Black Holes in String Theory

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Black holes and bubbled solutions in String Theory

Black holes and bubbled solutions in String Theory

6. Five-dimensional null and timelike supersymmetric geometries Hyper-K¨ ahler four-dimensional base space. It is well-known that in the time-like class the Killing vector can become null at some loci of the four-dimensional Hyper-K¨ ahler base manifold. Indeed, this is precisely what happens at the horizon of a black hole solution, or in the smooth five-dimensional solutions of [108] which will be considered in this chapter. A change in the causal character of the Killing vector is paralleled by a change of the supersymmetry conditions that the spinor satisfies. However, in all the solutions constructed so far this can happen only in some regions of codimension at most one of the space-time manifold, that are typically surfaces. Our goal in this chapter is to construct five-dimensional solutions in minimal Super- gravity whose Killing vector, which is generically time-like, becomes null at a point of the space-time manifold where all the derivatives of its norm vanish. The null condition is a closed condition, so if the norm of the spinor is a continuous function then the spinor can become null only on a closed subset of the manifold. Since all the derivatives of the norm vanish at the point where the Killing vector field becomes null, we conclude that the norm is not an analytic real function at this point, otherwise the Killing vector field would vanish on an open set, contradicting the fact that the null condition on the norm is a closed condition. Therefore, if we are able to construct a solution where the norm of the Killing vector field and all its derivatives vanish at some locus, we will know that the norm is not a real analytic function at those points. In either case, having a Killing vector whose norm has an infinite number of derivatives vanishing at a point is the closest scenario to having a null-spinor on an open set. These would be solutions that may mix, in a non-trivial way, the local classification that distinguishes between the time-like and the null classes. In this respect we consider smooth Supergravity solutions with a multi-center Gibbons-Hawking (GH) base manifold that asymptote to AdS 3 × S 2 . These can be gener-
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Black-Hole Microstates in String Theory : Black is the Color but Smooth are the Geometries?

Black-Hole Microstates in String Theory : Black is the Color but Smooth are the Geometries?

Unifying General Relativity and Quantum mechanics is not a theorist’s fantasy. Even if both frameworks have been experimentally tested with great precision in their domains of validity, the picture of the Universe remains scattered and their incompatibility gives rise to unsolved paradoxes. First, from observation, the matter well-described by those theories accounts only for 15% of the overall density and 68% of the energy allowing the expansion of the Universe to accelerate is unknown. Their names, dark matter and dark energy, are the only characteristics widely shared by the scientific community. Second, the understanding of our world is limited by the scales where the theoretical description breaks down. If the Standard model is naturally protected from divergences, General Relativity is not. General Relativity has two inherent singular behaviours delimiting the edge of the Universe as we know it today. First, the initial singularity, or big bang, corresponds to the furthest spacetime slice when the Universe was Planck size. Second, the theory contains also “black-hole-type” singularities where the curvature of spacetime diverges under strong deformations of compact masses. Those two singularities lie at the common theoretical border between General Relativity and Quantum Mechanics and must be resolved by a quantum theory of gravity. Because time travel back to the first nanoseconds of our Universe is not yet planned, black holes are the main theoretical and experimental laboratory for testing quantum theories of gravity such as String Theory.
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Testing Lorentz invariance by binary black holes

Testing Lorentz invariance by binary black holes

2.2.1 Percolation from the gravitational sector to the matter sector While several quantum gravity proposals (string theories with extra-dimensions [100], non-commutative field theory [101] and Hoˇ rava gravity [77, 78] for instance) hint towards Lorentz violations appearing in the ultraviolet, i.e., at small scales, it is not completely ob- vious that we may freely break Lorentz invariance in the gravitational sector without messing things out in the matter sector. Indeed, one could reasonably argue that any gravitational Lo- rentz violation would percolate into particle physics, and since there are very tight constraints on Lorentz violations in the matter sector, such as those mentioned in sections 2.1 and 2.2, then one would conclude that gravitational Lorentz violations must also be small. There exist counter-examples to this argument, however, and infrared (i.e., at long distances) Lorentz invariance could still be preserved by different mechanisms, even if gravity presents Lorentz violations in the ultraviolet. For instance, it could be protected by supersymmetry [102], or it could be an emergent symmetry appearing at low energies [103, 104] for different reasons, such as a renormalization group flow of the system leading to infrared Lorentz invariance [102, 105], or it could even be an accidental symmetry as suggested by [106]. It has also been proposed that a classically Lorentz invariant matter sector may co-exist with a Lorentz violating gravity sector provided that their interaction is mediated by higher-dimensional operators and is suppressed by a high-energy scale [107]. We therefore conclude that testing Lorentz invariance in the gravitational sector is still a reasonable enterprise since there is an ample spectrum of mechanisms able to control Lorentz violating percolation, despite the stringent constraints from the matter sector.
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Regular 3-charge 4D black holes and their microscopic description

