hole entropy. We end with some comments on other approaches that are motivated by loop quantum gravity.
Black hole spectroscopy from loop quantum gravity models
Barrau, Aurelien; Cao, Xiangyu; Noui, Karim; Perez, Alejandro
2015-12-01
Using Monte Carlo simulations, we compute the integrated emission spectra of black holes in the framework of loop quantum gravity (LQG). The black hole emission rates are governed by the entropy whose value, in recent holographic loop quantum gravity models, was shown to agree at leading order with the Bekenstein-Hawking entropy. Quantum corrections depend on the Barbero-Immirzi parameter γ . Starting with black holes of initial horizon area A ˜102 in Planck units, we present the spectra for different values of γ . Each spectrum clearly decomposes into two distinct parts: a continuous background which corresponds to the semiclassical stages of the evaporation and a series of discrete peaks which constitutes a signature of the deep quantum structure of the black hole. We show that γ has an effect on both parts that we analyze in detail. Finally, we estimate the number of black holes and the instrumental resolution required to experimentally distinguish between the considered models.
Phase transitions of black holes in massive gravity
Fernando, Sharmanthie
2016-01-01
In this paper we have studied thermodynamics of a black hole in massive gravity in the canonical ensemble. The massive gravity theory in consideration here has a massive graviton due to Lorentz symmetry breaking. The black hole studied here has a scalar charge due to the massive graviton and is asymptotically anti-de Sitter. We have computed various thermodynamical quantities such as temperature, specific heat and free energy. Both the local and global stability of the black hole are studied by observing the behavior of the specific heat and the free energy. We have observed that there is a first order phase transition between small and large black hole for a certain range of the scalar charge. This phase transition is similar to the liquid/gas phase transition at constant temperature for a Van der Waals fluid. The coexistence curves for the small and large black hole branches are also discussed in detail.
Quantum Gravity Effects On Charged Micro Black Holes Thermodynamics
Abbasvandi, N; Radiman, Shahidan; Abdullah, W A T Wan
2016-01-01
The charged black hole thermodynamics is corrected in terms of the quantum gravity effects. Most of the quantum gravity theories support the idea that near the Planck scale, the standard Heisenberg uncertainty principle should be reformulated by the so-called Generalized Uncertainty Principle (GUP) which provides a perturbation framework to perform required modifications of the black hole quantities. In this paper, we consider the effects of the minimal length and maximal momentum as GUP type I and the minimal length, minimal momentum, and maximal momentum as GUP type II on thermodynamics of the charged TeV-scale black holes. We also generalized our study to the universe with the extra dimensions based on the ADD model. In this framework, the effect of the electrical charge on thermodynamics of the black hole and existence of the charged black hole remnants as a potential candidate for the dark matter particles are discussed.
Quantum-Gravity Fluctuations and the Black-Hole Temperature
Hod, Shahar
2015-01-01
Bekenstein has put forward the idea that, in a quantum theory of gravity, a black hole should have a discrete energy spectrum with concomitant discrete line emission. The quantized black-hole radiation spectrum is expected to be very different from Hawking's semi-classical prediction of a thermal black-hole radiation spectrum. One naturally wonders: Is it possible to reconcile the {\\it discrete} quantum spectrum suggested by Bekenstein with the {\\it continuous} semi-classical spectrum suggested by Hawking ? In order to address this fundamental question, in this essay we shall consider the zero-point quantum-gravity fluctuations of the black-hole spacetime. In a quantum theory of gravity, these spacetime fluctuations are closely related to the characteristic gravitational resonances of the corresponding black-hole spacetime. Assuming that the energy of the black-hole radiation stems from these zero-point quantum-gravity fluctuations of the black-hole spacetime, we derive the effective temperature of the quanti...
Black supernovae and black holes in non-local gravity
Bambi, Cosimo; Modesto, Leonardo
2016-01-01
In a previous paper, we studied the interior solution of a collapsing body in a non-local theory of gravity super-renormalizable at the quantum level. We found that the classical singularity is replaced by a bounce, after which the body starts expanding. A black hole, strictly speaking, never forms. The gravitational collapse does not create an event horizon but only an apparent one for a finite time. In this paper, we solve the equations of motion assuming that the exterior solution is static. With such an assumption, we are able to reconstruct the solution in the whole spacetime, namely in both the exterior and interior regions. Now the gravitational collapse creates an event horizon in a finite comoving time, but the central singularity is approached in an infinite time. We argue that these black holes should be unstable, providing a link between the scenarios with and without black holes. Indeed, we find a non catastrophic ghost-instability of the metric in the exterior region. Interestingly, under certai...
Black hole entropy in higher curvature gravity
Jacobson, T; Myers, R C; Jacobson, Ted; Kang, Gungwon; Myers, Robert C
1995-01-01
We discuss some recent results on black hole thermodynamics within the context of effective gravitational actions including higher-curvature interactions. Wald's derivation of the First Law demonstrates that black hole entropy can always be expressed as a local geometric density integrated over a space-like cross-section of the horizon. In certain cases, it can also be shown that these entropy expressions satisfy a Second Law. One such simple example is considered from the class of higher curvature theories where the Lagrangian consists of a polynomial in the Ricci scalar.
Black Holes, Information, and Hilbert Space for Quantum Gravity
Nomura, Yasunori; Weinberg, Sean J
2012-01-01
A complete description for the formation and evaporation of a black hole is given within the framework of a unitary theory of quantum gravity preserving locality. The resulting picture depends strongly on the reference frame one chooses to describe the process. In one description based on a reference frame in which the reference point stays outside the black hole horizon for sufficiently long time, a late black hole state becomes a superposition of black holes in different locations and with different spins, even if the back hole is formed from collapsing matter that had a well-defined classical configuration with no angular momentum. The information about the initial state is partly encoded in relative coefficients---especially phases---of the terms representing macroscopically different geometries. In another description in which the reference point enters into the black hole horizon at late times, an S-matrix description in the asymptotically Minkowski spacetime is not applicable, but it sill allows for an...
Black holes and quantum gravity at the LHC
International Nuclear Information System (INIS)
We argue that the highly studied black hole signatures based on thermal multiparticle final states are very unlikely and only occur in a very limited parameter regime if at all. However, we show that if the higher-dimensional quantum gravity scale is low, it should be possible to study quantum gravity in the context of higher dimensions through detailed compositeness-type searches.
Modified gravity black holes and their observable shadows
Energy Technology Data Exchange (ETDEWEB)
Moffat, J.W. [Perimeter Institute for Theoretical Physics, Waterloo, ON (Canada); University of Waterloo, Department of Physics and Astronomy, Waterloo, ON (Canada)
2015-03-01
The shadows cast by non-rotating and rotating modified gravity black holes are determined by the two parameters mass M and angular momentum J = Ma. The sizes of the shadows cast by the spherically symmetric static modified gravity-Schwarzschild and modified gravity-Kerr rotating black holes increase significantly as the free parameter α is increased from zero. The Event Horizon Telescope shadow image measurements can determine whether Einstein's general relativity is correct or whether it should be modified in the presence of strong gravitational fields. (orig.)
Gravity, quantum theory and the evaporation of black holes
International Nuclear Information System (INIS)
Recent developments in blackhole physics are reviewed. It is pointed out that black hole thermodynamics is a theory of exceptional unity and elegance. Starting from the discovery of thermal emission from black holes (evaporation process) by Hawking, the four thermodynamic laws they obey, the nonzero temperature and entropy, angular momentum and charge of the black holes are dealt with. The influence of this thermodynamics on quantum theory and gravitation is discussed in relation to particle creation and quantum gravity. The formation and basic properties of black holes are described in terms of significant milestones. The decade-long development of black hole thermodynamics from 1963-73 is highlighted. The fundamental issues arising in particle physics as a result of these discoveries are discussed. (A.K.)
Quantum gravity effects in black holes at the LHC
International Nuclear Information System (INIS)
We study possible back-reaction and quantum gravity effects in the evaporation of black holes which could be produced at the LHC through a modification of the Hawking emission. The corrections are phenomenologically taken into account by employing a modified relation between the black hole mass and temperature. The usual assumption that black holes explode around 1 TeV is also released, and the evaporation process is extended to (possibly much) smaller final masses. We show that these effects could be observable for black holes produced with a relatively large mass and should therefore be taken into account when simulating micro-black hole events for the experiments planned at the LHC
Linear stability of nonbidiagonal black holes in massive gravity
Babichev, Eugeny; Brito, Richard; Pani, Paolo
2016-02-01
We consider generic linear perturbations of a nonbidiagonal class of static black-hole solutions in massive (bi-)gravity. We show that the quasinormal spectrum of these solutions coincides with that of a Schwarzschild black hole in general relativity, thus proving that these solutions are mode stable. This is in contrast to the case of bidiagonal black-hole solutions which are affected by a radial instability. On the other hand, the full set of perturbation equations is generically richer than that of a Schwarzschild black hole in general relativity, and this affects the linear response of the black hole to external perturbations. Finally, we argue that the generalization of these solutions to the spinning case does not suffer from the superradiant instability, despite the fact that the theory describes a massive graviton.
Phase transitions of black holes in massive gravity
Fernando, Sharmanthie
2016-05-01
In this paper, we have studied thermodynamics of a black hole in massive gravity in the canonical ensemble. The massive gravity theory in consideration here has a massive graviton due to Lorentz symmetry breaking. The black hole studied here has a scalar charge due to the massive graviton and is asymptotically anti-de Sitter (AdS). We have computed various thermodynamical quantities such as temperature, specific heat and free energy. Both the local and global stability of the black hole are studied by observing the behavior of the specific heat and the free energy. We have observed that there is a first-order phase transition between small (SBH) and large black hole (LBH) for a certain range of the scalar charge. This phase transition is similar to the liquid/gas phase transition at constant temperature for a van der Waals fluid. The coexistence curves for the SBH and LBH branches are also discussed in detail.
Black hole entropy and induced gravity
Jacobson, T
1994-01-01
In this short essay we review the arguments showing that black hole entropy is, at least in part, "entanglement entropy", i.e., missing information contained in correlations between quantum field fluctuations inside and outside the event horizon. Although the entanglement entropy depends upon the matter field content of the theory, it turns out that so does the Bekenstein-Hawking entropy A/4\\hbar G_{ren}, in precisely the same way, because the effective gravitational constant G_{ren} is renormalized by the very same quantum fluctuations. It appears most satisfactory if the entire gravitational action is "induced", in the manner suggested by Sakharov, since then the black hole entropy is purebred entanglement entropy, rather than being hybrid with bare gravitational entropy (whatever that might be.)
Black holes in an ultraviolet complete quantum gravity
Modesto, Leonardo; Nicolini, Piero
2010-01-01
In this paper we derive the gravity field equations by varying the action for an ultraviolet complete quantum gravity. Then we consider the case of a static source term and we determine an exact black hole solution. As a result we find a regular spacetime geometry: in place of the conventional curvature singularity extreme energy fluctuations of the gravitational field at small length scales provide an effective cosmological constant in a region locally described in terms of a deSitter space. We show that the new metric coincides with the noncommutative geometry inspired Schwarzschild black hole. Indeed we show that the ultraviolet complete quantum gravity, generated by ordinary matter is the dual theory of ordinary Einstein gravity coupled to a noncommutative smeared matter. In other words we obtain further insights about that quantum gravity mechanism which improves Einstein gravity in the vicinity of curvature singularities. This corroborates all the existing literature in the physics and phenomenology of ...
Black Hole Evaporation in Horava and New Massive Gravity
International Nuclear Information System (INIS)
Recently it has been a lot of interest in the theory proposed by Horava due to the renormalizability properties of the theory and as a candidate for the UV completion of Einstein gravity. On the other hand, we also investigate three dimensional black holes at a Lifshitz point. In the present work we study thermodynamical properties in this setups. In particular we are able to obtain time of evaporation for black hole solutions for the two formalisim.
Disappearance of Black Hole Singularity in Quantum Gravity
Modesto, Leonardo
2004-01-01
We apply techniques recently introduced in quantum cosmology to the Schwarzschild metric inside the horizon and near the black hole singularity at r = 0. In particular, we use the quantization introduced by Husain and Winkler, which is suggested by Loop Quantum Gravity and is based on an alternative to the Schrodinger representation introduced by Halvorson. Using this quantization procedure, we show that the black hole singularity disappears and spacetime can be dynamically extended beyond th...
An introduction to spherically symmetric loop quantum gravity black holes
Energy Technology Data Exchange (ETDEWEB)
Gambini, Rodolfo [Instituto de Física, Facultad de Ciencias, Iguá 4-225, esq. Mataojo, 11400 Montevideo (Uruguay); Pullin, Jorge [Department of Physics and Astronomy, Louisiana State University, Baton Rouge, LA 70803-4001 (United States)
2015-03-26
We review recent developments in the treatment of spherically symmetric black holes in loop quantum gravity. In particular, we discuss an exact solution to the quantum constraints that represents a black hole and is free of singularities. We show that new observables that are not present in the classical theory arise in the quantum theory. We also discuss Hawking radiation by considering the quantization of a scalar field on the quantum spacetime.
An introduction to spherically symmetric loop quantum gravity black holes
International Nuclear Information System (INIS)
We review recent developments in the treatment of spherically symmetric black holes in loop quantum gravity. In particular, we discuss an exact solution to the quantum constraints that represents a black hole and is free of singularities. We show that new observables that are not present in the classical theory arise in the quantum theory. We also discuss Hawking radiation by considering the quantization of a scalar field on the quantum spacetime
Thermodynamic geometry of black holes in f(R) gravity
Soroushfar, Saheb; Saffari, Reza; Kamvar, Negin
2016-01-01
In this paper, we consider three types (static, static charged and rotating charged) of black holes in f(R) gravity. We study the thermodynamical behavior, stability conditions and phase transition of these black holes. It will be shown that, the number and type of phase transition points are related to different parameters, which shows the dependency of stability conditions to these parameters. Also, we extended our study to different thermodynamic geometry methods (Ruppeiner, Weinhold and G...
Notes on black holes and three dimensional gravity
International Nuclear Information System (INIS)
In these notes we review some relevant results on 2+1 quantum gravity. These include the Chern-Simons formulation and its affine Kac-Moody symmetry, the asymptotic algebra of Brown and Henneaux, and the statistical mechanics description of 2+1 black holes. A brief introduction to the classical and semiclassical aspects of black holes is also included. The level of the notes is basic assuming only some knowledge on Statistical Mechanics, General Relativity and Yang-Mills theory
Statistical mechanics of black holes in induced gravity
International Nuclear Information System (INIS)
The density matrix of a black hole is constructed. On an example of induced gravity it is shown that the black hole entropy has a statistical mechanical meaning of the entropy of all dynamical degrees of freedom of matter fields that remain independent after resolution of effective constraint equations. This statement is independent of the particular variant of underlying microscopic field theory since it is based only on the low-energy asymptotic of the corresponding effective action
Quantum leaps of black holes: Magnifying glasses of quantum gravity
Chakraborty, Sumanta
2016-01-01
We show using simple arguments, that the conceptual triad of a {\\it classical} black hole, semi-classical Hawking emission and geometry quantization is inherently, mutually incompatible. Presence of any two explicitly violates the third. We argue that geometry quantization, if realized in nature, magnifies the quantum gravity features hugely to catapult them into the realm of observational possibilities. We also explore a quantum route towards extremality of the black holes.
Geometrothermodynamics of BTZ black hole in new massive gravity
Suresh, Jishnu
2016-01-01
We investigate the thermodynamics as well as thermodynamic geometry of chargeless BTZ black hole solution in new massive gravity. Phase structure and thermodynamic stability of the system is analyzed using the Geometrothermodynamic approach. The phase transition between BTZ black hole space time and thermal AdS$_{3}$ soliton is studied using the same approach and the existence of a second order phase transition is examined.
Loop quantum gravity in higher dimensions and black hole entropy
International Nuclear Information System (INIS)
A reformulation of higher-dimensional gravity theories is discussed which allows for the application of the loop quantum gravity program. To this end, a Hamiltonian formulation of the gravity theory has to be given on a Yang-Mills phase space such that the Yang-Mills gauge group is compact, the Poisson brackets are canonical, the variables are real and the theory is only subject to first class constraints. The computation of black hole entropy is discussed as an application.
Evolving Black Hole Horizons in General Relativity and Alternative Gravity
Directory of Open Access Journals (Sweden)
Valerio Faraoni
2013-09-01
Full Text Available From the microscopic point of view, realistic black holes are time-dependent and the teleological concept of the event horizon fails. At present, the apparent or trapping horizon seem to be its best replacements in various areas of black hole physics. We discuss the known phenomenology of apparent and trapping horizons for analytical solutions of General Relativity and alternative theories of gravity. These specific examples (we focus on spherically symmetric inhomogeneities in a background cosmological spacetime are useful as toy models for research on various aspects of black hole physics.
Thermodynamics and Geometrothermodynamics of Charged black holes in Massive Gravity
Suresh, Jishnu; Prabhakar, Geethu; Kuriakose, V C
2016-01-01
The objective of this paper is to study the thermodynamics and thermodynamic geometry of charged de-Sitter and charged anti de-Sitter black hole solutions in massive gravity. In this study, the presence of a negative cosmological constant is identified as a thermodynamic variable, the pressure. By incorporating this idea, we study the effect of curvature parameter as well as the mass of graviton in the thermodynamics of the black hole system. We further extend our studies to different topology of the space time and its effects on phase transition and thermodynamics. In addition, the phase transition structure of the black hole and its interactions are reproduced using geometrothermodynamics.
Evolving black hole horizons in General Relativity and alternative gravity
Faraoni, Valerio
2013-01-01
From the microscopic point of view, realistic black holes are time-dependent and the teleological concept of event horizon fails. At present, the apparent or the trapping horizon seem its best replacements in various areas of black hole physics. We discuss the known phenomenology of apparent and trapping horizons for analytical solutions of General Relativity and alternative theories of gravity. These specific examples (we focus on spherically symmetric inhomogeneities in a background cosmological spacetime) may be useful as toy models for research on various aspects of black hole physics.
Black Hole Thermodynamic Products in Einstein Gauss Bonnet Gravity
Mandal, Abhijit
2015-01-01
We study the thermodynamic properties of black hole horizons in Einstein Gauss Bonnet gravity. We derive the thermodynamic products of characteristic parameters to mark which are global. We further interpret the stability of the black holes by computing the specific heat for both horizons. Stable and unstable phases of horizons are pointed out. The phase transitions with respect to the charge in nature of specific heat are also observed. All these calculation might be helpful to understand the microscopic nature of such black holes.
Black holes in three dimensional higher spin gravity: a review
International Nuclear Information System (INIS)
We review recent progress in the construction of black holes in three dimensional higher spin gravity theories. Starting from spin-3 gravity and working our way toward the theory of an infinite tower of higher spins coupled to matter, we show how to harness higher spin gauge invariance to consistently generalize familiar notions of black holes. We review the construction of black holes with conserved higher spin charges and the computation of their partition functions to leading asymptotic order. In view of the anti-de Sitter/conformal field theory (CFT) correspondence as applied to certain vector-like conformal field theories with extended conformal symmetry, we successfully compare to CFT calculations in a generalized Cardy regime. A brief recollection of pertinent aspects of ordinary gravity is also given. This article is part of a special issue of Journal of Physics A: Mathematical and Theoretical devoted to ‘Higher spin theories and holography’. (review)
Black-hole dynamics in BHT massive gravity
Maeda, Hideki
2010-01-01
Using an exact Vaidya-type null-dust solution, we study the area and entropy laws for dynamical black holes defined by a future outer trapping horizon in (2+1)-dimensional Bergshoeff-Hohm-Townsend (BHT) massive gravity. We consider the theory admitting a degenerate (anti-)de Sitter vacuum and pure BHT gravity. It is shown that, while the area of a black hole decreases by the injection of a null dust with positive energy density in several cases, the Wald-Kodama dynamical entropy always increa...
Nonsingular black holes in quadratic Palatini gravity
Energy Technology Data Exchange (ETDEWEB)
Olmo, Gonzalo J. [Universidad de Valencia, Departamento de Fisica Teorica, Valencia (Spain); IFIC, Centro Mixto Universidad de Valencia-CSIC, Valencia (Spain); Rubiera-Garcia, D. [Universidad de Oviedo, Departamento de Fisica, Oviedo, Asturias (Spain)
2012-08-15
We find that if general relativity is modified at the Planck scale by a Ricci-squared term, electrically charged black holes may be nonsingular. These objects concentrate their mass in a microscopic sphere of radius r{sub core}{approx}N{sub q}{sup 1/2}l{sub P}/3, where l{sub P} is the Planck length and N{sub q} is the number of electric charges. The singularity is avoided if the mass of the object satisfies the condition M{sub 0}{sup 2}{approx}m{sub P}{sup 2}{alpha}{sub em}{sup 3/2}N{sub q}{sup 3}/2, where m{sub P} is the Planck mass and {alpha}{sub em} is the fine-structure constant. For astrophysical black holes this amount of charge is so small that their external horizon almost coincides with their Schwarzschild radius. We work within a first-order (Palatini) approach. (orig.)
Designer black holes from new 2D gravity
Kunstatter, Gabor; Taves, Tim
2015-01-01
We present a family of extensions of spherically symmetric Einstein-Lanczos-Lovelock gravity. The field equations are second order and obey a generalized Birkhoff's theorem. The Hamiltonian constraint can be written in terms of a generalized Misner-Sharp mass function that determines the form of the vacuum solution. The action can be designed to yield interesting non-singular black-hole spacetimes as the unique vacuum solutions, including the Hayward black hole as well as a completely new one. The new theories therefore provide a consistent starting point for studying the formation and evaporation of non-singular black holes as a possible resolution to the black hole information loss conundrum.
Charged Black Hole Solutions in Gauss-Bonnet-Massive Gravity
Hendi, S H; Panah, B Eslam
2015-01-01
Motivated by high interest in the close relation between string theory and black hole solutions, in this paper, we take into account the Einstein-Gauss-Bonnet Lagrangian in the context of massive gravity. We examine the possibility of black hole in this regard, and discuss the types of horizons. Next, we calculate conserved and thermodynamic quantities and check the validity of the first law of thermodynamics. In addition, we investigate the stability of these black holes in context of canonical ensemble. We show that number, type and place of phase transitions points may be significantly affected by the different parameters. Next, by considering cosmological constant as thermodynamical pressure, we will extend phase space and calculate critical values. Then, we construct thermodynamical spacetime by considering mass as thermodynamical potential. We study geometrical thermodynamics of these black holes in context of heat capacity and extended phase space. We show that studying heat capacity, geometrical therm...
Black-hole decay and topological stability in quantum gravity
International Nuclear Information System (INIS)
In the context of Quantum Gravity, the evolution of Schwarzschild black-holes is studied. The superspace of the theory is restricted to a class of geometries that contains the Schwarzschild solution for different masses as well as other geometries with different topologies. It is shown that, black-holes are topologically stable under quantum fluctuations but unstable under quantum processes of emission and absorption of gravitons. It is found that, the probability of emission behaves as exp (- α (Mf - Mi), where Mi and Mf are the masses associated to the initial and final states, respectively and α is a positive constant of the order of 1. As the black-hole looses mass it evolves towards a state corresponding to a black-hole of very small that cannot be distinguished from a pure graviton state. (author)
Black hole accretion in scalar-tensor-vector gravity
John, Anslyn J
2016-01-01
We examine the accretion of matter onto a black hole in scalar--tensor--vector gravity (STVG). The gravitational constant is $G=G_{N} (1 + \\alpha)$ where $\\alpha$ is a parameter taken to be constant for static black holes in the theory. The STVG black hole is spherically symmetric and characterised by two event horizons. The matter falling into the black hole obeys the polytrope equation of state and passes through two critical points before entering the outer horizon. We obtain analytical expressions for the mass accretion rate as well as for the outer critical point, critical velocity and critical sound speed. Our results complement existing strong field tests like lensing and orbital motion and could be used in conjunction to determine observational constraints on STVG.
Horava gravity vs. thermodynamics: the black hole case
Blas, D
2011-01-01
Under broad assumptions breaking of Lorentz invariance in gravitational theories leads to tension with unitarity because it allows for processes that apparently violate the second law of thermodynamics. The crucial ingredient of this argument is the existence of black hole solutions with the interior shielded from infinity by a causal horizon. We study how the paradox can be resolved in the healthy extension of Horava gravity. To this aim we analyze classical solutions describing large black holes in this theory with the emphasis on their causal structure. The notion of causality is subtle in this theory due to the presence of instantaneous interactions. Despite this fact, we find that within exact spherical symmetry a black hole solution contains a space-time region causally disconnected from infinity by a surface of finite area -- the `universal horizon'. We then consider small perturbations of arbitrary angular dependence in the black hole background. We argue that aspherical perturbations destabilize the ...
Dynamical surface gravity in spherically symmetric black hole formation
International Nuclear Information System (INIS)
We study dynamical surface gravity in a general spherically symmetric setting using Painleve-Gullstrand coordinates. Our analysis includes several definitions that have been proposed in the past as well as two new definitions adapted to Painleve-Gullstrand coordinates. Various properties are considered, including general covariance, value at extremality, locality and static limit. We illustrate with specific examples of 'dirty' black holes that even for spacetimes possessing a global timelike Killing vector, local definitions of surface gravity can differ substantially from 'nonlocal' ones that require an asymptotic normalization condition. Finally, we present numerical calculations of dynamical surface gravity for black hole formation via spherically symmetric scalar field collapse. Our results highlight the differences between the various definitions in a dynamical setting and provide further insight into the distinction between local and nonlocal definitions of surface gravity.
Another Approach to Test Gravity around a Black Hole
Iwata, Kengo
2016-01-01
Pulsars orbiting around the black hole at our galactic center provide us a unique testing site for gravity. In this work, we propose an approach to probe the gravity around the black hole introducing two phenomenological parameters which characterize deviation from the vacuum Einstein theory. The two phenomenological parameters are associated with the energy momentum tensor in the framework of the Einstein theory. Therefore, our approach can be regarded as the complement to the parametrized post-Newtonian framework in which phenomenological parameters are introduced for deviation of gravitational theories from general relativity. In our formulation, we take the possibility of a relativistic and exotic matter component into account. Since the pulsar can be regarded as a test particle, as the first step, we consider geodesic motions in the system composed of a central black hole and a perfect fluid whose distribution is static and spherically symmetric. It is found that the mass density of the fluid and a param...
2d quantum gravity and black hole formation
International Nuclear Information System (INIS)
The quantum integral of generic 2d quantum gravity can be performed exactly. The equivalence of dilaton theories to 2d theories with torsion and the use of a light cone gauge are crucial. Scalar matter can be treated perturbatively. A generalization of the Polyakov action emerges. For scattering of scalars in a flat background already in the tree approximation for the first time the intermediate formation of a black hole is observed in an ab initio quantum gravity computation
Quantum Gravity effects near the null black hole singularity
Bonanno, Alfio; Reuter, Martin
1998-01-01
The structure of the Cauchy Horizon singularity of a black hole formed in a generic collapse is studied by means of a renormalization group equation for quantum gravity. It is shown that during the early evolution of the Cauchy Horizon the increase of the mass function is damped when quantum fluctuations of the metric are taken into account.
Thermodynamic geometry of black holes in f(R) gravity
Soroushfar, Saheb; Kamvar, Negin
2016-01-01
In this paper, we consider three types (static, static charged and rotating charged) of black holes in f(R) gravity. We study the thermodynamical behavior, stability conditions and phase transition of these black holes. It will be shown that, the number and type of phase transition points are related to different parameters, which shows the dependency of stability conditions to these parameters. Also, we extended our study to different thermodynamic geometry methods (Ruppeiner, Weinhold and GTD). Next, we investigate the compatibility of curvature scalar of geothermodynamic methods with phase transition points of the above balck holes. In addition, we point out the effect of different values of spacetime parameters on stability conditions of mentioned black holes.
Black hole spectroscopy from Loop Quantum Gravity models
Barrau, Aurelien; Noui, Karim; Perez, Alejandro
2015-01-01
Using Monte Carlo simulations, we compute the integrated emission spectra of black holes in the framework of Loop Quantum Gravity (LQG). The black hole emission rates are governed by the entropy whose value, in recent holographic loop quantum gravity models, was shown to agree at leading order with the Bekenstein-Hawking entropy. Quantum corrections depend on the Barbero-Immirzi parameter $\\gamma$. Starting with black holes of initial horizon area $A \\sim 10^2$ in Planck units, we present the spectra for different values of $\\gamma$. Each spectrum clearly decomposes in two distinct parts: a continuous background which corresponds to the semi-classical stages of the evaporation and a series of discrete peaks which constitutes a signature of the deep quantum structure of the black hole. We show that $\\gamma$ has an effect on both parts that we analyze in details. Finally, we estimate the number of black holes and the instrumental resolution required to experimentally distinguish between the considered models.
Hawking Radiation of a Charged Black Hole in Quantum Gravity
Oda, Ichiro
2015-01-01
We study black hole radiation of a Reissner-Nordstrom black hole with an electric charge in the framework of quantum gravity. Based on a canonical quantization for a spherically symmetric geometry, under physically plausible assumptions, we solve the Wheeler-De Witt equation in the regions not only between the outer apparent horizon and the spatial infinity but also between the spacetime singularity and the inner apparent horizon, and then show that the mass loss rate of an evaporating black hole due to thermal radiation agrees with the semiclassical result when we choose an integration constant properly by physical reasoning. Furthermore, we also solve the Wheeler-De Witt equation in the region between the inner Cauchy horizon and the outer apparent horizon, and show that the mass loss rate of an evaporating black hole has the same expression. The present study is the natural generalization of the case of a Schwarzschild black hole to that of a charged Reissner-Nordstrom black hole.
Gravitation. [consideration of black holes in gravity theories
Fennelly, A. J.
1978-01-01
Investigations of several problems of gravitation are discussed. The question of the existence of black holes is considered. While black holes like those in Einstein's theory may not exist in other gravity theories, trapped surfaces implying such black holes certainly do. The theories include those of Brans-Dicke, Lightman-Lee, Rosen, and Yang. A similar two-tensor theory of Yilmaz is investigated and found inconsistent and nonviable. The Newman-Penrose formalism for Riemannian geometries is adapted to general gravity theories and used to implement a search for twisting solutions of the gravity theories for empty and nonempty spaces. The method can be used to find the gravitational fields for all viable gravity theories. The rotating solutions are of particular importance for strong field interpretation of the Stanford/Marshall gyroscope experiment. Inhomogeneous cosmologies are examined in Einstein's theory as generalizations of homogeneous ones by raising the dimension of the invariance groups by one more parameter. The nine Bianchi classifications are extended to Rosen's theory of gravity for homogeneous cosmological models.
Thermodynamic instability of nonlinearly charged black holes in gravity's rainbow
Hendi, S. H.; Panahiyan, S.; Panah, B. Eslam; Momennia, M.
2016-03-01
Motivated by the violation of Lorentz invariance in quantum gravity, we study black hole solutions in gravity's rainbow in the context of Einstein gravity coupled with various models of nonlinear electrodynamics. We regard an energy dependent spacetime and obtain the related metric functions and electric fields. We show that there is an essential singularity at the origin which is covered by an event horizon. We also compute the conserved and thermodynamical quantities and examine the validity of the first law of thermodynamics in the presence of rainbow functions. Finally, we investigate the thermal stability conditions for these black hole solutions in the context of canonical ensemble. We show that the thermodynamical structure of the solutions depends on the choices of nonlinearity parameters, charge, and energy functions.
Detailed black hole state counting in loop quantum gravity
International Nuclear Information System (INIS)
We give a complete and detailed description of the computation of black hole entropy in loop quantum gravity by employing the most recently introduced number-theoretic and combinatorial methods. The use of these techniques allows us to perform a detailed analysis of the precise structure of the entropy spectrum for small black holes, showing some relevant features that were not discernible in previous computations. The ability to manipulate and understand the spectrum up to the level of detail that we describe in the paper is a crucial step toward obtaining the behavior of entropy in the asymptotic (large horizon area) regime.
Black holes in three-dimensional dilaton gravity theories
Sá, P M; Lemos, J P S; Sa, Paulo M; Kleber, Antares; Lemos, Jose P S
1995-01-01
Three dimensional black holes in a generalized dilaton gravity action theory are analysed. The theory is specified by two fields, the dilaton and the graviton, and two parameters, the cosmological constant and the Brans-Dicke parameter. It contains seven different cases, of which one distinguishes as special cases, string theory, general relativity and a theory equivalent to four dimensional general relativity with one Killing vector. We study the causal structure and geodesic motion of null and timelike particles in the black hole geometries and find the ADM masses of the different solutions.
Constraints on rainbow gravity functions from black hole thermodynamics
Gangopadhyay, Sunandan
2016-01-01
In this paper, we investigate the thermodynamic properties of black holes in the framework of rainbow gravity. By considering rainbow functions in the metric of Schwarzschild and Reissner-Nordstr\\"{o}m black holes, remnant and critical masses are found to exist. Demanding the universality of logarithmic corrections to the semi-classical area law for the entropy leads to constraining the form of the rainbow functions. The mass output and the radiation rate for these constrained form of rainbow functions have been computed for different values of the rainbow parameter $\\eta$ and have striking similarity to those derived from the generalized uncertainty principle.
Black hole hair in generalized scalar-tensor gravity.
Sotiriou, Thomas P; Zhou, Shuang-Yong
2014-06-27
The most general action for a scalar field coupled to gravity that leads to second-order field equations for both the metric and the scalar--Horndeski's theory--is considered, with the extra assumption that the scalar satisfies shift symmetry. We show that in such theories, the scalar field is forced to have a nontrivial configuration in black hole spacetimes, unless one carefully tunes away a linear coupling with the Gauss-Bonnet invariant. Hence, black holes for generic theories in this class will have hair. This contradicts a recent no-hair theorem which seems to have overlooked the presence of this coupling. PMID:25014801
Black holes, TeV-scale gravity and the LHC
Winstanley, Elizabeth(Consortium for Fundamental Physics, School of Mathematics and Statistics, University of Sheffield, Hicks Building, Hounsfield Road, Sheffield, S3 7RH, United Kingdom)
2013-01-01
Over the past 15 years models with large extra space-time dimensions have been extensively studied. We have learned from these models that the energy scale of quantum gravity may be many orders of magnitude smaller than the conventional value of 10^19 GeV. This raises the tantalizing prospect of probing quantum gravity effects at the LHC. Of the possible quantum gravity processes at the LHC, the formation and subsequent evaporation of microscopic black holes is one of the most spectacular. We...
Thermodynamic and classical instability of AdS black holes in fourth-order gravity
International Nuclear Information System (INIS)
We study thermodynamic and classical instability of AdS black holes in fourth-order gravity. These include the BTZ black hole in new massive gravity, Schwarzschild-AdS black hole, and higher-dimensional AdS black holes in fourth-order gravity. All thermodynamic quantities which are computed using the Abbot-Deser-Tekin method are used to study thermodynamic instability of AdS black holes. On the other hand, we investigate the s-mode Gregory-Laflamme instability of the massive graviton propagating around the AdS black holes. We establish the connection between the thermodynamic instability and the GL instability of AdS black holes in fourth-order gravity. This shows that the Gubser-Mitra conjecture holds for AdS black holes found from fourth-order gravity
Notes on black holes and three dimensional gravity
Bañados, M
1999-01-01
These notes are the written version of two lectures delivered at the VIII Mexican School on Particles and Fields on November 1998. The level of the notes is basic assuming only some knowledge on Statistical Mechanics, General Relativity and Yang-Mills theory. After a brief introduction to the classical and semiclassical aspects of black holes, we review some relevant results on 2+1 quantum gravity. These include the Chern-Simons formulation and its affine Kac-Moody algebra, the asymptotic algebra of Brown and Henneaux, and the statistical mechanics description of 2+1 black holes. Hopefully, this contribution will be complementary with the review paper hep-th/9901148 by the same author, and perhaps, a shortcut to some recent developments in three dimensional gravity.
New 2D dilaton gravity for nonsingular black holes
Kunstatter, Gabor; Maeda, Hideki; Taves, Tim
2016-05-01
We construct a two-dimensional action that is an extension of spherically symmetric Einstein–Lanczos–Lovelock (ELL) gravity. The action contains arbitrary functions of the areal radius and the norm squared of its gradient, but the field equations are second order and obey Birkhoff’s theorem. In complete analogy with spherically symmetric ELL gravity, the field equations admit the generalized Misner–Sharp mass as the first integral that determines the form of the vacuum solution. The arbitrary functions in the action allow for vacuum solutions that describe a larger class of interesting nonsingular black hole spacetimes than previously available.
Charged Black Holes in Massive Gravity's Rainbow
Hendi, S H; Panahiyan, S
2016-01-01
Violation of Lorentz invariancy in the high energy quantum gravity, motivates one to consider an energy dependent spacetime with massive deformation of standard general relativity. In this paper, we take into account an energy dependent metric in the context of a massive gravity model to obtain exact solutions. We investigate the geometry of the solutions and show that that there is a curvature singularity at the origin ($r=0$) which can be covered with an event horizon. We also calculate the conserved and thermodynamic quantities, which are fully reproduced by the analysis performed with the standard techniques. Finally, we examine the validity of the first law of thermodynamics. Next, we conduct a study regarding the positivity and negativity of total mass in de Sitter and anti de Sitter spacetime.
Exact solutions of three dimensional black holes: Einstein gravity vs F(R) gravity
Hendi, S H; Saffari, R
2014-01-01
In this paper, we consider Einstein gravity in the presence of a class of nonlinear electrodynamics, called power Maxwell invariant (PMI). We take into account $(2+1)$-dimensional spacetime in Einstein-PMI gravity and obtain its black hole solutions. Then, we regard pure $F(R)$ gravity as well as $F(R)$-conformally invariant Maxwell theory to obtain exact solutions of the field equations with black hole interpretation. Finally, we investigate the conserved and thermodynamic quantities and discuss about the first law of thermodynamics for the mentioned gravitational models.
Charged black hole solutions in Gauss-Bonnet-massive gravity
Hendi, S. H.; Panahiyan, S.; Panah, B. Eslam
2016-01-01
Motivated by high interest in the close relation between string theory and black hole solutions, in this paper, we take into account the Einstein-Gauss-Bonnet Lagrangian in the context of massive gravity. We examine the possibility of black hole in this regard, and discuss the types of horizons. Next, we calculate conserved and thermodynamic quantities and check the validity of the first law of thermodynamics. In addition, we investigate the stability of these black holes in context of canonical ensemble. We show that number, type and place of phase transition points may be significantly affected by different parameters. Next, by considering cosmological constant as thermodynamical pressure, we will extend phase space and calculate critical values. Then, we construct thermodynamical spacetime by considering mass as thermodynamical potential. We study geometrical thermodynamics of these black holes in context of heat capacity and extended phase space. We show that studying heat capacity, geometrical thermodynamics and critical behavior in extended phase space lead to consistent results. Finally, we will employ a new method for obtaining critical values and show that the results of this method are consistent with those of other methods.
Black Hole Thermodynamic Products in Einstein Gauss Bonnet Gravity
Biswas, Ritabrata
2016-07-01
By now, there are many hints from string theory that collective excitations of solitonic objects can be described by effective low energy theories. The entropy of general rotating black holes in five dimensions may be interpreted as an indication that, it derives from two independent microscopic contributions and each of these may be attributed to a gas of strings. In the present work, we consider a charged black hole in five dimensional Einstein Gauss Bonnet gravity. In spite of presenting the thermodynamic quantities' product as summation/ subtraction of two independent integers, our motive is to check whether the product of the same quantity for event horizon and Cauchy horizon is free of mass, i.e., global, or not. We derive the thermodynamic products of characteristic parameters to mark which are global. We further interpret the stability of the black holes by computing the specific heat for both horizons. Stable and unstable phases of horizons are pointed out. The phase transitions with respect to the charge in nature of specific heat are also observed. All these calculation might be helpful to understand the microscopic nature of such black holes.
Hairy Black Holes in Massive Gravity: Thermodynamics and Phase Structure
Capela, Fabio
2012-01-01
The thermodynamic properties of a static and spherically-symmetric hairy black hole of massive gravity are investigated. The analysis is carried out by enclosing the black hole in a spherical cavity whose surface is maintained at a fixed temperature $T$. It turns out that the ensemble is well-defined only if the "hair" parameter $Q$ characterizing the solution is conserved. Under this condition we compute some relevant thermodynamic quantities, such as thermal energy and entropy, and we study stability and phase structure of the ensemble. In particular, for negative values of the hair parameter, the phase structure is isomorphic to the one of Reissner-Nordstrom black holes in the canonical ensemble. Moreover, the phase-diagram in the plan ($Q,T$) has a line of first-order phase transition that at a critical value of $Q$ terminates in a second-order phase transition. Below this line the dominant phase consists of small, cold black holes that are long-lived and may thus contribute much more to the energy densit...
Brane-world black holes and the scale of gravity
Alberghi, G L; Micu, O; Orlandi, A
2011-01-01
A particle in four dimensions should behave like a classical black hole if the horizon radius is larger than the Compton wavelength or, equivalently, if its degeneracy (measured by entropy in units of the Planck scale) is large. For spherically symmetric black holes in 4 + d dimensions, both arguments again lead to a mass threshold MC and degeneracy scale Mdeg of the order of the fundamental scale of gravity MG. In the brane-world, deviations from the Schwarzschild metric induced by bulk effects alter the horizon radius and effective four-dimensional Euclidean action in such a way that MC \\simeq Mdeg might be either larger or smaller than MG. This opens up the possibility that black holes exist with a mass smaller than MG and might be produced at the LHC even if M>10 TeV, whereas effects due to bulk graviton exchanges remain undetectable because suppressed by inverse powers of MG. Conversely, even if black holes are not found at the LHC, it is still possible that MC>MG and MG \\simeq 1TeV.