Regular 3-charge 4D black holes and their microscopic description

3.1 The String Theory dilaton As explained in appendix ( A ), for black hole solutions of ungauged four-dimensional su- pergravity, the hyperscalars are truncated to a constant value. In principle, the dilaton belongs to the universal hypermultiplet, and therefore one may naively conclude that it should be constant for every black hole solution. However, in the process of obtaining the effective N = 2 four-dimensional supergravity in its standard form ( A.1 ), several rescal- ings and redefinitons are performed on the original ten-dimensional fields. In addition, since we are considering all the perturbative corrections to the Special Kähler sector, the corresponding N = 2 ungauged supergravity action is not the effective compactification theory of Type-IIA String Theory at tree level, so we should expect more intrincate redef- initions. Our purpose is to show now that Type-IIA quantum black holes have a constant ten-dimensional dilaton and a constant Calabi-Yau manifold volume, and we will do this in two steps:
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Charged Schrodinger black holes

Charged Schrodinger black holes

 / r 2 near the horizon, with all other components Oðr 0 Þ. V. CONCLUSION In this paper we obtained a general expression for the action of the null Melvin twist, constructed a series of charged and rotating asymptotically Schro¨dinger black hole solutions of type IIB supergravity, found a 5D trunca- tion of the 10D IIB theory adapted to these solutions, and examined some of the salient features of their geometry and thermodynamics. Along the way we discovered that these space-times inherit extremal limits from their parent AdS spaces, but that some of their features—like the radii of curvature of the near-horizon regions—are not inherited, leading to a potentially interesting class of new solutions. The fact that these systems are explicitly embedded in IIB string theory allows us to identify the boundary CFT as the
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Black holes and fourfolds

Black holes and fourfolds

iosif.bena@cea.fr, hagen.triendl@cea.fr, bert.vercnocke@cea.fr Abstract We establish the relation between the structure governing supersymmetric and non- supersymmetric four- and five-dimensional black holes and multicenter solutions and Calabi- Yau flux compactifications of M-theory and type IIB string theory. We find that the known BPS and almost-BPS multicenter black hole solutions can be interpreted as GKP compact- ifications with (2,1) and (0,3) imaginary self-dual flux. We also show that the most general GKP compactification leads to new classes of BPS and non-BPS multicenter solutions. We explore how these solutions fit into N = 2 truncations, and elucidate how supersymmetry becomes camouflaged. As a necessary tool in our exploration we show how the fields in the largest N = 2 truncation fit inside the six-torus compactification of eleven-dimensional supergravity.
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M-theory Superstrata and the MSW String

M-theory Superstrata and the MSW String

8 Discussion Understanding the dynamics of multiple M5 branes has been one of the most challenging and interesting issues in string theory for quite a number of years. There has been a huge effort in understanding how M5-brane theories can describe strongly-coupled gauge theories in four dimensions. Our purpose in this paper has been to study what should, perhaps, be one of the simplest avatars of the M5-brane field theory: The (1+1)-dimensional MSW CFT that comes from wrappings of an M5 brane on a very ample divisor of a Calabi-Yau manifold. This seemingly simple CFT remains enigmatic, almost twenty years after it was first shown to be able to encode microstate structure of four-dimensional black holes [ 15 ]. In this paper we have considered M5 branes wrapping 4-cycles in T 6 and T 2 ×K3, but our resulting M-theory solutions can be trivially extended to compactifications with a more general field content.
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Anomaly constraints and string/F-theory geometry in 6D quantum gravity