Extremal Black Holes in Dynamical Chern-Simons Gravity
McNees, Robert; Yunes, Nicolás
2015-01-01
Rapidly rotating black hole solutions in theories beyond general relativity play a key role in experimental gravity, as they allow us to compute observables in extreme spacetimes that deviate from the predictions of general relativity (GR). Such solutions are often difficult to find in beyond-GR theories due to the inclusion of additional fields that couple to the metric non-linearly and non-minimally. In this paper, we consider rotating black hole solutions in one such theory, dynamical Chern-Simons gravity, where the Einstein-Hilbert action is modified by the introduction of a dynamical scalar field that couples to the metric through the Pontryagin density. We treat dynamical Chern-Simons gravity as an effective field theory and thus work in the decoupling limit, where corrections are treated as small perturbations from general relativity. We perturb about the maximally-rotating Kerr solution, the so-called extremal limit, and develop mathematical insight into the analysis techniques needed to construct sol...
Topological black holes in Horava-Lifshitz gravity
International Nuclear Information System (INIS)
We find topological (charged) black holes whose horizon has an arbitrary constant scalar curvature 2k in Horava-Lifshitz theory. Without loss of generality, one may take k=1, 0, and -1. The black hole solution is asymptotically anti-de Sitter with a nonstandard asymptotic behavior. Using the Hamiltonian approach, we define a finite mass associated with the solution. We discuss the thermodynamics of the topological black holes and find that the black hole entropy has a logarithmic term in addition to an area term. We find a duality in Hawking temperature between topological black holes in Horava-Lifshitz theory and Einstein's general relativity: the temperature behaviors of black holes with k=1, 0, and -1 in Horava-Lifshitz theory are, respectively, dual to those of topological black holes with k=-1, 0, and 1 in Einstein's general relativity. The topological black holes in Horava-Lifshitz theory are thermodynamically stable.
Rotating Black Holes in Metric-Affine Gravity
Baekler, P; Baekler, Peter; Hehl, Friedrich W.
2006-01-01
Within the framework of metric-affine gravity (MAG, metric and an independent linear connection constitute spacetime), we find, for a specific gravitational Lagrangian and by using {\\it prolongation} techniques, a stationary axially symmetric exact solution of the vacuum field equations. This black hole solution embodies a Kerr-deSitter metric and the post-Riemannian structures of torsion and nonmetricity. The solution is characterized by mass, angular momentum, and shear charge, the latter of which is a measure for violating Lorentz invariance.
Semiclassical Loop Quantum Gravity and Black Hole Thermodynamics
Directory of Open Access Journals (Sweden)
Arundhati Dasgupta
2013-02-01
Full Text Available In this article we explore the origin of black hole thermodynamics using semiclassical states in loop quantum gravity. We re-examine the case of entropy using a density matrix for a coherent state and describe correlations across the horizon due to SU(2 intertwiners. We further show that Hawking radiation is a consequence of a non-Hermitian term in the evolution operator, which is necessary for entropy production or depletion at the horizon. This non-unitary evolution is also rooted in formulations of irreversible physics.
Accretion in Strong Gravity: From Galactic to Supermassive Black Holes
Done, Chris; Gierlinski, Marek
2005-01-01
The galactic black hole binary systems give an observational template showing how the accretion flow changes as a function of increasing mass accretion rate, or L/L_Edd. These data can be synthetised with theoretical models of the accretion flow to give a coherent picture of accretion in strong gravity, in which the major hard-soft spectral transition is triggered by a change in the nature and geometry of the inner accretion flow from a hot, optically thin plasma to a cool, optically thick ac...
Notes on black holes and three dimensional gravity
Banados, Maximo
1999-01-01
These notes are the written version of two lectures delivered at the VIII Mexican School on Particles and Fields on November 1998. The level of the notes is basic assuming only some knowledge on Statistical Mechanics, General Relativity and Yang-Mills theory. After a brief introduction to the classical and semiclassical aspects of black holes, we review some relevant results on 2+1 quantum gravity. These include the Chern-Simons formulation and its affine Kac-Moody algebra, the asymptotic alg...
Remnants of black holes from rainbow gravity in terms of a new VSL theory
Zhao, Ying-Jie
2016-01-01
In this paper the gravity's rainbow function is derived in terms of a varying speed of light (VSL) theory. We calculate the modified temperature, entropy and heat capacity of the Schwarzschild, Kerr, AdS black holes, as well as spinning black rings. Our results demonstrate that in rainbow gravity the behaviors of various black holes have remarkably essential difference from those of standard black holes near the Planck scale.
Observational strong gravity and quantum black hole structure
Giddings, Steven B
2016-01-01
Quantum considerations have led many theorists to believe that classical black hole physics is modified not just deep inside black holes but at horizon scales, or even further outward. The near-horizon regime has just begun to be observationally probed for astrophysical black holes -- both by LIGO, and by the Event Horizon Telescope. This suggests exciting prospects for observational constraints on or discovery of new quantum black hole structure.
Limits on Observation in Quantum Gravity and Black Holes
Davila, George Alexander
2014-01-01
We discuss how the bounds on observation associated with the Planck units would affect an observers perception of a black hole. By simply imposing Planck scale quantities as the lower bounds for length, time, and mass of black hole formation, interesting insights into the nature of black holes can be gained.
Thermodynamics of topological black holes in $R^{2}$ gravity
Cognola, Guido; Vanzo, Luciano; Zerbini, Sergio
2015-01-01
We study topological black hole solutions of the simplest quadratic gravity action and we find that two classes are allowed. The first is asymptotically flat and mimics the Reissner-Nordstr\\"om solution, while the second is asymptotically de Sitter or anti-de Sitter. In both classes, the geometry of the horizon can be spherical, toroidal or hyperbolic. We focus in particular on the thermodynamical properties of the asymptotically anti-de Sitter solutions and we compute the entropy and the internal energy with Euclidean methods. We find that the entropy is positive-definite for all horizon geometries and this allows to formulate a consistent generalized first law of black hole thermodynamics, which keeps in account the presence of two arbitrary parameters in the solution. The two-dimensional thermodynamical state space is fully characterized by the underlying scale invariance of the action and it has the structure of a projective space. We find a kind of duality between black holes and other objects with the s...
Analytic continuation of black hole entropy in Loop Quantum Gravity
Jibril, Ben Achour; Mouchet, Amaury; Noui, Karim
2015-06-01
We define the analytic continuation of the number of black hole microstates in Loop Quantum Gravity to complex values of the Barbero-Immirzi parameter γ. This construction deeply relies on the link between black holes and Chern-Simons theory. Technically, the key point consists in writing the number of microstates as an integral in the complex plane of a holomorphic function, and to make use of complex analysis techniques to perform the analytic continuation. Then, we study the thermodynamical properties of the corresponding system (the black hole is viewed as a gas of indistinguishable punctures) in the framework of the grand canonical ensemble where the energy is defined à la Frodden-Gosh-Perez from the point of view of an observer located close to the horizon. The semi-classical limit occurs at the Unruh temperature T U associated to this local observer. When γ = ± i, the entropy reproduces at the semi-classical limit the area law with quantum corrections. Furthermore, the quantum corrections are logarithmic provided that the chemical potential is fixed to the simple value μ = 2 T U.
Hawking radiation from a spherical loop quantum gravity black hole
Gambini, Rodolfo
2013-01-01
We introduce quantum field theory on quantum space-times techniques to characterize the quantum vacua as a first step towards studying black hole evaporation in spherical symmetry in loop quantum gravity and compute the Hawking radiation. We use as quantum space time the recently introduced exact solution of the quantum Einstein equations in vacuum with spherical symmetry and consider a spherically symmetric test scalar field propagating on it. The use of loop quantum gravity techniques in the background space-time naturally regularizes the matter content, solving one of the main obstacles to back reaction calculations in more traditional treatments. The discreteness of area leads to modifications of the quantum vacua, eliminating the trans-Planckian modes close to the horizon, which in turn eliminates all singularities from physical quantities, like the expectation value of the stress energy tensor. Apart from this, the Boulware, Hartle--Hawking and Unruh vacua differ little from the treatment on a classical...
Slowly rotating black hole solutions in Horndeski gravity
Maselli, Andrea; Minamitsuji, Masato; Berti, Emanuele
2015-01-01
We study black hole solutions at first order in the Hartle-Thorne slow-rotation approximation in Horndeski gravity theories. We derive the equations of motion including also cases where the scalar depends linearly on time. In the Hartle-Thorne formalism, all first-order rotational corrections are described by a single frame-dragging function. We show that the frame dragging function is exactly the same as in general relativity for all known BH solutions in shift-symmetric Horndeski theories, with the exception of theories with a linear coupling to the Gauss-Bonnet invariant. Our results extend previous no-hair theorems for a broad class of Horndeski gravity theories.
Limits on Observation in Quantum Gravity and Black Holes
Davila, George Alexander
2014-01-01
We discuss how the bounds on observation associated with the Planck units would affect an observers perception of a black hole. By simply imposing Planck scale quantities as the lower bounds for length, time, and mass of black hole formation, interesting insights into the nature of black holes can be gained. We also see the emergence of a Planck-scale mass that plays an important role in the observation of black holes and the emergence of a new mechanism for virtual black hole formation.
Entropy of Non-Extremal Black Holes from Loop Gravity
Bianchi, Eugenio
2012-01-01
We compute the entropy of non-extremal black holes using the quantum dynamics of Loop Gravity. The horizon entropy is finite, scales linearly with the area A, and reproduces the Bekenstein-Hawking expression S = A/4 with the one-fourth coefficient for all values of the Immirzi parameter. The near-horizon geometry of a non-extremal black hole - as seen by a stationary observer - is described by a Rindler horizon. We introduce the notion of a quantum Rindler horizon in the framework of Loop Gravity. The system is described by a quantum surface and the dynamics is generated by the boost Hamiltonion of Lorentzian Spinfoams. We show that the expectation value of the boost Hamiltonian reproduces the local horizon energy of Frodden, Ghosh and Perez. We study the coupling of the geometry of the quantum horizon to a two-level system and show that it thermalizes to the local Unruh temperature. The derived values of the energy and the temperature allow one to compute the thermodynamic entropy of the quantum horizon. The...
Thermodynamics and quasinormal modes of Park black hole in Horava gravity
Energy Technology Data Exchange (ETDEWEB)
Suresh, Jishnu; Kuriakose, V.C. [Cochin University of Science and Technology, Department of Physics, Cochin, Kerala (India)
2013-10-15
We study the quasinormal modes of the massless scalar field of Park black hole in the Horava gravity using the third-order WKB approximation method and find that the black hole is stable against these perturbations. We compare and discuss the results with that of Schwarzschild-de Sitter black hole. Thermodynamic properties of Park black hole are investigated and the thermodynamic behavior of upper mass bound is also studied. (orig.)
Phantom energy accretion onto a black hole in Horava Lifshitz gravity
Abbas, G.(Department of Mathematics, COMSATS Institute of Information Technology, 57000, Sahiwal, Pakistan)
2013-01-01
In this Letter, we examine the phantom energy accretion onto a Kehagias-Sfetsos black hole in Ho$\\check{r}$ava Lifshitz gravity. To discuss the accretion process onto the black hole, the equations of phantom flow near the black hole have been derived. It is found that mass of the black hole decreases because of phantom accretion. We discuss the conditions for critical accretion. Graphically, it has been found that the critical accretion phenomena is possible for different values of parameters...
The instabilities and (anti)-evaporation of Schwarzschild-de Sitter black holes in modified gravity
L. Sebastiani; Momeni, D.; Myrzakulov, R.; Odintsov, S. D.
2013-01-01
We investigate the future evolution of Nariai black hole which is extremal limit of Schwarzschild-de Sitter one in modified gravity. The perturbations equations around Nariai black hole are derived in static and cosmological patches for general $F(R)$-gravity. The analytical and numerical study of several realistic $F(R)$-models shows the occurence of rich variety of scenarios: instabilities, celebrated Hawking evaporation and anti-evaporation of black hole. The realization of specific scenar...
Charged Black Hole Solutions in Einstein-Born-Infeld gravity with a Cosmological constant
Fernando, Sharmanthie; Krug, Don
2003-01-01
We construct black hole solutions to Einstein-Born-Infeld gravity with a cosmological constant. Since an elliptic function appears in the solutions for the metric, we construct horizons numerically. The causal structure of these solutions differ drastically from their counterparts in Einstein-Maxwell gravity with a cosmological constant. The charged de-Sitter black holes can have up to three horizons and the charged anti-de Sitter black hole can have one or two depending on the parameters cho...
Nam, Soonkeon
2016-01-01
We apply the Wald formalism to obtain masses and angular momenta of black holes in three dimensional gravity theories using first order formalism. Wald formalism suggests mass and angular momentum of black hole as an integration of some charge variation form at its boundary. The action of the three dimensional gravity theories can be represented by the form including some auxiliary fields. As well-known examples we have calculated mass and angular momentum of some black holes in topologically massive gravity and new massive gravity theories using first order formalism. We have also calculated mass and angular momentum of BTZ black hole and new type black hole in minimal massive gravity theory with the action represented by first order formalism.
Gauge-Gravity Duality and the Black Hole Interior
Marolf, Donald; Polchinski, Joseph
2013-10-01
We present a further argument that typical black holes with field theory duals have firewalls at the horizon. This argument makes no reference to entanglement between the black hole and any distant system, and so is not evaded by identifying degrees of freedom inside the black hole with those outside. We also address the Einstein-Rosen=Einstein-Podolsky-Rosen conjecture of Maldacena and Susskind, arguing that the correlations in generic highly entangled states cannot be geometrized as a smooth wormhole.
Gauge-gravity duality and the black hole interior.
Marolf, Donald; Polchinski, Joseph
2013-10-25
We present a further argument that typical black holes with field theory duals have firewalls at the horizon. This argument makes no reference to entanglement between the black hole and any distant system, and so is not evaded by identifying degrees of freedom inside the black hole with those outside. We also address the Einstein-Rosen=Einstein-Podolsky-Rosen conjecture of Maldacena and Susskind, arguing that the correlations in generic highly entangled states cannot be geometrized as a smooth wormhole. PMID:24206473
Exponential fading to white of black holes in quantum gravity
Barceló, Carlos; Carballo-Rubio, Raúl; Garay, Luis J.
2016-01-01
Quantization of the gravitational field could allow the existence of a hypothetical decay channel of black holes into white holes with an explicit time-reversal symmetry. The definition of a meaningful decay probability for this channel is studied in spherically symmetric situations. As a first nontrivial calculation, we present the functional integration over a set of geometries using a single-variable function to interpolate between black-hole and white-hole geometries in a bounded region o...
Isolated Horizons and Black Hole Entropy in Loop Quantum Gravity
Directory of Open Access Journals (Sweden)
Jacobo Diaz-Polo
2012-08-01
Full Text Available We review the black hole entropy calculation in the framework of Loop Quantum Gravity based on the quasi-local definition of a black hole encoded in the isolated horizon formalism. We show, by means of the covariant phase space framework, the appearance in the conserved symplectic structure of a boundary term corresponding to a Chern-Simons theory on the horizon and present its quantization both in the U(1 gauge fixed version and in the fully SU(2 invariant one. We then describe the boundary degrees of freedom counting techniques developed for an infinite value of the Chern-Simons level case and, less rigorously, for the case of a finite value. This allows us to perform a comparison between the U(1 and SU(2 approaches and provide a state of the art analysis of their common features and different implications for the entropy calculations. In particular, we comment on different points of view regarding the nature of the horizon degrees of freedom and the role played by the Barbero-Immirzi parameter. We conclude by presenting some of the most recent results concerning possible observational tests for theory.
Quantum Gravity Loses in the Big Bang and Black Holes
Rosenberg, David E.
2000-01-01
Applying the uncertainty principle to the stress-energy tensor, we investigate black holes, the big bang and galaxy formation. Dark energy, dark matter and other phenomena are readily explained using the principle of particle confinement. Evidence is presented that the universe results from a bounce and that black holes lose gravitational energy. PACS number 04.50Kd
Energetics and optical properties of 6-dimensional rotating black hole in pure Gauss-Bonnet gravity
International Nuclear Information System (INIS)
We study physical processes around a rotating black hole in pure Gauss-Bonnet (GB) gravity. In pure GB gravity, the gravitational potential has a slower fall-off as compared to the corresponding Einstein potential in the same dimension. It is therefore expected that the energetics of a pure GB black hole would be weaker, and our analysis bears out that the efficiency of energy extraction by the Penroseprocess is increased to 25.8 % and the particle acceleration is increased to 55.28 %; the optical shadow of the black hole is decreased. These are in principle distinguishing observable features of a pure GB black hole. (orig.)
Energetics and optical properties of 6-dimensional rotating black hole in pure Gauss-Bonnet gravity
Energy Technology Data Exchange (ETDEWEB)
Abdujabbarov, Ahmadjon; Ahmedov, Bobomurat [Institute of Nuclear Physics, Tashkent (Uzbekistan); Ulugh Beg Astronomical Institute, Tashkent (Uzbekistan); Atamurotov, Farruh [Institute of Nuclear Physics, Tashkent (Uzbekistan); Inha University in Tashkent, Tashkent (Uzbekistan); Dadhich, Naresh [Inter-University Centre for Astronomy and Astrophysics, Post Bag 4, Pune (India); Jamia Millia Islamia, Centre for Theoretical Physics, New Delhi (India); Stuchlik, Zdenek [Silesian University in Opava, Institute of Physics, Faculty of Philosophy and Science, Opava (Czech Republic)
2015-08-15
We study physical processes around a rotating black hole in pure Gauss-Bonnet (GB) gravity. In pure GB gravity, the gravitational potential has a slower fall-off as compared to the corresponding Einstein potential in the same dimension. It is therefore expected that the energetics of a pure GB black hole would be weaker, and our analysis bears out that the efficiency of energy extraction by the Penroseprocess is increased to 25.8 % and the particle acceleration is increased to 55.28 %; the optical shadow of the black hole is decreased. These are in principle distinguishing observable features of a pure GB black hole. (orig.)
Black Holes and Massive Elementary Particles in Resummed Quantum Gravity
Ward, B F L
2005-01-01
Einstein's general theory of relativity poses many problems to the quantum theory of point particle fields. Among them is the fate of a massive point particle. Since its rest mass exists entirely within its Schwarzschild radius, in the classical solutions of Einstein's theory, the respective system should be a black hole. We address this issue using exact results in a new approach to quantum gravity based upon well-tested resummation methods in point particle quantum field theory. We show that the classical conclusion is obviated by quantum loop effects. We show that our new approach already passes two theoretical checks with the published literature; for, it reproduces known results on the one-loop correction to the graviton self-energy in scaler matter coupled to Einstein's gravity as analyzed by 't Hooft and Veltman and it is consistent with the asymptotic safety results of Bonnanno and Reuter on the behavior of Newton's constant in the deep Euclidean regime. Indeed, our approach is consistent with the bla...
Hawking radiation from a spherical loop quantum gravity black hole
International Nuclear Information System (INIS)
We introduce quantum field theory on quantum space-times techniques to characterize the quantum vacua as a first step toward studying black hole evaporation in spherical symmetry in loop quantum gravity and compute the Hawking radiation. We use as quantum space-time the recently introduced exact solution of the quantum Einstein equations in vacuum with spherical symmetry and consider a spherically symmetric test scalar field propagating on it. The use of loop quantum gravity techniques in the background space-time naturally regularizes the matter content, solving one of the main obstacles to back-reaction calculations in more traditional treatments. The discreteness of area leads to modifications of the quantum vacua, eliminating the trans-Planckian modes close to the horizon, which in turn eliminates all singularities from physical quantities, like the expectation value of the stress–energy tensor. Apart from this, the Boulware, Hartle–Hawking and Unruh vacua differ little from the treatment on a classical space-time. The asymptotic modes near scri are reproduced very well. We show that the Hawking radiation can be computed, leading to an expression similar to the conventional one but with a high frequency cutoff. Since many of the conclusions concern asymptotic behavior, where the spherical mode of the field behaves in a similar way as higher multipole modes do, the results can be readily generalized to non spherically symmetric fields. (paper)
Another approach to test gravity around a black hole
Iwata, Kengo; Yoo, Chul-Moon
2016-08-01
Pulsars orbiting around the black hole (BH) at our galactic center provide us with a unique testing site for gravity. In this work, we propose an approach to probe the gravity around the BH introducing two phenomenological parameters which characterize deviation from the vacuum Einstein theory. The two phenomenological parameters are associated with the energy–momentum tensor in the framework of the Einstein theory. Therefore, our approach can be regarded as the complement to the parametrized post-Newtonian framework in which phenomenological parameters are introduced for deviation of gravitational theories from general relativity. In our formulation, we take into account the possibility of existence of a relativistic and exotic matter component. Since the pulsars can be regarded as test particles, as the first step, we consider geodesic motion in the system composed of a central BH and a perfect fluid whose distribution is static and spherically symmetric. It is found that the mass density of the fluid and a parameter of the equation of state can be determined with precision with 0.1 % if the density on the pulsar orbit is larger than {10}-9 {{g}} {{cm}}-3.
Black-hole relics in string gravity: last stages of Hawking evaporation
International Nuclear Information System (INIS)
The endpoint of black-hole evaporation is a very intriguing problem of modern physics. Based on the Einstein-dilaton-Gauss-Bonnet four-dimensional string gravity model, we show that black holes do not disappear and should become relics at the end of the evaporation process. The possibility of experimental detection of such remnant black holes is investigated. If they really exist, these objects could form a considerable part of the non-baryonic dark matter in our universe
Black Hole Relics in String Gravity: Last Stages of Hawking Evaporation
Alexeyev, S.; Barrau, A.; Boudoul, G.; Khovanskaya, O.; Sazhin, M.
2002-01-01
One of the most intriguing problem of modern physics is the question of the endpoint of black hole evaporation. Based on Einstein-dilaton-Gauss-Bonnet four dimensional string gravity model we show that black holes do not disappear and that the end of the evaporation process leaves some relic. The possibility of experimental detection of the remnant black holes is investigated. If they really exist, such objects could be a considerable part of the non baryonic dark matter in our Universe.
Absence of black holes at LHC due to gravity's rainbow
Energy Technology Data Exchange (ETDEWEB)
Ali, Ahmed Farag, E-mail: ahmed.ali@fsc.bu.edu.eg [Department of Physics, Florida State University, Tallahassee, FL 32306 (United States); Center for Fundamental Physics, Zewail City of Science and Technology, Giza 12588 (Egypt); Department of Physics, Faculty of Science, Benha University, Benha 13518 (Egypt); Faizal, Mir, E-mail: f2mir@uwaterloo.ca [Department of Physics and Astronomy, University of Waterloo, Waterloo, Ontario, N2L 3G1 (Canada); Khalil, Mohammed M., E-mail: moh.m.khalil@gmail.com [Department of Electrical Engineering, Alexandria University, Alexandria 12544 (Egypt)
2015-04-09
In this paper, we investigate the effect of Planckian deformation of quantum gravity on the production of black holes at colliders using the framework of gravity's rainbow. We demonstrate that a black hole remnant exists for Schwarzschild black holes in higher dimensions using gravity's rainbow. The mass of this remnant is found to be greater than the energy scale at which experiments were performed at the LHC. We propose this as a possible explanation for the absence of black holes at the LHC. Furthermore, we demonstrate that it is possible for black holes in six (and higher) dimensions to be produced at energy scales that will be accessible in the near future.
Absence of black holes at LHC due to gravity's rainbow
International Nuclear Information System (INIS)
In this paper, we investigate the effect of Planckian deformation of quantum gravity on the production of black holes at colliders using the framework of gravity's rainbow. We demonstrate that a black hole remnant exists for Schwarzschild black holes in higher dimensions using gravity's rainbow. The mass of this remnant is found to be greater than the energy scale at which experiments were performed at the LHC. We propose this as a possible explanation for the absence of black holes at the LHC. Furthermore, we demonstrate that it is possible for black holes in six (and higher) dimensions to be produced at energy scales that will be accessible in the near future
On Black Hole Structures in Scalar-Tensor Theories of Gravity
Bronnikov, Kirill A; Rodrigues, Denis C
2016-01-01
We review some properties of black hole structures appearing in gravity with a massless scalar field, with both minimal and nonminimal coupling. The main properties of the resulting cold black holes are described. The study of black holes in scalar-gravity systems is extended to $k$-essence theories, and some examples are explicitly worked out. In these cases, even while the existence of horizons is possible, the metric regularity requirement on the horizon implies either a cold black type structure or a singular behavior of the scalar field.
Exponential fading to white of black holes in quantum gravity
Barceló, Carlos; Garay, Luis J
2016-01-01
Quantization of the gravitational field could allow the existence of a hypothetical decay channel of black holes into white holes with an explicit time-reversal symmetry. The definition of a meaningful decay probability for this channel is studied in spherically symmetric situations. As a first nontrivial calculation, we present the functional integration over a set of geometries using a single-variable function to interpolate between black-hole and white-hole geometries in a bounded region of spacetime. This computation gives a finite result which depends only on the Schwarzschild mass and a parameter measuring the width of the interpolating region. The associated probability distribution displays an exponential decay law on the latter parameter, with the Planck time as its mean lifetime (up to subdominant terms). In physical terms this would imply that matter collapsing to a black hole from a finite radius bounces back elastically and instantaneously, with negligible time delay as measured by external obser...
Predictability in Quantum Gravity and Black Hole Evaporation
Moffat, J. W.
1993-01-01
A possible resolution of the information loss paradox for black holes is proposed in which a phase transition occurs when the temperature of an evaporating black hole equals a critical value, $T_c$, and Lorentz invariance and diffeomorphism invariance are spontaneously broken. This allows a generalization of Schr\\"odinger's equation for the quantum mechanical density matrix, such that a pure state can evolve into a mixed state, because in the symmetry broken phase the conservation of energy-m...
Phenomenology of bouncing black holes in quantum gravity: a closer look
Barrau, Aurélien; Bolliet, Boris; Vidotto, Francesca; Weimer, Celine
2016-02-01
It was recently shown that black holes could be bouncing stars as a consequence of quantum gravity. We investigate the astrophysical signals implied by this hypothesis, focusing on primordial black holes. We consider different possible bounce times and study the integrated diffuse emission.
Phenomenology of bouncing black holes in quantum gravity: a closer look
Barrau, A.; Bolliet, B.; Vidotto, F.; Weimer, C.
2016-01-01
It was recently shown that black holes could be bouncing stars as a consequence of quantum gravity. We investigate the astrophysical signals implied by this hypothesis, focusing on primordial black holes. We consider different possible bounce times and study the integrated diffuse emission.
Dirac quasinormal modes of new type black holes in new massive gravity
Energy Technology Data Exchange (ETDEWEB)
Gonzalez, P.A. [Universidad Diego Portales, Facultad de Ingenieria, Santiago (Chile); Vasquez, Yerko [Universidad de La Serena, Departamento de Fisica, Facultad de Ciencias, La Serena (Chile)
2014-07-15
We study a new type of black holes in three-dimensional new massive gravity and we calculate analytically the quasinormal modes for fermionic perturbations for some special cases. Then we show that for these cases black holes of the new type are stable under fermionic field perturbations. (orig.)
Horizons of radiating black holes in Einstein-Gauss-Bonnet gravity
International Nuclear Information System (INIS)
A Vaidya-based model of a radiating black hole is studied in a 5-dimensional Einstein gravity with Gauss-Bonnet contribution of quadratic curvature terms. The structure and locations of the apparent and event horizons of the radiating black hole are determined
Marel, R. P. van der; Schaller, D.; Kleijn, G. V.
2006-01-01
Abstract: We have created a website, called "Black Holes: Gravity's Relentless Pull", which explains the physics and astronomy of black holes for a general audience. The site emphasizes user participation and is rich in animations and astronomical imagery. It won the top prize of the 2005 Pirelli IN
Remarks on the black hole entropy and Hawking spectrum in Loop Quantum Gravity
Alekseev, A.; Polychronakos, A. P.; Smedback, M.
2004-01-01
In this note we reply to the criticism by Corichi concerning our proposal for an equidistant area spectrum in loop quantum gravity. We further comment on the emission properties of black holes and on the statistics of links.
Emergent gravity and entanglement entropy of black holes
International Nuclear Information System (INIS)
When the gravitational interaction emerges from some underlying quantum field theory, black hole entropy should be completely explained in terms of the entanglement entropy (EE) of the quantum fields We show that this is the case of the anti-de Sitter black hole in two spacetime dimensions. In this case two-dimensional (2D) Newton constant is wholly induced by a conformal field theory and an exact formula for the EE can be derived. In the large black hole mass limit the leading term of this formula reproduces exactly the Bekenstein-Hawking entropy of the hole, whereas the subleading term behaves logarithmically. This subleading term has the universal form of the entanglement entropy of physical systems described by effective conformal fields theories (e.g. one-dimensional statistical models at the critical point).
Charged Fermions Tunnel from the Kerr-Newman Black Hole Influenced by Quantum Gravity Effects
Ren, Ruyi; Chen, Deyou; Pu, Jin
2016-03-01
Taking into account quantum gravity effects, we investigate the tunnelling radiation of charged fermions in the Kerr-Newman black hole. The result shows that the corrected Hawking temperature is determined not only by the parameters of the black hole, but also by the energy, angular momentum and mass of the emitted fermion. Meanwhile, an interesting found is that the temperature is affected by the angle 𝜃. The quantum gravity correction slows down the evaporation.
Hawking radiation of asymptotically non-flat dyonic black holes in Einstein-Maxwell-dilaton gravity
Slavov, Peter I.; Yazadjiev, Stoytcho S.
2012-01-01
In the present paper we investigate the Hawking radiation of asymptotically non-flat dyonic black holes in 4D Einstein-Maxwell-dilaton gravity in semi-classical approximation. We show that the problem allows an exact analytical treatment and we compute exactly the semi-classical radiation spectrum of both non-extremal and extremal black holes under consideration. In the high frequency regime we find that the Hawking temperature does not agree with the surface gravity when the magnetic charge ...
Hawking Tunneling Radiation of Black Holes in Deformed H(o)rava-Lifshitz Gravity*
Institute of Scientific and Technical Information of China (English)
ZENG Xiao-Xiong; LI Ling
2011-01-01
Tunneling of scalar particles and Dirac particles from a black hole in the deformed H(o)rava-Lifshitz gravity is discussed in this paper. We consider the case that the dynamical coupling constant λ = 1, when it reduces to Einstein's General Relativity at large scales and the black hole behaves like the Reissner-Nordstr(o)m black hole. The result shows that though the black hole entropy bears logarithmic correction, the tunneling probability is still related to its differences for the scalar particles and Dirac particles.
Critical behavior of charged black holes in Gauss-Bonnet gravity`s rainbow
Hendi, Seyed Hossein; Panah, Behzad Eslam; Faizal, Mir; Momennia, Mehrab
2016-01-01
Following an earlier study regarding Gauss-Bonnet-Maxwell black holes in the presence of gravity's rainbow [S. H. Hendi and M. Faizal, Phys. Rev. D 92, 044027 (2015)], in this paper, we will consider all constants as energy dependent ones. The geometrical and thermodynamical properties of this generalization are studied and the validation of the first law of thermodynamics is examined. Next, through the use of proportionality between cosmological constant and thermodynamical pressure, van der Waals-like behavior of these black holes in extended phase space is investigated. An interesting critical behavior for sets of rainbow functions in this case is reported. Also, the critical behavior of uncharged and charged solutions is analyzed and it is shown that the generalization to a charged case puts an energy dependent restriction on values of different parameters.
Energy extraction and particle acceleration around a rotating black hole in Horava-Lifshitz gravity
International Nuclear Information System (INIS)
The Penrose process on rotational energy extraction of the black hole in the original nonprojectable Horava-Lifshitz gravity is studied. The strong dependence of the extracted energy from the special range of parameters of the Horava-Lifshitz gravity, such as parameter ΛW and specific angular momentum a, has been found. Particle acceleration near the rotating black hole in Horava-Lifshitz gravity has been studied. It is shown that the fundamental parameter of the Horava-Lifshitz gravity can impose a limitation on the energy of the accelerating particles preventing them from the infinite value.
A Note on Schwarzschild de Sitter Black Holes in Mimetic $F(R)$ Gravity
Oikonomou, V K
2016-01-01
In this brief note we investigate the conditions under which a Schwarzschild de Sitter black hole spacetime is a solution of the mimetic $F(R)$ gravity with Lagrange multiplier and potential. As we demonstrate, the resulting mimetic $F(R)$ gravity is a slight modification of the ordinary $F(R)$ gravity case, however the resulting perturbation equations are not in all cases identical to the ordinary $F(R)$ gravity case. In the latter case, the perturbation equations are identical to the ones corresponding to the Reissner-Nordstr\\"{o}m anti-de Sitter black hole.
A note on Schwarzschild-de Sitter black holes in mimetic F(R) gravity
Oikonomou, V. K.
2016-05-01
In this paper, we investigate the conditions under which a Schwarzschild-de Sitter black hole spacetime is a solution of the mimetic F(R) gravity with Lagrange multiplier and potential. As we demonstrate, the resulting mimetic F(R) gravity is a slight modification of the ordinary F(R) gravity case, however the resulting perturbation equations are not in all cases identical to the ordinary F(R) gravity case. In the latter case, the perturbation equations are identical to the ones corresponding to the Reissner-Nordström anti-de Sitter black hole.
Fast Spinning Pulsars as Probes of Massive Black Holes' Gravity
Singh, Dinesh; Sarty, Gordon E
2014-01-01
Dwarf galaxies and globular clusters may contain intermediate mass black holes ($10^{3}$ to $10^{5}$ solar masses) in their cores. Estimates of ~$10^{3}$ neutron stars in the central parsec of the Galaxy and similar numbers in small elliptical galaxies and globular clusters along with an estimated high probability of ms-pulsar formation in those environments has led many workers to propose the use of ms-pulsar timing to measure the mass and spin of intermediate mass black holes. Models of pulsar motion around a rotating black hole generally assume geodesic motion of a "test" particle in the Kerr metric. These approaches account for well-known effects like de Sitter precession and the Lense-Thirring effect but they do not account for the non-linear effect of the pulsar's stress-energy tensor on the space-time metric. Here we model the motion of a pulsar near a black hole with the Mathisson-Papapetrou-Dixon (MPD) equations. Numerical integration of the MPD equations for black holes of mass 2 X $10^{6}$, $10^{5}...
Black holes in the gravity/gauge theory correspondence
Gregory, J P
2002-01-01
Schwarzschild-AdS x Sphere, which are relevant to my study of the AdS/CFT correspondence. The AdS/CFT correspondence provides a microscopic description of black hole thermodynamics. In this thesis, I study the relation between the classical physics of black holes and this microscopic description. I first consider the gauge theory's holographic encoding of non-trivial global causal structure, by studying various probes of the black hole. I study the charged black hole, so that the thermal scale is separated from the horizon scale, to demonstrate which relates to the field theory scale size. I find that, when probing the horizon, both Wilson loops and the duals of static supergravity probes have a scale size determined by the horizon, but the field theory scale size is divergent for a time-dependent probe. I also use the bulk black hole geometry to study the physics of the boundary theory. If we consider a dynamical boundary, a braneworld cosmology is induced from the bulk. However, the presence of matter on th...
Warped AdS_3 Black Holes in Higher Derivative Gravity Theories
Detournay, Stéphane; Ng, Gim Seng; Zwikel, Céline
2016-01-01
We consider warped AdS_3 black holes in generic higher derivatives gravity theories in 2+1 dimensions. The asymptotic symmetry group of the phase space containing these black holes is the semi-direct product of a centrally extended Virasoro algebra and an affine u(1) Kac-Moody algebra. Previous works have shown that in some specific theories, the entropy of these black holes agrees with a Cardy-like entropy formula derived for warped conformal field theories. In this paper, we show that this entropy matching continues to hold for the most general higher derivative theories of gravity. We also discuss the existence of phase transitions.
Warped AdS3 black holes in higher derivative gravity theories
Detournay, Stéphane; Douxchamps, Laure-Anne; Ng, Gim Seng; Zwikel, Céline
2016-06-01
We consider warped AdS3 black holes in generic higher derivatives gravity theories in 2+1 dimensions. The asymptotic symmetry group of the phase space containing these black holes is the semi-direct product of a centrally extended Virasoro algebra and an affine u(1) Kac-Moody algebra. Previous works have shown that in some specific theories, the entropy of these black holes agrees with a Cardy-like entropy formula derived for warped conformal field theories. In this paper, we show that this entropy matching continues to hold for the most general higher derivative theories of gravity. We also discuss the existence of phase transitions.
Anomalies and Hawking fluxes from the black holes of topologically massive gravity
Porfyriadis, Achilleas P
2009-01-01
The anomaly cancelation method proposed by Wilczek et al. is applied to the black holes of topologically massive gravity (TMG) and topologically massive gravito-electrodynamics (TMGE). Thus the Hawking temperature and fluxes of the ACL and ACGL black holes are found. The Hawking temperatures obtained agree with the surface gravity formula. Both black holes are rotating and this gives rise to appropriate terms in the effective U(1) gauge field of the reduced (1+1)-dimensional theory. It is found that the terms in this U(1) gauge field correspond exactly to the correct angular velocities on the horizon of both black holes as well as the correct electrostatic potential of the ACGL black hole. So the results for the Hawking fluxes derived here from the anomaly cancelation method, are in complete agreement with the ones obtained from integrating the Planck distribution.
MicroBlack Holes Thermodynamics in the Presence of Quantum Gravity Effects
Directory of Open Access Journals (Sweden)
H. Soltani
2014-01-01
Full Text Available Black hole thermodynamics is corrected in the presence of quantum gravity effects. Some phenomenological aspects of quantum gravity proposal can be addressed through generalized uncertainty principle (GUP which provides a perturbation framework to perform required modifications of the black hole quantities. In this paper, we consider the effects of both a minimal measurable length and a maximal momentum on the thermodynamics of TeV-scale black holes. We then extend our study to the case that there are all natural cutoffs as minimal length, minimal momentum, and maximal momentum simultaneously. We also generalize our study to the model universes with large extra dimensions (LED. In this framework existence of black holes remnants as a possible candidate for dark matter is discussed. We study probability of black hole production in the Large Hadronic Collider (LHC and we show this rate decreasing for sufficiently large values of the GUP parameter.
MicroBlack Holes Thermodynamics in the Presence of Quantum Gravity Effects
International Nuclear Information System (INIS)
Black hole thermodynamics is corrected in the presence of quantum gravity effects. Some phenomenological aspects of quantum gravity proposal can be addressed through generalized uncertainty principle (GUP) which provides a perturbation framework to perform required modifications of the black hole quantities. In this paper, we consider the effects of both a minimal measurable length and a maximal momentum on the thermodynamics of TeV-scale black holes. We then extend our study to the case that there are all natural cutoffs as minimal length, minimal momentum, and maximal momentum simultaneously. We also generalize our study to the model universes with large extra dimensions (LED). In this framework existence of black holes remnants as a possible candidate for dark matter is discussed. We study probability of black hole production in the Large Hadronic Collider (LHC) and we show this rate decreasing for sufficiently large values of the GUP parameter
The fate of Schwarzschild-de Sitter black holes in f(R) gravity
Addazi, Andrea; Capozziello, Salvatore
2016-03-01
The semiclassical effects of anti-evaporating black holes can be discussed in the framework of f(R) gravity. In particular, the Bousso-Hawking-Nojiri-Odinstov anti-evaporation instability of degenerate Schwarzschild-de Sitter black holes (the so-called Nariai spacetime) leads to a dynamical increasing of black hole horizon in f(R) gravity. This phenomenon causes the following transition: emitting marginally trapped surfaces (TS) become space-like surfaces before the effective Bekenstein-Hawking emission time. As a consequence, Bousso-Hawking thermal radiation cannot be emitted in an anti-evaporating Nariai black hole. Possible implications in cosmology and black hole physics are also discussed.
Thermodynamic stability of modified Schwarzschild-AdS black hole in rainbow gravity
Kim, Yong-Wan; Park, Young-Jai
2016-01-01
In this paper, we have extended the previous study of the thermodynamics and phase transition of the Schwarzschild black hole in the rainbow gravity to the Schwarzschild-AdS black hole where metric depends on the energy of a probe. Making use of the Heisenberg uncertainty principle and the modified dispersion relation, we have obtained the modified local Hawking temperature and thermodynamic quantities in an isothermal cavity. Moreover, we carry out the analysis of constant temperature slices of a black hole. As a result, we have shown that there also exists another Hawking-Page-like phase transition in which case a locally stable small black hole tunnels into a globally stable large black hole as well as the standard Hawking-Page phase transition from a hot flat space to a black hole.
Topological black holes in pure Gauss-Bonnet gravity and phase transitions
Aránguiz, Ligeia; Kuang, Xiao-Mei; Miskovic, Olivera
2016-03-01
We study charged, static, topological black holes in pure Gauss-Bonnet gravity in asymptotically AdS space. As in general relativity, the theory possesses a unique nondegenerate AdS vacuum. It also admits charged black hole solutions which asymptotically behave as the Reissner-Nordström AdS black hole. We discuss black hole thermodynamics of these black holes. Then we study phase transitions in a dual quantum field theory in four dimensions, with the Stückelberg scalar field as an order parameter. We find in the probe limit that the black hole can develop hair below some critical temperature, which suggests a phase transition. Depending on the scalar coupling constants, the phase transition can be first or second order. Analysis of the free energy reveals that, comparing the two solutions, the hairy state is energetically favorable, thus a phase transition will occur in a dual field theory.
Holography, Gauge-Gravity Connection and Black Hole Entropy
Majumdar, Parthasarathi
2009-01-01
The issues of holography and possible links with gauge theories in spacetime physics is discussed, in an approach quite distinct from the more restricted AdS-CFT correspondence. A particular notion of holography in the context of black hole thermodynamics is derived (rather than conjectured) from rather elementary considerations, which also leads to a criterion of thermal stability of radiant black holes, without resorting to specific classical metrics. For black holes that obey this criterion, the canonical entropy is expressed in terms of the microcanonical entropy of an Isolated Horizon which is essentially a local generalization of the very global event horizon and is a null inner boundary of spacetime, with marginal outer trapping. It is argued why degrees of freedom on this horizon must be described by a topological gauge theory. Quantizing this boundary theory leads to the microcanonical entropy of the horizon expressed in terms of an infinite series asymptotic in the cross-sectional area, with the lea...
Quantum Field Theory And Gravity Black Holes And Dark Matter
Heo, J
1998-01-01
This thesis examines the various field theory related issues motivated by the gravitational phenomena. Black Holes with quantum degrees of freedom, non-abelian generalization of vortex solutions, and WIMP detection rates for the ongoing experimental search for dark matter are explored. We derive a close relation between the Minkowski signature approach and the Euclidean formalism in the construction of quantum degrees of freedom on a Black hole solution. We demonstrate the benefit of a physically transparent energy momentum consideration and extend the previous analysis on Hawking temperature shifts. Specifically we clear up the issue of thick string limit behavior that obscures the direct intuition and draw an analogy that brings the instanton solutions in flat two dimensional planes to Euclidean vortex solutions in the black hole background...
Nature of Microscopic Black Holes and Gravity in Theories with Particle Species
Dvali, Gia
2010-01-01
Relying solely on unitarity and the consistency with large-distance black hole physics, we derive model-independent properties of the microscopic black holes and of short-distance gravity in theories with N particle species. In this class of theories black holes can be as light as MPlanck /√ N and be produced in particle collisions above this energy. We show, that the micro black holes must come in the same variety as the species do, although their label is not associated with any conserved charge measurable at large distances. In contrast with big Schwarzschildian ones, the evaporation of the smallest black holes is maximally undemocratic and is biased in favor of particular species. With an increasing mass the democracy characteristic to the usual macro black holes is gradually regained. The lowest possible mass above which black holes become Einsteinian is √ N MPlanck . This fact uncovers the new fundamental scale (below the quantum gravity scale) above which gravity changes classically, and the properties of black holes and gravity are such as if some extra dimensions open up, although no such input exists in the theory. Our observations indicate that geometry of space may be an emergent concept following from large number of species and the consistency with macro black hole physics. We apply our findings to the phenomenological properties of the micro black holes that can be observed at LHC for large N. Extrapolating our findings to small N, one may ask whether the existence of quark and lepton flavors is already an evidence for emergent extra dimensions at short distances.
Van der Marel, R P; Kleijn, G V; Marel, Roeland P. van der; Schaller, David; Kleijn, Gijs Verdoes
2006-01-01
We have created a website, called "Black Holes: Gravity's Relentless Pull", which explains the physics and astronomy of black holes for a general audience. The site emphasizes user participation and is rich in animations and astronomical imagery. It won the top prize of the 2005 Pirelli INTERNETional Awards competition for the best communication of science and technology using the internet. This article provides a brief overview of the site. The site starts with an opening animation that introduces the basic concept of a black hole. The user is then invited to embark on a journey from a backyard view of the night sky to a personal encounter with a singularity. This journey proceeds through three modules, which allow the user to: find black holes in the night sky; travel to a black hole in an animated starship; and explore a black hole from up close. There are also five "experiments" that allow the user to: create a black hole; orbit around a black hole; weigh a black hole; drop a clock into a black hole; or f...
Symmetry reduction in twisted noncommutative gravity with applications to cosmology and black holes
International Nuclear Information System (INIS)
Noncommutative Riemannian geometry is an attractive mathematical tool for constructing modifications of Einsteins theory of general relativity. One particular approach is to deform the symmetries of gravity, i.e. the diffeomorphisms, into a noncocommutative Hopf algebra and establish a gravity theory based on these deformed symmetries. Having such a deformed theory, it is of great importance to understand symmetry reduction in this framework in order to apply it to physical problems, like e.g. cosmology or black holes. In this presentation we will focus on twisted noncommutative gravity theories constructed by abelian twists and discuss symmetry reduction in these models. We apply the formalism to FRW cosmology and black holes and classify all possible models for this particular class of twists. As one result we obtain isotropic twists for FRW universes and twists of black holes, which are invariant under all classical black hole symmetries
Symmetry reduction in twisted noncommutative gravity with applications to cosmology and black holes
Energy Technology Data Exchange (ETDEWEB)
Schenkel, Alexander; Ohl, Thorsten [Lehrstuhl fuer Theoretische Physik II, Universitaet Wuerzburg (Germany)
2009-07-01
Noncommutative Riemannian geometry is an attractive mathematical tool for constructing modifications of Einsteins theory of general relativity. One particular approach is to deform the symmetries of gravity, i.e. the diffeomorphisms, into a noncocommutative Hopf algebra and establish a gravity theory based on these deformed symmetries. Having such a deformed theory, it is of great importance to understand symmetry reduction in this framework in order to apply it to physical problems, like e.g. cosmology or black holes. In this presentation we will focus on twisted noncommutative gravity theories constructed by abelian twists and discuss symmetry reduction in these models. We apply the formalism to FRW cosmology and black holes and classify all possible models for this particular class of twists. As one result we obtain isotropic twists for FRW universes and twists of black holes, which are invariant under all classical black hole symmetries.
Hawking, Fiducial, and Free-fall Temperatures of Black Hole on Gravity's Rainbow
Gim, Yongwan
2015-01-01
On gravity's rainbow, the energy of particles affects the geometry of black hole in such a way that the Hawking temperature of black hole is appropriately modified. It means that the fiducial and free-fall temperatures on the background of black hole should also be modified according to deformation of the geometry. We find that the fiducial temperature takes the blue-shifted modified Hawking temperature so that it is divergent at the horizon, while the free-fall temperature defined by employing the thermodynamic Stefan-Boltzmann relation on gravity's rainbow is finite everywhere without the blue-shift effect; in particular, it is vanishing at the horizon. In this respect, the behaviors of the two-different temperatures at the horizon show that black hole complementarity is still required on gravity's rainbow.
Increase of black hole entropy in higher curvature gravity
Jacobson, T; Myers, R C; Jacobson, Ted; Kang, Gungwon; Myers, Robert C
1995-01-01
We examine the Zeroth Law and the Second Law of black hole thermodynamics within the context of effective gravitational actions including higher curvature interactions. We show that entropy can never decrease for quasi-stationary processes in which a black hole accretes positive energy matter, independent of the details of the gravitational action. Within a class of higher curvature theories where the Lagrangian consists of a polynomial in the Ricci scalar, we use a conformally equivalent theory to establish that stationary black hole solutions with a Killing horizon satisfy the Zeroth Law, and that the Second Law holds in general for any dynamical process. We also introduce a new method for establishing the Second Law based on a generalization of the area theorem, which may prove useful for a wider class of Lagrangians. Finally, we show how one can infer the form of the black hole entropy, at least for the Ricci polynomial theories, by integrating the changes of mass and angular momentum in a quasistationary...
Black hole from dark energy in 2+1 gravity
International Nuclear Information System (INIS)
In this paper we solve the Einsteins' field equations for a spherically symmetric anisotropic fluid, with kinematic self-similarity of the first kind, in spacetimes (2+1)-dimensional. Considering a null radial pressure we show that the fluid collapses forming a black hole in the end, even if it is constituted by phantom energy. (author)
Nature of Microscopic Black Holes and Gravity in Theories with Particle Species
Dvali, Gia
2010-01-01
Relying solely on unitarity and the consistency with large-distance black hole physics, we derive model-independent properties of the microscopic black holes and of short-distance gravity in theories with N particle species. In this class of theories black holes can be as light as M_{Planck}/\\sqrt{N} and be produced in particle collisions above this energy. We show, that the micro black holes must come in the same variety as the species do, although their label is not associated with any conserved charge measurable at large distances. In contrast with big Schwarzschildian ones, the evaporation of the smallest black holes is maximally undemocratic and is biased in favor of particular species. With an increasing mass the democracy characteristic to the usual macro black holes is gradually regained. The lowest possible mass above which black holes become Einsteinian is \\sqrt{N} M_{Planck}. This fact uncovers the new fundamental scale (below the quantum gravity scale) above which gravity changes classically, and ...
Quantum Gravity Effects on the Tunneling Radiation of the Einstein-Maxwell-Dilaton-Axion Black Hole
Cheng, Tianhu; Ren, Ruyi; Chen, Deyou; Liu, Zixiang; Li, Guopin
2016-07-01
Taking into account effects of quantum gravity, we investigate the evaporation of an Einstein-Maxwell-Dilaton-Axion black hole. The corrected Hawking temperature is gotten respectively by the scalar particle's and the fermion's tunneling across the horizon. This temperature is lower than the original one derived by Hawking, which means quantum gravity effects slow down the rise of the temperature.
Anti-evaporation of Schwarzschild–de Sitter black holes in F(R) gravity
International Nuclear Information System (INIS)
We studied the anti-evaporation of a degenerate Schwarzschild–de Sitter black hole (so-called Nariai space-time) in modified F(R) gravity. We analyze the perturbations in the Nariai black hole and find that anti-evaporation may occur in F(R) gravity even at a classical level. For several power-law F(R) gravities which may describe the inflation and/or dark energy eras, we presented the theory parameter bounds for the occurrence of anti-evaporation and conjectured creation of an infinite number of horizons. (paper)
Gravitational Lensing by Self-Dual Black Holes in Loop Quantum Gravity
Sahu, Satyabrata; Narasimha, D
2015-01-01
We study gravitational lensing by a recently proposed black hole solution in Loop Quantum Gravity. We highlight the fact that the quantum gravity corrections to the Schwarzschild metric in this model evade the `mass suppression' effects (that the usual quantum gravity corrections are susceptible to) by virtue of one of the parameters in the model being dimensionless, which is unlike any other quantum gravity motivated parameter. Gravitational lensing in the strong and weak deflection regimes is studied and a sample consistency relation is presented which could serve as a test of this model. We discuss that though the consistency relation for this model is qualitatively similar to what would have been in Brans-Dicke, in general it can be a good discriminator between many alternative theories. Although the observational prospects do not seem to be very optimistic even for a galactic supermassive black hole case, time delay between relativistic images for billion solar mass black holes in other galaxies might be...
Does a black hole rotate in Chern-Simons modified gravity?
Konno, Kohkichi; Tanda, Satoshi
2007-01-01
Rotating black hole solutions in the (3+1)-dimensional Chern-Simons modified gravity theory are discussed by taking account of perturbation around the Schwarzschild solution. The zenith-angle dependence of a metric function related to the frame-dragging effect is determined from a constraint equation independently of a choice of the embedding coordinate. We find that at least within the framework of the first-order perturbation method, the black hole cannot rotate for finite black hole mass if the embedding coordinate is taken to be a timelike vector. However, the rotation can be permitted in the limit of $M/r \\to 0$ (where $M$ is the black hole mass and $r$ is the radius). For a spacelike vector, the rotation can also be permitted for any value of the black hole mass.
Waveforms in massive gravity and neutralization of giant black hole ringings
Décanini, Yves; Hadj, Mohamed Ould El
2016-01-01
A distorted black hole radiates gravitational waves in order to settle down in a smoother geometry. During that relaxation phase, a characteristic damped ringing is generated. It can be theoretically constructed from both the black hole quasinormal frequencies (which govern its oscillating behavior and its decay) and the associated excitation factors (which determine intrinsically its amplitude) by carefully taking into account the source of the distortion. In the framework of massive gravity, the excitation factors of the Schwarzschild black hole have an unexpected strong resonant behavior which, theoretically, could lead to giant and slowly decaying ringings. If massive gravity is relevant to physics, one can hope to observe these extraordinary ringings by using the next generations of gravitational wave detectors. In fact, we shall show here that such ringings are neutralized in waveforms due to (i) the excitation of the quasibound states of the black hole and (ii) the evanescent nature of the particular p...
Conditions on holographic entangling surfaces for black hole geometries in higher derivative gravity
Erdmenger, Johanna; Sleight, Charlotte
2014-01-01
We study the extremal surfaces of functionals recently proposed for the holographic calculation of entanglement entropy in general higher curvature theories, using New Massive gravity and Gauss-Bonnet gravity as concrete examples. We show that the entropy functionals admit closed extremal surfaces, which for black hole backgrounds can encircle the event horizon of the black hole. In the examples considered, such closed surfaces correspond to a lower value of the entropy functional than that given by the black hole bifurcation surface, implying a seeming mismatch between the entropy of the black hole and the dual CFT. We show that this problem can be resolved by either imposing a causality constraint on the extremal surfaces, or by deriving conditions from an alternative conical boundary condition method as proposed by Lewkowycz and Maldacena.
Rotating black holes in a draining bathtub: superradiant scattering of gravity waves
Richartz, Mauricio; Liberati, Stefano; Weinfurtner, Silke
2014-01-01
In a draining rotating fluid flow background, surface perturbations behave as a scalar field on a rotating effective black hole spacetime. We propose a new model for the background flow which takes into account the varying depth of the water. Numerical integration of the associated Klein-Gordon equation using accessible experimental parameters shows that gravity waves in an appropriate frequency range are amplified through the mechanism of superradiance. Our numerical results suggest that the observation of this phenomenon in a common fluid mechanical system is within experimental reach. Unlike the case of wave scattering around Kerr black holes, which depends only on one dimensionless background parameter (the ratio $a/M$ between the specific angular momentum and the mass of the black hole), our system depends on two dimensionless background parameters, namely the normalized angular velocity and surface gravity at the effective black hole horizon.
Black Hole Fluctuations and Backreaction in Stochastic Gravity
Sinha, S; Hu, B L; Sinha, Sukanya; Raval, Alpan
2003-01-01
We present a framework for analyzing black hole backreaction from the point of view of quantum open systems using influence functional formalism. We focus on the model of a black hole described by a radially perturbed quasi-static metric and Hawking radiation by a conformally coupled massless quantum scalar field. It is shown that the closed-time-path (CTP) effective action yields a non-local dissipation term as well as a stochastic noise term in the equation of motion, the Einstein-Langevin equation. Once the thermal Green's function in a Schwarzschild background becomes available to the required accuracy the strategy described here can be applied to obtain concrete results on backreaction. We also present an alternative derivation of the CTP effective action in terms of the Bogolyubov coefficients, thus making a connection with the interpretation of the noise term as measuring the difference in particle production in alternative histories.
Probability for Primordial Black Holes Pair in 1/R Gravity
Paul, D; Paul, Dilip; Paul, Bikash Chandra
2005-01-01
The probability for quantum creation of an inflationary universe with a pair of black holes in 1/R - gravitational theory has been studied. Considering a gravitational action which includes a cosmological constant ($\\Lambda$) in addition to $ \\delta R^{- 1} $ term, the probability has been evaluated in a semiclassical approximation with Hartle-Hawking boundary condition. We obtain instanton solutions determined by the parameters $\\delta$ and $\\Lambda$ satisfying the constraint $ \\delta \\leq \\frac{4 \\Lambda^{2}}{3}$. However, we note that two different classes of instanton solutions exists in the region $0 < \\delta < \\frac{4 \\Lambda^{2}}{3}$. The probabilities of creation of such configurations are evaluated. It is found that the probability of creation of a universe with a pair of black holes is strongly suppressed with a positive cosmological constant except in one case when $0 < \\delta < \\Lambda^{2}$. It is also found that gravitational instanton solution is permitted even with $\\Lambda = 0$ but...
Cosmological and black hole spacetimes in twisted noncommutative gravity
International Nuclear Information System (INIS)
We derive noncommutative Einstein equations for abelian twists and their solutions in consistently symmetry reduced sectors, corresponding to twisted FRW cosmology and Schwarzschild black holes. While some of these solutions must be rejected as models for physical spacetimes because they contradict observations, we find also solutions that can be made compatible with low energy phenomenology, while exhibiting strong noncommutativity at very short distances and early times.
van der Marel, R. P.; Schaller, D; Kleijn, G. V.
2006-01-01
Abstract: We have created a website, called "Black Holes: Gravity's Relentless Pull", which explains the physics and astronomy of black holes for a general audience. The site emphasizes user participation and is rich in animations and astronomical imagery. It won the top prize of the 2005 Pirelli INTERNETional Awards competition for the best communication of science and technology using the internet. This article provides a brief overview of the site. The site starts with an opening animation...
Noncommutative Black Holes, The Final Appeal To Quantum Gravity: A Review
Nicolini, Piero
2008-01-01
We present the state of the art regarding the relation between the physics of Quantum Black Holes and Noncommutative Geometry. We start with a review of models proposed in the literature for describing deformations of General Relativity in the presence of noncommutativity, seen as an effective theory of Quantum Gravity. We study the resulting metrics, proposed to replace or at least to improve the conventional black hole solutions of Einstein's equation. In particular, we analyze noncommutati...
Finsler Black Holes Induced by Noncommutative Anholonomic Distributions in Einstein Gravity
Sergiu I. Vacaru
2009-01-01
We study Finsler black holes induced from Einstein gravity as possible effects of quantum spacetime noncommutativity. Such Finsler models are defined by nonholonomic frames not on tangent bundles but on (pseudo) Riemannian manifolds being compatible with standard theories of physics. We focus on noncommutative deformations of Schwarzschild metrics into locally anisotropic stationary ones with spherical/rotoid symmetry. There are derived the conditions when black hole configurations can be ext...
Thermodynamic properties of the noncommutative black hole in (z = 3)-Horava-Lifshitz gravity
NACH, Mourad; BILAL, Khadija; SEDRA, My Brahim; BOUKILI, Abderrahman EL
2013-01-01
In this work, we investigate the effects of noncommutative spaces on the Horava-Lifshitz black hole. We construct the black hole solutions in the noncommutative space of (z = 3)-Horava-Lifshitz gravity. We calculate the horizon and the thermodynamic properties such as the Hawking temperature, the ADM-Mass, and entropy, which reduce to their commutative limits when the noncommutativity parameter tends to zero.
New Electrically Charged Black Hole in Higher Derivative Gravity as Particle Colliders
Lin, Kai; Pavan, A. B.; Flores-Hidalgo, G.; Abdalla, E.
2016-01-01
In this paper, new electrically charged asymptotically flat black hole solutions are numerically derived in the context of higher derivative gravity. These solutions can be interpreted as generalizations of two different classes of non-charged asymptotically flat spacetimes: Schwarzschild and non-Schwarzschild solutions. The possibility to use these black holes as particle colliders have been analysed. Our results show that the center-of-mass energy of two accelerated charged particles could ...
Strong deflection lensing by charged black holes in scalar-tensor gravity
Energy Technology Data Exchange (ETDEWEB)
Eiroa, Ernesto F.; Sendra, Carlos M. [Instituto de Astronomia y Fisica del Espacio (IAFE, CONICET-UBA), Buenos Aires (Argentina); Universidad de Buenos Aires, Departamento de Fisica, Facultad de Ciencias Exactas y Naturales, Buenos Aires (Argentina)
2014-11-15
We examine a class of charged black holes in scalar-tensor gravity as gravitational lenses. We find the deflection angle in the strong deflection limit, from which we obtain the positions and the magnifications of the relativistic images. We compare our results with those corresponding to the Reissner-Norstroem spacetime and we analyze the observational aspects in the case of the Galactic supermassive black hole. (orig.)
A new metric for rotating black holes in Gauss-Bonnet gravity
Institute of Scientific and Technical Information of China (English)
Yue Rui-Hong; Zou De-Cheng; Yu Tian-Yi; Yang Zhan-Ying
2011-01-01
This paper presents a new metric and studies slowly rotating Gauss-Bonnet black holes with a nonvanishing angular momentum in five dimensional anti-de Sitter spaces. Taking the angular momentum parameter a up to second order, the slowly rotating black hole solutions are obtained by working directly in the action. In addition, it also finds that this method is applicable in higher order Lovelock gravity.
A new metric for rotating black holes in Gauss—Bonnet gravity
International Nuclear Information System (INIS)
This paper presents a new metric and studies slowly rotating Gauss-Bonnet black holes with a nonvanishing angular momentum in five dimensional anti-de Sitter spaces. Taking the angular momentum parameter a up to second order, the slowly rotating black hole solutions are obtained by working directly in the action. In addition, it also finds that this method is applicable in higher order Lovelock gravity. (general)
A Soliton and a Black Hole are in Gauss-Bonnet gravity. Who wins?
Wong, Anson W. C.; Mann, Robert B.
2012-01-01
We study here the phase-transitional evolution between the Eguchi-Hanson soliton, the orbifolded Schwarzschild Anti de-Sitter black hole, and orbifolded thermal Anti de-Sitter space in Gauss-Bonnet gravity for a small Gauss-Bonnet coefficient $\\alpha$. Novel phase structure is uncovered for both negative and positive $\\alpha$ with spacetime configurations that are stable in Gauss-Bonnet gravity without being so in Einsteinian gravity. The evolutionary tracks taken towards such stable configur...
New Electrically Charged Black Hole in Higher Derivative Gravity as Particle Colliders
Lin, Kai; Flores-Hidalgo, G; Abdalla, E
2016-01-01
In this paper, new electrically charged asymptotically flat black hole solutions are numerically derived in the context of higher derivative gravity. These solutions can be interpreted as generalizations of two different classes of non-charged asymptotically flat spacetimes: Schwarzschild and non-Schwarzschild solutions. The possibility to use these black holes as particle colliders have been analysed. Our results show that the center-of-mass energy of two accelerated charged particles could be arbitrarily high near the event horizon of the extreme charged black hole.
A class of black holes in dRGT massive gravity and their thermodynamical properties
Energy Technology Data Exchange (ETDEWEB)
Ghosh, Suchant G. [Jamia Millia Islamia, Centre of Theoretical Physics, New Delhi (India); University of Kwazulu-Natal, Astrophysics and Cosmology Research Unit, School of Mathematical Sciences, Private Bag 54001, Durban (South Africa); Tannukij, Lunchakorn [Mahidol University, Department of Physics, Faculty of Science, Bangkok (Thailand); Wongjun, Pitayuth [Naresuan University, The Institute for Fundamental Study, Phitsanulok (Thailand); Ministry of Education, Thailand Center of Excellence in Physics, Bangkok (Thailand)
2016-03-15
We present an exact spherical black hole solution in de Rham, Gabadadze, and Tolley (dRGT) massive gravity for a generic choice of the parameters in the theory, and also discuss the thermodynamical and phase structure of the black hole in both the grand canonical and the canonical ensembles (for the charged case). It turns out that the dRGT black hole solution includes other known solutions to the Einstein field equations, such as the monopole-de Sitter-Schwarzschild solution with the coefficients of the third and fourth terms in the potential and the graviton mass in massive gravity naturally generates the cosmological constant and the global monopole term. Furthermore, we compute the mass, temperature and entropy of the dRGT black hole, and also perform thermodynamical stability analysis. It turns out that the presence of the graviton mass completely changes the black hole thermodynamics, and it can provide the Hawking-Page phase transition which also occurs for the charged black holes. Interestingly, the entropy of a black hole is barely affected and still obeys the standard area law. In particular, our results, in the limit m{sub g} → 0, reduced exactly to the results of general relativity. (orig.)
A class of black holes in dRGT massive gravity and their thermodynamical properties
Ghosh, Suchant G.; Tannukij, Lunchakorn; Wongjun, Pitayuth
2016-03-01
We present an exact spherical black hole solution in de Rham, Gabadadze, and Tolley (dRGT) massive gravity for a generic choice of the parameters in the theory, and also discuss the thermodynamical and phase structure of the black hole in both the grand canonical and the canonical ensembles (for the charged case). It turns out that the dRGT black hole solution includes other known solutions to the Einstein field equations, such as the monopole-de Sitter-Schwarzschild solution with the coefficients of the third and fourth terms in the potential and the graviton mass in massive gravity naturally generates the cosmological constant and the global monopole term. Furthermore, we compute the mass, temperature and entropy of the dRGT black hole, and also perform thermodynamical stability analysis. It turns out that the presence of the graviton mass completely changes the black hole thermodynamics, and it can provide the Hawking-Page phase transition which also occurs for the charged black holes. Interestingly, the entropy of a black hole is barely affected and still obeys the standard area law. In particular, our results, in the limit m_g → 0, reduced exactly to the results of general relativity.
A class of black holes in dRGT massive gravity and their thermodynamical properties
International Nuclear Information System (INIS)
We present an exact spherical black hole solution in de Rham, Gabadadze, and Tolley (dRGT) massive gravity for a generic choice of the parameters in the theory, and also discuss the thermodynamical and phase structure of the black hole in both the grand canonical and the canonical ensembles (for the charged case). It turns out that the dRGT black hole solution includes other known solutions to the Einstein field equations, such as the monopole-de Sitter-Schwarzschild solution with the coefficients of the third and fourth terms in the potential and the graviton mass in massive gravity naturally generates the cosmological constant and the global monopole term. Furthermore, we compute the mass, temperature and entropy of the dRGT black hole, and also perform thermodynamical stability analysis. It turns out that the presence of the graviton mass completely changes the black hole thermodynamics, and it can provide the Hawking-Page phase transition which also occurs for the charged black holes. Interestingly, the entropy of a black hole is barely affected and still obeys the standard area law. In particular, our results, in the limit mg → 0, reduced exactly to the results of general relativity. (orig.)
Husain, Viqar
2012-03-01
researchers in other areas who wish to learn about the canonical approach to gravity. However, given the brief chapter on quantization, the book would go well with a review paper, or parts of the other three quantum gravity books cited above. References [1] Kiefer C 2006 Quantum Gravity 2nd ed. (Oxford University Press) [2] Rovelli C 2007 Quantum Gravity (Cambridge University Press) [3] Thiemann T 2008 Modern Canonical Quantum Gravity (Cambridge University Press) [4] Posson E 2004 A Relativist's Toolkit: The Mathematics of Black-Hole Mechanics (Cambridge University Press) [5] Ryan M P and Shepley L C 1975 Homogeneous Relativistic Cosmology (Princeton University Press)
Late Inspiral and Merger of Binary Black Holes in Scalar-Tensor Theories of Gravity
Healy, James; Haas, Roland; Pazos, Enrique; Laguna, Pablo; Shoemaker, Deirdre M; Yunes, Nicolás
2011-01-01
Gravitational wave observations will probe non-linear gravitational interactions and thus enable strong tests of Einstein's theory of general relativity. We present a numerical relativity study of the late inspiral and merger of binary black holes in scalar-tensor theories of gravity. We consider black hole binaries in an inhomogeneous scalar field, specifically binaries inside a scalar field bubble, in some cases with a potential. We calculate the emission of dipole radiation. We also show how these configurations trigger detectable differences between gravitational waves in scalar-tensor gravity and the corresponding waves in general relativity. We conclude that, barring an external mechanism to induce dynamics in the scalar field, scalar-tensor gravity binary black holes alone are not capable of awaking a dormant scalar field, and are thus observationally indistinguishable from their general relativistic counterparts.
Hawking, fiducial, and free-fall temperature of black hole on gravity's rainbow
Energy Technology Data Exchange (ETDEWEB)
Gim, Yongwan; Kim, Wontae [Sogang University, Department of Physics, Seoul (Korea, Republic of)
2016-03-15
On gravity's rainbow, the energy of test particles deforms the geometry of a black hole in such a way that the corresponding Hawking temperature is expected to be modified. It means that the fiducial and free-fall temperatures on the black hole background should also be modified according to deformation of the geometry. In this work, the probing energy of test particles is assumed as the average energy of the Hawking particle in order to study the particle back reaction of the geometry by using the advantage of gravity's rainbow. We shall obtain the modified fiducial and free-fall temperatures, respectively. The behaviors of these two temperatures on the horizon tell us that black hole complementarity is still well defined on gravity's rainbow. (orig.)
Black-hole horizons in modified spacetime structures arising from canonical quantum gravity
International Nuclear Information System (INIS)
Several properties of canonical quantum gravity modify spacetime structures, sometimes to the degree that no effective line elements exist to describe the geometry. An analysis of solutions, for instance in the context of black holes, then requires new insights. In this paper, standard definitions of horizons in spherical symmetry are first reformulated canonically, and then evaluated for solutions of equations and constraints modified by inverse-triad corrections of loop quantum gravity. When possible, a spacetime analysis is performed which reveals a mass threshold for black holes and small changes to Hawking radiation. For more general conclusions, canonical perturbation theory is developed to second order to include back-reaction from matter. The results shed light on the questions of whether renormalization of Newton's constant or other modifications of horizon conditions should be taken into account in computations of black-hole entropy in loop quantum gravity.
Thermodynamics and Phase transition of Schwarzschild black hole in Gravity's Rainbow
Feng, Zhong-Wen; Li, Hui-Ling; Zu, Xiao-Tao
2016-01-01
The Planck length and Planck energy should be taken as invariant scales are in agreement with various theories of quantum gravity. In this scenario, the original general relativity can be changed to the so-called gravity's rainbow which produces significant modifications to the black holes' evolution. In this paper, using two kinds of rainbow functions, we investigate the thermodynamics and the phase transition of Schwarzschild black hole in the context of gravity's rainbow theory. Firstly, with the help of the Heisenberg uncertainty principle, we calculate the modified Hawking temperature. Then, based on this modification, we derive the local temperature, free energy and other thermodynamic quantities in an isothermal cavity. Finally, the critical behavior, the thermodynamic stability and phase transition of the rainbow Schwarzschild black hole are analyzed. It turns out that our results are different from the those of Hawking-Page phase transition. Meanwhile, it is found that there are many similarities and...
Hawking, fiducial, and free-fall temperature of black hole on gravity's rainbow
International Nuclear Information System (INIS)
On gravity's rainbow, the energy of test particles deforms the geometry of a black hole in such a way that the corresponding Hawking temperature is expected to be modified. It means that the fiducial and free-fall temperatures on the black hole background should also be modified according to deformation of the geometry. In this work, the probing energy of test particles is assumed as the average energy of the Hawking particle in order to study the particle back reaction of the geometry by using the advantage of gravity's rainbow. We shall obtain the modified fiducial and free-fall temperatures, respectively. The behaviors of these two temperatures on the horizon tell us that black hole complementarity is still well defined on gravity's rainbow. (orig.)
Shining Light on Quantum Gravity with Pulsar-Black Hole Binaries
Estes, John; Kavic, Michael; Lippert, Matthew; Simonetti, John H.
2016-01-01
Pulsars are some of the most accurate clocks found in nature, while black holes offer a unique arena for the study of quantum gravity. As such, pulsar-black hole (PSR-BH) binaries provide ideal astrophysical systems for detecting effects of quantum gravity. With the success of aLIGO and the advent of instruments like the SKA and eLISA, the prospects for discovery of such PSR-BH binaries are very promising. We argue that PSR-BH binaries can serve as ready-made testing grounds for proposed reso...
Tunnelling of relativistic particles from new type black hole in new massive gravity
Energy Technology Data Exchange (ETDEWEB)
Gecim, Ganim; Sucu, Yusuf, E-mail: ganimgecim@akdeniz.edu.tr, E-mail: ysucu@akdeniz.edu.tr [Department of Physics, Akdeniz University, Antalya (Turkey)
2013-02-01
In the framework of the three dimensional New Massive Gravity theory introduced by Bergshoeff, Hohm and Townsend, we analyze the behavior of relativistic spin-1/2 and spin-0 particles in the New-type Black Hole backgroud, solution of the New Massive Gravity.We solve Dirac equation for spin-1/2 and Klein-Gordon equation for spin-0. Using Hamilton-Jacobi method, we discuss tunnelling probability and Hawking temperature of the spin-1/2 and spin-0 particles for the black hole. We observe that the tunnelling probability and Hawking temperature are same for the spin-1/2 and spin-0.
Anti-Evaporation of Schwarzschild-de Sitter Black Holes in $F(R)$ gravity
Nojiri, Shin'ichi; Odintsov, Sergei D.
2013-01-01
We studied the anti-evaporation of degenerate Schwarzschild-de Sitter black hole (so-called Nariai space-time) in modified $F(R)$ gravity. The analysis of perturbations of the Nariai black hole is done with the conclusion that anti-evaporation may occur in such a theory already on classical level. For several power-law $F(R)$ gravities which may describe the inflation and/or dark energy eras we presented the theory parameters bounds for occurrence of anti-evaporation and conjectured creation ...
Membrane paradigm of black holes in Chern-Simons modified gravity
Zhao, Tian-Yi
2015-01-01
The membrane paradigm of black hole is studied in the Chern-Simons modified gravity. Derived with the action principle a la Parikh-Wilczek, the stress tensor of membrane manifests a rich structure arising from the Chern-Simons term. The membrane stress tensor, if related to the bulk stress tensor in a special form, obeys the low-dimensional fluid continuity equation and the Navier-Stokes equation. This paradigm is applied to spherically symmetric static geometries, and in particular, the Schwarzschild black hole, which is a solution of a large class of dynamical Chern-Simons gravity.
Membrane paradigm of black holes in Chern-Simons modified gravity
Zhao, Tian-Yi; Wang, Towe
2016-06-01
The membrane paradigm of black hole is studied in the Chern-Simons modified gravity. Derived with the action principle a la Parikh-Wilczek, the stress tensor of membrane manifests a rich structure arising from the Chern-Simons term. The membrane stress tensor, if related to the bulk stress tensor in a special form, obeys the low-dimensional fluid continuity equation and the Navier-Stokes equation. This paradigm is applied to spherically symmetric static geometries, and in particular, the Schwarzschild black hole, which is a solution of a large class of dynamical Chern-Simons gravity.
Tunnelling of relativistic particles from new type black hole in new massive gravity
International Nuclear Information System (INIS)
In the framework of the three dimensional New Massive Gravity theory introduced by Bergshoeff, Hohm and Townsend, we analyze the behavior of relativistic spin-1/2 and spin-0 particles in the New-type Black Hole backgroud, solution of the New Massive Gravity.We solve Dirac equation for spin-1/2 and Klein-Gordon equation for spin-0. Using Hamilton-Jacobi method, we discuss tunnelling probability and Hawking temperature of the spin-1/2 and spin-0 particles for the black hole. We observe that the tunnelling probability and Hawking temperature are same for the spin-1/2 and spin-0
Fermions Tunnelling from Black String and Kerr AdS Black Hole with Consideration of Quantum Gravity
Li, Zhong-hua; Zhang, Li-mei
2016-01-01
In this paper, using the Hamilton-Jacobi Ansatz, we discuss the tunnelling of fermions when effects of quantum gravity are taken into account. We investigate two cases, black string and Kerr AdS black hole. For black string, the uncharged and un-rotating case, we find that the correction of Hawking temperature is only affected by the mass of emitted fermions and the quantum gravitational corrections slow down the increases of the temperature, which naturally leads to remnants left in the evaporation. For another case, the Kerr AdS black hole, we find that the quantum gravitational corrections are not only determined by the mass of the emitted fermions but also affected by the rotating properties of the AdS black hole. So with consideration of the quantum gravity corrections, an offset around the standard temperature always exists.
A class of black holes in dRGT massive gravity and their thermodynamical properties
Ghosh, Sushant G; Wongjun, Pitayuth
2015-01-01
We present exact spherical black hole solutions in de Rham, Gabadadze and Tolley (dRGT) massive gravity for a generic choice of the parameters in the theory, and also discuss the thermodynamical and phase structure of the black hole in both the grand canonical and canonical ensembles (for charged case). It turns out that the dGRT black hole solutions includes the known solutions to the Einstein field equations, such as, the monopole-de Sitter-Schwarzschild ones with the coefficients for the third and fourth terms in the potential and the graviton mass in massive gravity naturally generates the cosmological constant and the global monopole term. Furthermore, we compute the mass, temperature, and entropy of dGRT black hole solutions and also perform thermodynamical stability. It turns out that the presence of the graviton mass completely changes the black hole thermodynamics, and it can provide the Hawking-Page phase transition which is also true for the obtained charged black holes. Interestingly, the entropy ...
Testing quantum gravity effects through Dyonic charged AdS black hole
Sadeghi, J; Rostami, M
2016-01-01
In this paper, we consider dyonic charged AdS black hole which is holographic dual of a van der Waals fluid. We use logarithmic corrected entropy and study thermodynamics of the black hole and show that holographic picture is still valid. Critical behaviors and stability also discussed. Logarithmic corrections arises due to thermal fluctuations which are important when size of black hole be small. So, thermal fluctuations interpreted as quantum effect. It means that we can see quantum effect of a black hole which is a gravitational system. Hence, one can use result of this paper to compare with that of van der Waals fluid in the lab and see quantum gravity effects.
Brown-York quasilocal energy in Lanczos-Lovelock gravity and black hole horizons
Chakraborty, Sumanta; Dadhich, Naresh
2015-12-01
A standard candidate for quasilocal energy in general relativity is the Brown-York energy, which is essentially a two dimensional surface integral of the extrinsic curvature on the two-boundary of a spacelike hypersurface referenced to flat spacetime. Several years back one of us had conjectured that the black hole horizon is defined by equipartition of gravitational and non-gravitational energy. By employing the above definition of quasilocal Brown-York energy, we have verified the equipartition conjecture for static charged and charged axi-symmetric black holes in general relativity. We have further generalized the Brown-York formalism to all orders in Lanczos-Lovelock theories of gravity and have verified the conjecture for pure Lovelock charged black hole in all even d = 2 m + 2 dimensions, where m is the degree of Lovelock action. It turns out that the equipartition conjecture works only for pure Lovelock, and not for Einstein-Lovelock black holes.
Topological black holes in Pure Gauss-Bonnet gravity and phase transitions
Aránguiz, Ligeia; Miskovic, Olivera
2015-01-01
We study charged, static, topological black holes in Pure Gauss-Bonnet gravity in asymptotically AdS space. As in General Relativity, the theory has a unique non-degenerate AdS vacuum. It also admits charged black hole solutions which asymptotically behave as the Reissner-Nordstr\\"{o}m AdS black hole. We study phase transitions in a dual quantum field theory in four dimensions, with the St\\"{u}ckelberg scalar field as an order parameter. We find that the black hole develops hair below some critical temperature, which indicates a phase transition. Depending on the scalar coupling constants, the phase transition can be first or second order, or the one not covered by the Ehrenfest classification because the free energy diverges at the critical temperature.
Critical behaviors of a black hole in an asymptotically safe gravity with cosmological constant
International Nuclear Information System (INIS)
We study the P−V/r+ criticality and phase transition of a quantum-corrected black hole in asymptotic safety (AS) gravity in the extended phase space. For a black hole, the cosmological constant is dependent on the momentum cutoff or energy scale; therefore, one can naturally treat it as a variable and connect it with thermodynamic pressure. We find that for a quantum-corrected black hole there is a first-order phase transition similar to that of the van der Waals liquid–gas system. We also analyze the types of phase transition between the smaller and larger black hole phases according to Ehrenfest's classification. It is shown that they are second-order phase transitions. (paper)
Hendi, S H; Panahiyan, S
2015-01-01
Motivated by gauge/gravity group in the low energy effective theory of the heterotic string theory, the minimal coupling of Gauss-Bonnet-massive gravity with Born-Infeld electrodynamics is considered. At first the metric function is calculated and then the geometrical properties of the solutions are investigated. It is found that there is an essential singularity at the origin and the intrinsic curvature is regular elsewhere. In addition, the effects of massive parameters on the horizons of black holes are studied and the conserved and thermodynamic quantities are calculated. Also, it is shown that the solutions satisfy the first law of thermodynamics. Furthermore using heat capacity of these black holes, thermal stability and phase transitions are investigated. The variation of different parameters and related modifications on the (number of) phase transition are examined. Next, the critical behavior of the Gauss-Bonnet-Born-Infeld-massive black holes in context of extended phase space is studied. It is show...
A Note on Schwarzschild de Sitter Black Holes in Mimetic $F(R)$ Gravity
Oikonomou, V.K.
2016-01-01
In this brief note we investigate the conditions under which a Schwarzschild de Sitter black hole spacetime is a solution of the mimetic $F(R)$ gravity with Lagrange multiplier and potential. As we demonstrate, the resulting mimetic $F(R)$ gravity is a slight modification of the ordinary $F(R)$ gravity case, however the resulting perturbation equations are not in all cases identical to the ordinary $F(R)$ gravity case. In the latter case, the perturbation equations are identical to the ones c...
Microscopic quantum structure of black hole and vacuum versus quantum statistical origin of gravity
Wang, Shun-Jin
2012-01-01
The Planckon densely piled model of vacuum is proposed. Based on it, the microscopic quantum structure of Schwarzschild black hole and quantum statistical origin of its gravity are studied. It is shown that thermodynamic temperature equilibrium and mechanical acceleration balance make the space-time of the black hole horizon singular and Casimir effect works inside the horizon. This effect makes the inside vacuum have less zero fluctuation energy than the outside vacuum, and a temperature difference as well as gravity as thermal pressure are created. A dual relation between inside and outside regions of the black hole is found. By dual relation, an attractor behaviour of the horizon surface is unveiled. Outside horizon, there exist thermodynamic non-equilibrium and mechanical non-balance which lead to outward centrifugal energy flow and inward gravitation energy flow, their compensation establishes local equilibrium. The lost vacuum energy in negative gravitation potential regions has been removed to the blac...