Anomaly constraints and string/F-theory geometry in 6D quantum gravity

Classification of elliptically fibered Calabi-Yau manifolds It has been shown by Gross [30] that the number of distinct topological types of elliptically fibered Calabi-Yau threefolds is finite up to birational equivalence. Finiteness of the set of topologically distinct elliptically-fibered Calabi-Yau threefolds is shown in [6] using minimal surface theory and the fact that the Weierstrass form for an elliptic fibration over a fixed base has a finite number of possible distinct singularity structures. These arguments, however, do not give a clear picture of how such compactifications can be sys- tematically classified. A complete mathematical classification of elliptically fibered Calabi-Yau threefolds would be helpful in understanding the range of F-theory compactifications. The analogue of this question for four dimen- sions, while probably much more difficult, would be of even greater interest, since at this time we have very little handle on the scope of the space of four dimensional supergravity theories which can be realized through F-theory compactifications on Calabi-Yau fourfolds.
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Black holes, information, and Hilbert space for quantum gravity

Black holes, information, and Hilbert space for quantum gravity

In treating a system with gravity, it is often assumed that there is a fixed semi-classical background geometry. For example, this is the case in the original complementarity argument [4] and in most treatments of defining probabil- ities in the eternally inflating multiverse [29]. At first sight, this does not lead to any problem because the relevant systems are large—we usually do not need to keep track of the whole quantum nature of the state in those cases, including a superposition of possible outcomes, entangle- ment with the observer, and so on. These intrinsically quantum properties, however, are crucial when we discuss the fundamental structure of the theory, such as unitarity and information. As discussed in Sec. II F, by focusing on a particular outcome—which is a completely legitimate procedure in discussing the outcome of a particular experiment—we will never be able to see the correct unitary structure of the underlying quantum theory. Committing to a specific semi-classical geometry is precisely such a treat- ment. An important message is that avoiding these treat- ments, i.e., keeping the full superposition—or many worlds—of the state is a key to evade many apparent prob- lems or paradoxes in black hole physics [10] and in eternally inflating multiverse cosmology [5,6]. Hopefully, the present paper adds further clarifications on this issue and provides a useful framework for further studies of fundamental issues in black hole physics.
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BINARY BLACK HOLES IN DENSE STAR CLUSTERS: EXPLORING THE THEORETICAL UNCERTAINTIES

BINARY BLACK HOLES IN DENSE STAR CLUSTERS: EXPLORING THE THEORETICAL UNCERTAINTIES

K1R1, K2R1; Table 3 ). In general, the larger the value of N BH , the lower the final total mass of the cluster. This is because higher N BH expands the cluster more, and a more expanded cluster loses more mass due to galactic tides. The exact amount of expansion, mass loss, and the final cluster mass also depends on the metallicity (Z) of the cluster, since the metallicity controls the wind-driven mass loss and the resulting mass of the BH population. Higher Z leads to the formation of lower-mass BHs, and as a result the overall expansion due to BH ejections is reduced. The adopted wind prescription yields a similar effect. While the strong wind prescription leads to a higher mass loss at early times compared to the weak wind prescription, the latter leads to the formation of more massive BHs in a cluster than the former. As a result, the same initial cluster under the weak wind assumption eventually undergoes more expansion when the energy production in the center is dominated by BH dynamics. This increased expansion leads to an increased rate of star loss in models with weak winds compared to those with strong winds, which is re flected in the final N in these clusters (Table 3 ).
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Theoretical and phenomenological aspects of non-singular black holes