Micro black holes in the laboratory and other experimental signatures of quantum gravity
International Nuclear Information System (INIS)
We investigate the possibility of quantum gravity effects setting in at much lower energies than the Planck scale. In particular, we study the formation and detection of microscopic black holes at the LHC as well as precision measurements of the gyroscopic moment of the muon and neutrino oscillations. We find that quantum gravity effects lead to observable signatures both in high energy and high precision scenarios. Comparison with experimental data allows us to constrain the parameters of the models. (author)
Black hole solution and strong gravitational lensing in Eddington-inspired Born-Infeld gravity
International Nuclear Information System (INIS)
A new theory of gravity called Eddington-inspired Born-Infeld (EiBI) gravity was recently proposed by Banados and Ferreira. This theory leads to some exciting new features, such as free of cosmological singularities. In this paper, we first obtain a charged EiBI black hole solution with a nonvanishing cosmological constant when the electromagnetic field is included in. Then based on it, we study the strong gravitational lensing by the asymptotic flat charged EiBI black hole. The strong deflection limit coefficients and observables are shown to closely depend on the additional coupling parameter κ in the EiBI gravity. It is found that, compared with the corresponding charged black hole in general relativity, the positive coupling parameter κ will shrink the black hole horizon and photon sphere. Moreover, the coupling parameter will decrease the angular position and relative magnitudes of the relativistic images, while increase the angular separation, which may shine new light on testing such gravity theory in near future by the astronomical instruments. (orig.)
Black Hole Entropy with and without Log Correction in Loop Quantum Gravity
International Nuclear Information System (INIS)
Earlier calculations of black hole entropy in loop quantum gravity have given a term proportional to the area with a correction involving the logarithm of the area when the area eigenvalue is close to the classical area. However the calculations yield an entropy proportional to the area eigenvalue with no such correction when the area eigenvalue is large compared to the classical area
Entropy Spectrum of a KS Black Hole in IR Modified Hořava-Lifshitz Gravity
International Nuclear Information System (INIS)
As a renormalizable theory of gravity, Hořava-Lifshitz gravity, might be an ultraviolet completion of general relativity and reduces to Einstein gravity with a nonvanishing cosmological constant in infrared. Kehagias and Sfetsos obtained a static spherically symmetric black hole solution called KS black hole in the IR modified Hořava-Lifshitz theory. In this paper, the entropy spectrum and area spectrum of a KS black hole are investigated based on the proposal of adiabatic invariant quantity. By calculating the action of producing a pair of particles near the horizon, it is obtained that the action of the system is exactly equivalent to the change of black hole entropy, which is an adiabatic invariant quantity. With the help of Bohr-Sommerfeld quantization rule, it is concluded that the entropy spectrum is discrete and equidistant spaced and the area spectrum is not equidistant spaced, which depends on the parameter of gravity theory. Some summary and discussion will be given in the last
Palatini–Born–Infeld gravity, bouncing universe, and black hole formation
Meguru Komada; Shin'ichi Nojiri; Taishi Katsuragawa
2016-01-01
We consider the Palatini formalism of the Born–Infeld gravity. In the Palatini formalism, the propagating mode is only graviton, whose situation is different from that in the metric formalism. We discuss the FRW cosmology by using an effective potential. Especially we consider the condition that the bouncing could occur. We also give some speculations about the black hole formation
Barrau, A
2006-01-01
Physics is facing contingency. Not only in facts but also in laws (the frontier becoming extremely narrow). Cosmic natural selection is a tantalizing idea to explain the apparently highly improbable structure of our Universe. In this brief note I will study the creation of Universes by black holes in -string inspired- higher order curvature gravity.
Interior Solutions for Non-singular Gravity and the Dark Star alternative to Black Holes
Cornish, Neil
1994-01-01
The general equations describing hydrostatic equilibrium are developed for Non-singular Gravity. A new type of astrophysical structure, a Super Dense Object (SDO) or "Dark Star", is shown to exist beyond Neutron star field strengths. These structures are intrinsically stable against gravitational collapse and represent the non-singular alternative to General Relativity's Black Holes.
(Un)attractor black holes in higher derivative AdS gravity
Astefanesei, D.; Banerjee, N.; Dutta, S.
2008-01-01
We investigate five-dimensional static (non-)extremal black hole solutions in higher derivative Anti-de Sitter gravity theories with neutral scalars non- minimally coupled to gauge fields. We explicitly identify the boundary counterterms to regularize the gravitational action and the stress tensor. We illustrate these results by applying the method of holographic renormalization to computing thermodynamical properties in several concrete examples. We also construct numerical extremal black ho...
(Anti-) de Sitter Electrically Charged Black Hole Solutions in Higher-Derivative Gravity
Lin, Kai; Qian, Wei-Liang; Pavan, A. B.; Abdalla, E.
2016-01-01
In this paper, static electrically charged black hole solutions with cosmological constant are investigated in an Einstein-Hilbert theory of gravity with additional quadratic curvature terms. Beside the analytic Schwarzschild (Anti-) de Sitter solutions, non-Schwarzschild (Anti-) de Sitter solutions are also obtained numerically by employing the shooting method. The results show that there exist two groups of asymptotically (Anti-) de Sitter spacetimes for both charged and uncharged black hol...
Prasia, P
2016-01-01
In this work we study the Quasi Normal Modes(QNMs) under massless scalar perturbations and the thermodynamics of linearly charged BTZ black holes in massive gravity in the (Anti)de Sitter((A)dS) space time. It is found that the behavior of QNMs changes with the massive parameter and also with the charge of the black hole. The thermodynamics of such black holes in the (A)dS space time is also analyzed in detail. The behavior of specific heat with temperature for such black holes gives an indication of a phase transition that depends on the massive parameter and also on the charge of the black hole.
Brown-York quasilocal energy in Lanczos-Lovelock gravity and black hole horizons
Chakraborty, Sumanta
2015-01-01
A standard candidate for quasilocal energy in general relativity is the Brown-York energy, which is essentially a two dimensional surface integral of the extrinsic curvature on the two-boundary of a spacelike hypersurface referenced to flat spacetime. Several years back one of us had conjectured that the black hole horizon is defined by equipartition of gravitational and non-gravitational energy. By employing the above definition of quasilocal Brown-York energy, we have verified the equipartition conjecture for static charged and charged axi-symmetric blck holes in general relativity. We have further generalized the Brown-York formalism to all orders in Lanczos-Lovelock theories of gravity and have verified the conjecture for pure Lovelock charged black hole in all even $d=2m+2$ dimensions, where $m$ is the degree of Lovelock action. It turns out that the equipartition conjecture works only for pure Lovelock, and not for Einstein-Lovelock, black holes.
Shining Light on Quantum Gravity with Pulsar-Black Hole Binaries
Estes, John; Lippert, Matthew; Simonetti, John H
2016-01-01
Pulsars are some of the most accurate clocks found in nature, while black holes offer a unique arena for the study of quantum gravity. As such, pulsar-black hole (PSR-BH) binaries provide ideal astrophysical systems for detecting effects of quantum gravity. With the success of aLIGO and the advent of instruments like the SKA and eLISA, the prospects for discovery of such PSR-BH binaries are very promising. We argue that PSR-BH binaries can serve as ready-made testing grounds for proposed resolutions to the black hole information paradox. We propose using timing signals from a pulsar beam passing through the region near a BH event horizon as a probe of quantum gravitational effects. In particular, we demonstrate that fluctuations of the geometry outside a black hole lead to an increase in the measured root-mean-square deviation of arrival times of pulsar pulses traveling near the horizon. This allows for a clear observational test of the nonviolent nonlocality proposal for black hole information escape. For a ...
Black Holes - a Simplified Theory for Quantum Gravity Non-Specialists
Pankovic, Vladan
2009-01-01
In this work we present a simplified description and calculation of the Kerr-Newman black hole basic dynamical (horizons) and thermo-dynamical (Bekenstein-Hawking entropy, Bekenstein entropy/surface quantization, Hawking temperature and radiation) characteristics. Also, a possibility of the fission of nearly extremal black hole is considered in full analogy with remarkable, simple Bohr-Wheeler theory of the nuclear fission. Given black is physically based on the well-known principles of the classical physics (mechanics, thermodynamics and electro-dynamics). It includes the non-relativistic quantum mechanics and statistical mechanics too. Finally, it includes the elementary form of the general relativistic equivalence principle only. Also, suggested simplified description includes mathematically, practically, only simple algebraic equations. Here many steps are extremely simplified and formal, representing, in fact, a linear approximation of the quantum gravity theories (black hole entropy and temperature can ...
The rotating black hole in renormalizable quantum gravity: The three-dimensional Hořava gravity case
International Nuclear Information System (INIS)
Recently Hořava proposed a renormalizable quantum gravity, without the ghost problem, by abandoning Einstein's equal-footing treatment of space and time through the anisotropic scaling dimensions. Since then various interesting aspects, including the exact black hole solutions have been studied but no rotating black hole solutions have been found yet, except some limiting cases. In order to fill the gap, I consider a simpler three-dimensional set-up with z=2 and obtain the exact rotating black hole solution. This solution has a ring curvature singularity inside the outer horizon, like the four-dimensional Kerr black hole in Einstein gravity, as well as a curvature singularity at the origin. The usual mass bound works also here but in a modified form. Moreover, it is shown that the conventional first law of thermodynamics with the usual Hawking temperature and chemical potential does not work, which seems to be the genuine effect of Lorentz-violating gravity due to lack of the absolute horizon.
Waveforms in massive gravity and neutralization of giant black hole ringings
Décanini, Yves; Folacci, Antoine; Ould El Hadj, Mohamed
2016-06-01
A distorted black hole radiates gravitational waves in order to settle down in a smoother geometry. During that relaxation phase, a characteristic damped ringing is generated. It can be theoretically constructed from both the black hole quasinormal frequencies (which govern its oscillating behavior and its decay) and the associated excitation factors (which determine intrinsically its amplitude) by carefully taking into account the source of the distortion. In the framework of massive gravity, the excitation factors of the Schwarzschild black hole have an unexpected strong resonant behavior which, theoretically, could lead to giant and slowly decaying ringings. If massive gravity is relevant to physics, one can hope to observe these extraordinary ringings by using the next generations of gravitational wave detectors. Indeed, they could be generated by supermassive black holes if the graviton mass is not too small. In fact, by focusing on the odd-parity ℓ=1 mode of the Fierz-Pauli field, we shall show here that such ringings are neutralized in waveforms due to (i) the excitation of the quasibound states of the black hole and (ii) the evanescent nature of the particular partial modes which could excite the concerned quasinormal modes. Despite this, with observational consequences in mind, it is interesting to note that the waveform amplitude is nevertheless rather pronounced and slowly decaying (this effect is now due to the long-lived quasibound states). It is worth noting also that, for very low values of the graviton mass (corresponding to the weak instability regime for the black hole), the waveform is now very clean and dominated by an ordinary ringing which could be used as a signature of massive gravity.
Reissner-Nordstr\\"om Black Holes in Mimetic $F(R)$ Gravity
Oikonomou, V K
2015-01-01
In this paper we study under which conditions the Reissner-Nordstr\\"om-anti de Sitter black hole can be a solution of the vacuum mimetic $F(R)$ gravity with Lagrange multiplier and mimetic scalar potential. As we demonstrate, the resulting picture in the mimetic $F(R)$ gravity case, is different in comparison to the ordinary $F(R)$ gravity case, with the two descriptions resulting to a different set of constraints that need to hold true. We also investigate the metric perturbations in the mimetic $F(R)$ gravity case, for the Reissner-Nordstr\\"om-anti de Sitter black hole metric, at first order of the perturbed variables. Interestingly enough, the resulting equations are identical to the ones corresponding to the ordinary $F(R)$ gravity Reissner-Nordstr\\"om-anti de Sitter black hole, at least at first order. We attribute this feature to the particular form of the Reissner-Nordstr\\"om-anti de Sitter metric, and we speculate for which cases there could be differences between the mimetic and non-mimetic case. Sin...
Thermodynamic instability of nonlinearly charged black holes in gravity's rainbow
Energy Technology Data Exchange (ETDEWEB)
Hendi, S.H. [Shiraz University, Physics Department and Biruni Observatory, College of Sciences, Shiraz (Iran, Islamic Republic of); Research Institute for Astronomy and Astrophysics of Maragha (RIAAM), Maragha (Iran, Islamic Republic of); Panahiyan, S. [Shiraz University, Physics Department and Biruni Observatory, College of Sciences, Shiraz (Iran, Islamic Republic of); Shahid Beheshti University, Physics Department, Tehran (Iran, Islamic Republic of); Panah, B.E.; Momennia, M. [Shiraz University, Physics Department and Biruni Observatory, College of Sciences, Shiraz (Iran, Islamic Republic of)
2016-03-15
Motivated by the violation of Lorentz invariance in quantum gravity, we study black hole solutions in gravity's rainbow in the context of Einstein gravity coupled with various models of nonlinear electrodynamics. We regard an energy dependent spacetime and obtain the related metric functions and electric fields. We show that there is an essential singularity at the origin which is covered by an event horizon. We also compute the conserved and thermodynamical quantities and examine the validity of the first law of thermodynamics in the presence of rainbow functions. Finally, we investigate the thermal stability conditions for these black hole solutions in the context of canonical ensemble. We show that the thermodynamical structure of the solutions depends on the choices of nonlinearity parameters, charge, and energy functions. (orig.)
Thermodynamic instability of nonlinearly charged black holes in gravity's rainbow
International Nuclear Information System (INIS)
Motivated by the violation of Lorentz invariance in quantum gravity, we study black hole solutions in gravity's rainbow in the context of Einstein gravity coupled with various models of nonlinear electrodynamics. We regard an energy dependent spacetime and obtain the related metric functions and electric fields. We show that there is an essential singularity at the origin which is covered by an event horizon. We also compute the conserved and thermodynamical quantities and examine the validity of the first law of thermodynamics in the presence of rainbow functions. Finally, we investigate the thermal stability conditions for these black hole solutions in the context of canonical ensemble. We show that the thermodynamical structure of the solutions depends on the choices of nonlinearity parameters, charge, and energy functions. (orig.)
Spherical Accretion of Matter by Charged Black Holes on f(T) Gravity
Rodrigues, Manuel E
2016-01-01
We studied the spherical accretion of matter by charged black holes on $f(T)$ Gravity. Considering the accretion model of a isentropic perfect fluid we obtain the general form of the Hamiltonian and the dynamic system for the fluid. We have analysed the movements of an isothermal fluid model with $p=\\omega e$ and where $p$ is the pressure and $e$ the total energy density. The analysis of the cases shows the possibility of spherical accretion of fluid by black holes, revealing new phenomena as cyclical movement inside the event horizon.
(Un)attractor black holes in higher derivative AdS gravity
International Nuclear Information System (INIS)
We investigate five-dimensional static (non-)extremal black hole solutions in higher derivative Anti-de Sitter gravity theories with neutral scalars non-minimally coupled to gauge fields. We explicitly identify the boundary counterterms to regularize the gravitational action and the stress tensor. We illustrate these results by applying the method of holographic renormalization to computing thermodynamical properties in several concrete examples. We also construct numerical extremal black hole solutions and discuss the attractor mechanism by using the entropy function formalism.
Daniel Heineman Prize: QCD, strings and black holes: A duality between gravity and field theory
Maldacena, Juan
2007-04-01
We discuss Yang Mills theory with a large number of colors. In this limit it becomes a theory of strings. We describe the string theory associated to the most supersymmetric version of Yang Mills theory. These strings live in a ten dimensional curved space. Thus supersymmetric Yang Mills theory is related to the ordinary ten dimensional superstring theory which describes quantum gravity. We will review some results in this area and discuss some recent developments. We will also discuss the implications for black hole entropy and the black hole information puzzle.
Thermodynamic analysis of topological black holes in Gauss-Bonnet gravity with nonlinear source
Energy Technology Data Exchange (ETDEWEB)
Hendi, S.H. [Shiraz University, Physics Department and Biruni Observatory, College of Sciences, Shiraz (Iran, Islamic Republic of); Research Institute for Astrophysics and Astronomy of Maragha (RIAAM), P.O. Box 55134-441, Maragha (Iran, Islamic Republic of); Panahiyan, S.; Mahmoudi, E. [Shiraz University, Physics Department and Biruni Observatory, College of Sciences, Shiraz (Iran, Islamic Republic of)
2014-10-15
Employing two classes of nonlinear electrodynamics, we obtain topological black hole solutions of Gauss-Bonnet gravity. We investigate geometric properties of the solutions and find that there is an intrinsic singularity at the origin. We investigate the thermodynamic properties of the asymptotically flat black holes and also asymptotically adS solutions. Using a suitable local transformation, we generalize static horizon-flat solutions to rotating ones. We discuss their conserved and thermodynamic quantities as well as the first law of thermodynamics. Finally, we calculate the heat capacity of the solutions to obtain a constraint on the horizon radius of stable solutions. (orig.)
Black Holes with Scalar Hairs in Einstein-Gauss-Bonnet Gravity
Brihaye, Y
2015-01-01
The Einstein-Gauss-Bonnet gravity in five dimensions is extended by scalar fields and the corresponding equations are reduced to a system of non-linear differential equations. A large family of regular solutions of these equations is shown to exist. Generically, these solutions are spinning black holes with scalar hairs. They can be characterized (but not uniquely) by an horizon and an angular velocity on this horizon. Taking particular limits the black holes approach boson star or become extremal, in any case the limiting configurations remain hairy.
Geodesic motion in the spacetime of a static charged black hole in $f(R)$ gravity
Soroushfar, Saheb; Grunau, Saskia
2016-01-01
In the present paper we study the geodesic motion of test particles and light rays in the spacetime of a static charged black hole in $f(R)$ gravity. The complete set of analytic solutions of the geodesic equations in the spacetime of this black hole are presented. The geodesic equations are solved in terms of Weierstrass elliptic $\\wp$ function and derivatives of Kleinian $\\sigma$ function. With the help of parametric diagrams and effective potentials we analyze the geodesic motion and give a list of all possible orbit types. The different types of the resulting orbits are characterized in terms of the conserved energy, angular momentum, charge and cosmological constant.
Finsler Black Holes Induced by Noncommutative Anholonomic Distributions in Einstein Gravity
Vacaru, Sergiu I
2009-01-01
We study Finsler black holes induced from Einstein gravity as possible effects of quantum spacetime noncommutativity. We focus on noncommutative deformations of Schwarzschild metrics into locally anisotropic stationary ones with spherical/ rotoid symmetry. There are derived the conditions when black hole configurations can be extracted from two classes of exact solutions depending on noncommutative parameters. The first class of metrics is defined by nonholonomic deformations of the gravitational vacuum by noncommutative geometry. The second class of such solutions is induced by noncommutative matter fields and/or effective polarizations of cosmological constants.
Reissner-Nordstr\\"om Black Holes in Mimetic $F(R)$ Gravity
Oikonomou, V. K.
2015-01-01
In this paper we study under which conditions the Reissner-Nordstr\\"om-anti de Sitter black hole can be a solution of the vacuum mimetic $F(R)$ gravity with Lagrange multiplier and mimetic scalar potential. As we demonstrate, the resulting picture in the mimetic $F(R)$ gravity case, is different in comparison to the ordinary $F(R)$ gravity case, with the two descriptions resulting to a different set of constraints that need to hold true. We also investigate the metric perturbations in the mim...
P-V criticality of topological black holes in Lovelock-Born-Infeld gravity
Energy Technology Data Exchange (ETDEWEB)
Mo, Jie-Xiong [Beijing Normal University, Department of Physics, Institute of Theoretical Physics, Beijing (China); Zhanjiang Normal University, Institute of Theoretical Physics, Zhanjiang (China); Liu, Wen-Biao [Beijing Normal University, Department of Physics, Institute of Theoretical Physics, Beijing (China)
2014-04-15
To understand the effect of third order Lovelock gravity, P-V criticality of topological AdS black holes in Lovelock-Born-Infeld gravity is investigated. The thermodynamics is further explored with some more extensions and in some more detail than the previous literature. A detailed analysis of the limit case β → ∞ is performed for the sevendimensional black holes. It is shown that, for the spherical topology, P-V criticality exists for both the uncharged and the charged cases. Our results demonstrate again that the charge is not the indispensable condition of P-V criticality. It may be attributed to the effect of higher derivative terms of the curvature because similar phenomenon was also found for Gauss-Bonnet black holes. For k = 0, there would be no P-V criticality. Interesting findings occur in the case k = -1, in which positive solutions of critical points are found for both the uncharged and the charged cases. However, the P-v diagram is quite strange. To check whether these findings are physical, we give the analysis on the non-negative definiteness condition of the entropy. It is shown that, for any nontrivial value of α, the entropy is always positive for any specific volume v. Since no P-V criticality exists for k = -1 in Einstein gravity and Gauss-Bonnet gravity, we can relate our findings with the peculiar property of third order Lovelock gravity. The entropy in third order Lovelock gravity consists of extra terms which are absent in the Gauss-Bonnet black holes, which makes the critical points satisfy the constraint of non-negative definiteness condition of the entropy. We also check the Gibbs free energy graph and ''swallow tail'' behavior can be observed. Moreover, the effect of nonlinear electrodynamics is also included in our research. (orig.)
Luminet, Jean-Pierre
1992-09-01
Foreword to the French edition; Foreword to the English edition; Acknowledgements; Part I. Gravitation and Light: 1. First fruits; 2. Relativity; 3. Curved space-time; Part II. Exquisite Corpses: 4. Chronicle of the twilight years; 5. Ashes and diamonds; 6. Supernovae; 7. Pulsars; 8. Gravitation triumphant; Part III. Light Assassinated: 9. The far horizon; 10. Illuminations; 11. A descent into the maelstrom; 12. Map games; 13. The black hole machine; 14. The quantum black hole; Part IV. Light Regained: 15. Primordial black holes; 16. The zoo of X-ray stars; 17. Giant black holes; 18. Gravitational light; 19. The black hole Universe; Appendices; Bibliography; Name index; Subject index.
Hawking radiation as tunneling from a Vaidya black hole in noncommutative gravity
Mehdipour, S. Hamid
2010-06-01
In the context of a noncommutative model of coordinate coherent states, we present a Schwarzschild-like metric for a Vaidya solution instead of the standard Eddington-Finkelstein metric. This leads to the appearance of an exact (t-r) dependent case of the metric. We analyze the resulting metric in three possible causal structures. In this setup, we find a zero remnant mass in the long-time limit, i.e. an instable black hole remnant. We also study the tunneling process across the quantum horizon of such a Vaidya black hole. The tunneling probability including the time-dependent part is obtained by using the tunneling method proposed by Parikh and Wilczek in terms of the noncommutative parameter σ. After that, we calculate the entropy associated to this noncommutative black hole solution. However, the corrections are fundamentally trifling; one could respect this as a consequence of quantum inspection at the level of semiclassical quantum gravity.
Hawking radiation as tunneling from a Vaidya black hole in noncommutative gravity
International Nuclear Information System (INIS)
In the context of a noncommutative model of coordinate coherent states, we present a Schwarzschild-like metric for a Vaidya solution instead of the standard Eddington-Finkelstein metric. This leads to the appearance of an exact (t-r) dependent case of the metric. We analyze the resulting metric in three possible causal structures. In this setup, we find a zero remnant mass in the long-time limit, i.e. an instable black hole remnant. We also study the tunneling process across the quantum horizon of such a Vaidya black hole. The tunneling probability including the time-dependent part is obtained by using the tunneling method proposed by Parikh and Wilczek in terms of the noncommutative parameter σ. After that, we calculate the entropy associated to this noncommutative black hole solution. However, the corrections are fundamentally trifling; one could respect this as a consequence of quantum inspection at the level of semiclassical quantum gravity.
Hawking radiation as tunneling from a Vaidya black hole in noncommutative gravity
Mehdipour, S Hamid
2010-01-01
In the context of a noncommutative model of coordinate coherent states, we present a Schwarzschild-like metric for a Vaidya solution instead of the standard Eddington-Finkelstein metric. This leads to the appearance of an exact $(t - r)$ dependent case of the metric. We analyze the resulting metric in three possible causal structures. In this setup, we find a zero remnant mass in the long-time limit, i.e. an instable black hole remnant. We also study the tunneling process across the quantum horizon of such a Vaidya black hole. The tunneling probability including the time-dependent part is obtained by using the tunneling method proposed by Parikh and Wilczek in terms of the noncommutative parameter $\\sigma$. After that, we calculate the entropy associated to this noncommutative black hole solution. However the corrections are fundamentally trifling; one could respect this as a consequence of quantum inspection at the level of semiclassical quantum gravity.
Black hole solutions in functional extensions of Born-Infeld gravity
Bambi, Cosimo; Wang, Yixu
2016-01-01
We consider electrovacuum black hole spacetimes in classical extensions of Eddington-inspired Born-Infeld gravity. By rewriting Born-Infeld action as the square root of the determinant of a matrix $\\hat{\\Omega}$, we consider the family of models $f (|\\hat{\\Omega}|)$, and study black hole solutions for a power-law family of models labelled by a simple parameter. We show how the innermost structure of the corresponding black holes is modified as compared to their General Relativity counterparts, discussing in which cases a wormhole structure replaces the point-like singularity. We go forward to argue that in such cases a geodesically complete and thus non-singular spacetime is present, despite the existence of curvature divergences at the wormhole throat.
(Anti-) de Sitter Electrically Charged Black Hole Solutions in Higher-Derivative Gravity
Lin, Kai; Pavan, A B; Abdalla, E
2016-01-01
In this paper, static electrically charged black hole solutions with cosmological constant are investigated in an Einstein-Hilbert theory of gravity with additional quadratic curvature terms. Beside the analytic Schwarzschild (Anti-) de Sitter solutions, non-Schwarzschild (Anti-) de Sitter solutions are also obtained numerically by employing the shooting method. The results show that there exist two groups of asymptotically (Anti-) de Sitter spacetimes for both charged and uncharged black holes. In particular, it was found that for uncharged black holes the first group can be reduced to the Schwarzschild (Anti-) de Sitter solution, while the second group is intrinsically different from a Schwarzschild (Anti-) de Sitter solution even when the charge and the cosmological constant become zero.
(Anti-) de Sitter electrically charged black-hole solutions in higher-derivative gravity
Lin, Kai; Qian, Wei-Liang; Pavan, A. B.; Abdalla, E.
2016-06-01
In this paper, static electrically charged black-hole solutions with cosmological constant are investigated in an Einstein-Hilbert theory of gravity with additional quadratic curvature terms. Beside the analytic Schwarzschild (Anti-) de Sitter solutions, non-Schwarzschild (Anti-) de Sitter solutions are also obtained numerically by employing the shooting method. The results show that there exist two groups of asymptotically (Anti-) de Sitter spacetimes for both charged and uncharged black holes. In particular, it was found that for uncharged black holes the first group can be reduced to the Schwarzschild (Anti-) de Sitter solution, while the second group is intrinsically different from a Schwarzschild (Anti-) de Sitter solution even when the charge and the cosmological constant become zero.
Regular black holes in f (R ) gravity coupled to nonlinear electrodynamics
Rodrigues, Manuel E.; Junior, Ednaldo L. B.; Marques, Glauber T.; Zanchin, Vilson T.
2016-07-01
We obtain a class of regular black hole solutions in four-dimensional f (R ) gravity, R being the curvature scalar, coupled to a nonlinear electromagnetic source. The metric formalism is used and static spherically symmetric spacetimes are assumed. The resulting f (R ) and nonlinear electrodynamics functions are characterized by a one-parameter family of solutions which are generalizations of known regular black holes in general relativity coupled to nonlinear electrodynamics. The related regular black holes of general relativity are recovered when the free parameter vanishes, in which case one has f (R )∝R . We analyze the regularity of the solutions and also show that there are particular solutions that violate only the strong energy condition.
On static black holes solutions in Einstein and Einstein–Gauss–Bonnet gravity with topology Sn×Sn
International Nuclear Information System (INIS)
We study static black hole solutions in Einstein and Einstein–Gauss–Bonnet gravity with the topology of the product of two spheres, Sn×Sn, in higher dimensions. There is an unusual new feature of the Gauss–Bonnet black hole: the avoidance of a non-central naked singularity prescribes a mass range for the black hole in terms of Λ>0. For an Einstein–Gauss–Bonnet black hole a limited window of negative values for Λ is also permitted. This topology encompasses black strings, branes, and generalized Nariai metrics. We also give new solutions with the product of two spheres of constant curvature
On static black holes solutions in Einstein and Einstein-Gauss-Bonnet gravity with topology Sn x Sn
International Nuclear Information System (INIS)
We study static black hole solutions in Einstein and Einstein-Gauss-Bonnet gravity with the topology of the product of two spheres, Sn x Sn, in higher dimensions. There is an unusual new feature of the Gauss-Bonnet black hole: the avoidance of a non-central naked singularity prescribes a mass range for the black hole in terms of Λ > 0. For an Einstein-Gauss-Bonnet black hole a limited window of negative values for Λ is also permitted. This topology encompasses black strings, branes, and generalized Nariai metrics. We also give new solutions with the product of two spheres of constant curvature. (orig.)
Gravitational lensing by self-dual black holes in loop quantum gravity
Sahu, Satyabrata; Lochan, Kinjalk; Narasimha, D.
2015-03-01
We study gravitational lensing by a recently proposed black hole solution in loop quantum gravity. We highlight the fact that the quantum gravity corrections to the Schwarzschild metric in this model evade the "mass suppression" effects (that the usual quantum gravity corrections are susceptible to) by virtue of one of the parameters in the model being dimensionless, which is unlike any other quantum gravity motivated parameter. Gravitational lensing in the strong and weak deflection regimes is studied, and a sample consistency relation is presented which could serve as a test of this model. We discuss that, though the consistency relation for this model is qualitatively similar to what would have been in Brans-Dicke, in general it can be a good discriminator between many alternative theories. Although the observational prospects do not seem to be very optimistic even for a galactic supermassive black hole case, time delay between relativistic images for a billion solar mass black holes in other galaxies might be within reach of future relativistic lensing observations.
Hawking evaporation of cosmogenic black holes in TeV-gravity models
International Nuclear Information System (INIS)
We study the properties of black holes of mass 104–1011 GeV in models with the fundamental scale of gravity at the TeV. These black holes could be produced in the collision of a ultrahigh energy cosmic ray with a dark matter particle in our galactic halo or with another cosmic ray. We show that QCD bremsstrahlung and pair production processes are unable to thermalize the particles exiting the black hole, so a chromosphere is never formed during Hawking evaporation. We evaluate with HERWIG the spectrum of stable four-dimensional particles emitted during the Schwarzschild phase and find that in all cases it is peaked at energies around 0.2 GeV, with an approximate 43% of neutrinos, 28% of photons, 16% of electrons and 13% of protons. Bulk gravitons are peaked at higher energies; they account for 0.4% of the particles (16% of the total energy) emitted by the most massive black holes in n = 6 extra dimensions or just the 0.02% of the particles (1.4% of the energy) emitted by a 10 TeV black hole for n = 2
Shadow of a Charged Rotating Black Hole in $f(R)$ Gravity
Dastan, Sara; Soroushfar, Saheb
2016-01-01
We study the shadow of a charged rotating black hole in $f(R)$ gravity. This black hole is characterized by mass, $M$, spin, $a$, electric charge, $Q$ and $R_{0}$ which is proportional to cosmological constant. We analyze the image of the black hole's shadow in four types 1) at $r\\rightarrow\\infty$, 2) at $r\\rightarrow r_{o}$, in vacuum, 3) at $r\\rightarrow\\infty$, 4) at $r\\rightarrow r_{o}$, for an observer at the presence of plasma. Moreover, we investigate the effect of spin, charge and modfication of gravity on the shape of shadow. In addition, we use two observables, the radius $R_{s}$ and the distortion parameter $\\delta_{s}$, characterizing the apparent shape. We show that for all cases, the shadow becomes smaller with increasing electric charge. Also, by increasing the rotation parameters, circular symmetry of the image of black hole's shadow will change. Furthermore, in the presence of plasma, plasma parameter also effects on size of the shadow.
AdS and Lifshitz Scalar Hairy Black Holes in Gauss-Bonnet Gravity
Chen, Bin; Zhu, Lu-Yao
2016-01-01
We consider Gauss-Bonnet (GB) gravity in general dimensions, which is non-minimally coupled to a scalar field, together with a generic scalar potential. By choosing the scalar potential of the type $V(\\phi)=2\\Lambda_0+\\frac{1}{2}m^2\\phi^2+\\gamma_4\\phi^4$, we first obtain large classes of scalar hairy black holes with spherical/hyperbolic/planar topologies that are asymptotic to locally anti-de Sitter (AdS) space-times. We derive the first law of black hole thermodynamics using Wald formalism. In particular, for one class of the solutions, the scalar hair forms a thermodynamic conjugate with the graviton and nontrivially contributes to the thermodynamical first law. We observe that except for one class of planar black holes, all these solutions are constructed at the critical point of GB gravity where there exists an unique AdS vacua. Actually Lifshitz vacuum is also allowed at the critical point. We then construct many new classes of neutral and charged Lifshitz black hole solutions for a either minimally or ...
Zangeneh, M Kord; Sheykhi, A; Dehghani, M H
2016-01-01
In this paper, we construct a new class of topological black hole Lifshitz solutions in the presence of nonlinear exponential electrodynamics for Einstein-dilaton gravity. We show that the reality of Lifshitz supporting Maxwell matter fields exclude the negative horizon curvature solutions except for the asymptotic AdS case. Calculating the conserved and thermodynamical quantities, we obtain a Smarr type formula for the mass and confirm that thermodynamics first law is satisfied on the black hole horizon. Afterward, we study the thermal stability of our solutions and figure out the effects of different parameters on the stability of solutions under thermal perturbations. Next, we apply the gauge/gravity duality in order to calculate the ratio of shear viscosity to entropy for a three-dimensional hydrodynamic system by using the pole method. Furthermore, we study the behavior of holographic conductivity for two-dimensional systems such as graphene. We consider linear Maxwell and nonlinear exponential electrody...
Geometrothermodynamics of black holes in Lovelock gravity with a nonlinear electrodynamics
Hendi, Seyed Hossein
2015-01-01
The objective of the present paper is to analyze the phase transition of asymptotically anti-de Sitter (AdS) black hole solutions in Lovelock gravity in the presence of nonlinear electrodynamics. First, we present the asymptotically AdS black hole solutions for two classes of the Born-Infeld type of nonlinear electrodynamics coupled with Einstein, Gauss-Bonnet and third order Lovelock gravity, separately. Then, in order to discuss the phase transition, we calculate both the heat capacity and the Ricci scalar of the thermodynamical line element. We present a comparison between the singular points of the Ricci scalar using Geometrothermodynamics method and the corresponding vanishing points of the heat capacity in the canonical ensemble. In addition, we discuss the effects of both Lovelock and nonlinear electrodynamics on the phase transition points.
Static black holes and strictly static spacetimes in Einstein-Gauss-Bonnet gravity with gauge field
Rogatko, Marek
2014-01-01
We examine strictly static asymptotically flat spacetimes in Einstein-Gauss-Bonnet gravity with U(1) gauge field, revealing that, up to small curvature corrections, confomally flat slices of the spacetime in question are of Minkowski origin. We consider uncharged and charged black hole solutions in the theory, showing that, up to the small curvature limit, they are diffeomorphic to Schwarzschild_Tangherlini or Reissner-Nordstrom solutions, respectively.
Quantum Gravity and Black Hole Dynamics in 1+1 Dimensions
Hamada, K; Tsuchiya, A
1992-01-01
We study the quantum theory of 1+1 dimensional dilaton gravity, which is an interesting toy model of the black hole dynamics. The functional measures are explicitly evaluated and the physical state conditions corresponding to the Hamiltonian and the momentum constraints are derived. It is pointed out that the constraints form the Virasoro algebra without central charge. In ADM formalism the measures are very ambiguous, but in our formalism they are explicitly defined. Then the new features wh...
Loop Quantum Gravity meets Topological Phases of Matter at the Black Hole horizon
Pithis, Andreas Georg Aristides; Ruiz Euler, Hans-Christian
2015-01-01
In this work we investigate the role played by large diffeomorphisms of quantum isolated horizons for the statistics of Loop Quantum Gravity black holes by means of their relation to the braid group. The mutual exchange of quantum entities in two dimensions is achieved by the braid group, rendering the statistics anyonic. With this we argue that the quantum isolated horizon model of LQG based on SU(2)_k-Chern-Simons theory explicitly exhibits non-abelian anyonic statistics, since the quantum ...
Sectors of solutions in three-dimensional gravity and black holes
Energy Technology Data Exchange (ETDEWEB)
Fjelstad, Jens E-mail: jens.fjelstad@kau.se; Hwang, Stephen E-mail: stephen.hwang@kau.se
2002-04-29
We examine the connection between three-dimensional gravity with negative cosmological constant and two-dimensional CFT via the Chern-Simons formulation. A set of generalized spectral flow transformations are shown to yield new sectors of solutions. One implication is that the microscopic calculation of the entropy of the Banados-Teitelboim-Zanelli (BTZ) black hole is corrected by a multiplicative factor with the result that it saturates the Bekenstein-Hawking expression.
Sectors of solutions in three-dimensional gravity and black holes
International Nuclear Information System (INIS)
We examine the connection between three-dimensional gravity with negative cosmological constant and two-dimensional CFT via the Chern-Simons formulation. A set of generalized spectral flow transformations are shown to yield new sectors of solutions. One implication is that the microscopic calculation of the entropy of the Banados-Teitelboim-Zanelli (BTZ) black hole is corrected by a multiplicative factor with the result that it saturates the Bekenstein-Hawking expression
Sectors of solutions in three-dimensional gravity and Black Holes
Fjelstad, Jens; Hwang, Stephen
2001-01-01
We examine the connection between three dimensional gravity with negative cosmological constant and two-dimensional CFT via the Chern-Simons formulation. A set of generalized spectral flow transformations are shown to yield new sectors of solutions. One implication is that the microscopic calculation of the entropy of the Banados-Teitelboim-Zanelli (BTZ) black hole is corrected by a multiplicative factor with the result that it saturates the Bekenstein-Hawking expression.
The string landscape, black holes and gravity as the weakest force
Energy Technology Data Exchange (ETDEWEB)
Arkani-Hamed, Nima; Motl, Lubos; Nicolis, Alberto; Vafa, Cumrun [Jefferson Laboratory of Physics, Harvard University, Cambridge, Massachusetts 02138 (United States)
2007-06-15
We conjecture a general upper bound on the strength of gravity relative to gauge forces in quantum gravity. This implies, in particular, that in a four-dimensional theory with gravity and a U(1) gauge field with gauge coupling g, there is a new ultraviolet scale {lambda} = gM{sub Pl}, invisible to the low-energy effective field theorist, which sets a cutoff on the validity of the effective theory. Moreover, there is some light charged particle with mass smaller than or equal to {lambda}. The bound is motivated by arguments involving holography and absence of remnants, the (in) stability of black holes as well as the non-existence of global symmetries in string theory. A sharp form of the conjecture is that there are always light ''elementary'' electric and magnetic objects with a mass/charge ratio smaller than the corresponding ratio for macroscopic extremal black holes, allowing extremal black holes to decay. This conjecture is supported by a number of non-trivial examples in string theory. It implies the necessary presence of new physics beneath the Planck scale, not far from the GUT scale, and explains why some apparently natural models of inflation resist an embedding in string theory.
The String Landscape, Black Holes and Gravity as the Weakest Force
Arkani-Hamed, N; Nicolis, A; Vafa, C; Arkani-Hamed, Nima; Motl, Lubos; Nicolis, Alberto; Vafa, Cumrun
2007-01-01
We conjecture a general upper bound on the strength of gravity relative to gauge forces in quantum gravity. This implies, in particular, that in a four-dimensional theory with gravity and a U(1) gauge field with gauge coupling g, there is a new ultraviolet scale Lambda=g M_{Pl}, invisible to the low-energy effective field theorist, which sets a cutoff on the validity of the effective theory. Moreover, there is some light charged particle with mass smaller than or equal to Lambda. The bound is motivated by arguments involving holography and absence of remnants, the (in) stability of black holes as well as the non-existence of global symmetries in string theory. A sharp form of the conjecture is that there are always light "elementary" electric and magnetic objects with a mass/charge ratio smaller than the corresponding ratio for macroscopic extremal black holes, allowing extremal black holes to decay. This conjecture is supported by a number of non-trivial examples in string theory. It implies the necessary pr...
The string landscape, black holes and gravity as the weakest force
Arkani-Hamed, Nima; Motl, Luboš; Nicolis, Alberto; Vafa, Cumrun
2007-06-01
We conjecture a general upper bound on the strength of gravity relative to gauge forces in quantum gravity. This implies, in particular, that in a four-dimensional theory with gravity and a U(1) gauge field with gauge coupling g, there is a new ultraviolet scale Λ = gMPl, invisible to the low-energy effective field theorist, which sets a cutoff on the validity of the effective theory. Moreover, there is some light charged particle with mass smaller than or equal to Λ. The bound is motivated by arguments involving holography and absence of remnants, the (in) stability of black holes as well as the non-existence of global symmetries in string theory. A sharp form of the conjecture is that there are always light ``elementary'' electric and magnetic objects with a mass/charge ratio smaller than the corresponding ratio for macroscopic extremal black holes, allowing extremal black holes to decay. This conjecture is supported by a number of non-trivial examples in string theory. It implies the necessary presence of new physics beneath the Planck scale, not far from the GUT scale, and explains why some apparently natural models of inflation resist an embedding in string theory.
Setare, M. R.; Adami, H.
2016-09-01
We consider the Generalized Minimal Massive Gravity (GMMG) model in the first order formalism. We show that all the solutions of the Einstein gravity with negative cosmological constants solve the equations of motion of considered model. Then we find an expression for the off-shell conserved charges of this model. By considering the near horizon geometry of a three dimensional black hole in the Gaussian null coordinates, we find near horizon conserved charges and their algebra. The obtained algebra is centrally extended. By writing the algebra of conserved charges in terms of Fourier modes and considering the BTZ black hole solution as an example, one can see that the charge associated with rotations along Y0 coincides exactly with the angular momentum, and the charge associated with time translations T0 is the product of the black hole entropy and its temperature. As we expect, in the limit when the GMMG tends to the Einstein gravity, all the results we obtain in this paper reduce to the results of the paper [1].
Black holes in the TeVeS theory of gravity and their thermodynamics
Sagi, Eva
2007-01-01
TeVeS, a relativistic theory of gravity, was designed to provide a basis for the modified Newtonian dynamics. Since TeVeS differs from general relativity (e.g., it has two metrics, an Einstein metric and a physical metric), black hole solutions of it would be valuable for a number of endeavors ranging from astrophysical modeling to investigations into the interrelation between gravity and thermodynamics. Giannios has recently found a TeVeS analogue of the Schwarzschild black hole solution. We proceed further with the program by analytically solving the TeVeS equations for a static spherically symmetric and asymptotically flat system of electromagnetic and gravity fields. We show that one solution is provided by the Reissner-Nordstr\\" om metric as physical metric, the TeVeS vector field pointing in the time direction, and a TeVeS scalar field positive everywhere (the last feature protects from superluminal propagation of disturbances in the fields). We work out black hole thermodynamics in TeVeS using the phys...
Setare, M R
2016-01-01
We consider the Generalized Minimal Massive Gravity (GMMG) model in the first order formalism. We show that all the solutions of the Einstein gravity with negative cosmological constants solve the equations of motion of considered model. Then we find an expression for the off-shell conserved charges of this model. By considering the near horizon geometry of a three dimensional black hole in the Gaussian null coordinates, we find near horizon conserved charges and their algebra. The obtained algebra is centrally extended. By writing the algebra of conserved charges in terms of Fourier modes and considering the BTZ black hole solution as an example, one can see that the charge associated with rotations along $\\mathcal{Y}_{0}$ coincides exactly with the angular momentum, and he charge associated with time translations $\\mathcal{T}_{0}$ is the product of the black hole entropy and its temperature. As we expect, in the limit when the GMMG tends to the Einstein gravity, all the result we obtain in this paper reduce...
The evaporation spectrum of black holes from a local quantum gravity perspective
Barrau, Aurélien
2016-01-01
We revisit the hypothesis of a possible line structure in the Hawking evaporation spectrum of black holes, due to non-perturbative quantum gravity effects, even arbitrarily far away from the Planck mass. We show that this naive prediction might in fact hold in the specific context of loop quantum gravity, with a small departure from the ideal case for some low-spin transitions. We also show that the effect is neither washed out by the dynamics of the process, nor by existence of a mass spectrum up to a given width, nor by the secondary component induced by the decay of neutral pions emitted during the time-integrated evaporation.
Photon paths around hyperbolic topological black holes in conformal Weyl gravity
Olivares, Marco; Villanueva, J R
2016-01-01
In this research we find analytical solutions to the null geodesics around a hyperbolic topolical black hole in the conformal Weyl gravity. Exact expressions for the horizons are found, and they depend on the cosmological constant and the coupling constants of the conformal Weyl gravity. The angular motion is examined qualitatively by means of an effective potential; quantitatively, the equation of motion is solved in terms of $\\wp$-Weierstra{\\ss} elliptic function. Thus, we find the deflection angle for photons without using any approximation, which is a novel result for this topology.
De Sitter space versus Nariai Black Hole: stability in d5 higher derivative gravity
Nojiri, Shin'ichi; Odintsov, Sergei D.
2001-01-01
d5 higher derivative gravity on the Schwarzschild-de Sitter (SdS) black hole background is considered. Two horizons SdS BHs are not in thermal equilibrium and Hawking-Page phase transitions are not expected there, unlike to the case of AdS BHs. It is demonstrated that there exists the regime of d5 theory where Nariai BH which is extremal limit of SdS BH is stable. It is in the contrast with Einstein gravity on such backgroundwhere only pure de Sitter space is always stable. Speculating on the...
Hajdukovic, D
2006-01-01
We speculate about impact of antigravity (i.e. gravitational repulsion between matter and antimatter) on the creation and emission of particles by a black hole. If antigravity is present a black hole made of matter may radiate particles as a black body, but this shouldn't be true for antiparticles. It may lead to radical change of radiation process predicted by Hawking and should be taken into account in preparation of the attempt to create and study mini black holes at CERN. Gravity, including antigravity is more than ever similar to electrodynamics and such similarity with a successfully quantized interaction may help in quantization of gravity.
Mass Gap for Black-Hole Formation in Higher-Derivative and Ghost-Free Gravity.
Frolov, Valeri P
2015-07-31
We study a spherical gravitational collapse of a small mass in higher-derivative and ghost-free theories of gravity. By boosting a solution of linearized equations for a static point mass in such theories we obtain in the Penrose limit the gravitational field of an ultrarelativistic particle. Taking a superposition of such solutions we construct a metric of a collapsing null shell in the linearized higher-derivative and ghost-free gravity. The latter allows one to find the gravitational field of a thick null shell. By analyzing these solutions we demonstrate that in a wide class of the higher dimensional theories of gravity as well as for the ghost-free gravity there exists a mass gap for mini-black-hole production. We also found conditions when the curvature invariants remain finite at r=0 for the collapse of the thick null shell. PMID:26274408
Horowitz, Gary T.; Maldacena, Juan
2003-01-01
We propose that in quantum gravity one needs to impose a final state boundary condition at black hole singularities. This resolves the apparent contradiction between string theory and semiclassical arguments over whether black hole evaporation is unitary.
Testing models of supermassive black hole seed formation through gravity waves
Koushiappas, Savvas M.; Zentner, Andrew R.
2005-01-01
We study the gravitational wave background produced from the formation and assembly of supermassive black holes within the cosmological paradigm of hierarchical structure formation. In particular, we focus on a supermassive black hole formation scenario in which the present-day population of supermassive black holes is built from high-mass seed black holes and we compute the concomitant spectrum of gravitational radiation produced by mergers of the seed black holes. We find that this scenario...
Born-Infeld-de Sitter gravity: Cold, ultracold and Nariai black holes
Fernando, Sharmanthie
2013-01-01
In this paper, we have presented interesting properties of the static charged Born-Infeld-de Sitter black hole. They can have time-like as well as space-like singularities depending on the parameters of the theory. The degenerate black holes lead to cold, ultra cold and Nariai black holes. The geometry of such black holes are discussed. A comparison is done with the Reissner-Nordstrom-de Sitter black holes.
Blázquez-Salcedo, Jose Luis; Cardoso, Vitor; Ferrari, Valeria; Gualtieri, Leonardo; Khoo, Fech Scen; Kunz, Jutta; Pani, Paolo
2016-01-01
Gravitational waves emitted by distorted black holes---such as those arising from the coalescence of two neutron stars or black holes---carry not only information about the corresponding spacetime but also about the underlying theory of gravity. Although general relativity remains the simplest, most elegant and viable theory of gravitation, there are generic and robust arguments indicating that it is not the ultimate description of the gravitational universe. Here we focus on a particularly appealing extension of general relativity, which corrects Einstein's theory through the addition of terms which are second order in curvature: the topological Gauss-Bonnet invariant coupled to a dilaton. We study gravitational-wave emission from black holes in this theory, and (i) find strong evidence that black holes are linearly (mode) stable against both axial and polar perturbations; (ii) discuss how the quasinormal modes of black holes can be excited during collisions involving black holes, and finally (iii) show that...
New results on black hole entropy in loop quantum gravity
Fernández-Borja, Enrique
2009-01-01
En esta tesis se presentan los resultados obtenidos dentro del formalismo de la gravedad cuántica de bucles (Loop Quantum Gravity, LQG) sobre la entropía de agujeros negros. Como principal resultado se presenta el fenómeno de la discretización de la entropía. En este formalismo se encuentra que la relación entre entropía y área del horizonte del agujero negro se comporta como una función escalonada. Posteriormente se detalla el procedimiento de conteo de los estados cuánticos responsa...
Ma, Meng-Sen; Liu, Yan-Song
2016-01-01
On the basis of horizon thermodynamics we study the thermodynamic stability and $P-V$ criticality of topological black holes constructed in Ho\\v{r}ava-Lifshitz (HL) gravity without the detailed-balance condition (with general $\\epsilon$). In the framework of horizon thermodynamics, the temperature $T$ and pressure $P$ are independent quantities. It is not necessary to derive $T$ according to the metric function and $P$ according to any matter content. It is shown that the HL black hole for $k=0$ is always thermodynamically stable. For $k=1$, the temperature of HL black hole can be classified in five different cases. In one case, the thermodynamic behaviors of HL black hole is similar to that of Reissner- Nordstr\\"{o}m (RN) black hole. There are larger/smaller black hole phase transition and smaller/larger black hole phase transition in different cases. For $k=-1$, there are six cases for the temperature of HL black hole, in one of which the HL black hole exhibits itself like Schwarzschild-AdS black hole. It i...
Black holes in an asymptotically safe gravity theory with higher derivatives
International Nuclear Information System (INIS)
We present a class of spherically symmetric vacuum solutions to an asymptotically safe theory of gravity containing high-derivative terms. We find quantum corrected Schwarzschild-(anti)-de Sitter solutions with running gravitational coupling parameters. The evolution of the couplings is determined by their corresponding renormalization group flow equations. These black holes exhibit properties of a classical Schwarzschild solution at large length scales. At the center, the metric factor remains smooth but the curvature singularity, while softened by the quantum corrections, persists. The solutions have an outer event horizon and an inner Cauchy horizon which equate when the physical mass decreases to a critical value. Super-extremal solutions with masses below the critical value correspond to naked singularities. The Hawking temperature of the black hole vanishes when the physical mass reaches the critical value. Hence, the black holes in the asymptotically safe gravitational theory never completely evaporate. For appropriate values of the parameters such stable black hole remnants make excellent dark matter candidates
Thermodynamics of AdS Black Holes in Einstein-Scalar Gravity
Lu, H; Wen, Qiang
2014-01-01
We study the thermodynamics of $n$-dimensional static asymptotically AdS black holes in Einstein gravity coupled to a scalar field with a potential admitting a stationary point with an AdS vacuum. Such black holes with non-trivial scalar hair can exist provided that the mass-squared of the scalar field is negative, and above the Breitenlohner-Freedman bound. We use the Wald procedure to derive the first law of thermodynamics for these black holes, showing how the scalar hair (or charge) contributes non-trivially in the expression. We show in general that the black hole mass can be deduced by isolating an integrable contribution to the (non-integrable) variation of the Hamiltonian arising in the Wald construction, and that this is consistent with the mass calculated using the renormalised holographic stress tensor and also, in those cases where it is defined, with the mass calculated using the conformal method of Ashtekar, Magnon and Das. Similar arguments can also be given for the smooth solitonic solutions i...
International Nuclear Information System (INIS)
The energy content of the Lee-Kim-Myung slowly-rotating black hole (Lee et al., Eur. Phys. J. C 70, 361 (2010)), in the Horava-Lifshitz (HL) theory of gravity is investigated by using approximate Lie symmetry methods for differential equations. The energy of this slowly-rotating black hole in the HL gravity is found to be is rescaled by a r-dependent factor. From the rescaling of energy, the rotation is observed to be added to the mass of the black hole, and this effect decreases with increasing coordinate r. This expression of energy rescaling reduces to the Schwarzschild mass for the limits in which the Lee-Kim-Myung slowly rotating black hole solution in the HL gravity reduces to the Schwarzschild solution in general relativity.
Chakraborty, Sumanta
2015-04-01
The hydrodynamic behavior of perfect fluid orbiting around black holes in spherically symmetric spacetime for various alternative gravity theories has been investigated. For this purpose we have assumed a uniform distribution for the angular momentum density of the rotating perfect fluid. The contours of equipotential surfaces are illustrated in order to obtain the nature of inflow and outflow of matter. It has been noticed that the marginally stable circular orbits originating from decreasing angular momentum density lead to closed equipotential surfaces along with cusps, allowing the existence of accretion disks. On the other hand, the growing part of the angular momentum density exhibits central rings for which stable configurations are possible. However, inflow of matter is prohibited. Among the solutions discussed in this work, the charged F(R) gravity and Einstein-Maxwell-Gauss-Bonnet solutions exhibit inflow and outflow of matter with central rings present. These varied accretion disk structures of perfect fluid attribute astrophysical importance to these spacetimes. The effect of higher curvature terms predominantly arises from the region near the black hole horizon. Hence the structural difference of the accretion disk in modified gravity theories in comparison to general relativity may act as an experimental probe for these alternative gravity theories.
Self-dual black holes in loop quantum gravity: Theory and phenomenology
International Nuclear Information System (INIS)
In this paper we have recalled the semiclassical metric obtained from a classical analysis of the loop quantum black hole (LQBH). We show that the regular Reissner-Nordstroem-like metric is self-dual in the sense of T-duality: the form of the metric obtained in loop quantum gravity is invariant under the exchange r→a0/r where a0 is proportional to the minimum area in loop quantum gravity and r is the standard Schwarzschild radial coordinate at asymptotic infinity. Of particular interest, the symmetry imposes that if an observer in r→+∞ sees a black hole of mass m an observer in the other asymptotic infinity beyond the horizon (at r≅0) sees a dual mass mP/m. We then show that small LQBH are stable and could be a component of dark matter. Ultralight LQBHs created shortly after the big bang would now have a mass of approximately 10-5mP and emit radiation with a typical energy of about 1013-1014 eV but they would also emit cosmic rays of much higher energies, albeit few of them. If these small LQBHs form a majority of the dark matter of the Milky Way's Halo, the production rate of ultra-high-energy-cosmic-rays (UHECR) by these ultralight black holes would be compatible with the observed rate of the Auger detector.
P-V Criticality of Topological Black Holes in Lovelock-Born-Infeld Gravity
Mo, Jie-Xiong
2014-01-01
To understand the effect of third order Lovelock gravity, $P-V$ criticality of topological AdS black holes in Lovelock-Born-Infeld gravity is investigated. The thermodynamics is further explored with some more extensions and details than the former literature. A detailed analysis of the limit case $\\beta\\rightarrow\\infty$ is performed for the seven-dimensional black holes. It is shown that for the spherical topology, $P-V$ criticality exists for both the uncharged and charged cases. Our results demonstrate again that the charge is not the indispensable condition of $P-V$ criticality. It may be attributed to the effect of higher derivative terms of curvature because similar phenomenon was also found for Gauss-Bonnet black holes. For $k=0$, there would be no $P-V$ criticality. Interesting findings occur in the case $k=-1$, in which positive solutions of critical points are found for both the uncharged and charged cases. However, the $P-v$ diagram is quite strange. To check whether these findings are physical, w...
International Nuclear Information System (INIS)
We study black hole formation in a model of two dimensional dilaton gravity and 24 massless scalar fields with a boundary. We find the most general boundary condition consistent with perfect reflection of matter and the constraints. We show that in the semiclassical approximation and for the generic value of a parameter which characterizes the boundary conditions, the boundary starts receding to infinity at the speed of light whenever the total energy of the incoming matter flux exceeds a certain critical value. This is also the critical energy which marks the onset of black hole formation. We then compute the quantum fluctuations of the boundary and of the rescaled scalar curvature and show that as soon as the incoming energy exceeds this critical value, and asymptotic observer using normal time resolutions will always measure large quantum fluctuations of space-time near the horizon, even though the freely falling observer does not. This is an aspect of black hole complementarity relating directly to quantum gravity effects. (author). 30 refs, 4 figs
Critical behavior of charged black holes in Gauss-Bonnet gravity's rainbow
Hendi, Seyed Hossein; Panahiyan, Shahram; Eslam Panah, Behzad; Faizal, Mir; Momennia, Mehrab
2016-07-01
Following an earlier study regarding Gauss-Bonnet-Maxwell black holes in the presence of gravity's rainbow [S. H. Hendi and M. Faizal, Phys. Rev. D 92, 044027 (2015)], in this paper, we consider all constants as energy dependent ones. The geometrical and thermodynamical properties of this generalization is studied and the validation of the first law of thermodynamics is examined. Next, through the use of proportionality between the cosmological constant and the thermodynamical pressure, van der Waals-like behavior of these black holes in extended phase space is investigated. An interesting critical behavior for sets of rainbow functions in this case is reported. Also, the critical behavior of uncharged and charged solutions is analyzed and it is shown that the generalization to a charged case puts an energy dependent restriction on values of different parameters.
Finsler black holes induced by noncommutative anholonomic distributions in Einstein gravity
International Nuclear Information System (INIS)
We study Finsler black holes induced from Einstein gravity as possible effects of quantum spacetime noncommutativity. Such Finsler models are defined by nonholonomic frames not on tangent bundles but on (pseudo)Riemannian manifolds being compatible with standard theories of physics. We focus on noncommutative deformations of Schwarzschild metrics into locally anisotropic stationary ones with spherical/rotoid symmetry. The conditions are derived when black hole configurations can be extracted from two classes of exact solutions depending on noncommutative parameters. The first class of metrics is defined by nonholonomic deformations of the gravitational vacuum by noncommutative geometry. The second class of such solutions is induced by noncommutative matter fields and/or effective polarizations of cosmological constants.
Symmetry reduction in twisted noncommutative gravity with applications to cosmology and black holes
International Nuclear Information System (INIS)
As a preparation for a mathematically consistent study of the physics of symmetric spacetimes in a noncommutative setting, we study symmetry reductions in deformed gravity. We focus on deformations that are given by a twist of a Lie algebra acting on the spacetime manifold. We derive conditions on those twists that allow a given symmetry reduction. A complete classification of admissible deformations is possible in a class of twists generated by commuting vector fields. As examples, we explicitly construct the families of vector fields that generate twists which are compatible with Friedmann-Robertson-Walker cosmologies and Schwarzschild black holes, respectively. We find nontrivial isotropic twists of FRW cosmologies and nontrivial twists that are compatible with all classical symmetries of black hole solutions.
Finsler black holes induced by noncommutative anholonomic distributions in Einstein gravity
Energy Technology Data Exchange (ETDEWEB)
Vacaru, Sergiu I, E-mail: sergiu.vacaru@uaic.r, E-mail: Sergiu.Vacaru@gmail.co [Science Department, University ' Al. I. Cuza' Iasi, 54 Lascar Catargi street, 700107 Iasi (Romania)
2010-05-21
We study Finsler black holes induced from Einstein gravity as possible effects of quantum spacetime noncommutativity. Such Finsler models are defined by nonholonomic frames not on tangent bundles but on (pseudo)Riemannian manifolds being compatible with standard theories of physics. We focus on noncommutative deformations of Schwarzschild metrics into locally anisotropic stationary ones with spherical/rotoid symmetry. The conditions are derived when black hole configurations can be extracted from two classes of exact solutions depending on noncommutative parameters. The first class of metrics is defined by nonholonomic deformations of the gravitational vacuum by noncommutative geometry. The second class of such solutions is induced by noncommutative matter fields and/or effective polarizations of cosmological constants.
Finsler black holes induced by noncommutative anholonomic distributions in Einstein gravity
Vacaru, Sergiu I.
2010-05-01
We study Finsler black holes induced from Einstein gravity as possible effects of quantum spacetime noncommutativity. Such Finsler models are defined by nonholonomic frames not on tangent bundles but on (pseudo)Riemannian manifolds being compatible with standard theories of physics. We focus on noncommutative deformations of Schwarzschild metrics into locally anisotropic stationary ones with spherical/rotoid symmetry. The conditions are derived when black hole configurations can be extracted from two classes of exact solutions depending on noncommutative parameters. The first class of metrics is defined by nonholonomic deformations of the gravitational vacuum by noncommutative geometry. The second class of such solutions is induced by noncommutative matter fields and/or effective polarizations of cosmological constants.
Rotating black holes in Einstein-Dilaton-Gauss-Bonnet gravity with finite coupling
Maselli, Andrea; Gualtieri, Leonardo; Ferrari, Valeria
2015-01-01
Among various strong-curvature extensions to General Relativity, Einstein-Dilaton-Gauss-Bonnet gravity stands out as the only nontrivial theory containing quadratic curvature corrections while being free from the Ostrogradsky instability to any order in the coupling parameter. We derive an approximate stationary and axisymmetric black-hole solution of this gravitational theory in closed form, which is quadratic in the black-hole spin angular momentum and of seventh order in the coupling parameter of the theory. This extends previous work that obtained the corrections to the metric only at the leading order in the coupling parameter, and allows us to consider values of the coupling parameter close to the maximum permitted by theoretical constraints. We compute some geometrical properties of this solution, such as the dilaton charge, the moment of inertia and the quadrupole moment, and its geodesic structure, including the innermost-stable circular orbit and the epicyclic frequencies for massive particles. The ...
Gravitational signature of Schwarzschild black holes in dynamical Chern-Simons gravity
International Nuclear Information System (INIS)
Dynamical Chern-Simons gravity is an extension of general relativity in which the gravitational field is coupled to a scalar field through a parity-violating Chern-Simons term. In this framework, we study perturbations of spherically symmetric black hole spacetimes, assuming that the background scalar field vanishes. Our results suggest that these spacetimes are stable, and small perturbations die away as a ringdown. However, in contrast to standard general relativity, the gravitational waveforms are also driven by the scalar field. Thus, the gravitational oscillation modes of black holes carry imprints of the coupling to the scalar field. This is a smoking gun for Chern-Simons theory and could be tested with gravitational-wave detectors, such as LIGO or LISA. For negative values of the coupling constant, ghosts are known to arise, and we explicitly verify their appearance numerically. Our results are validated using both time evolution and frequency domain methods.
Black Holes in AdS/BCFT and Fluid/Gravity Correspondence
Magán, Javier M; Silva, Madson R O
2014-01-01
A proposal to describe gravity duals of conformal theories with boundaries (AdS/BCFT correspondence) was put forward by Takayanagi few years ago. However interesting solutions describing field theories at finite temperature and charge density are still lacking. In this paper we describe a class of theories with boundary, which admit black hole type gravity solutions. The theories are specified by stress-energy tensors that reside on the extensions of the boundary to the bulk. From this perspective AdS/BCFT appears analogous to the fluid/gravity correspondence. Among the class of the boundary extensions there is a special (integrable) one, for which the stress-energy tensor is fluid-like. We discuss features of that special solution as well as its thermodynamic properties.
Einstein-Born-Infeld-Massive Gravity: adS-Black Hole Solutions and their Thermal Stability
Hendi, Seyed Hossein; Panahiyan, Shahram
2015-01-01
In this paper, we study massive gravity in the presence of Born-Infeld nonlinear electrodynamics. First, we obtain metric function related to this gravity and investigate the geometry of the solutions and find that there is an essential singularity at the origin ($r=0$). It will be shown that due to contribution of the massive part, the number, types and places of horizons may be changed. Next, we calculate the conserved and thermodynamic quantities and check the validation of the first law of thermodynamics. We also investigate thermal stability of these black holes in context of canonical ensemble. It will be shown that number, type and place of phase transitions points are functions of the different parameters which lead to dependency of stability conditions to these parameters. Also, it will be shown how the behavior of the temperature is modified due to extension of massive gravity and strong nonlinearity parameter.
Reissner–Nordström Anti-de Sitter Black Holes in Mimetic F(R) Gravity
Oikonomou, V. K.
2016-05-01
In this paper we study under which conditions the Reissner-Nordstr\\"om-anti de Sitter black hole can be a solution of the vacuum mimetic $F(R)$ gravity with Lagrange multiplier and mimetic scalar potential. As we demonstrate, the resulting picture in the mimetic $F(R)$ gravity case, is different in comparison to the ordinary $F(R)$ gravity case, with the two descriptions resulting to a different set of constraints that need to hold true. We also investigate the metric perturbations in the mimetic $F(R)$ gravity case, for the Reissner-Nordstr\\"om-anti de Sitter black hole metric, at first order of the perturbed variables. Interestingly enough, the resulting equations are identical to the ones corresponding to the ordinary $F(R)$ gravity Reissner-Nordstr\\"om-anti de Sitter black hole, at least at first order. We attribute this feature to the particular form of the Reissner-Nordstr\\"om-anti de Sitter metric, and we speculate for which cases there could be differences between the mimetic and non-mimetic case. Since the perturbation equations are the same for the two cases, it is possible to have black hole instabilities in the mimetic $F(R)$ gravity case too, which can be interpreted as anti-evaporation of the black hole.
Stimulated Black Hole Evaporation
Spaans, Marco
2016-01-01
Black holes are extreme expressions of gravity. Their existence is predicted by Einstein's theory of general relativity and is supported by observations. Black holes obey quantum mechanics and evaporate spontaneously. Here it is shown that a mass rate $R_f\\sim 3\\times 10^{-8} (M_0/M)^{1/2}$ $M_0$ yr$^{-1}$ onto the horizon of a black hole with mass $M$ (in units of solar mass $M_0$) stimulates a black hole into rapid evaporation. Specifically, $\\sim 3 M_0$ black holes can emit a large fraction of their mass, and explode, in $M/R_f \\sim 3\\times 10^7 (M/M_0)^{3/2}$ yr. These stimulated black holes radiate a spectral line power $P \\sim 2\\times 10^{39} (M_0/M)^{1/2}$ erg s$^{-1}$, at a wavelength $\\lambda \\sim 3\\times 10^5 (M/M_0)$ cm. This prediction can be observationally verified.
Reissner–Nordström Anti-de Sitter Black Holes in Mimetic F(R Gravity
Directory of Open Access Journals (Sweden)
V. K. Oikonomou
2016-05-01
Full Text Available In this paper, we study under which conditions the Reissner–Nordström anti-de Sitter black hole can be a solution of the vacuum mimetic F ( R gravity with Lagrange multiplier and mimetic scalar potential. As the author demonstrates, the resulting picture in the mimetic F ( R gravity case is a trivial extension of the standard F ( R approach, and in effect, the metric perturbations in the mimetic F ( R gravity case, for the Reissner–Nordström anti-de Sitter black hole metric, at the first order of the perturbed variables are the same at the leading order.
Ahn, Eun-Joo; Cavaglia, Marco
2003-01-01
Production of high-energy gravitational objects is a common feature of gravitational theories. The primordial universe is a natural setting for the creation of black holes and other nonperturbative gravitational entities. Cosmic black holes can be used to probe physical properties of the very early universe which would usually require the knowledge of the theory of quantum gravity. They may be the only tool to explore thermalisation of the early universe. Whereas the creation of cosmic black ...
AdS and dS black hole solutions in analogue gravity: The relativistic and non-relativistic cases
Dey, Ramit; Turcati, Rodrigo
2016-01-01
We show that Schwarzschild black hole solutions in asymptotically Anti-de Sitter (AdS) and de Sitter (dS) spaces may, up to a conformal factor, be reproduced in the framework of analogue gravity. The aforementioned derivation is performed using relativistic and non-relativistic Bose-Einstein condensates. In addition, we demonstrate that the (2+1) planar AdS black hole can be mapped into the non-relativistic acoustic metric. Given that AdS black holes are extensively employed in the gauge/gravity duality, we then comment on the possibility to study the AdS/CFT correspondence and gravity/fluid duality from an analogue gravity perspective.
International Nuclear Information System (INIS)
Belief in the existence of black holes is the ultimate act of faith for a physicist. First suggested by the English clergyman John Michell in the year 1784, the gravitational pull of a black hole is so strong that nothing - not even light - can escape. Gravity might be the weakest of the fundamental forces but black-hole physics is not for the faint-hearted. Black holes present obvious problems for would-be observers because they cannot, by definition, be seen with conventional telescopes - although before the end of the decade gravitational-wave detectors should be able to study collisions between black holes. Until then astronomers can only infer the existence of a black hole from its gravitational influence on other matter, or from the X-rays emitted by gas and dust as they are dragged into the black hole. However, once this material passes through the 'event horizon' that surrounds the black hole, we will never see it again - not even with X-ray specs. Despite these observational problems, most physicists and astronomers believe that black holes do exist. Small black holes a few kilometres across are thought to form when stars weighing more than about two solar masses collapse under the weight of their own gravity, while supermassive black holes weighing millions of solar masses appear to be present at the centre of most galaxies. Moreover, some brave physicists have proposed ways to make black holes - or at least event horizons - in the laboratory. The basic idea behind these 'artificial black holes' is not to compress a large amount of mass into a small volume, but to reduce the speed of light in a moving medium to less than the speed of the medium and so create an event horizon. The parallels with real black holes are not exact but the experiments could shed new light on a variety of phenomena. The first challenge, however, is to get money for the research. One year on from a high-profile meeting on artificial black holes in London, for instance, the UK
Black Holes in Higher Dimensions
Directory of Open Access Journals (Sweden)
Reall Harvey S.
2008-09-01
Full Text Available We review black-hole solutions of higher-dimensional vacuum gravity and higher-dimensional supergravity theories. The discussion of vacuum gravity is pedagogical, with detailed reviews of Myers–Perry solutions, black rings, and solution-generating techniques. We discuss black-hole solutions of maximal supergravity theories, including black holes in anti-de Sitter space. General results and open problems are discussed throughout.
Black hole and de Sitter solutions in a covariant renormalizable field theory of gravity
Cognola, G; Sebastiani, L; Zerbini, S
2010-01-01
It is shown that Schwarzschild black hole and de Sitter solutions exist as exact solutions of a recently proposed relativistic covariant formulation of (power-counting) renormalizable gravity with a fluid. The formulation without a fluid is also presented here. The stability of the solutions is studied and their corresponding entropies are computed, by using the covariant Wald method. The area law is shown to hold both for the Schwarzschild and for the de Sitter solutions found, confirming that, for the $\\beta=1$ case, one is dealing with a minimal modification of GR.
Bouncing black holes in quantum gravity and the Fermi gamma-ray excess
Barrau, Aurélien; Schutten, Marrit; Vidotto, Francesca
2016-01-01
Non-perturbative quantum-gravity effects can change the fate of black holes and make them bounce in a time scale shorter than the Hawking evaporation time. In this article, we show that this hypothesis can account for the GeV excess observed from the galactic center by the Fermi satellite. By carefully taking into account the secondary component due to the decay of unstable hadrons, we show that the model is fully self-consistent. This phenomenon presents a specific redshift-dependance that could allow to distinguish it from other astrophysical phenomena possibly contributing to the GeV excess.
(Anti-) de Sitter Black Holes in higher derivative gravity and dual Conformal Field Theories
Nojiri, Shin'ichi; Odintsov, Sergei D.
2002-01-01
Thermodynamics of five-dimensional Schwarzschild Anti-de Sitter (SAdS) and SdS black holes in the particular model of higher derivative gravity is considered. The free energy, mass (thermodynamical energy) and entropy are evaluated. There exists the parameters region where BH entropy is zero or negative. The arguments are given that corresponding BH solutions are not stable. We also present the FRW-equations of motion of time (space)-like branes in SAdS or SdS BH background. The properties of...
Gravitational waves from quasicircular black-hole binaries in dynamical Chern-Simons gravity.
Yagi, Kent; Yunes, Nicolás; Tanaka, Takahiro
2012-12-21
Dynamical Chern-Simons gravity cannot be strongly constrained with current experiments because it reduces to general relativity in the weak-field limit. This theory, however, introduces modifications in the nonlinear, dynamical regime, and thus it could be greatly constrained with gravitational waves from the late inspiral of black-hole binaries. We complete the first self-consistent calculation of such gravitational waves in this theory. For favorable spin orientations, advanced ground-based detectors may improve existing solar system constraints by 6 orders of magnitude. PMID:23368447
Exact Schwarzschild-de Sitter black holes in a family of massive gravity models
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The Schwarzschild-de Sitter and Reissner-Nordstroem-de Sitter black hole metrics appear as exact solutions in the recently formulated massive gravity of de Rham, Gabadadze and Tolley, where the mass term sets the curvature scale. They occur within a two-parameter family of de Rham, Gabadadze and Tolley mass terms. They show no trace of a cloud of scalar graviton modes, and in the limit of vanishing graviton mass they go smoothly to the Schwarzschild and Reissner-Nordstroem metrics.
Miskovic, Olivera
2010-01-01
Motivated by possible applications within the framework of anti-de Sitter gravity/Conformal Field Theory (AdS/CFT) correspondence, charged black holes with AdS asymptotics, which are solutions to Einstein-Gauss-Bonnet gravity in D dimensions, and whose electric field is described by a nonlinear electrodynamics (NED) are studied. For a topological static black hole ansatz, the field equations are exactly solved in terms of the electromagnetic stress tensor for an arbitrary NED Lagrangian, in any dimension D and for arbitrary positive values of Gauss-Bonnet coupling. In particular, this procedure reproduces the black hole metric in Born-Infeld and conformally invariant electrodynamics previously found in the literature. Altogether, it extends to D>4 the four-dimensional solution obtained by Soleng in logarithmic electrodynamics, which comes from vacuum polarization effects. Fall-off conditions for the electromagnetic field that ensure the finiteness of the electric charge are also discussed. The black hole mass...
Instabilities and anti-evaporation of Reissner–Nordström black holes in modified F(R) gravity
International Nuclear Information System (INIS)
We study the instabilities and related anti-evaporation of the extremal Reissner–Nordström (RN) black hole in F(R) gravity. It is remarkable that the effective electric charge can be generated for some solutions of F(R) gravity without electromagnetic field. The anti-evaporation effect occurs but it emerges only in the strong coupling limit of the effective gravitational coupling. The instabilities of RN black hole are also investigated when the electromagnetic sector is added to the action of F(R) gravity. We show the anti-evaporation occurs in the Maxwell-F(R) gravity with the arbitrary gravitational coupling constant although it does not occur in the Maxwell–Einstein gravity. Furthermore, general spherically-symmetric solution of F(R) gravity in the Einstein frame is obtained
Indian Academy of Sciences (India)
Koustubh Ajit Kabe
2012-09-01
In the following paper, certain black hole dynamic potentials have been developed definitively on the lines of classical thermodynamics. These potentials have been refined in view of the small differences in the equations of the laws of black hole dynamics as given by Bekenstein and those of thermodynamics. Nine fundamental black hole dynamical relations have been developed akin to the four fundamental thermodynamic relations of Maxwell. The specific heats , and , have been defined. For a black hole, these quantities are negative. The d equation has been obtained as an application of these fundamental relations. Time reversible processes observing constancy of surface gravity are considered and an equation connecting the internal energy of the black hole , the additional available energy defined as the first free energy function , and the surface gravity , has been obtained. Finally as a further application of the fundamental relations, it has been proved for a homogeneous gravitational field in black hole space times or a de Sitter black hole that $C_{\\Omega,\\Phi}-C_{J,Q}=\\kappa \\left[\\left(\\dfrac{\\partial J}{\\partial \\kappa}\\right)_{\\Omega,\\Phi}\\left(\\dfrac{\\partial \\Omega}{\\partial \\kappa}\\right)_{J,Q}+\\left(\\dfrac{\\partial Q}{\\partial \\kappa}\\right)_{\\Omega,\\Phi}\\left(\\dfrac{\\partial\\Phi}{\\partial \\kappa}\\right)_{J,Q}\\right]$. This is dubbed as the homogeneous fluid approximation in context of the black holes.
General parametrization of axisymmetric black holes in metric theories of gravity
Konoplya, Roman; Rezzolla, Luciano; Zhidenko, Alexander
2016-03-01
Following previous work of ours in spherical symmetry, we here propose a new parametric framework to describe the spacetime of axisymmetric black holes in generic metric theories of gravity. In this case, the metric components are functions of both the radial and the polar angular coordinates, forcing a double expansion to obtain a generic axisymmetric metric expression. In particular, we use a continued-fraction expansion in terms of a compactified radial coordinate to express the radial dependence, while we exploit a Taylor expansion in terms of the cosine of the polar angle for the polar dependence. These choices lead to a superior convergence in the radial direction and to an exact limit on the equatorial plane. As a validation of our approach, we build parametrized representations of Kerr, rotating dilaton, and Einstein-dilaton-Gauss-Bonnet black holes. The match is already very good at lowest order in the expansion and improves as new orders are added. We expect a similar behavior for any stationary and axisymmetric black-hole metric.
Rotating black holes in Einstein-dilaton-Gauss-Bonnet gravity with finite coupling
Maselli, Andrea; Pani, Paolo; Gualtieri, Leonardo; Ferrari, Valeria
2015-10-01
Among various strong-curvature extensions of general relativity, Einstein-dilaton-Gauss-Bonnet gravity stands out as the only nontrivial theory containing quadratic curvature corrections while being free from the Ostrogradsky instability to any order in the coupling parameter. We derive an approximate stationary and axisymmetric black hole solution of this gravitational theory in closed form, which is of fifth order in the black hole spin and of seventh order in the coupling parameter of the theory. This extends previous work that obtained the corrections to the metric only to second order in the spin and at the leading order in the coupling parameter, and allows us to consider values of the coupling parameter close to the maximum permitted by theoretical constraints. We compute some quantities which characterize this solution, such as the dilaton charge, the moment of inertia, and the quadrupole moment, and its geodesic structure, including the innermost stable circular orbit and the epicyclic frequencies for massive particles. The latter provides a valuable tool to test general relativity against strong-curvature corrections through observations of the electromagnetic spectrum of accreting black holes.
Das, S R; Sumit R Das; Sudipta Mukherji
1994-01-01
We study black hole formation in a model of two dimensional dilaton gravity and $24$ massless scalar fields with a boundary. We find the most general boundary condition consistent with perfect reflection of matter and the constraints. We show that in the semiclassical approximation and for the generic value of a parameter which characterizes the boundary conditions, the boundary starts receeding to infinity at the speed of light whenever the {\\it total} energy of the incoming matter flux exceeds a certain critical value. This is also the critical energy which marks the onset of black hole formation. We then compute the quantum fluctuations of the boundary and of the rescaled scalar curvature and show that as soon as the incoming energy exceeds this critical value, an asymptotic observer using normal time resolutions will always measure large quantum fluctuations of space-time near the {\\it horizon}, even though the freely falling observer does not. This is an aspect of black hole complementarity relating dire...
Microscopic entropy of the three-dimensional rotating black hole of BHT massive gravity
Giribet, Gaston; Tempo, David; Troncoso, Ricardo
2009-01-01
Asymptotically AdS rotating black holes for the Bergshoeff-Hohm-Townsend (BHT) massive gravity theory in three dimensions are considered. In the special case when the theory admits a unique maximally symmetric solution, apart from the mass and the angular momentum, the black hole is described by an independent "gravitational hair" parameter, which provides a negative lower bound for the mass. This bound is saturated at the extremal case and, since the temperature and the semiclassical entropy vanish, it is naturally regarded as the ground state. The absence of a global charge associated with the gravitational hair parameter reflects through the first law of thermodynamics in the fact that the variation of this parameter can be consistently reabsorbed by a shift of the global charges, giving further support to consider the extremal case as the ground state. The rotating black hole fits within relaxed asymptotic conditions as compared with the ones of Brown and Henneaux, such that they are invariant under the s...
El-Menoufi, Basem Kamal
2016-05-01
In the context of effective field theory, we consider quantum gravity with minimally coupled massless particles. Fixing the background geometry to be of the Kerr-Schild type, we fully determine the one-loop effective action of the theory whose finite non-local part is induced by the long-distance portion of quantum loops. This is accomplished using the non-local expansion of the heat kernel in addition to a non-linear completion technique through which the effective action is expanded in gravitational curvatures. Via Euclidean methods, we identify a logarithmic correction to the Bekenstein-Hawking entropy of Schwarzschild black hole. Using dimensional transmutation the result is shown to exhibit an interesting interplay between the UV and IR properties of quantum gravity.
International Nuclear Information System (INIS)
In this paper, we study static vacuum solutions of quantum gravity at a fixed Lifshitz point in (2+1) dimensions, and present all the diagonal solutions in closed forms in the infrared limit. The exact solutions represent spacetimes with very rich structures: they can represent generalized BTZ black holes, Lifshitz space-times or Lifshitz solitons, in which the spacetimes are free of any kind of space-time singularities, depending on the choices of the free parameters of the solutions. We also find several classes of exact static non-diagonal solutions, which represent similar space-time structures as those given in the diagonal case. The relevance of these solutions to the non-relativistic Lifshitz-type gauge/gravity duality is discussed
Joshi, Pankaj S
2015-01-01
This book journeys into one of the most fascinating intellectual adventures of recent decades - understanding and exploring the final fate of massive collapsing stars in the universe. The issue is of great interest in fundamental physics and cosmology today, from both the perspective of gravitation theory and of modern astrophysical observations. This is a revolution in the making and may be intimately connected to our search for a unified understanding of the basic forces of nature, namely gravity that governs the cosmological universe, and the microscopic forces that include quantum phenomena. According to the general theory of relativity, a massive star that collapses catastrophically under its own gravity when it runs out of its internal nuclear fuel must give rise to a space-time singularity. Such singularities are regions in the universe where all physical quantities take their extreme values and become arbitrarily large. The singularities may be covered within a black hole, or visible to faraway observ...
De Sitter space versus Nariai Black Hole stability in d5 higher derivative gravity
Nojiri, S; Nojiri, Shin'ichi; Odintsov, Sergei D.
2001-01-01
d5 higher derivative gravity on the Schwarzschild-de Sitter (SdS) black hole background is considered. Two horizons SdS BHs are not in thermal equilibrium and Hawking-Page phase transitions are not expected there, unlike to the case of AdS BHs. It is demonstrated that there exists the regime of d5 theory where Nariai BH which is extremal limit of SdS BH is stable. It is in the contrast with Einstein gravity on such backgroundwhere only pure de Sitter space is always stable. Speculating on the applications in proposed dS/CFT correspondence, these two (de Sitter and Nariai) stable spaces may correspond to confining-deconfining phases in dual CFT.