Theoretical and phenomenological aspects of non-singular black holes

A fter exploring static or stationary non-singular black holes in the previous chapters, let us now turn to dynamical ones and describe the results obtained with P. Binétruy and A. Helou in [ 19 ]. Astrophysical black holes are by essence dynamical: they are formed after a gravitational collapse (contrarily to Schwarzschild’s eternal black holes and its maximal extension presented in Sec. 1 of Chap. 2 ), and are also thought to radiate via Hawking’s evaporation [ 66 ]. A few solutions to Einstein’s equations describe the dynamical formation of a black hole, such as Vaidya’s metric presented in Chap. 1 , but they remain classical. In this Chapter, we aim at studying effective metrics which incorporate quantum effects both near the outer horizon, to describe Hawking’s evaporation, and in the high curvature regime near r = 0 in order to avoid the singularity. A way of doing so consists in studying closed trapping horizons, whose dynamics can implement these two types of quantum effects. In Sec. 1 of this Chapter, we will start by deriving general conditions for the existence of singularity-free closed trapping horizons. We will then implement and study in Sec. 2 explicit models of closed trapping horizons inspired by the work of Hayward, Frolov and Bardeen, before discussing the behaviour of null geodesics in those models (Sec. 3 ). Finally, in Sec. 4 we solve Einstein’s equations in reverse to obtain the expression of the energy-momentum tensor for these models and analyse the weakest of energy conditions, the null energy condition (NEC). We find an explicit metric that recovers a null outgoing fluid mimicking Hawking radiation on I + , without having to make junctions. We
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Formation and growth of the first supermassive black holes

Formation and growth of the first supermassive black holes

• Naoki Yoshida and his research group for their hospitality during my internship at the University of Tokyo. ありがとうございます • The current and former PhD students at IAP, especially bureau 10 for the main motivation to come to IAP daily, Caterina, Siwei, and Alba for support in difficult times, and Melanie and Rebekka for help and support at the beginning.

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Asymptotics of Linear Waves and Resonances with Applications to Black Holes

Asymptotics of Linear Waves and Resonances with Applications to Black Holes

u(0) E , and the existence of a large family of solutions with the latter property follows from the construction of u  . We remark that Theorems 1 and 2 are completely independent from the behavior of linear waves at low frequency. In fact, we do not even use the boundedness in time of solutions for the wave equation, assuming merely that they grow at most exponentially (which is trivially true in our case); this suffices since O(h ∞ ) remainders overcome such growth for t = O(log(1/h)). If a boundedness statement is available, then our results can be extended to all times, though the corresponding rate of decay stays fixed for t  log(1/h) because of the O(h ∞ ) term.
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Higher-loop amplitude monodromy relations in string and gauge theory.

Higher-loop amplitude monodromy relations in string and gauge theory.

‡ Institut de physique th´ eorique, Universit´ e Paris Saclay, CNRS, F-91191 Gif-sur-Yvette, France The monodromy relations in string theory provide a powerful and elegant formalism to understand some of the deepest properties of tree-level field theory amplitudes, like the color-kinematics duality. This duality has been instrumental in tremendous progress on the computations of loop amplitudes in quantum field theory, but a higher-loop generalisation of the monodromy construction was lacking. In this letter, we extend the monodromy relations to higher loops in open string theory. Our construction, based on a contour deformation argument of the open string diagram integrands, leads to new identities that relate planar and non-planar topologies in string theory. We write one and two-loop monodromy formulæ explicitly at any multiplicity. In the field theory limit, at one-loop we obtain identities that reproduce known results. At two loops, we check our formulæ by unitarity in the case of the four-point N = 4 super-Yang-Mills amplitude.
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Full radiative coupling in two-phase models for accreting black holes

Full radiative coupling in two-phase models for accreting black holes

2.1. The NOAR/TITAN and NLMC codes TITAN is a code designed for warm media (T > a few 10 4 K) optically thick to Compton scattering. It computes the struc- ture of a plane-parallel slab of gas in thermal and ionization equilibrium, illuminated by a given spectrum on one or two sides of the slab (Dumont et al. 2000). It takes into account the returning flux using a two-stream approximation to solve the transfer in the lines (instead of the escape probability formal- ism). This code is coupled with a Monte Carlo code, NOAR, which takes into account Compton and inverse Compton dif- fusions in any geometry (Abrassart 2000). NOAR uses the lo- cal fractional ion abundances and the temperature provided by TITAN, while NOAR provides TITAN with the local Compton gains and losses in each layer. The Compton heating-cooling rate is indeed dominated by energy losses of photons at high energies ( >25 keV), not considered by TITAN. The coupling thus allows one to solve consistently both the global and the local energy balance. NOAR also allows computing the fluores- cence line profiles which are significantly Compton-broadened in the case of strong illumination, and the Comptonised reflec- tion spectrum above 25 keV.
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Creation of fermions by rotating charged black-holes