International Nuclear Information System (INIS)
Black hole dominance, assumed to be a fairly ubiquitous feature of any theory of quantum gravity, amounts to that any observer trying to perform a localized experiment on ever smaller length scales will ultimately be thwarted by the formation of a trapped surface within the spatial domain of the experiment. The argument based on Thorne's hoop conjecture, conjointly leads to a fundamental length scale in physics. Black hole dominance also suggests that ordinary field theory cannot be used to describe quantum gravity in the extreme UV, contrary to implications of asymptotic safety. We re-examine black hole dominance in an asymptotically safe scenario, in the presence of higher curvature terms an with running couplings, by modifying a proof of Thorne's hoop conjecture. We find that the proof falls apart, and along with it, so does the argument for a mandatory formation of a trapped surface inside the domain of the experiment. However, neither is there a contrary proof that local trapped surfaces do not form. Instead in this approach whether an observer can perform local measurements in arbitrary small regions of spacetime depends on the specific values of the couplings near the UV fixed point. In this sense there is no all pervasive local version of the minimal length argument. However, we argue that one trapped surface must still form outside an experiment, when the domain of this experiment is localized to scales much smaller than the Planck length. This enshrouding horizon then prevents any information from reaching observers at infinity, thus retaining a vestige of 'asymptotic darkness' for them.
P -V criticality in the extended phase space of black holes in massive gravity
Xu, Jianfei; Cao, Li-Ming; Hu, Ya-Peng
2015-06-01
We study the P -V criticality and phase transition in the extended phase space of charged anti-de Sitter black holes in canonical ensemble of ghost-free massive gravity, where the cosmological constant is viewed as a dynamical pressure of the black hole system. We give the generalized thermodynamic first law and the Smarr relation with massive gravity correction. We find that not only when the horizon topology is spherical but also in the Ricci flat or hyperbolic case, there appear the P -V criticality and phase transition up to the combination k +c02c2m2 in the four-dimensional case, where k characterizes the horizon curvature and c2m2 is the coefficient of the second term of massive potential associated with the graviton mass. The positivity of such combination indicate the van der Waals-like phase transition. When the spacetime dimension is larger then four, the Maxwell charge there seems unnecessary for the appearance of critical behavior, but a infinite repulsion effect needed, which can also be realized through negative valued c3m2 or c4m2 , which is third or fourth term of massive potential. When c3m2 is positive, a Hawking-Page-like black hole to vacuum phase transition is shown in the five-dimensional chargeless case. For the van der Waals-like phase transition in four and five spacetime dimensions, we calculate the critical exponents near the critical point and find they are the same as those in the van der Waals liquid-gas system.
Analytic continuation of real Loop Quantum Gravity : Lessons from black hole thermodynamics
Achour, Jibril Ben
2015-01-01
This contribution is devoted to summarize the recent results obtained in the construction of an "analytic continuation" of Loop Quantum Gravity (LQG). By this, we mean that we construct analytic continuation of physical quantities in LQG from real values of the Barbero-Immirzi parameter $\\gamma$ to the purely imaginary value $\\gamma = \\pm i$. This should allow us to define a quantization of gravity with self-dual Ashtekar variables. We first realized in [1] that this procedure, when applied to compute the entropy of a spherical black hole in LQG for $\\gamma=\\pm i$, allows to reproduce exactly the Bekenstein-Hawking area law at the semi-classical limit. The rigorous construction of the analytic continuation of spherical black hole entropy has been done in [2]. Here, we start with a review of the main steps of this construction: we recall that our prescription turns out to be unique (under natural assumptions) and leads to the right semi-classical limit with its logarithmic quantum corrections. Furthermore, the...
Conserved charges of black holes in Weyl and Einstein-Gauss-Bonnet gravities
International Nuclear Information System (INIS)
An off-shell generalization of the Abbott-Deser-Tekin (ADT) conserved charge was recently proposed by Kim et al. They achieved this by introducing off-shell Noether currents and potentials. In this paper, we construct the crucial off-shell Noether current by the variation of the Bianchi identity for the expression of EOM, with the help of the property of Killing vector. Our Noether current, which contains an additional term that is just one half of the Lie derivative of a surface term with respect to the Killing vector, takes a different form in comparison with the one in their work. Then we employ the generalized formulation to calculate the quasi-local conserved charges for the most general charged spherically symmetric and the dyonic rotating black holes with AdS asymptotics in four-dimensional conformal Weyl gravity, as well as the charged spherically symmetric black holes in arbitrary dimensional Einstein-Gauss-Bonnet gravity coupled to Maxwell or nonlinear electrodynamics in AdS spacetime. Our results confirm those obtained through other methods in the literature. (orig.)
Conserved charges of black holes in Weyl and Einstein-Gauss-Bonnet gravities
Energy Technology Data Exchange (ETDEWEB)
Peng, Jun-Jin [SEEE, Wuhan Textile University, Institute of Technical Physics, Wuhan, Hubei (China); Chinese Academy of Sciences, Kavli Institute for Theoretical Physics China, Institute of Theoretical Physics, P.O. Box 2735, Beijing (China)
2014-11-15
An off-shell generalization of the Abbott-Deser-Tekin (ADT) conserved charge was recently proposed by Kim et al. They achieved this by introducing off-shell Noether currents and potentials. In this paper, we construct the crucial off-shell Noether current by the variation of the Bianchi identity for the expression of EOM, with the help of the property of Killing vector. Our Noether current, which contains an additional term that is just one half of the Lie derivative of a surface term with respect to the Killing vector, takes a different form in comparison with the one in their work. Then we employ the generalized formulation to calculate the quasi-local conserved charges for the most general charged spherically symmetric and the dyonic rotating black holes with AdS asymptotics in four-dimensional conformal Weyl gravity, as well as the charged spherically symmetric black holes in arbitrary dimensional Einstein-Gauss-Bonnet gravity coupled to Maxwell or nonlinear electrodynamics in AdS spacetime. Our results confirm those obtained through other methods in the literature. (orig.)
P-V criticality in the extended phase space of black holes in massive gravity
Xu, Jianfei; Hu, Ya-Peng
2015-01-01
We study the P-V criticality and phase transition in the extended phase space of charged anti-de Sitter black holes in canonical ensemble of ghost-free massive gravity, where the cosmological constant is viewed as a dynamical pressure of the black hole system. We give the generalized thermodynamic first law and the Smarr relation with massive gravity correction. We find that not only when the horizon topology is spherical but also in the Ricci flat or hyperbolic case, there appear the P-V criticality and phase transition up to the combination k+c02c2m2 in the four-dimensional case, where k characterizes the horizon curvature and c2m2 is the coefficient of the second term of massive potential associated with the graviton mass. The positivity of such combination indicate the van der Waals-like phase transition. When the spacetime dimension is larger then four, the Maxwell charge there seems unnecessary for the appearance of critical behavior, but a infinite repulsion effect needed, which can also be realized th...
Zangeneh, M. Kord; Dehyadegari, A.; Sheykhi, A.; Dehghani, M. H.
2016-03-01
In this paper, we construct a new class of topological black hole Lifshitz solutions in the presence of nonlinear exponential electrodynamics for Einstein-dilaton gravity. We show that the reality of Lifshitz supporting Maxwell matter fields exclude the negative horizon curvature solutions except for the asymptotic AdS case. Calculating the conserved and thermodynamical quantities, we obtain a Smarr type formula for the mass and confirm that thermodynamics first law is satisfied on the black hole horizon. Afterward, we study the thermal stability of our solutions and figure out the effects of different parameters on the stability of solutions under thermal perturbations. Next, we apply the gauge/gravity duality in order to calculate the ratio of shear viscosity to entropy for a three-dimensional hydrodynamic system by using the pole method. Furthermore, we study the behavior of holographic conductivity for two-dimensional systems such as graphene. We consider linear Maxwell and nonlinear exponential electrodynamics separately and disclose the effect of nonlinearity on holographic conductivity. We indicate that holographic conductivity vanishes for z > 3 in the case of nonlinear electrodynamics while it does not in the linear Maxwell case. Finally, we solve perturbative additional field equations numerically and plot the behaviors of real and imaginary parts of conductivity for asymptotic AdS and Lifshitz cases. We present experimental results match with our numerical ones.
International Nuclear Information System (INIS)
No particle theory can be complete without gravity. Einstein's theory of gravity is of the Euler-Lagrange form, but standard quantization procedure fails. In quantum gravity the higher order interactions have a dimensionality different form the fundamental ones, because Newton's constant G has dimensions and the renormalization procedure fails. Another problem with quantum gravity is even more mysterious. Suppose that we had regularized the gravitational forces at the small distance end in the way that the weak intermediate vector boson regularized the fundamental 4-fermion interaction vertex of the weak interactions. Then what we discover is that the gravitational forces are unstable. Given sufficiently large amount of matter, it can collapse under its own weight. Classical general relativity tells us what will happen: a black hole is formed. But how is this formulated in quantum theory. S. Hawking observed that when a field theory is quantized in the background metric of a black hole, the black hole actually emits particles in a completely random thermal way. Apparently black holes are just another form of matter unstable against Hawking decay. Unfortunately this picture cannot be complete. The problem is that the quantum version of black holes has infinite phase space, and other symptoms of a run-away solution. Black holes are the heaviest and most compact forms of matter that can be imagined. A complete particle theory can have nothing but a spectrum of black-hole like objects at it high-energy end. This is why it is believed that a resolution of the black hole problem will in time disclose the complete small-distance structure of our world. 6 references
Noncommutative Solitonic Black Hole
Chang-Young, Ee; Lee, Daeho; Lee, Youngone
2012-01-01
We investigate solitonic black hole solutions in three dimensional noncommutative spacetime. We do this in gravity with negative cosmological constant coupled to a scalar field using the Moyal product expanded up to first order in the noncommutativity parameter in the two noncommutative spatial directions. By numerical simulation we look for black hole solutions by increasing the non- commutativity parameter value starting from regular solutions with vanishing noncommutativity. We find that even a regular soliton solution in the commutative case becomes a black hole solution when the noncommutativity parameter reaches a certain value.
Hayward, Sean Alan
2013-01-01
Black holes, once just fascinating theoretical predictions of how gravity warps space-time according to Einstein's theory, are now generally accepted as astrophysical realities, formed by post-supernova collapse, or as supermassive black holes mysteriously found at the cores of most galaxies, powering active galactic nuclei, the most powerful objects in the universe. Theoretical understanding has progressed in recent decades with a wider realization that local concepts should characterize black holes, rather than the global concepts found in textbooks. In particular, notions such as trapping h
Prospects for probing strong gravity with a pulsar-black hole system
Wex, N; Eatough, R P; Kramer, M; Cordes, J M; Lazio, T J W
2012-01-01
The discovery of a pulsar (PSR) in orbit around a black hole (BH) is expected to provide a superb new probe of relativistic gravity and BH properties. Apart from a precise mass measurement for the BH, one could expect a clean verification of the dragging of space-time caused by the BH spin. In order to measure the quadrupole moment of the BH for testing the no-hair theorem of general relativity (GR), one has to hope for a sufficiently massive BH. In this respect, a PSR orbiting the super-massive BH in the center of our Galaxy would be the ultimate laboratory for gravity tests with PSRs. But even for gravity theories that predict the same properties for BHs as GR, a PSR-BH system would constitute an excellent test system, due to the high grade of asymmetry in the strong field properties of these two components. Here we highlight some of the potential gravity tests that one could expect from different PSR-BH systems, utilizing present and future radio telescopes, like FAST and SKA.
Prospects for Probing Strong Gravity with a Pulsar-Black Hole System
Wex, N.; Liu, K.; Eatough, R. P.; Kramer, M.; Cordes, J. M.; Lazio, T. J. W.
2012-01-01
The discovery of a pulsar (PSR) in orbit around a black hole (BH) is expected to provide a superb new probe of relativistic gravity and BH properties. Apart from a precise mass measurement for the BH, one could expect a clean verification of the dragging of space-time caused by the BH spin. In order to measure the quadrupole moment of the BH for testing the no-hair theorem of general relativity (GR), one has to hope for a sufficiently massive BH. In this respect, a PSR orbiting the super-massive BH in the center of our Galaxy would be the ultimate laboratory for gravity tests with PSRs. But even for gravity theories that predict the same properties for BHs as GR, a PSR-BH system would constitute an excellent test system, due to the high grade of asymmetry in the strong field properties of these two components. Here we highlight some of the potential gravity tests that one could expect from different PSR-BH systems.
Einstein-Born-Infeld-massive gravity: adS-black hole solutions and their thermodynamical properties
Hendi, S. H.; Panah, B. Eslam; Panahiyan, S.
2015-11-01
In this paper, we study massive gravity in the presence of Born-Infeld nonlinear electrodynamics. First, we obtain metric function related to this gravity and investigate the geometry of the solutions and find that there is an essential singularity at the origin ( r = 0). It will be shown that due to contribution of the massive part, the number, type and place of horizons may be changed. Next, we calculate the conserved and thermodynamic quantities and check the validation of the first law of thermodynamics. We also investigate thermal stability of these black holes in context of canonical ensemble. It will be shown that number, type and place of phase transition points are functions of different parameters which lead to dependency of stability conditions to these parameters. Also, it will be shown how the behavior of temperature is modified due to extension of massive gravity and strong nonlinearity parameter. Next, critical behavior of the system in extended phase space by considering cosmological constant as pressure is investigated. A study regarding neutral Einstein-massive gravity in context of extended phase space is done. Geometrical approach is employed to study the thermodynamical behavior of the system in context of heat capacity and extended phase space. It will be shown that GTs, heat capacity and extended phase space have consistent results. Finally, critical behavior of the system is investigated through use of another method. It will be pointed out that the results of this method is in agreement with other methods and follow the concepts of ordinary thermodynamics.
Hidden Conformal Symmetry of Self-Dual Warped AdS_3 Black Holes in Topological Massive Gravity
Li, Ran; Ren, Ji-Rong
2010-01-01
We consider the hidden conformal symmetry of the self-dual warped $AdS_3$ black holes in topological massive gravity. It is shown that the wave equation of massive scalar field propagating in the self-dual warped $AdS_3$ black hole background can be reproduced by the Casimir operator of $SL_L(2, R)\\times SL_R(2, R)$ Lie algebra, which implies that self-dual warped $AdS_3$ black hole is holographically dual to a two dimensional conformal field theory with the left temperature $T_L=\\frac{\\alpha}{2\\pi}$ and the right temperature $T_R=\\frac{x_+-x_-}{4\\pi}$. Furthermore, we find the entropy of conformal field given by the Cardy formula matches exactly with the Bekenstein-Hawking entropy of self-dual warped $AdS_3$ black hole.
Effect of vacuum energy on evolution of primordial black holes in Einstein gravity
International Nuclear Information System (INIS)
We study the evolution of primordial black holes by considering present universe is no more matter dominated rather vacuum energy dominated. We also consider the accretion of radiation, matter and vacuum energy during respective dominance period. In this scenario, we found that radiation accretion efficiency should be less than 0.366 and accretion rate is much larger than previous analysis by Nayak et al. (2009) . Thus here primordial black holes live longer than previous works Nayak and Singh (2011). Again matter accretion slightly increases the mass and lifetime of primordial black holes. However, the vacuum energy accretion is slightly complicated one, where accretion is possible only up to a critical time. If a primordial black hole lives beyond critical time, then its' lifespan increases due to vacuum energy accretion. But for presently evaporating primordial black holes, critical time comes much later than their evaporating time and thus vacuum energy could not affect those primordial black holes.
Testing quantum gravity effects through Dyonic charged AdS black hole
Sadeghi, J.; Pourhassan, B.; Rostami, M.
2016-01-01
In this paper, we consider dyonic charged AdS black hole which is holographic dual of a van der Waals fluid. We use logarithmic corrected entropy and study thermodynamics of the black hole and show that holographic picture is still valid. Critical behaviors and stability also discussed. Logarithmic corrections arises due to thermal fluctuations which are important when size of black hole be small. So, thermal fluctuations interpreted as quantum effect. It means that we can see quantum effect ...
Thermodynamics of Phantom Energy Accreting onto a Black Hole in Einstein-Power-Maxwell Gravity
Abbas, G.
2013-01-01
In this paper, we investigate the phantom energy accretion onto 3D black hole formulated in Einstein-Power-Maxwell theory. We have presented the conditions for critical accretion of phantom energy onto black hole. Further, we discuss the thermodynamics of phantom energy accreting onto black hole and found that first law of thermodynamics is easily satisfied while second law and generalized second law of thermodynamics remain invalid and conditionally valid, respectively. The results for BTZ b...
Stability of the Schwarzschild black hole in f(R) gravity with the dynamical Chern-Simons term
International Nuclear Information System (INIS)
We perform the stability analysis of the Schwarzschild black hole in f(R) gravity with the parity-violating Chern-Simons (CS) term coupled to a dynamical scalar field θ. For this purpose, we transform the f(R) gravity into the scalar-tensor theory by introducing a scalaron φ, providing the dynamical CS modified gravity with two scalars. The perturbation equation for the scalar θ is coupled to the odd-parity metric perturbation equation, providing a system of two coupled second-order equations, while the scalaron is coupled to the even-parity perturbation equation. This implies that the CS coupling affects the Regge-Wheeler equation, while f(R) gravity does not affect the Zerilli equation. It turns out that the Schwarzschild black hole is stable against the external perturbations if the scalaron is free from the tachyon.
Two aspects of black hole entropy in Lanczos-Lovelock models of gravity
Kolekar, Sanved; Kothawala, Dawood; Padmanabhan, T.
2012-03-01
We consider two specific approaches to evaluate the black hole entropy which are known to produce correct results in the case of Einstein’s theory and generalize them to Lanczos-Lovelock models. In the first approach (which could be called extrinsic), we use a procedure motivated by earlier work by Pretorius, Vollick, and Israel, and by Oppenheim, and evaluate the entropy of a configuration of densely packed gravitating shells on the verge of forming a black hole in Lanczos-Lovelock theories of gravity. We find that this matter entropy is not equal to (it is less than) Wald entropy, except in the case of Einstein theory, where they are equal. The matter entropy is proportional to the Wald entropy if we consider a specific mth-order Lanczos-Lovelock model, with the proportionality constant depending on the spacetime dimensions D and the order m of the Lanczos-Lovelock theory as (D-2m)/(D-2). Since the proportionality constant depends on m, the proportionality between matter entropy and Wald entropy breaks down when we consider a sum of Lanczos-Lovelock actions involving different m. In the second approach (which could be called intrinsic), we generalize a procedure, previously introduced by Padmanabhan in the context of general relativity, to study off-shell entropy of a class of metrics with horizon using a path integral method. We consider the Euclidean action of Lanczos-Lovelock models for a class of metrics off shell and interpret it as a partition function. We show that in the case of spherically symmetric metrics, one can interpret the Euclidean action as the free energy and read off both the entropy and energy of a black hole spacetime. Surprisingly enough, this leads to exactly the Wald entropy and the energy of the spacetime in Lanczos-Lovelock models obtained by other methods. We comment on possible implications of the result.
Hennigar, Robie A; Tjoa, Erickson
2016-01-01
We present what we believe is the first example of a "$\\lambda$-line" phase transition in black hole thermodynamics. This is a line of (continuous) second order phase transitions which in the case of liquid $^4$He marks the onset of superfluidity. The phase transition occurs for a class of asymptotically AdS hairy black holes in Lovelock gravity where a real scalar field is conformally coupled to gravity. We discuss the origin of this phase transition and outline the circumstances under which it (or generalizations of it) could occur.
A new cubic theory of gravity in five dimensions: black hole, Birkhoff's theorem and C-function
Energy Technology Data Exchange (ETDEWEB)
Oliva, Julio [Instituto de Fisica, Facultad de Ciencias, Universidad Austral de Chile, Valdivia (Chile); Ray, Sourya, E-mail: julio.oliva@docentes.uach.c, E-mail: ray@cecs.c [Centro de Estudios CientIficos (CECS), Casilla 1469, Valdivia (Chile)
2010-11-21
We present a new cubic theory of gravity in five dimensions which has second-order traced field equations, analogous to BHT new massive gravity in three dimensions. Moreover, for static spherically symmetric spacetimes all the field equations are of second order, and the theory admits a new asymptotically locally flat black hole. Furthermore, we prove the uniqueness of this solution, study its thermodynamical properties and show the existence of a C-function for the theory following the arguments of Anber and Kastor (2008 J. High Energy Phys. JHEP05(2008)061 (arXiv:0802.1290 [hep-th])) in pure Lovelock theories. Finally, we include the Einstein-Gauss-Bonnet and cosmological terms and find new asymptotically AdS black holes at the point where the three maximally symmetric solutions of the theory coincide. These black holes may also possess a Cauchy horizon.
New class of rotating perfect fluid black holes in three dimensional gravity
Energy Technology Data Exchange (ETDEWEB)
Wu, Bin [Nankai University, School of Physics, Tianjin (China); Xu, Wei [Nankai University, School of Physics, Tianjin (China); Huazhong University of Science and Technology, School of Physics, Wuhan (China)
2014-08-15
We obtain a new class of rotating black holes for Einstein theory with perfect fluid source in (2 + 1) dimensions. We conclude that these black hole solutions only depend on the variable of the angular velocity m(r). Some examples of these black holes are given explicitly. In particular, an unknown static black hole in this special background is obtained. In addition, the general properties including the horizon structure, energy conditions and equation of state, mass, and angular momentum are explained in detail. (orig.)
Thermodynamics and phase transition of black hole in an asymptotically safe gravity
International Nuclear Information System (INIS)
We study the effects of quantum gravitational correction on the thermodynamics of black holes in the asymptotic safety scenario. Owing to the quantum-corrected Schwarzschild metric, the thermodynamic quantities are also corrected and a Hawking–Page-type phase transition may exist. We also employ the concept of thermodynamic geometry to the black hole to characterize the phase transition. By introducing a cavity enclosing the black hole, we apply the spatially finite boundary conditions to further investigate the thermodynamic phase transition of the black hole. It is shown that the larger and small black holes are both locally stable according to heat capacity. According to free energy, we find that the quantum-corrected black hole has similar thermodynamic phase structure to that of RN–AdS black hole. In addition, we also discuss the possibility of the phase transition between the black hole and the hot curved space. Above a certain temperature T0, the black hole is more probable than the hot space
New class of rotating perfect fluid black holes in three dimensional gravity
International Nuclear Information System (INIS)
We obtain a new class of rotating black holes for Einstein theory with perfect fluid source in (2 + 1) dimensions. We conclude that these black hole solutions only depend on the variable of the angular velocity m(r). Some examples of these black holes are given explicitly. In particular, an unknown static black hole in this special background is obtained. In addition, the general properties including the horizon structure, energy conditions and equation of state, mass, and angular momentum are explained in detail. (orig.)
International Nuclear Information System (INIS)
The black hole information paradox forces us into a strange situation: we must find a way to break the semiclassical approximation in a domain where no quantum gravity effects would normally be expected. Traditional quantizations of gravity do not exhibit any such breakdown, and this forces us into a difficult corner: either we must give up quantum mechanics or we must accept the existence of troublesome ‘remnants’. In string theory, however, the fundamental quanta are extended objects, and it turns out that the bound states of such objects acquire a size that grows with the number of quanta in the bound state. The interior of the black hole gets completely altered to a ‘fuzzball’ structure, and information is able to escape in radiation from the hole. The semiclassical approximation can break at macroscopic scales due to the large entropy of the hole: the measure in the path integral competes with the classical action, instead of giving a subleading correction. Putting this picture of black hole microstates together with ideas about entangled states leads to a natural set of conjectures on many long-standing questions in gravity: the significance of Rindler and de Sitter entropies, the notion of black hole complementarity, and the fate of an observer falling into a black hole. - Highlights: ► The information paradox is a serious problem. ► To solve it we need to find ‘hair’ on black holes. ► In string theory we find ‘hair’ by the fuzzball construction. ► Fuzzballs help to resolve many other issues in gravity.
Self-accelerating cosmologies and hairy black holes in ghost-free bigravity and massive gravity
International Nuclear Information System (INIS)
We present a survey of the known cosmological and black hole solutions in ghost-free bigravity and massive gravity theories. These can be divided into three classes. First, there are solutions with proportional metrics, which are the same as in General Relativity with a cosmological term, which can be positive, negative or zero. Secondly, for spherically symmetric systems, there are solutions with non-bidiagonal metrics. The g-metric fulfils Einstein equations with a positive cosmological term and a matter source, while the f-metric is anti-de Sitter. The third class contains solutions with bidiagonal metrics, and these can be quite complex. The time-dependent solutions describe homogeneous (isotropic or anisotropic) cosmologies which show a late-time self-acceleration or other types of behavior. The static solutions describe black holes with a massive graviton hair, and also globally regular lumps of energy. None of these are asymptotically flat. Including a matter source gives rise to asymptotically flat solutions which exhibit the Vainshtein mechanism of recovery of General Relativity in a finite region. (paper)
General parametrization of axisymmetric black holes in metric theories of gravity
Konoplya, Roman; Zhidenko, Alexander
2016-01-01
Following previous work of ours in spherical symmetry, we here propose a new parametric framework to describe the spacetime of axisymmetric black holes in generic metric theories of gravity. In this case, the metric components are functions of both the radial and the polar angular coordinates, forcing a double expansion to obtain a generic axisymmetric metric expression. In particular, we use a continued-fraction expansion in terms of a compactified radial coordinate to express the radial dependence, while we exploit a Taylor expansion in terms of the cosine of the polar angle for the polar dependence. These choices lead to a superior convergence in the radial direction and to an exact limit on the equatorial plane. As a validation of our approach, we build parametrized representations of Kerr, rotating dilaton, and Einstein-dilaton-Gauss-Bonnet black holes. The match is already very good at lowest order in the expansion and improves as new orders are added. We expect a similar behavior for any stationary and...
Warped solitonic deformations and propagation of black holes in 5D vacuum gravity
International Nuclear Information System (INIS)
In this paper we use the anholonomic frames method to construct exact solutions for vacuum 5D gravity with metrics having off-diagonal components. The solutions are, in general, anisotropic and possess interesting features such as an anisotropic warp factor with respect to the extra dimension, or a gravitational scaling/running of some of the physical parameters associated with the solutions. A certain class of solutions is found to describe Schwarzschild black holes which 'solitonically' propagate in spacetime. The solitonic character of these black-hole solutions arises from the embedding of the sine-Gordon soliton configuration into certain ansatz functions of the 5D metric. These solitonic solutions may either violate or preserve local Lorentz invariance. In addition, there is a connection between these solutions and non-commutative field theory. In addition to the possible physical applications of the solutions presented here, this paper is meant to illustrate the strength of the anholonomic frames method in handling anisotropic solutions of the gravitational field equations
Asymptotically flat black holes and gravitational waves in three-dimensional massive gravity
Troessaert, Cédric; Troncoso, Ricardo
2015-01-01
Different classes of exact solutions for the BHT massive gravity theory are constructed and analyzed. We focus in the special case of the purely quadratic Lagrangian, whose field equations are irreducibly of fourth order and are known to admit asymptotically locally flat black holes endowed with gravitational hair. The first class corresponds to a Kerr-Schild deformation of Minkowski spacetime along a covariantly constant null vector. As in the case of General Relativity, the field equations linearize so that the solution can be easily shown to be described by four arbitrary functions of a single null coordinate. These solutions can be regarded as a new sort of pp-waves. The second class is obtained from a deformation of the static asymptotically locally flat black hole, that goes along the spacelike (angular) Killing vector. Remarkably, although the deformation is not of Kerr-Schild type, the field equations also linearize, and hence the generic solution can be readily integrated. It is neither static nor sp...
Two Aspects of Black hole entropy in Lanczos-Lovelock models of gravity
Kolekar, Sanved; Padmanabhan, T
2011-01-01
We consider two specific approaches to evaluate the black hole entropy which are known to produce correct results in the case of Einstein's theory and generalize them to Lanczos-Lovelock models. In the first approach (which could be called extrinsic) we use a procedure motivated by earlier work by Pretorius, Vollick and Israel, and by Oppenheim, and evaluate the entropy of a configuration of densely packed gravitating shells on the verge of forming a black hole in Lanczos-Lovelock theories of gravity. We find that this matter entropy is not equal to (it is less than) Wald entropy, except in the case of Einstein theory, where they are equal. The matter entropy is proportional to the Wald entropy if we consider a specific m-th order Lanczos-Lovelock model, with the proportionality constant depending on the spacetime dimensions D and the order m of the Lanczos-Lovelock theory as (D-2m)/(D-2). Since the proportionality constant depends on m, the proportionality between matter entropy and Wald entropy breaks down ...
Partition functions for quantum gravity, black holes, elliptic genera and Lie algebra homologies
International Nuclear Information System (INIS)
There is a remarkable connection between quantum generating functions of field theory and formal power series associated with dimensions of chains and homologies of suitable Lie algebras. We discuss the homological aspects of this connection with its applications to partition functions of the minimal three-dimensional gravities in the space-time asymptotic to AdS3, which also describe the three-dimensional Euclidean black holes, the pure N=1 supergravity, and a sigma model on N-fold generalized symmetric products. We also consider in the same context elliptic genera of some supersymmetric sigma models. These examples can be considered as a straightforward application of the machinery of modular forms and spectral functions (with values in the congruence subgroup of SL(2,Z)) to partition functions represented by means of formal power series that encode Lie algebra properties.
Rotating black hole solution in a generalized topological 3D gravity with torsion
International Nuclear Information System (INIS)
A first order version of topological massive gravity is achieved by liberating its translational gauge degrees of freedom. In three dimensions, our Lagrangian consists of Chern-Simons (CS) terms for curvature and torsion inducing an effective cosmological constant dynamically, whereas a 'mixed' CS term is substituting for the topological related Einstein-Cartan action. Anti-de Sitter and rotating black hole configurations are exact vacuum solutions. They also apply to a large class of Yang-Mills-type generalizations including 'exotic' terms exclusively permitted in 3D. The reason for this can be partially traced back to a new strong/weak duality of the translational and rotational dynamical degrees of freedom
Generalisation for regular black holes on general relativity to f( R) gravity
Rodrigues, Manuel E.; Fabris, Júlio C.; Junior, Ednaldo L. B.; Marques, Glauber T.
2016-05-01
In this paper, we determine regular black hole solutions using a very general f( R) theory, coupled to a non-linear electromagnetic field given by a Lagrangian L_NED. The functions f( R) and L_NED are in principle left unspecified. Instead, the model is constructed through a choice of the mass function M( r) presented in the metric coefficients. Solutions which have a regular behaviour of the geometric invariants are found. These solutions have two horizons, the event horizon and the Cauchy horizon. All energy conditions are satisfied in the whole space-time, except the strong energy condition (SEC), which is violated near the Cauchy horizon. We present also a new theorem related to the energy conditions in f( R) gravity, re-obtaining the well-known conditions in the context of general relativity when the geometry of the solution is the same.
The black hole and FRW geometries of non-relativistic gravity
Kehagias, Alex
2009-01-01
We consider the recently proposed non-relativistic Ho\\v{r}ava-Lifshitz four-dimensional theory of gravity. We study a particular limit of the theory which admits flat Minkowski vacuum and we discuss thoroughly the quadratic fluctuations around it. We find that there are two propagating polarizations of the metric. We then explicitly construct a spherically symmetric, asymptotically flat, black hole solution that represents the analog of the Schwarzschild solution of GR. We show that this theory has the same Newtonian and post-Newtonian limits as GR and thus, it passes the classical tests. We also consider homogeneous and isotropic cosmological solutions and we show that although the equations are identical with GR cosmology, the couplings are constrained by the observed primordial abundance of ${}^4{\\rm He}$.
The black hole and FRW geometries of non-relativistic gravity
International Nuclear Information System (INIS)
We consider the recently proposed non-relativistic Horava-Lifshitz four-dimensional theory of gravity. We study a particular limit of the theory which admits flat Minkowski vacuum and we discuss thoroughly the quadratic fluctuations around it. We find that there are two propagating polarizations of the metric. We then explicitly construct a spherically symmetric, asymptotically flat, black hole solution that represents the analog of the Schwarzschild solution of GR. We show that this theory has the same Newtonian and post-Newtonian limits as GR and thus, it passes the classical tests. We also consider homogeneous and isotropic cosmological solutions and we show that although the equations are identical with GR cosmology, the couplings are constrained by the observed primordial abundance of 4He.
Black hole critical phenomena without black holes
Indian Academy of Sciences (India)
Steven L Liebling
2000-10-01
Studying the threshold of black hole formation via numerical evolution has led to the discovery of fascinating nonlinear phenomena. Power-law mass scaling, aspects of universality, and self-similarity have now been found for a large variety of models. However, questions remain. Here I brieﬂy review critical phenomena, discuss some recent results, and describe a model which demonstrates similar phenomena without gravity.
Effect of Vacuum Energy on Evolution of Primordial Black Holes in Einstein Gravity
Nayak, Bibekananda
2011-01-01
We study the evolution of primordail black holes by considering present universe is no more matter dominated rather vacuum energy dominated. We also consider the accretion of radiation, matter and vacuum energy during respective dominance period. In this scenario, we found that radiation accretion efficiency should be less than 0.366 and accretion rate is much larger than previous analysis by B. Nayak et al. \\cite{ns}. Thus here primordial black holes live longer than previous works \\cite{ns}. Again matter accretion slightly increases the mass and lifetime of primordial black holes. However, the vacuum energy accretion is slightly complicated one, where accretion is possible only upto a critical time. This critical time depends on the values of accretion efficiency and formation time. If a primordial black hole lives beyond critical time, then its lifespan increases due to vacuum energy accretion. But for presently evaporating primordial black holes, critical time comes much later than their evaporating time ...
New perspective for black hole thermodynamics in Gauss-Bonnet-Born-Infeld massive gravity
Hendi, Seyed Hossein; Mo, Jie-Xiong; Panahiyan, Shahram; Panah, Behzad Eslam
2016-01-01
Following earlier study regarding Einstein-Gauss-Bonnet-massive black holes in the presence of Born-Infeld nonlinear electromagnetic field [S. H. Hendi, B. Eslam Panah and S. Panahiyan, arXiv:1510.00108], we study thermodynamical structure and critical behavior of these black holes through different methods in this paper. Geometrical thermodynamics is employed to give a picture regarding phase transition of these black holes. Next, a new method is used to derive critical pressure and horizon radius of these black holes. In addition, Maxwell equal area law is employed to study the Van der Waals like behavior of these black holes. Moreover, the critical exponents are calculated and by using Ehrenfest equations, the type of the phase transitions are determined.
Applications of gauge/gravity dualities with charged Anti-de Sitter black holes
Energy Technology Data Exchange (ETDEWEB)
Grass, Viviane Theresa
2010-05-17
In this thesis, we deal with different applications of the Anti-de Sitter/Conformal Field Theory (AdS/CFT) correspondence. The AdS/CFT correspondence, which is also more generally referred to as gauge/gravity duality, is a conjectured duality in superstring theory between strongly-coupled four-dimensional N=4 superconformal Yang-Mills theory and weakly-coupled type IIB string theory in five-dimensional AdS spacetime. This duality provides a powerful method to investigate strongly-coupled low-energy systems in four dimensions by substitutionally carrying out calculations in five-dimensional weakly-coupled supergravity. In this work, we use the AdS/CFT correspondence to explore three different strongly-coupled systems, namely a brane world accommodating a strongly-coupled field theory, a strongly-coupled fluid on a three-sphere and a strongly-coupled p-wave superfluid. In all these cases, the dual supergravity descriptions involve charged AdS black holes. The first system studied here is a Randall-Sundrum brane world moving in the background of a five-dimensional non-extremal black hole of N=2 gauged supergravity. The equations of motion of the brane are found to be equal to the Friedmann-Robertson-Walker (FRW) equations for a closed universe. The closed brane universe has special thermodynamic properties. The energy of the brane field theory exhibits a subextensive Casimir contribution, and the entropy can be expressed as a Cardy-Verlinde-type formula. We show that the equations for both quantities can take forms that strongly resemble the two FRW equations. At the horizon of the black hole, these two sets of equations are shown to even merge with each other which might suggest the existence of a common underlying theory. In addition, as a by-product result, the non-extremal black hole solutions considered here are found to admit an alternative description in terms of first-order flow equations similar to those which are well-known from the attractor mechanism of
Applications of gauge/gravity dualities with charged Anti-de Sitter black holes
International Nuclear Information System (INIS)
In this thesis, we deal with different applications of the Anti-de Sitter/Conformal Field Theory (AdS/CFT) correspondence. The AdS/CFT correspondence, which is also more generally referred to as gauge/gravity duality, is a conjectured duality in superstring theory between strongly-coupled four-dimensional N=4 superconformal Yang-Mills theory and weakly-coupled type IIB string theory in five-dimensional AdS spacetime. This duality provides a powerful method to investigate strongly-coupled low-energy systems in four dimensions by substitutionally carrying out calculations in five-dimensional weakly-coupled supergravity. In this work, we use the AdS/CFT correspondence to explore three different strongly-coupled systems, namely a brane world accommodating a strongly-coupled field theory, a strongly-coupled fluid on a three-sphere and a strongly-coupled p-wave superfluid. In all these cases, the dual supergravity descriptions involve charged AdS black holes. The first system studied here is a Randall-Sundrum brane world moving in the background of a five-dimensional non-extremal black hole of N=2 gauged supergravity. The equations of motion of the brane are found to be equal to the Friedmann-Robertson-Walker (FRW) equations for a closed universe. The closed brane universe has special thermodynamic properties. The energy of the brane field theory exhibits a subextensive Casimir contribution, and the entropy can be expressed as a Cardy-Verlinde-type formula. We show that the equations for both quantities can take forms that strongly resemble the two FRW equations. At the horizon of the black hole, these two sets of equations are shown to even merge with each other which might suggest the existence of a common underlying theory. In addition, as a by-product result, the non-extremal black hole solutions considered here are found to admit an alternative description in terms of first-order flow equations similar to those which are well-known from the attractor mechanism of
International Nuclear Information System (INIS)
General consensus on the nature of the degrees of freedom responsible for the black hole entropy remains elusive despite decades of effort dedicated to the problem. Different approaches to quantum gravity disagree in their description of the microstates and, more significantly, in the statistics used to count them. In some approaches (string theory, AdS/CFT) the elementary degrees of freedom are indistinguishable, whereas they must be treated as distinguishable in other approaches to quantum gravity (eg., LQG) in order to recover the Bekenstein-Hawking area-entropy law. However, different statistics will imply different behaviors of the black hole outside the thermodynamic limit. We illustrate this point by quantizing the Bañados-Teitelboim-Zanelli (BTZ) black hole, for which we argue that Bose condensation will occur leading to a cold, stable remnant
Vaz, Cenalo; Wijewardhana, L. C. R.
2013-12-01
General consensus on the nature of the degrees of freedom responsible for the black hole entropy remains elusive despite decades of effort dedicated to the problem. Different approaches to quantum gravity disagree in their description of the microstates and, more significantly, in the statistics used to count them. In some approaches (string theory, AdS/CFT) the elementary degrees of freedom are indistinguishable, whereas they must be treated as distinguishable in other approaches to quantum gravity (eg., LQG) in order to recover the Bekenstein-Hawking area-entropy law. However, different statistics will imply different behaviors of the black hole outside the thermodynamic limit. We illustrate this point by quantizing the Bañados-Teitelboim-Zanelli (BTZ) black hole, for which we argue that Bose condensation will occur leading to a "cold", stable remnant.
International Nuclear Information System (INIS)
We derive general formulae for the first-order variation of the ADM mass and angular momentum for the linear perturbations of a stationary background in Einstein-Maxwell axion-dilaton gravity which is the low-energy limit of the heterotic string theory. All these variations were expressed in terms of the perturbed matter energy-momentum tensor and the perturbed charge current density. Combining these expressions, we reached at the form of the physical process version of the first law of black-hole dynamics for the stationary black holes in the considered theory which is a strong support for the cosmic censorship hypothesis
Jusufi, Kimet
2016-01-01
In this paper we study the quantum tunneling of charged and magnetized particles (magnetic monopoles) from the global monopole black hole by incorporating the quantum gravity effects. Starting from the modified Maxwell's equations and Generalized Uncertainty Relation (GUP), we recover the GUP corrected temperate for the global monopole black hole by solving the modified Dirac equation via Hamilton-Jacobi method. Furthermore, we also include the quantum corrections beyond the semiclassical approximation, in particular, first we find the logarithmic corrections of GUP corrected entropy and finally we calculate the GUP corrected specific heat capacity.
Reissner–Nordström Anti-de Sitter Black Holes in Mimetic F(R) Gravity
Oikonomou, V. K.
2016-01-01
In this paper, we study under which conditions the Reissner–Nordström anti-de Sitter black hole can be a solution of the vacuum mimetic F ( R ) gravity with Lagrange multiplier and mimetic scalar potential. As the author demonstrates, the resulting picture in the mimetic F ( R ) gravity case is a trivial extension of the standard F ( R ) approach, and in effect, the metric perturbations in the mimetic F ( R ) gravity case, for the Reissner–Nordström anti-de Sit...
Reissner–Nordström Anti-de Sitter Black Holes in Mimetic F(R) Gravity
Oikonomou, V.K.
2016-01-01
In this paper we study under which conditions the Reissner-Nordstr\\"om-anti de Sitter black hole can be a solution of the vacuum mimetic $F(R)$ gravity with Lagrange multiplier and mimetic scalar potential. As we demonstrate, the resulting picture in the mimetic $F(R)$ gravity case, is different in comparison to the ordinary $F(R)$ gravity case, with the two descriptions resulting to a different set of constraints that need to hold true. We also investigate the metric perturbations in the mim...
Gravity, black holes and the very early Universe an introduction to general relativity and cosmology
Chow, Tai L
2008-01-01
In the early 1900s, Albert Einstein formulated two theories that would forever change the landscape of physics: the Special Theory of Relativity and the General Theory of Relativity. By 1925, quantum mechanics had been born out of the dissection of these two theories, and shortly after that, relativistic quantum field theory. We now had in place some important ties between the laws of physics and the types of particle interactions the new physics was uncovering. Gravity is one of the four types of forces that are found throughout the universe. In fact, although it is a relatively weak force, it operates at huge distances, and so must be accounted for in any cosmological system. Unfortunately, gravity continues to defy our neat categorization of how all the forces in nature work together. Professor Tai Chow, from the California State University at Stanislaus in Turlock, lays out for us the basic ideas of Einstein, including his law of gravitation, explains the physics behind black holes, and weaves into this a...
Spherically symmetric black holes in $f(R)$ gravity: Is geometric scalar hair supported ?
Cañate, Pedro; Salgado, Marcelo
2015-01-01
We discuss with a rather critical eye the current situation of black hole (BH) solutions in $f(R)$ gravity and shed light about its geometrical and physical significance. We also argue about the meaning, existence or lack thereof of a Birkhoff's theorem in this kind of modified gravity. We focus then on the analysis and quest of $non-trivial$ (i.e. hairy) $asymptotically\\,\\,flat$ (AF) BH solutions in static and spherically symmetric (SSS) spacetimes in vacuum having the property that the Ricci scalar does $not$ vanish identically in the domain of outer communication. To do so, we provide and enforce the $regularity\\,\\,conditions$ at the horizon in order to prevent the presence of singular solutions there. Specifically, we consider several classes of $f(R)$ models like those proposed recently for explaining the accelerated expansion in the universe and which have been thoroughly tested in several physical scenarios. Finally, we report analytical and numerical evidence about the $absence$ of $geometric\\,\\,hair$...
Energy Technology Data Exchange (ETDEWEB)
Dadhich, Naresh, E-mail: nkd@iucaa.ernet.in [Centre for Theoretical Physics, Jamia Millia Islamia, 110025, New Delhi (India); Inter-University Centre for Astronomy and Astrophysics, Post Bag 4, 411 007, Pune (India); Pons, Josep M., E-mail: pons@ecm.ub.es [Departament d’Estructura i Constituents de la Matèria and Institut de Ciències del Cosmos (ICCUB), Facultat de Fsica, Universitat de Barcelona, Diagonal 647, 08028, Barcelona, Catalonia (Spain)
2015-06-24
We study static black hole solutions in Einstein and Einstein–Gauss–Bonnet gravity with the topology of the product of two spheres, S{sup n}×S{sup n}, in higher dimensions. There is an unusual new feature of the Gauss–Bonnet black hole: the avoidance of a non-central naked singularity prescribes a mass range for the black hole in terms of Λ>0. For an Einstein–Gauss–Bonnet black hole a limited window of negative values for Λ is also permitted. This topology encompasses black strings, branes, and generalized Nariai metrics. We also give new solutions with the product of two spheres of constant curvature.
Corda, Christian
2015-01-01
Some recent important results on black hole (BH) quantum physics concerning the BH effective state and the natural correspondence between Hawking radiation and BH quasi-normal modes (QNMs) are reviewed, clarified and refined. Such a correspondence permits to naturally interpret QNMs as quantum levels in a semi-classical model. This is a model of BH somewhat similar to the historical semi-classical model of the structure of a hydrogen atom introduced by Bohr in 1913. In a certain sense, QNMs represent the "electron" which jumps from a level to another one and the absolute values of the QNMs frequencies "triggered" by emissions (Hawking radiation) and absorption of particles represent the energy "shells" of the "gravitational hydrogen atom". Important consequences on the BH information puzzle are discussed. In fact, it is shown that the time evolution of this "Bohr-like BH model" obeys to a time dependent Schr\\"odinger equation which permits the final BH state to be a pure quantum state instead of a mixed one. ...
Testing gravity of a regular and slowly rotating phantom black hole by quasi-periodic oscillations
Chen, Songbai; Jing, Jiliang
2016-01-01
We extend firstly the regular phantom black hole solution to a slowly rotating black hole case and find that the phantom field depresses the angular velocity of the event horizon and suppresses the super-radiation of black hole. We also probe the dependence of quasi-periodic oscillations frequencies in relativistic precession model on the phantom parameter. With the observation data of GRO J1655-40, we make a constraint on the parameters of the regular and slowly rotating phantom black hole. Our results show that although the best-fit value of the phantom parameter $b$ is small, the allowed value of $b$ in the $1\\sigma$ region is $b<0.619$, which means that the phantom theoretical model can not be excluded by the constraint from quasi-periodic oscillations with the observation data of GRO J1655-40.
Energy Technology Data Exchange (ETDEWEB)
NONE
2002-02-01
Belief in the existence of black holes is the ultimate act of faith for a physicist. First suggested by the English clergyman John Michell in the year 1784, the gravitational pull of a black hole is so strong that nothing - not even light - can escape. Gravity might be the weakest of the fundamental forces but black-hole physics is not for the faint-hearted. Black holes present obvious problems for would-be observers because they cannot, by definition, be seen with conventional telescopes - although before the end of the decade gravitational-wave detectors should be able to study collisions between black holes. Until then astronomers can only infer the existence of a black hole from its gravitational influence on other matter, or from the X-rays emitted by gas and dust as they are dragged into the black hole. However, once this material passes through the 'event horizon' that surrounds the black hole, we will never see it again - not even with X-ray specs. Despite these observational problems, most physicists and astronomers believe that black holes do exist. Small black holes a few kilometres across are thought to form when stars weighing more than about two solar masses collapse under the weight of their own gravity, while supermassive black holes weighing millions of solar masses appear to be present at the centre of most galaxies. Moreover, some brave physicists have proposed ways to make black holes - or at least event horizons - in the laboratory. The basic idea behind these 'artificial black holes' is not to compress a large amount of mass into a small volume, but to reduce the speed of light in a moving medium to less than the speed of the medium and so create an event horizon. The parallels with real black holes are not exact but the experiments could shed new light on a variety of phenomena. The first challenge, however, is to get money for the research. One year on from a high-profile meeting on artificial black holes in London, for
Noncommutative solitonic black hole
International Nuclear Information System (INIS)
We investigate solitonic black hole solutions in three-dimensional noncommutative spacetime. We do this in gravity with a negative cosmological constant coupled to a scalar field. Noncommutativity is realized with the Moyal product which is expanded up to first order in the noncommutativity parameter in two spatial directions. With numerical simulation we study the effect of noncommutativity by increasing the value of the noncommutativity parameter starting from commutative solutions. We find that even a regular soliton solution in the commutative case becomes a black hole solution when the noncommutativity parameter reaches a certain value. (paper)
Noncommutative solitonic black hole
Chang-Young, Ee; Kimm, Kyoungtae; Lee, Daeho; Lee, Youngone
2012-05-01
We investigate solitonic black hole solutions in three-dimensional noncommutative spacetime. We do this in gravity with a negative cosmological constant coupled to a scalar field. Noncommutativity is realized with the Moyal product which is expanded up to first order in the noncommutativity parameter in two spatial directions. With numerical simulation we study the effect of noncommutativity by increasing the value of the noncommutativity parameter starting from commutative solutions. We find that even a regular soliton solution in the commutative case becomes a black hole solution when the noncommutativity parameter reaches a certain value.
Good, Michael R R
2014-01-01
A $(3+1)$-dimensional asymptotically flat Kerr black hole angular speed $\\Omega_+$ can be used to define an effective spring constant, $k=m\\Omega_+^2$. Its maximum value is the Schwarzschild surface gravity, $k = \\kappa $, which rapidly weakens as the black hole spins down and the temperature increases. The Hawking temperature is expressed in terms of the spring constant: $2\\pi T = \\kappa - k$. Hooke's law, in the extremal limit, provides the force $F = 1/4$, which is consistent with the conjecture of maximum force in general relativity.
Effect of Vacuum Energy on Evolution of Primordial Black Holes in Einstein Gravity
Nayak, Bibekananda; Jamil, Mubasher
2011-01-01
We study the evolution of primordail black holes by considering present universe is no more matter dominated rather vacuum energy dominated. We also consider the accretion of radiation, matter and vacuum energy during respective dominance period. In this scenario, we found that radiation accretion efficiency should be less than 0.366 and accretion rate is much larger than previous analysis by B. Nayak et al. \\cite{ns}. Thus here primordial black holes live longer than previous works \\cite{ns}...
A mechanism of supermassive primordial black hole formation
International Nuclear Information System (INIS)
A mechanism of supermassive primordial black hole formation is proposed in the framework of a multidimensional gravity theory. Possible observable manifestations of primordial black holes are discussed
Mišković, Olivera; Olea, Rodrigo
2011-01-01
Motivated by possible applications within the framework of anti-de Sitter gravity/conformal field theory correspondence, charged black holes with AdS asymptotics, which are solutions to Einstein-Gauss-Bonnet gravity in D dimensions, and whose electric field is described by nonlinear electrodynamics are studied. For a topological static black hole ansatz, the field equations are exactly solved in terms of the electromagnetic stress tensor for an arbitrary nonlinear electrodynamic Lagrangian in any dimension D and for arbitrary positive values of Gauss-Bonnet coupling. In particular, this procedure reproduces the black hole metric in Born-Infeld and conformally invariant electrodynamics previously found in the literature. Altogether, it extends to D>4 the four-dimensional solution obtained by Soleng in logarithmic electrodynamics, which comes from vacuum polarization effects. Falloff conditions for the electromagnetic field that ensure the finiteness of the electric charge are also discussed. The black hole mass and vacuum energy as conserved quantities associated to an asymptotic timelike Killing vector are computed using a background-independent regularization of the gravitational action based on the addition of counterterms which are a given polynomial in the intrinsic and extrinsic curvatures.
International Nuclear Information System (INIS)
Motivated by possible applications within the framework of anti-de Sitter gravity/conformal field theory correspondence, charged black holes with AdS asymptotics, which are solutions to Einstein-Gauss-Bonnet gravity in D dimensions, and whose electric field is described by nonlinear electrodynamics are studied. For a topological static black hole ansatz, the field equations are exactly solved in terms of the electromagnetic stress tensor for an arbitrary nonlinear electrodynamic Lagrangian in any dimension D and for arbitrary positive values of Gauss-Bonnet coupling. In particular, this procedure reproduces the black hole metric in Born-Infeld and conformally invariant electrodynamics previously found in the literature. Altogether, it extends to D>4 the four-dimensional solution obtained by Soleng in logarithmic electrodynamics, which comes from vacuum polarization effects. Falloff conditions for the electromagnetic field that ensure the finiteness of the electric charge are also discussed. The black hole mass and vacuum energy as conserved quantities associated to an asymptotic timelike Killing vector are computed using a background-independent regularization of the gravitational action based on the addition of counterterms which are a given polynomial in the intrinsic and extrinsic curvatures.
Institute of Scientific and Technical Information of China (English)
CHEN Qiang; REN Ji-Rong
2013-01-01
In this paper,we use the modified Hod's treatment and the Kunstatter's method to study the horizon area spectrum and entropy spectrum in Gauss-Bonnet de-Sitter space-time,which is regarded as the natural generalization of Einstein gravity by including higher derivative correction terms to the original Einstein-Hilbert action.The horizon areas have some properties that are very different from the vacuum solutions obtained from the frame of Einstein gravity.With the new physical interpretation of quasinormal modes,the area/entropy spectrum for the event horizon for nearextremal Gauss-Bonnet de Sitter black holes are obtained.Meanwhile,we also extend the discussion of area/entropy quantization to the non-extremal black holes solutions.
International Nuclear Information System (INIS)
In this paper, we use the modified Hod's treatment and the Kunstatter's method to study the horizon area spectrum and entropy spectrum in Gauss—Bonnet de-Sitter space-time, which is regarded as the natural generalization of Einstein gravity by including higher derivative correction terms to the original Einstein—Hilbert action. The horizon areas have some properties that are very different from the vacuum solutions obtained from the frame of Einstein gravity. With the new physical interpretation of quasinormal modes, the area/entropy spectrum for the event horizon for near-extremal Gauss—Bonnet de Sitter black holes are obtained. Meanwhile, we also extend the discussion of area/entropy quantization to the non-extremal black holes solutions. (general)
Inner Structure of Black Holes in Eddington-inspired Born-Infeld gravity: the role of mass inflation
Avelino, P P
2015-01-01
We investigate the interior dynamics of accreting black holes in Eddington-inspired Born-Infeld gravity using the homogeneous approximation and taking charge as a surrogate for angular momentum, showing that accretion can have an enormous impact on their inner structure. We find that, unlike in general relativity, there is a minimum accretion rate bellow which the mass inflation instability, which drives the centre-of-mass streaming density to exponentially high values in an extremely short interval of time, does not occur. We further show that, above this threshold, mass inflation takes place inside black holes very much in the same way as in general relativity, but is brought to a halt at a maximum energy density which is, in general, much smaller than the fundamental energy density of the theory. We conjecture that some of these results may be a common feature of modified gravity theories in which significant deviations from general relativity manifest themselves at very high densities.
Li, Ran; Zhao, Jun-Kun
2016-04-01
We investigate the massive vector particles' Hawking radiation from the neutral rotating Anti-de Sitter (AdS) black holes in conformal gravity by using the tunneling method. It is well known that the dynamics of massive vector particles are governed by the Proca field equation. Applying WKB approximation to the Proca equation, the tunneling probabilities and radiation spectrums of the emitted particles are derived. Hawking temperature of the neutral rotating AdS black holes in conformal gravity is recovered, which is consistent with the previous result in the literature. Supported by the National Natural Science Foundation of China under Grant No. 11205048, and the Foundation for Young Key Teacher of Henan Normal University
Geodesic Motion in the Spacetime Of a SU(2)-Colored (A)dS Black Hole in Conformal Gravity
Hoseini, Bahareh; Soroushfar, Saheb
2016-01-01
In this paper we are interested to study the geodesic motion in the spacetime of a SU(2)-colored (A)dS black hole solving in conformal gravity. Using Weierstrass elliptic and Kleinian {\\sigma} hyperelliptic functions, we derive the analytical solutions for the equation of motion of test particles and light rays. Also, we classify the possible orbits according to the particle's energy and angular momentum.
Soroushfar, Saheb; Kazempour, Sobhan; Grunau, Saskia; Kunz, Jutta
2016-01-01
We study the geodesic equations in the space time of a rotating charged black hole in $f(R)$ gravity. We derive the equations of motion for test particles and light rays and present their solutions in terms of the Weierstrass $\\wp$, $\\zeta$ and $\\sigma$ functions as well as the Kleinian $\\sigma$ function. With the help of parametric diagrams and effective potentials we analyze the geodesic motion and classify the possible orbit types.
Quasinormal modes of a black hole with a cloud of strings in Einstein-Gauss-Bonnet gravity
Graça, J. P. Morais; Bezerra, V. B.
2016-01-01
The quasinormal modes for a scalar field in the background spacetime corresponding to a black hole, with a cloud of strings, in Einstein-Gauss-Bonnet gravity, and the tensor quasinormal modes corresponding to perturbations in such spacetime, were both calculated using the WKB approximation. In the obtained results we emphasize the role played by the parameter associated with the string cloud, comparing them with the results already obtained for the Boulware-Deser metric. We also study how the...
Spherically symmetric black holes in f (R) gravity: is geometric scalar hair supported?
Cañate, Pedro; Jaime, Luisa G.; Salgado, Marcelo
2016-08-01
We critically discuss current research on black hole (BH) solutions in f (R) gravity and shed light on its geometrical and physical significance. We also investigate the meaning, existence or lack thereof of Birkhoff’s theorem (BT) in this kind of modified gravity. We then focus on the analysis and search for non-trivial (i.e. hairy) asymptotically flat (AF) BH solutions in static and spherically symmetric (SSS) spacetimes in vacuum having the property that the Ricci scalar does not vanish identically in the domain of outer communication. To do so, we provide and enforce regularity conditions at the horizon in order to prevent the presence of singular solutions there. Specifically, we consider several classes of f (R) models like those proposed recently for explaining the accelerated expansion in the Universe and which have been thoroughly tested in several physical scenarios. Finally, we report analytical and numerical evidence about the absence of geometric hair in AFSSSBH solutions in those f (R) models. First, we submit the models to the available no-hair theorems (NHTs), and in the cases where the theorems apply, the absence of hair is demonstrated analytically. In the cases where the theorems do not apply, we resort to a numerical analysis due to the complexity of the non-linear differential equations. With that aim, a code to solve the equations numerically was built and tested using well-known exact solutions. In a future investigation we plan to analyze the problem of hair in de Sitter and anti-de Sitter backgrounds.
Hayward, Sean A.; Mukohyama, Shinji; Ashworth, M. C.
1998-01-01
We consider two non-statistical definitions of entropy for dynamic (non-stationary) black holes in spherical symmetry. The first is analogous to the original Clausius definition of thermodynamic entropy: there is a first law containing an energy-supply term which equals surface gravity times a total differential. The second is Wald's Noether-charge method, adapted to dynamic black holes by using the Kodama flow. Both definitions give the same answer for Einstein gravity: one-quarter the area ...
Noncommutative black hole thermodynamics
International Nuclear Information System (INIS)
We give a general derivation, for any static spherically symmetric metric, of the relation Th=(K/2π) connecting the black hole temperature (Th) with the surface gravity (K), following the tunneling interpretation of Hawking radiation. This derivation is valid even beyond the semi-classical regime, i.e. when quantum effects are not negligible. The formalism is then applied to a spherically symmetric, stationary noncommutative Schwarzschild space-time. The effects of backreaction are also included. For such a black hole the Hawking temperature is computed in a closed form. A graphical analysis reveals interesting features regarding the variation of the Hawking temperature (including corrections due to noncommutativity and backreaction) with the small radius of the black hole. The entropy and tunneling rate valid for the leading order in the noncommutative parameter are calculated. We also show that the noncommutative Bekenstein-Hawking area law has the same functional form as the usual one
Yang, Huan; Zimmerman, Aaron; Lehner, Luis
2015-02-27
We demonstrate that rapidly spinning black holes can display a new type of nonlinear parametric instability-which is triggered above a certain perturbation amplitude threshold-akin to the onset of turbulence, with possibly observable consequences. This instability transfers from higher temporal and azimuthal spatial frequencies to lower frequencies-a phenomenon reminiscent of the inverse cascade displayed by (2+1)-dimensional fluids. Our finding provides evidence for the onset of transitory turbulence in astrophysical black holes and predicts observable signatures in black hole binaries with high spins. Furthermore, it gives a gravitational description of this behavior which, through the fluid-gravity duality, can potentially shed new light on the remarkable phenomena of turbulence in fluids. PMID:25768746
Centrella, Joan
2012-01-01
The final merger of two black holes is expected to be the strongest source of gravitational waves for both ground-based detectors such as LIGO and VIRGO, as well as future. space-based detectors. Since the merger takes place in the regime of strong dynamical gravity, computing the resulting gravitational waveforms requires solving the full Einstein equations of general relativity on a computer. For many years, numerical codes designed to simulate black hole mergers were plagued by a host of instabilities. However, recent breakthroughs have conquered these instabilities and opened up this field dramatically. This talk will focus on.the resulting 'gold rush' of new results that is revealing the dynamics and waveforms of binary black hole mergers, and their applications in gravitational wave detection, testing general relativity, and astrophysics
Yang, Huan; Lehner, Luis
2014-01-01
We show that rapidly-spinning black holes can display turbulent gravitational behavior which is mediated by a new type of parametric instability. This instability transfers energy from higher temporal and azimuthal spatial frequencies to lower frequencies--- a phenomenon reminiscent of the inverse energy cascade displayed by 2+1-dimensional turbulent fluids. Our finding reveals a path towards gravitational turbulence for perturbations of rapidly-spinning black holes, and provides the first evidence for gravitational turbulence in an asymptotically flat spacetime. Interestingly, this finding predicts observable gravitational wave signatures from such phenomena in black hole binaries with high spins and gives a gravitational description of turbulence relevant to the fluid-gravity duality.
Yang, Huan; Zimmerman, Aaron; Lehner, Luis
2015-02-01
We demonstrate that rapidly spinning black holes can display a new type of nonlinear parametric instability—which is triggered above a certain perturbation amplitude threshold—akin to the onset of turbulence, with possibly observable consequences. This instability transfers from higher temporal and azimuthal spatial frequencies to lower frequencies—a phenomenon reminiscent of the inverse cascade displayed by (2 +1 )-dimensional fluids. Our finding provides evidence for the onset of transitory turbulence in astrophysical black holes and predicts observable signatures in black hole binaries with high spins. Furthermore, it gives a gravitational description of this behavior which, through the fluid-gravity duality, can potentially shed new light on the remarkable phenomena of turbulence in fluids.
Thermodynamics of Lifshitz black holes
Devecioǧlu, Deniz Olgu; Sarıoǧlu, Özgür
2011-06-01
We apply the recently extended conserved Killing charge definition of Abbott-Deser-Tekin formalism to compute, for the first time, the energies of analytic Lifshitz black holes in higher dimensions. We then calculate the temperature and the entropy of this large family of solutions, and study and discuss the first law of black hole thermodynamics. Along the way we also identify the possible critical points of the relevant quadratic curvature gravity theories. Separately, we also apply the generalized Killing charge definition to compute the energy and the angular momentum of the warped AdS3 black hole solution of the three-dimensional new massive gravity theory.
Blandford-Znajek mechanism in black holes in alternative theories of gravity
Pei, Guancheng; Bambi, Cosimo; Middleton, Matthew J
2016-01-01
According to the Blandford-Znajek mechanism, black hole jets are powered by the rotational energy of the compact object. In this work, we consider the possibility that the metric around black holes may not be described by the Kerr solution and we study how this changes the Blandford-Znajek model. If the Blandford-Znajek mechanism is responsible for the formation of jets, the estimate of the jet power in combination with another measurement can test the nature of black hole candidates and constrain possible deviations from the Kerr solution. However, this approach might become competitive with respect to other techniques only when it will be possible to have measurements much more precise than those available today.
Noncommutative Solitonic Black Hole
Chang-Young, Ee; Kimm, Kyoungtae; Lee, Daeho; Lee, Youngone
2011-01-01
We investigate solitonic black hole solutions in three dimensional noncommutative spacetime. We do this in gravity with negative cosmological constant coupled to a scalar field. Noncommutativity is realized with the Moyal product which is expanded up to first order in the noncommutativity parameter in two spatial directions. With numerical simulation we study the effect of noncommutativity by increasing the value of the noncommutativity parameter starting from commutative solutions. We find t...
International Nuclear Information System (INIS)
We study noncommutative black holes, by using a diffeomorphism between the Schwarzschild black hole and the Kantowski-Sachs cosmological model, which is generalized to noncommutative minisuperspace. Through the use of the Feynman-Hibbs procedure we are able to study the thermodynamics of the black hole, in particular, we calculate Hawking's temperature and entropy for the 'noncommutative' Schwarzschild black hole
Scaling phenomena in gravity and Yang-Mills theories, or black hole formation and its unitarization
International Nuclear Information System (INIS)
This talk was based on an earlier paper of the author and others (arXiv:0804.1464) and on a general discussion of the problems of black hole physics in the context of string theory. Adequate reference can be found in this paper. Here we only present a short summary of the seminar. (Abstract Copyright [2009], Wiley Periodicals, Inc.)
Magnetic Neutral Points and Electric Lines of Force in Strong Gravity of a Rotating Black Hole
Czech Academy of Sciences Publication Activity Database
Karas, Vladimír; Kopáček, Ondřej; Kunneriath, Devaky
2013-01-01
Roč. 3, 3A (2013), s. 18-24. ISSN 2161-4717 R&D Projects: GA ČR(CZ) GC13-00070J Institutional support: RVO:67985815 Keywords : galaxies * nuclei * black hole physics Subject RIV: BN - Astronomy, Celestial Mechanics, Astrophysics
2006-01-01
[figure removed for brevity, see original site] Poster Version This artist's concept shows a supermassive black hole at the center of a remote galaxy digesting the remnants of a star. NASA's Galaxy Evolution Explorer had a 'ringside' seat for this feeding frenzy, using its ultraviolet eyes to study the process from beginning to end. The artist's concept chronicles the star being ripped apart and swallowed by the cosmic beast over time. First, the intact sun-like star (left) ventures too close to the black hole, and its own self-gravity is overwhelmed by the black hole's gravity. The star then stretches apart (middle yellow blob) and eventually breaks into stellar crumbs, some of which swirl into the black hole (cloudy ring at right). This doomed material heats up and radiates light, including ultraviolet light, before disappearing forever into the black hole. The Galaxy Evolution Explorer was able to watch this process unfold by observing changes in ultraviolet light. The area around the black hole appears warped because the gravity of the black hole acts like a lens, twisting and distorting light.
Thermodynamics of topological black holes in Brans-Dicke gravity with a power-law Maxwell field
Zangeneh, M Kord; Sheykhi, A
2015-01-01
In this paper, we present a new class of higher dimensional exact topological black hole solutions of the Brans-Dicke theory in the presence of a power-law Maxwell field as the matter source. For this aim, we introduce a conformal transformation which transforms the Einstein-dilaton-power-law Maxwell gravity Lagrangian to the Brans-Dicke-power-law Maxwell theory one. Then, by using this conformal transformation, we obtain the desired solutions. Next, we study the properties of the solutions and conditions under which we have black holes. Interestingly enough, we show that there is a cosmological horizon in the presence of a negative cosmological constant. Finally, we calculate the temperature and charge and then by calculating the Euclidean action, we obtain the mass, the entropy and the electromagnetic potential energy. We find that the entropy does not respect the area law, and also the conserved and thermodynamic quantities are invariant under conformal transformation. Using these thermodynamic and conserv...
Micro black holes in the laboratory
Bleicher, Marcus; Nicolini, Piero; Sprenger, Martin; Winstanley, Elizabeth(Consortium for Fundamental Physics, School of Mathematics and Statistics, University of Sheffield, Hicks Building, Hounsfield Road, Sheffield, S3 7RH, United Kingdom)
2011-01-01
The possibility of creating microscopic black holes is one of the most exciting predictions for the LHC, with potentially major consequences for our current understanding of physics. We briefly review the theoretical motivation for micro black hole production, and our understanding of their subsequent evolution. Recent work on modelling the radiation from quantum-gravity-corrected black holes is also discussed.
Are black holes totally black?
Grib, A A
2014-01-01
Geodesic completeness needs existence near the horizon of the black hole of "white hole" geodesics coming from the region inside of the horizon. Here we give the classification of all such geodesics with the energies $E/m \\le 1$ for the Schwarzschild and Kerr's black hole. The collisions of particles moving along the "white hole" geodesics with those moving along "black hole" geodesics are considered. Formulas for the increase of the energy of collision in the centre of mass frame are obtained and the possibility of observation of high energy particles arriving from the black hole to the Earth is discussed.
Baker, John
2010-01-01
Among the fascinating phenomena predicted by General Relativity, Einstein's theory of gravity, black holes and gravitational waves, are particularly important in astronomy. Though once viewed as a mathematical oddity, black holes are now recognized as the central engines of many of astronomy's most energetic cataclysms. Gravitational waves, though weakly interacting with ordinary matter, may be observed with new gravitational wave telescopes, opening a new window to the universe. These observations promise a direct view of the strong gravitational dynamics involving dense, often dark objects, such as black holes. The most powerful of these events may be merger of two colliding black holes. Though dark, these mergers may briefly release more energy that all the stars in the visible universe, in gravitational waves. General relativity makes precise predictions for the gravitational-wave signatures of these events, predictions which we can now calculate with the aid of supercomputer simulations. These results provide a foundation for interpreting expect observations in the emerging field of gravitational wave astronomy.
Strong Gravitational Lensing as a Probe of Gravity, Dark-Matter and Super-Massive Black Holes
Koopmans, L V E; Barnabe, M; Bolton, A; Bradac, M; Ciotti, L; Congdon, A; Czoske, O; Dye, S; Dutton, A; Elliasdottir, A; Evans, E; Fassnacht, C D; Jackson, N; Keeton, C; Lazio, J; Marshall, P; Meneghetti, M; McKean, J; Moustakas, L; Myers, S; Nipoti, C; Suyu, S; van de Ven, G; Vegetti, S; Wambsganss, J; Webster, R; Wucknitz, O; Zhao, H-S
2009-01-01
Whereas considerable effort has been afforded in understanding the properties of galaxies, a full physical picture, connecting their baryonic and dark-matter content, super-massive black holes, and (metric) theories of gravity, is still ill-defined. Strong gravitational lensing furnishes a powerful method to probe gravity in the central regions of galaxies. It can (1) provide a unique detection-channel of dark-matter substructure beyond the local galaxy group, (2) constrain dark-matter physics, complementary to direct-detection experiments, as well as metric theories of gravity, (3) probe central super-massive black holes, and (4) provide crucial insight into galaxy formation processes from the dark matter point of view, independently of the nature and state of dark matter. To seriously address the above questions, a considerable increase in the number of strong gravitational-lens systems is required. In the timeframe 2010-2020, a staged approach with radio (e.g. EVLA, e-MERLIN, LOFAR, SKA phase-I) and optica...
Quantum strings and black holes
Damour, Thibault Marie Alban Guillaume
2001-01-01
The transition between (non supersymmetric) quantum string states and Schwarzschild black holes is discussed. This transition occurs when the string coupling $g^2$ (which determines Newton's constant) increases beyond a certain critical value $g_c^2$. We review a calculation showing that self-gravity causes a typical string state of mass $M$ to shrink, as the string coupling $g^2$ increases, down to a compact string state whose mass, size, entropy and luminosity match (for the critical value $g_c^2 \\sim (M \\sqrt{\\alpha'})^{-1}$) those of a Schwarzschild black hole. This confirms the idea (proposed by several authors) that the entropy of black holes can be accounted for by counting string states. The level spacing of the quantum states of Schwarzschild black holes is expected to be exponentially smaller than their radiative width. This makes it very difficult to conceive (even Gedanken) experiments probing the discreteness of the quantum energy levels of black holes.
Black holes sourced by a massless scalar
Cadoni, Mariano
2015-01-01
We construct asymptotically flat black hole solutions of Einstein-scalar gravity sourced by a nontrivial scalar field with 1/r asymptotic behaviour. Near the singularity the black hole behaves as the Janis-Newmann-Winicour-Wyman solution. The hairy black hole solutions allow for a consistent thermodynamical description. At large mass they have the same thermodynamical behaviour of the Schwarzschild black hole, whereas for small masses they differ substantially from the latter.
Natario, J; Natario, Jose; Schiappa, Ricardo
2004-01-01
We provide a complete classification of asymptotic quasinormal frequencies for static, spherically symmetric black hole spacetimes in d dimensions. This includes all possible types of gravitational perturbations (tensor, vector and scalar type) as described by the Ishibashi-Kodama master equations. The frequencies for Schwarzschild are dimension independent, while for Reissner-Nordstrom are dimension dependent (the extremal Reissner-Nordstrom case must be considered separately from the non-extremal case). For Schwarzschild de Sitter, there is a dimension independent formula for the frequencies, except in dimension d=5 where the formula is different. For Reissner-Nordstrom de Sitter there is a dimension dependent formula for the frequencies, except in dimension d=5 where the formula is different. Schwarzschild and Reissner-Nordstrom Anti-de Sitter black hole spacetimes are simpler: the formulae for the frequencies will depend upon a parameter related to the tortoise coordinate at spatial infinity. We also addr...
Higher spin gravity in 3D: Black holes, global charges and thermodynamics
Energy Technology Data Exchange (ETDEWEB)
Pérez, Alfredo, E-mail: aperez@cecs.cl [Centro de Estudios Científicos (CECs), Casilla 1469, Valdivia (Chile); Tempo, David, E-mail: tempo@cecs.cl [Centro de Estudios Científicos (CECs), Casilla 1469, Valdivia (Chile); Troncoso, Ricardo, E-mail: troncoso@cecs.cl [Centro de Estudios Científicos (CECs), Casilla 1469, Valdivia (Chile); Universidad Andrés Bello, Av. República 440, Santiago (Chile)
2013-10-07
Global charges and thermodynamic properties of three-dimensional higher spin black holes that have been recently found in the literature are revisited. Since these solutions possess a relaxed asymptotically AdS behavior, following the canonical approach, it is shown that the global charges, and in particular the energy, acquire explicit nontrivial contributions given by nonlinear terms in the deviations with respect to the reference background. It is also found that there are cases for which the first law of thermodynamics can be readily worked out in the canonical ensemble, i.e., without work terms associated to the presence of higher spin fields, and remarkably, the semiclassical higher spin black hole entropy is exactly reproduced from Cardy formula.
Sun, Yuan; Zhao, Liu
2016-01-01
The holographic entanglement entropy is studied numerically in (4+1)-dimensional spherically symmetric Gauss-Bonnet AdS black hole spacetime with compact boundary. On the bulk side the black hole spacetime undergoes a van der Waals-like phase transition in the extended phase space, which is reviewed with emphasis on the behavior on the temperature-entropy plane. On the boundary, we calculated the regularized HEE of a disk region of different sizes. We find strong numerical evidence for the failure of equal area law for isobaric curves on the temperature-HEE plane and for the correctness of first law of entanglement entropy, and briefly give an explanation for why the latter may serve as a reason for the former, i.e. the failure of equal area law on the temperature-HEE plane.
Dias, O J C; Dias, Oscar J. C.; Lemos, Jose' P. S.
2001-01-01
We obtain static and rotating electrically charged black holes of a Einstein-Maxwell-Dilaton theory of the Brans-Dicke type in (2+1)-dimensions. The theory is specified by three fields, the dilaton, the graviton and the electromagnetic field, and two parameters, the cosmological constant and the Brans-Dicke parameter. It contains eight different cases, of which one distinguishes as special cases, string theory, general relativity and a theory equivalent to four dimensional general relativity with one Killing vector. We find the ADM mass, angular momentum, electric charge and dilaton charge and compute the Hawking temperature of the solutions. Causal structure and geodesic motion of null and timelike particles in the black hole geometries are studied in detail.
Black hole accretion disks in brane gravity via a confining potential
Energy Technology Data Exchange (ETDEWEB)
Heydari-Fard, Malihe, E-mail: heydarifard@qom.ac.i, E-mail: m.heydarifard@mail.sbu.ac.i [Department of Physics, University of Qom, PO Box 37185-359, Qom (Iran, Islamic Republic of)
2010-12-07
Accretion disks are among the most luminous and ubiquitous sources in astrophysics and they have drawn a good deal of attention from the observational and theoretical communities. In this paper, we study the process of matter forming thin accretion disks around black hole solutions in the context of the brane-world scenario where our universe is a three-brane embedded in an m-dimensional bulk and localization of matter on the brane is achieved by means of a confining potential. The physical properties of thin accretion disks including the time averaged energy flux, temperature distribution, the emission spectrum as well as the energy conversion efficiency are obtained, and the results are compared with the DMPR, CFM and BMD brane black holes and the standard general relativistic Schwarzschild solution.
Combinatorics of the SU(2) black hole entropy in loop quantum gravity
International Nuclear Information System (INIS)
We use the combinatorial and number-theoretical methods developed in previous works by the authors to study black hole entropy in the new proposal put forth by Engle, Noui, and Perez. Specifically, we give the generating functions relevant for the computation of the entropy and use them to derive its asymptotic behavior, including the value of the Immirzi parameter and the coefficient of the logarithmic correction.
Clement, María E Gabach
2015-01-01
It is well known that celestial bodies tend to be spherical due to gravity and that rotation produces deviations from this sphericity. We discuss what is known and expected about the shape of black holes' horizons from their formation to their final, stationary state. We present some recent results showing that black hole rotation indeed manifests in the widening of their central regions, limits their global shapes and enforces their whole geometry to be close to the extreme Kerr horizon geometry at almost maximal rotation speed. The results depend only on the horizon area and angular momentum. In particular they are entirely independent of the surrounding geometry of the spacetime and of the presence of matter satisfying the strong energy condition. We also discuss the the relation of this result with the Hoop conjecture.
Resource Letter BH-2: Black Holes
Gallo, Elena
2008-01-01
This resource letter is designed to guide students, educators, and researchers through (some of) the literature on black holes. Both the physics and astrophysics of black holes are discussed. Breadth has been emphasized over depth, and review articles over primary sources. We include resources ranging from non-technical discussions appropriate for broad audiences to technical reviews of current research. Topics addressed include classification of stationary solutions, perturbations and stability of black holes, numerical simulations, collisions, the production of gravity waves, black hole thermodynamics and Hawking radiation, quantum treatments of black holes, black holes in both higher and lower dimensions, and connections to nuclear and condensed matter physics. On the astronomical end, we also cover the physics of gas accretion onto black holes, relativistic jets, gravitationally red-shifted emission lines, evidence for stellar-mass black holes in binary systems and super-massive black holes at the centers...
Vacuum metastability with black holes.
Burda, Philipp; Gregory, Ruth; Moss, Ian
2015-01-01
We consider the possibility that small black holes can act as nucleation seeds for the decay of a metastable vacuum, focussing particularly on the Higgs potential. Using a thin-wall bubble approximation for the nucleation process, which is possible when generic quantum gravity corrections are added to the Higgs potential, we show that primordial black holes can stimulate vacuum decay. We demonstrate that for suitable parameter ranges, the vacuum decay process dominates over the Hawking evapor...
Mass spectrum and statistical entropy of the BTZ black hole from canonical quantum gravity
International Nuclear Information System (INIS)
In a recent publication we developed a canonical quantization program describing the gravitational collapse of a spherical dust cloud in 2+1 dimensions with a negative cosmological constant -Λ≡-l-2n=((ℎ/2π)/l)(n+(1/2)). The discrete spectrum is obtained by applying the Wheeler-DeWitt equation with a particular choice of factor ordering and interpreted as giving the energy levels of the collapsed matter shells that form the black hole. Treating a black hole microstate as a particular distribution of shells among the levels, we determine the canonical entropy of the BTZ black hole. Comparison with the Bekenstein-Hawking entropy shows that the boundary energy is related to the central charge of the Virasoro algebra that generates the asymptotic symmetry group of the three-dimensional anti-de Sitter space AdS3. This gives a connection between the Wheeler-DeWitt approach and the conformal field theory approach.
Integrability in conformally coupled gravity: Taub-NUT spacetimes and rotating black holes
Bardoux, Yannis; Charmousis, Christos
2013-01-01
We consider four dimensional stationary and axially symmetric spacetimes for conformally coupled scalar-tensor theories. We show that, in analogy to the Lewis-Papapetrou problem in General Relativity (GR), the theory at hand can be recast in an analogous integrable form. We give the relevant rod formalism, introduced by Weyl for vacuum GR, explicitly giving the rod structure of the black hole of Bocharova et al. and Bekenstein (BBMB), in complete analogy to the Schwarzschild solution. The additional scalar field is shown to play the role of an extra Weyl potential. We then employ the Ernst method as a concrete solution generating example to obtain the Taub-NUT version of the BBMB hairy black hole, with or without a cosmological constant. We show that the anti-de Sitter hyperbolic version of this solution is free of closed timelike curves that plague usual Taub-NUT metrics, and thus consists of a rotating, asymptotically locally anti-de Sitter black hole. This stationary solution has no curvature singularities...
Probability for a primordial black hole pair in 1/R gravity
International Nuclear Information System (INIS)
The probability for quantum creation of an inflationary universe with a pair of black holes in 1/R-gravitational theory has been studied. Considering a gravitational action which includes a cosmological constant (Λ) in addition to δR-1 term, the probability has been evaluated in a semiclassical approximation with Hartle-Hawking boundary condition. We obtain instanton solutions determined by the parameters δ and Λ satisfying the constraint δ≤(4Λ2/3). However, we note that two different classes of instanton solutions exists in the region 02/3). The probabilities of creation of such configurations are evaluated. It is found that the probability of creation of a universe with a pair of black holes is strongly suppressed with a positive cosmological constant except in one case when 02. It is also found that gravitational instanton solution is permitted even with Λ=0 but one has to consider δ<0. However, in the later case a universe with a pair of black holes is less probable
Black hole physics from two-dimensional dilaton gravity based on the SL(2,R)/U(1) coset model
International Nuclear Information System (INIS)
We analyze the quantum two-dimensional dilaton gravity model, which is described by the SL(2,R)/U(1) gauged Wess-Zumino-Witten model deformed by a (1,1) operator. We show that the curvature singularity does not appear when the central charge cmatter of the matter fields is given by 22mattermattermatter∝δ(x+-x0+), create a kind of wormholes, i.e., causally disconnected regions. Most of the quantum information in past null infinity is lost in future null infinity but the lost information would be carried by the wormholes. We also discuss the problem of defining the mass of quantum black holes. On the basis of the argument by Regge and Teitelboim, we show that the ADM mass measured by the observer who lives in one of the asymptotically flat regions is finite and does not vanish in general. On the other hand, the Bondi mass is ill defined in this model. Instead of the Bondi mass, we consider the mass measured by observers who live in an asymptotically flat region at first. A class of observers finds the mass of the black hole created by a shock wave changes as the observers' proper time goes by, i.e., they observe Hawking radiation. The measured mass vanishes after the infinite proper time and the black hole evaporates completely. Therefore the total Hawking radiation is positive even when N<24
Thermodynamics of topological black holes in Brans-Dicke gravity with a power-law Maxwell field
Zangeneh, M. Kord; Dehghani, M. H.; Sheykhi, A.
2015-11-01
In this paper, we present a new class of higher-dimensional exact topological black hole solutions of the Brans-Dicke theory in the presence of a power-law Maxwell field as the matter source. For this aim, we introduce a conformal transformation which transforms the Einstein-dilaton-power-law Maxwell gravity Lagrangian to the Brans-Dicke-power-law Maxwell theory one. Then, by using this conformal transformation, we obtain the desired solutions. Next, we study the properties of the solutions and conditions under which we have black holes. Interestingly enough, we show that there is a cosmological horizon in the presence of a negative cosmological constant. Finally, we calculate the temperature and charge and then by calculating the Euclidean action, we obtain the mass, the entropy and the electromagnetic potential energy. We find that the entropy does not respect the area law, and also the conserved and thermodynamic quantities are invariant under conformal transformation. Using these thermodynamic and conserved quantities, we show that the first law of black hole thermodynamics is satisfied on the horizon.
Nonstationary analogue black holes
International Nuclear Information System (INIS)
We study the existence of analogue nonstationary spherically symmetric black holes. The prime example is the acoustic model see Unruh (1981 Phys. Rev. Lett. 46 1351). We consider also a more general class of metrics that could be useful in other physical models of analogue black and white holes. We give examples of the appearance of black holes and of disappearance of white holes. We also discuss the relation between the apparent and the event horizons for the case of analogue black holes. In the end we study the inverse problem of determination of black or white holes by boundary measurements for the spherically symmetric nonstationary metrics. (paper)
Energy Technology Data Exchange (ETDEWEB)
Dadhich, Naresh [Jamia Millia Islamia, Centre for Theoretical Physics, New Delhi (India); Inter-University Centre for Astronomy and Astrophysics, Pune (India); Pons, Josep M. [Universitat de Barcelona, Departament d' Estructura i Constituents de la Materia y Institut de Ciencies del Cosmos (ICCUB), Facultat de Fsica, Barcelona, Catalonia (Spain)
2015-06-15
We study static black hole solutions in Einstein and Einstein-Gauss-Bonnet gravity with the topology of the product of two spheres, S{sup n} x S{sup n}, in higher dimensions. There is an unusual new feature of the Gauss-Bonnet black hole: the avoidance of a non-central naked singularity prescribes a mass range for the black hole in terms of Λ > 0. For an Einstein-Gauss-Bonnet black hole a limited window of negative values for Λ is also permitted. This topology encompasses black strings, branes, and generalized Nariai metrics. We also give new solutions with the product of two spheres of constant curvature. (orig.)
Prasia, P
2016-01-01
We investigate black holes in a class of dRGT massive gravity for their quasi normal modes (QNMs) for neutral and charged ones using Improved Asymptotic Iteration Method (Improved AIM) and their thermodynamic behavior. The QNMs are studied for different values of the massive parameter m_g for both neutral and charged dRGT black holes under a massless scalar perturbation. As m_g increases, the magnitude of the quasi normal frequencies are found to be increasing. The results are also compared with the Schwarzchild de Sitter (SdS) case. P-V criticallity of the aforesaid black hoels under massles scalar perturbation in the de Sitter space are also studied in this paper. It is found that the thermodynamic behavior of a neutral black hole shows no physically feasible phase transition while a charged black hole shows a definite phase transition.
Hayward, Sean A.
2008-01-01
This is a review of current theory of black-hole dynamics, concentrating on the framework in terms of trapping horizons. Summaries are given of the history, the classical theory of black holes, the defining ideas of dynamical black holes, the basic laws, conservation laws for energy and angular momentum, other physical quantities and the limit of local equilibrium. Some new material concerns how processes such as black-hole evaporation and coalescence might be described by a single trapping h...
Energy Technology Data Exchange (ETDEWEB)
Lopez-DomInguez, J C [Instituto de Fisica de la Universidad de Guanajuato PO Box E-143, 37150 Leoen Gto. (Mexico); Obregon, O [Instituto de Fisica de la Universidad de Guanajuato PO Box E-143, 37150 Leoen Gto. (Mexico); RamIrez, C [Facultad de Ciencias FIsico Matematicas, Universidad Autonoma de Puebla, PO Box 1364, 72000 Puebla (Mexico); Sabido, M [Instituto de Fisica de la Universidad de Guanajuato PO Box E-143, 37150 Leoen Gto. (Mexico)
2007-11-15
We study noncommutative black holes, by using a diffeomorphism between the Schwarzschild black hole and the Kantowski-Sachs cosmological model, which is generalized to noncommutative minisuperspace. Through the use of the Feynman-Hibbs procedure we are able to study the thermodynamics of the black hole, in particular, we calculate Hawking's temperature and entropy for the 'noncommutative' Schwarzschild black hole.
Strominger, Andrew
1993-01-01
The quantum statistics of charged, extremal black holes is investigated beginning with the hypothesis that the quantum state is a functional on the space of closed three-geometries, with each black hole connected to an oppositely charged black hole through a spatial wormhole. From this starting point a simple argument is given that a collection of extremal black holes obeys neither Bose nor Fermi statistics. Rather they obey an exotic variety of particle statistics known as ``infinite statist...
Gao, C. J.; Zhang, S. N.
2006-01-01
The exact solutions of electrically charged phantom black holes with the cosmological constant are constructed. They are labelled by the mass, the electrical charge, the cosmological constant and the coupling constant between the phantom and the Maxwell field. It is found that the phantom has important consequences on the properties of black holes. In particular, the extremal charged phantom black holes can never be achieved and so the third law of thermodynamics for black holes still holds. ...
$P$ – $V$ criticality of topological black holes in Lovelock–Born–Infeld gravity
Mo, Jie-Xiong; Liu, Wen-Biao
2014-01-01
To understand the effect of third order Lovelock gravity, P – V criticality of topological AdS black holes in Lovelock–Born–Infeld gravity is investigated. The thermodynamics is further explored with some more extensions and in some more detail than the previous literature. A detailed analysis of the limit case β→∞ is performed for the seven-dimensional black holes. It is shown that, for the spherical topology, P – V criticality exists for both the uncharged and the charged cases. Our results...
Extremal dyonic black holes in D=4 Gauss-Bonnet gravity
Chen, Chiang-Mei; Orlov, Dmitry G
2008-01-01
We investigate extremal dyon black holes in the Einstein-Maxwell-dilaton (EMD) theory with higher curvature corrections in the form of the Gauss-Bonnet density coupled to the dilaton. In the same theory without the Gauss-Bonnet term the extremal dyon solutions exist only for discrete values of the dilaton coupling constant $a$. We show that the Gauss-Bonnet term acts as a dyon hair tonic enlarging the allowed values of $a$ to continuous domains in the plane $(a, q_m)$ the second parameter being the magnetic charge. In the limit of the vanishing curvature coupling (a large magnetic charge) the dyon solutions obtained tend to the Reissner-Nordstr\\"om solution but not to the extremal dyons of the EMD theory. Both solutions have the same values of the horizon radius as a function of charges. The entropy of new dyonic black holes interpolates between the Bekenstein-Hawking value in the limit of the large magnetic charge (equivalent to the vanishing Gauss-Bonnet coupling) and twice this value for the vanishing magn...
Quantum compositeness of gravity: black holes, AdS and inflation
International Nuclear Information System (INIS)
Gravitational backgrounds, such as black holes, AdS, de Sitter and inflationary universes, should be viewed as composite of N soft constituent gravitons. It then follows that such systems are close to quantum criticality of graviton Bose-gas to Bose-liquid transition. Generic properties of the ordinary metric description, including geodesic motion or particle-creation in the background metric, emerge as the large-N limit of quantum scattering of constituent longitudinal gravitons. We show that this picture correctly accounts for physics of large and small black holes in AdS, as well as reproduces well-known inflationary predictions for cosmological parameters. However, it anticipates new effects not captured by the standard semi-classical treatment. In particular, we predict observable corrections that are sensitive to the inflationary history way beyond last 60 e-foldings. We derive an absolute upper bound on the number of e-foldings, beyond which neither de Sitter nor inflationary Universe can be approximated by a semi-classical metric. However, they could in principle persist in a new type of quantum eternity state. We discuss implications of this phenomenon for the cosmological constant problem
Levin, Janna; D'Orazio, Daniel
2016-03-01
Black holes are dark dead stars. Neutron stars are giant magnets. As the neutron star orbits the black hole, an electronic circuit forms that generates a blast of power just before the black hole absorbs the neutron star whole. The black hole battery conceivably would be observable at cosmological distances. Possible channels for luminosity include synchro-curvature radiation, a blazing fireball, or even an unstable, short-lived black hole pulsar. As suggested by Mingarelli, Levin, and Lazio, some fraction of the battery power could also be reprocessed into coherent radio emission to populate a subclass of fast radio bursts.
Phase transition in black holes
Roychowdhury, Dibakar
2014-01-01
The present thesis is devoted towards the study of various aspects of the phase transition phenomena occurring in black holes defined in an Anti-de-Sitter (AdS) space. Based on the fundamental principles of thermodynamics and considering a grand canonical framework we examine various aspects of the phase transition phenomena occurring in AdS black holes. We analytically check that this phase transition between the smaller and larger mass black holes obey Ehrenfest relations defined at the critical point and hence confirm a second order phase transition. This include both the rotating and charged black holes in Einstein gravity. Apart from studying these issues, based on a canonical framework, we also investigate the critical behavior in charged AdS black holes. The scaling laws for these black holes are found to be compatible with the static scaling hypothesis. Finally, based on the usual framework of AdS/CFT duality, we investigate the phase transition phenomena occurring in charged hairy black holes defined...
A nonsingular rotating black hole
International Nuclear Information System (INIS)
The spacetime singularities in classical general relativity are inevitable, as predicated by the celebrated singularity theorems. However, it is a general belief that singularities do not exist in Nature and that they are the limitations of the general relativity. In the absence of a welldefined quantum gravity, models of regular black holes have been studied. We employ a probability distribution inspired mass function m(r) to replace the Kerr black hole mass M to represent a nonsingular rotating black hole that is identified asymptotically (r >> k, k > 0 constant) exactly as the Kerr-Newman black hole, and as the Kerr black hole when k = 0. The radiating counterpart renders a nonsingular generalization of Carmeli's spacetime as well as Vaidya's spacetime, in the appropriate limits. The exponential correction factor changing the geometry of the classical black hole to remove the curvature singularity can also be motivated by quantum arguments. The regular rotating spacetime can also be understood as a black hole of general relativity coupled to nonlinear electrodynamics. (orig.)
A nonsingular rotating black hole
Energy Technology Data Exchange (ETDEWEB)
Ghosh, Sushant G. [Jamia Millia Islamia, Centre for Theoretical Physics, New Delhi (India); University of KwaZulu-Natal, Astrophysics and Cosmology Research Unit, School of Mathematical Sciences, Durban (South Africa)
2015-11-15
The spacetime singularities in classical general relativity are inevitable, as predicated by the celebrated singularity theorems. However, it is a general belief that singularities do not exist in Nature and that they are the limitations of the general relativity. In the absence of a welldefined quantum gravity, models of regular black holes have been studied. We employ a probability distribution inspired mass function m(r) to replace the Kerr black hole mass M to represent a nonsingular rotating black hole that is identified asymptotically (r >> k, k > 0 constant) exactly as the Kerr-Newman black hole, and as the Kerr black hole when k = 0. The radiating counterpart renders a nonsingular generalization of Carmeli's spacetime as well as Vaidya's spacetime, in the appropriate limits. The exponential correction factor changing the geometry of the classical black hole to remove the curvature singularity can also be motivated by quantum arguments. The regular rotating spacetime can also be understood as a black hole of general relativity coupled to nonlinear electrodynamics. (orig.)
Black hole evaporation: a paradigm
International Nuclear Information System (INIS)
A paradigm describing black hole evaporation in non-perturbative quantum gravity is developed by combining two sets of detailed results: (i) resolution of the Schwarzschild singularity using quantum geometry methods and (ii) time evolution of black holes in the trapping and dynamical horizon frameworks. Quantum geometry effects introduce a major modification in the traditional spacetime diagram of black hole evaporation, providing a possible mechanism for recovery of information that is classically lost in the process of black hole formation. The paradigm is developed directly in the Lorentzian regime and necessary conditions for its viability are discussed. If these conditions are met, much of the tension between expectations based on spacetime geometry and structure of quantum theory would be resolved
Black hole thermodynamics from decoherence
Guo, Xiao-Kan
2015-01-01
We present an approach to the four laws of black hole thermodynamics by utilizing the thermodynamics of quantum coherence. Firstly, Hawking effect is attributed to the decoherence of the two-mode squeezed state in a black hole spacetime. Then use is made of the relative entropy between undecohered and decohered squeezed states whose monotonicity gives the zeroth and the second law, while the first law can be obtained either by the vanishing of the first derivative of relative entropy or by studying the effective thermal model generated by the modular Hamiltonian. Futhermore, information-theoretic arguments give a Planck's form of the third law of black hole thermodynamics. With this approach we can understand the laboratory analogues of black holes solely by quantum theory. This approach also opens a way to reconstruct classical geometry from quantum gravity.
Black hole interior mass formula
International Nuclear Information System (INIS)
We argue by explicit computations that, although the area product, horizon radii product, entropy product, and irreducible mass product of the event horizon and Cauchy horizon are universal, the surface gravity product, the surface temperature product and the Komar energy product of the said horizons do not seem to be universal for Kerr-Newman black hole spacetimes. We show the black hole mass formula on the Cauchy horizon following the seminal work by Smarr [Phys Rev Lett 30:71 (1973), Phys Rev D 7:289 (1973)] for the outer horizon. We also prescribe the four laws of black hole mechanics for the inner horizon. A new definition of the extremal limit of a black hole is discussed. (orig.)
Anyonic statistics and large horizon diffeomorphisms for Loop Quantum Gravity Black Holes
Pithis, Andreas G A
2014-01-01
In this article we investigate the role played by large diffeomorphisms of quantum Isolated Horizons for the statistics of LQG Black Holes by means of their relation to the braid group. To this aim the symmetries of Chern-Simons theory are recapitulated with particular regard to the aforementioned type of diffeomorphisms. For the punctured spherical horizon, these are elements of the mapping class group of $S^2$, which is almost isomorphic to a corresponding braid group on this particular manifold. The mutual exchange of quantum entities in $2$-dimensions is communicated by the braid group, rendering the statistics anyonic. With this we argue that the quantum Isolated Horizon model of LQG based on $SU(2)_k$-Chern-Simons theory exhibits non-abelian anyonic statistics. In this way a connection to theory behind the fractional quantum Hall effect and that of topological quantum computation is established, where non-abelian anyons play a significant role.
On Black Holes and Cosmological Constant in Noncommutative Gauge Theory of Gravity
International Nuclear Information System (INIS)
Deformed Reissner-Nordstroem, as well as Reissner-Nordstroem de Sitter, solutions are obtained in a noncommutative gauge theory of gravitation. The gauge potentials (tetrad fields) and the components of deformed metric are calculated to second order in the noncommutativity parameter. The solutions reduce to the deformed Schwarzschild ones when the electric charge of the gravitational source and the cosmological constant vanish. Corrections to the thermodynamical quantities of the corresponding black holes and to the radii of different horizons have been determined. All the independent invariants, such as the Ricci scalar and the so-called Kretschmann scalar, have the same singularity structure as the ones of the usual undeformed case and no smearing of singularities occurs. The possibility of such a smearing is discussed. In the noncommutative case we have a local disturbance of the geometry around the source, although asymptotically at large distances the geometry becomes flat
Black Hole Formation in AdS Einstein-Gauss-Bonnet Gravity
Deppe, Nils; Frey, Andrew R; Kunstatter, Gabor
2016-01-01
AdS spacetime has been shown numerically to be unstable against a large class of arbitrarily small perturbations. In arXiv:1410.1869, the authors presented a preliminary study of the effects on stability of changing the local dynamics by adding a Gauss-Bonnet term to the Einstein action. Here we provide further details as well as new results with improved numerical methods. In particular, we elucidate new structure in Choptuik scaling plots. We also provide evidence of chaotic behavior at the transition between immediate horizon formation and horizon formation after the matter pulse reflects from the AdS conformal boundary. Finally, we present data suggesting the formation of naked singularities in spacetimes with ADM mass below the algebraic bound for black hole formation.
International Nuclear Information System (INIS)
In this paper, we study electromeganetic static spacetimes in the nonrelativisitc general covariant theory of the Hořava-Lifshitz (HL) gravity, proposed recently by Hořava and Melby-Thompson, and present all the electric static solutions, which represent the generalization of the Reissner-Nordström solution found in Einstein's general relativity (GR). The global/local structures of spacetimes in the HL theory in general are different from those given in GR, because the dispersion relations of test particles now contain high-order momentum terms, so the speeds of these particles are unbounded in the ultraviolet (UV). As a result, the conception of light-cones defined in GR becomes invalid and test particles do not follow geodesics. To study black holes in the HL theory, we adopt the geometrical optical approximations, and define a horizon as a (two-closed) surface that is free of spacetime singularities and on which massless test particles are infinitely redshifted. With such a definition, we show that some of our solutions give rise to (charged) black holes, although the radii of their horizons in general depend on the energies of the test particles
Stability of the Schwarzschild–de Sitter black hole in the dRGT massive gravity theory
International Nuclear Information System (INIS)
The Schwarzschild–de Sitter solution in the Einstein theory with a positive cosmological constant Λ=m2/α becomes an exact solution to the de Rham–Gabadadze–Tolley (dRGT) nonlinear massive gravity theory with the mass parameter m when the theory parameters α and β satisfy the relation β=α2. We study the perturbative behavior of this black hole solution in the nonlinear dRGT theory with β=α2. We find that the linear perturbation equations become identical to those for the vacuum Einstein theory when they are expressed in terms of gauge-invariant variables. This implies that this black hole is stable in the dRGT theory as far as the spacetime structure is concerned, in contrast to the case of the bi-Schwarzschild solution in the bi-metric theory. However, we have also found a pathological feature that the general solution to the perturbation equations contain a single arbitrary function of spacetime coordinates. This implies a degeneracy of dynamics in the Stückelberg field sector at the linear perturbation level in this background. The physical significance of this degeneracy depends on how the Stückelberg fields couple observable fields
International Nuclear Information System (INIS)
We consider curvature-squared corrections to Einstein-Hilbert gravity action in the form of a Gauss-Bonnet term in D>4 dimensions. In this theory, we study the thermodynamics of charged static black holes with anti-de Sitter (AdS) asymptotics, and whose electric field is described by nonlinear electrodynamics. These objects have received considerable attention in recent literature on gravity/gauge dualities. It is well-known that, within the framework of anti-de Sitter/conformal field theory (AdS/CFT) correspondence, there exists a nonvanishing Casimir contribution to the internal energy of the system, manifested as the vacuum energy for global AdS spacetime in odd dimensions. Because of this reason, we derive a quantum statistical relation directly from the Euclidean action and not from the integration of the first law of thermodynamics. To this end, we employ a background-independent regularization scheme which consists, in addition to the bulk action, of counterterms that depend on both extrinsic and intrinsic curvatures of the boundary (Kounterterm series). This procedure results in a consistent inclusion of the vacuum energy and chemical potential in the thermodynamic description for Einstein-Gauss-Bonnet AdS gravity regardless of the explicit form of the nonlinear electrodynamics Lagrangian.
International Nuclear Information System (INIS)
Using a new tortoise coordinate transformation, we discuss the quantum nonthermal radiation characteristics near an event horizon by studying the Hamilton-Jacobi equation of a scalar particle in curved space-time, and obtain the event horizon surface gravity and the Hawking temperature on that event horizon. The results show that there is a crossing of particle energy near the event horizon. We derive the maximum overlap of the positive and negative energy levels. It is also found that the Hawking temperature of a black hole depends not only on the time, but also on the angle. There is a problem of dimension in the usual tortoise coordinate, so the present results obtained by using a correct-dimension new tortoise coordinate transformation may be more reasonable
Mehdipour, S Hamid
2013-01-01
We study some features of entropic force approach in the presence of a noncommutative Schwarzschild-deSitter black hole. In this setup, there exists a similarity between the small and large scales. There are two finite cut-off in very short and long distances wherein the force and energy graph stop abruptly at those scales. We find that the existence of a deSitter core around the origin, induced by noncommutativity, in addition to a standard deSitter background at large scale may lead to a violation of the equivalence principle. Finally in order to directly observe the finite cut-off at short-scale gravity, caused by noncommutativity quantum fluctuations, we derive an effective gravitational constant.
Mehdipour, S. Hamid
2013-06-01
We study some features of entropic force approach in the presence of a noncommutative Schwarzschild-deSitter black hole. In this setup, there exists a similarity between the small and large scales. There are two finite cut-off in very short and long distances wherein the force and energy graph stop abruptly at those scales. We find that the existence of a deSitter core around the origin, induced by noncommutativity, in addition to a standard deSitter background at large scale may lead to a violation of the equivalence principle. Finally in order to directly observe the finite cut-off at short-scale gravity, caused by noncommutativity quantum fluctuations, we derive an effective gravitational constant.
Institute of Scientific and Technical Information of China (English)
Xie Zhi-Kun; Pan Wei-Zhen; Yang Xue-Jun
2013-01-01
Using a new tortoise coordinate transformation,we discuss the quantum nonthermal radiation characteristics near an event horizon by studying the Hamilton-Jacobi equation of a scalar particle in curved space-time,and obtain the event horizon surface gravity and the Hawking temperature on that event horizon.The results show that there is a crossing of particle energy near the event horizon.We derive the maximum overlap of the positive and negative energy levels.It is also found that the Hawking temperature of a black hole depends not only on the time,but also on the angle.There is a problem of dimension in the usual tortoise coordinate,so the present results obtained by using a correct-dimension new tortoise coordinate transformation may be more reasonable.
On wormholes and black holes solutions of Einstein gravity coupled to a K-massless scalar field
International Nuclear Information System (INIS)
We investigate the nature of black holes and wormholes admitted by a K-essence model involving a massless scalar field φ, minimally coupled to gravity. Via Weyl's formalism, we show that any axial wormhole of the theory can be generated by a unique pair of harmonic functions: U(λ) = π/2 C + C arctan(λ/λ0), φ(λ) = π/2 D + D arctan(λ/λ0) where λ is one of the oblate coordinate, λ0 > 0 and (C, D) real parameters. The properties of the wormholes depends crucially upon the values of the parameters (C, D). Whenever (C, D) are chosen so that 2C2 - kD2 = -2 the wormhole is spherical, while for the case where 2C2 - kD2 = -4 or 2C2 - kD2 = -6 the wormhole throat possesses toroidal topology. Those two families of wormholes exhaust all regular static and axisymmetric wormholes admitted by this theory. For completeness we add that whenever (C, D) satisfy 2C2 - kD2 = -2l with l ≥ 3/2 one still generates a spacetime possessing two asymptotically flat but the throat connecting the two ends contains a string like singularity. For the refined case where 2C2 - kD2 = -2l with l = 4,5, ... the resulting spacetime represents a multi-sheeted configuration which even though free of curvature singularities nevertheless the spacetime topology is distinct to so far accepted wormhole topology. Spacetimes generated by the pair (U(λ), φ(λ)) and parameters (C, D) subject to 2C2 - kD2 = -2l with l 2 bifurcating, regular Killing horizon necessary possesses a constant exterior scalar field. Under the assumption that the event horizon of any static black hole of this theory is a Killing horizon, the results show that the only static black hole admitted by this K-essence model, is the Schwarzschild black hole
String condensation: Nemesis of Black Holes?
Hewitt, Michael
2015-01-01
This paper puts forward a conjecture that there are no black holes in M theory. We will show that a mechanism to prevent black hole formation is needed in 4 dimensions to make string theory a viable high energy model of quantum gravity. Black hole formation may be averted by a gravity regulation mechanism based on string condensation. In this scenario, black holes are replaced by `hot holograms' that form during gravitational collapse. The geometric conditions based on the properties of free thermalon solutions that are proposed for conversion to a high temperature hologram to occur, however, are local and generic in dimension and could apply throughout M space. This idea can be applied to resolve the problems presented by the process of black hole evaporation, which appears to be inconsistent with quantum information theory. Whereas, in the conventional view, black holes are real and firewalls are probably a chimera, in the scenario proposed here that situation would be reversed.
Gorini, Vittorio; Moschella, Ugo; Treves, Aldo; Colpi, Monica
2016-01-01
Based on graduate school lectures in contemporary relativity and gravitational physics, this book gives a complete and unified picture of the present status of theoretical and observational properties of astrophysical black holes. The chapters are written by internationally recognized specialists. They cover general theoretical aspects of black hole astrophysics, the theory of accretion and ejection of gas and jets, stellar-sized black holes observed in the Milky Way, the formation and evolution of supermassive black holes in galactic centers and quasars as well as their influence on the dynamics in galactic nuclei. The final chapter addresses analytical relativity of black holes supporting theoretical understanding of the coalescence of black holes as well as being of great relevance in identifying gravitational wave signals. With its introductory chapters the book is aimed at advanced graduate and post-graduate students, but it will also be useful for specialists.
International Nuclear Information System (INIS)
By using a new approach, we demonstrate the analytic expressions for slowly rotating Gauss—Bonnet charged black hole solutions with one non-vanishing angular momentum in higher-dimensional anti-de Sitter spaces. Up to linear order of the rotating parameter a, the mass, Hawking temperature and entropy of the charged black holes get no corrections from rotation. (general)
International Nuclear Information System (INIS)
By using a new approach, we demonstrate the analytic expressions for slowly rotating Gauss-Bonnet charged black hole solutions with one non-vanishing angular momentum in higher-dimensional anti-de Sitter spaces. Up to linear order of the rotating parameter a, the mass, Hawking temperature and entropy of the charged black holes get no corrections from rotation. (authors)
Banerjee, S.; Gupta, R.K.; Mandal, I.; Sen, A.
2011-01-01
We compute logarithmic corrections to the entropy of supersymmetric extremal black holes in {N} = {4} and {N} = {8} supersymmetric string theories and find results in perfect agreement with the microscopic results. In particular these logarithmic corrections vanish for quarter BPS black holes in {N}
Quantum Evaporation of Liouville Black Holes
Mann, R. B.
1993-01-01
The classical field equations of a Liouville field coupled to gravity in two spacetime dimensions are shown to have black hole solutions. Exact solutions are also obtained when quantum corrections due to back reaction effects are included, modifying both the ADM mass and the black hole entropy. The thermodynamic limit breaks down before evaporation of the black hole is complete, indicating that higher-loop effects must be included for a full description of the process. A scenario for the fina...
Black holes and the LHC: A review
Park, Seong Chan
2012-01-01
In low-scale gravity models, a particle collider with trans-Planckian collision energies can be an ideal place for producing black holes because a large amount of energy can be concentrated at the collision point, which can ultimately lead to black hole formation. In this article, the theoretical foundation for microscopic higher dimensional black holes is reviewed and the possible production and detection at the LHC is described and critically examined.
Black Hole Based Tests of General Relativity
Yagi, Kent
2016-01-01
General relativity has passed all solar system experiments and neutron star based tests, such as binary pulsar observations, with flying colors. A more exotic arena for testing general relativity is in systems that contain one or more black holes. Black holes are the most compact objects in the universe, providing probes of the strongest-possible gravitational fields. We are motivated to study strong-field gravity since many theories give large deviations from general relativity only at large field strengths, while recovering the weak-field behavior. In this article, we review how one can probe general relativity and various alternative theories of gravity by using electromagnetic waves from a black hole with an accretion disk, and gravitational waves from black hole binaries. We first review model-independent ways of testing gravity with electromagnetic/gravitational waves from a black hole system. We then focus on selected examples of theories that extend general relativity in rather simple ways. Some impor...
Mathur, Samir D.
2007-01-01
String theory tells us that quantum gravity has a dual description as a field theory (without gravity). We use the field theory dual to ask what happens to an object as it falls into the simplest black hole: the 2-charge extremal hole. In the field theory description the wavefunction of a particle is spread over a large number of `loops', and the particle has a well-defined position in space only if it has the same `position' on each loop. For the infalling particle we find one definition of ...
Begelman, Mitchell C
2003-06-20
Black holes are common objects in the universe. Each galaxy contains large numbers-perhaps millions-of stellar-mass black holes, each the remnant of a massive star. In addition, nearly every galaxy contains a supermassive black hole at its center, with a mass ranging from millions to billions of solar masses. This review discusses the demographics of black holes, the ways in which they interact with their environment, factors that may regulate their formation and growth, and progress toward determining whether these objects really warp spacetime as predicted by the general theory of relativity. PMID:12817138
International Nuclear Information System (INIS)
The quantum statistics of charged, extremal black holes is investigated beginning with the hypothesis that the quantum state is a functional on the space of closed three-geometries, with each black hole connected to an oppositely charged black hole through a spatial wormhole. From this starting point a simple argument is given that a collection of extremal black holes obeys neither Bose nor Fermi statistics. Rather, they obey an exotic variety of particle statistics known as ''infinite statistics'' which resembles that of distinguishable particles and is realized by a q deformation of the quantum commutation relations
Neves, J C S
2015-01-01
In this work, we have deformed regular black holes which possess a general mass term described by a function which generalizes the Bardeen and Hayward mass terms. Using linear constraints in the energy-momentum tensor, the solutions are either regular or singular. That is, with this approach, it is possible to generate singular black holes from regular black holes and vice versa. Moreover, contrary to the Bardeen and Hayward regular solutions, the regular deformed metrics may violate the weak energy condition despite the presence of the spherical symmetry. Some comments on accretion of deformed black holes in cosmological scenarios are made.
White holes and eternal black holes
International Nuclear Information System (INIS)
We investigate isolated white holes surrounded by vacuum, which correspond to the time reversal of eternal black holes that do not evaporate. We show that isolated white holes produce quasi-thermal Hawking radiation. The time reversal of this radiation, incident on a black hole precursor, constitutes a special preparation that will cause the black hole to become eternal. (paper)
White holes and eternal black holes
Stephen D. H. Hsu
2010-01-01
We investigate isolated white holes surrounded by vacuum, which correspond to the time reversal of eternal black holes that do not evaporate. We show that isolated white holes produce quasi- thermal Hawking radiation. The time reversal of this radiation, incident on a black hole precursor, constitutes a special preparation that will cause the black hole to become eternal.
n-Dimensional Gravity Little Black Holes, Dark Matter, and Ball Lightning
Rabinowitz, M
2001-01-01
The gravitational field, and radiation from quantized gravitational atoms and little black holes (LBH) are analyzed in n-space, i.e. in all dimensions from 0 to o to develop insights into possible additional compacted dimensions as predicted by hierarchy and string theory. It is shown that the entropy of LBH is significantly greater in higher dimensional space with potential implications to the initial entropy of the universe. A case is made that LBH are the dark matter of the universe, and can manifest themselves as the core energy source of ball lightning (BL). The LBH incidence rate on earth is related to BL occurrence and has the potential of aiding in the determination of the distribution of LBH and hence dark matter in the universe. Examination of LBH interactions with the atmosphere are found to be in accord with observations of BL. Possibilities are explored as to why Hawking radiation has been undetected in over 25 years. An alternate LBH tunneling radiation model is described.
Information Loss in Black Holes
Hawking, Stephen William
2005-01-01
The question of whether information is lost in black holes is investigated using Euclidean path integrals. The formation and evaporation of black holes is regarded as a scattering problem with all measurements being made at infinity. This seems to be well formulated only in asymptotically AdS spacetimes. The path integral over metrics with trivial topology is unitary and information preserving. On the other hand, the path integral over metrics with non-trivial topologies leads to correlation functions that decay to zero. Thus at late times only the unitary information preserving path integrals over trivial topologies will contribute. Elementary quantum gravity interactions do not lose information or quantum coherence.
Information loss in black holes
Hawking, S. W.
2005-10-01
The question of whether information is lost in black holes is investigated using Euclidean path integrals. The formation and evaporation of black holes is regarded as a scattering problem with all measurements being made at infinity. This seems to be well formulated only in asymptotically AdS spacetimes. The path integral over metrics with trivial topology is unitary and information preserving. On the other hand, the path integral over metrics with nontrivial topologies leads to correlation functions that decay to zero. Thus at late times only the unitary information preserving path integrals over trivial topologies will contribute. Elementary quantum gravity interactions do not lose information or quantum coherence.
Prasia, P; Kuriakose, V. C.
2016-01-01
We investigate black holes in a class of dRGT massive gravity for their quasi normal modes (QNMs) for neutral and charged ones using Improved Asymptotic Iteration Method (Improved AIM) and their thermodynamic behavior. The QNMs are studied for different values of the massive parameter m_g for both neutral and charged dRGT black holes under a massless scalar perturbation. As m_g increases, the magnitude of the quasi normal frequencies are found to be increasing. The results are also compared w...
International Nuclear Information System (INIS)
In an arbitrary dimension D, we study quadratic corrections to Einstein-Hilbert action described by the Gauss-Bonnet term. We consider charged black hole solutions with anti-de Sitter (AdS) asymptotics, of interest in the context of gravity/gauge theory dualities (AdS/CFT). The electric charge here is due to the addition of an arbitrary nonlinear electrodynamics (NED) Lagrangian. Due to the existence of a vacuum energy for global AdS spacetime in odd dimensions in the framework of AdS/CFT correspondence, we derive a Quantum Statistical Relation directly from the Euclidean action and not from the First Law of thermodynamics. To this end, we employ a background-independent regularization scheme which consists in supplementing the bulk action with counterterms that depend both on the extrinsic and intrinsic curvatures of the boundary (also known as Kounterterms). This procedure results in a consistent inclusion of the vacuum energy in the thermodynamic description for Einstein-Gauss-Bonnet AdS gravity regardless the explicit form of the NED Lagrangian.
Miskovic, Olivera
2010-01-01
We consider curvature-squared corrections to Einstein-Hilbert gravity action in the form of Gauss-Bonnet term in D>4 dimensions. In this theory, we study the thermodynamics of charged static black holes with anti-de Sitter (AdS) asymptotics, and whose electric field is described by nonlinear electrodynamics (NED). These objects have received considerable attention in recent literature on gravity/gauge dualities. It is well-known that, within the framework of anti de-Sitter/Conformal Field Theory (AdS/CFT) correspondence, there exists a nonvanishing Casimir contribution to the internal energy of the system, manifested as the vacuum energy for global AdS spacetime in odd dimensions. Because of this reason, we derive a Quantum Statistical Relation directly from the Euclidean action and not from the integration of the First Law of thermodynamics. To this end, we employ a background-independent regularization scheme which consists in the addition to the bulk action of counterterms that depend on both extrinsic and...
Black hole mimickers: Regular versus singular behavior
International Nuclear Information System (INIS)
Black hole mimickers are possible alternatives to black holes; they would look observationally almost like black holes but would have no horizon. The properties in the near-horizon region where gravity is strong can be quite different for both types of objects, but at infinity it could be difficult to discern black holes from their mimickers. To disentangle this possible confusion, we examine the near-horizon properties, and their connection with far away asymptotic properties, of some candidates to black mimickers. We study spherically symmetric uncharged or charged but nonextremal objects, as well as spherically symmetric charged extremal objects. Within the uncharged or charged but nonextremal black hole mimickers, we study nonextremal ε-wormholes on the threshold of the formation of an event horizon, of which a subclass are called black foils, and gravastars. Within the charged extremal black hole mimickers we study extremal ε-wormholes on the threshold of the formation of an event horizon, quasi-black holes, and wormholes on the basis of quasi-black holes from Bonnor stars. We elucidate whether or not the objects belonging to these two classes remain regular in the near-horizon limit. The requirement of full regularity, i.e., finite curvature and absence of naked behavior, up to an arbitrary neighborhood of the gravitational radius of the object enables one to rule out potential mimickers in most of the cases. A list ranking the best black hole mimickers up to the worst, both nonextremal and extremal, is as follows: wormholes on the basis of extremal black holes or on the basis of quasi-black holes, quasi-black holes, wormholes on the basis of nonextremal black holes (black foils), and gravastars. Since in observational astrophysics it is difficult to find extremal configurations (the best mimickers in the ranking), whereas nonextremal configurations are really bad mimickers, the task of distinguishing black holes from their mimickers seems to be less
High-energy black hole production
Giddings, Steven B.
2007-01-01
Black hole production in high-energy collisions is briefly surveyed. Included is a summary of recent developments and open problems relevant to collider (LHC) production, as well as of some theoretical issues pointing towards fundamental principles of quantum gravity.
Black Holes Shed Light on Galaxy Formation
2000-01-01
This videotape is comprised of several segments of animations on black holes and galaxy formation, and several segments of an interview with Dr. John Kormendy. The animation segments are: (1) a super massive black hole, (2) Centarus A active black hole found in a collision, (3) galaxy NGC-4261 (active black hole and jet model), (4) galaxy M-32 (orbits of stars are effected by the gravity of the black hole), (5) galaxy M-37 (motion of stars increases as mass of black hole increases), (6) Birth of active galactic nuclei, (7) the collision of two galaxy leads to merger of the black holes, (8) Centarus A and simulation of the collision of 2 galaxies. There are also several segments of an interview with John Kormendy. In these segments he discusses the two most important aspects of his recent black hole work: (1) the correlations between galaxies speed and the mass of the black holes, and (2) the existence of black holes and galactic formation. He also discusses the importance of the Hubble Space Telescope and the Space Telescope Imaging Spectrograph to the study of black holes. He also shows the methodology of processing images from the spectrograph in his office.
Noncommutative Singular Black Holes
International Nuclear Information System (INIS)
In this paper, applying the method of coordinate coherent states to describe a noncommutative model of Vaidya black holes leads to an exact (t - r) dependence of solution in terms of the noncommutative parameter σ. In this setup, there is no black hole remnant at long times.
Noncommutative Singular Black Holes
Hamid Mehdipour, S.
2010-11-01
In this paper, applying the method of coordinate coherent states to describe a noncommutative model of Vaidya black holes leads to an exact (t — r) dependence of solution in terms of the noncommutative parameter σ. In this setup, there is no black hole remnant at long times.
DEFF Research Database (Denmark)
Kragh, Helge Stjernholm
2016-01-01
Review essay, Marcia Bartusiak, Black Hole: How an Idea Abandoned by Newtonians, Hated by Einstein, and Gambled On by Hawking Became Loved (New Haven: Yale University Press, 2015).......Review essay, Marcia Bartusiak, Black Hole: How an Idea Abandoned by Newtonians, Hated by Einstein, and Gambled On by Hawking Became Loved (New Haven: Yale University Press, 2015)....
Bousso, R.; Hawking, S. W.
1997-08-01
We summarise recent work on the quantum production of black holes in the inflationary era. We describe, in simple terms, the Euclidean approach used, and the results obtained both for the pair creation rate and for the evolution of the black holes.
Andersson, N
2000-01-01
This is a chapter on Black-hole Scattering that was commissioned for an Encyclopaedia on Scattering edited by Pike and Sabatier, to be published by Academic Press. The chapter surveys wave propagation in black-hole spacetimes, diffraction effects in wave scattering, resonances, quasinormal modes and related topics.
Black-hole entropy and horizon area
Energy Technology Data Exchange (ETDEWEB)
Hong-Wei Yu [Medford, Tufts Univ. (United States). Dept. of Physics and Astronomy, Inst. of Cosmology]|[Hunan Univ. (China). Inst. of Physics and Pysics Dept.
1998-08-01
Employing the relationship between the black-hole thermodynamic functions and the Euclidean path-integral approach to quantum gravity, the Authors prove, in the framework of four-dimensional Einstein gravity, that the entropy of a stationary black-hole with a bifurcating Killing horizon surrounded by arbitrary classical matter fields is one quarter of the area of the event horizon independent of the matter fields involved.
Scrambling with matrix black holes
Brady, Lucas; Sahakian, Vatche
2013-08-01
If black holes are not to be dreaded sinks of information but rather fully described by unitary evolution, they must scramble in-falling data and eventually leak it through Hawking radiation. Sekino and Susskind have conjectured that black holes are fast scramblers; they generate entanglement at a remarkably efficient rate, with the characteristic time scaling logarithmically with the entropy. In this work, we focus on Matrix theory—M-theory in the light-cone frame—and directly probe the conjecture. We develop a concrete test bed for quantum gravity using the fermionic variables of Matrix theory and show that the problem becomes that of chains of qubits with an intricate network of interactions. We demonstrate that the black hole system evolves much like a Brownian quantum circuit, with strong indications that it is indeed a fast scrambler. We also analyze the Berenstein-Maldacena-Nastase model and reach the same tentative conclusion.
Massive Black Holes and Galaxies
CERN. Geneva
2016-01-01
Evidence has been accumulating for several decades that many galaxies harbor central mass concentrations that may be in the form of black holes with masses between a few million to a few billion time the mass of the Sun. I will discuss measurements over the last two decades, employing adaptive optics imaging and spectroscopy on large ground-based telescopes that prove the existence of such a massive black hole in the Center of our Milky Way, beyond any reasonable doubt. These data also provide key insights into its properties and environment. Most recently, a tidally disrupting cloud of gas has been discovered on an almost radial orbit that reached its peri-distance of ~2000 Schwarzschild radii in 2014, promising to be a valuable tool for exploring the innermost accretion zone. Future interferometric studies of the Galactic Center Black hole promise to be able to test gravity in its strong field limit.
Kuchiev, M Yu
2003-01-01
Black holes are presumed to have an ideal ability to absorb and keep matter. Whatever comes close to the event horizon, a boundary separating the inside region of a black hole from the outside world, inevitably goes in and remains inside forever. This work shows, however, that quantum corrections make possible a surprising process, reflection: a particle can bounce back from the event horizon. For low energy particles this process is efficient, black holes behave not as holes, but as mirrors, which changes our perception of their physical nature. Possible ways for observations of the reflection and its relation to the Hawking radiation process are outlined.