Creation of fermions by rotating charged black-holes

Abstract : This work is devoted to the mathematical study of the Hawking effect for fermions in the setting of the collapse of a rotating charged star. We show that an observer who is located far away from the star and at rest with respect to the Boyer Lindquist coordinates observes the emergence of a thermal state when his proper time goes to infinity. We first introduce a model of the collapse of the star. We suppose that the space-time outside the star is given by the Kerr-Newman metric. The assumptions on the asymptotic behavior of the surface of the star are inspired by the asymptotic be- havior of certain timelike geodesics in the Kerr-Newman metric. The Dirac equation is then written using coordinates and a Newman-Penrose tetrad which are adapted to the collapse. This coordinate system and tetrad are based on the so called simple null geodesics. The quantization of Dirac fields in a globally hyperbolic space-time is described. We formulate and prove a theorem about the Hawking effect in this set- ting. The proof of the theorem contains a minimal velocity estimate for Dirac fields that is slightly stronger than the usual ones and an existence and uniqueness result for solutions of a characteristic Cauchy problem for Dirac fields in the Kerr-Newman space-time. In an appendix we construct explicitly a Penrose compactification of block I of the Kerr-Newman space-time based on simple null geodesics.
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Inverse scattering at fixed energy in de Sitter-Reissner-Nordström black holes

Inverse scattering at fixed energy in de Sitter-Reissner-Nordström black holes

In particular, it is now well known established that much can be learned by observing how incoming waves are scattered off a black hole. We refer for instance to [2, 3, 12, 15, 16, 22, 30, 33] where direct scattering theories for various waves have been obtained, to [4, 5, 21, 31] for an application of the previous results to the study of the Hawking effect and to [6, 17] for an analysis of the superradiance phenomenon. In this paper, we follow this general strategy and address the problem of identifying the metric of a black hole by observing how incoming waves with a given energy λ propagate and scatter at late times. This information is encoded in the scattering matrix S(λ) introduced below. More specifically, we shall focus here on the special case of de Sitter-Reissner-Nordstr¨om black holes and we shall show that the parameters (and thus the metric) of such black holes can be uniquely recovered from the partial knowledge of the scattering matrix S(λ) at a fixed energy λ 6= 0. This is a continuation of our previous works [13, 14] in which similar questions were addressed and solved from inverse scattering experiments at high energies.
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Non-rational conformal field theories and applications in string theory.

Non-rational conformal field theories and applications in string theory.

Indeed, since the theory is local and since the parent bulk theory on the sphere determines already the operator product expansion of any two fields, the descendant field theory in the b[r]

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Predicting software revision outcomes on GitHub using structural holes theory

Predicting software revision outcomes on GitHub using structural holes theory

For example, social media users might be connected because they directly communicate with each other, or – as is the case in this paper: they may just be linked because they follow each other. 3.3 Survival analysis Assuming there are observations with variables (also known as covariates) in the dataset , and each observation (a pull request) is one row in , then describes the characteristics of observation . An observation contains information in a pull request: user who sends the pull request (sender), who receives it (receiver), their networks, repositories, organizations, and so on. There are
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The problem of the high iron abundance in accretion disks around black holes

The problem of the high iron abundance in accretion disks around black holes

n levels will be largely quenched at high density with exception of transitions from H- and He-like ions. We are presently involved in a systematic project to compute atomic parameters taking into account the plasma effects arising at high densities. In particular, Deprince et al. (2018a) have estimated the effects of the plasma environment on the atomic pa- rameters associated with K-vacancy states in He- and Li-like oxygen ions using multi- configuration Dirac–Fock and Breit–Pauli approaches. These computations have been carried out assuming a time-averaged Debye–Hückel potential for both the electron– nucleus and electron–electron interactions. Plasma effects on the ionization potential, excitation thresholds, transition wavelengths, and radiative emission rates are reported therein for O vi and O vii. The same methodology is also being applied to compute the plasma effects on the atomic structure and radiative and Auger decay rates of the K-lines of Fe xvii – Fe xxv (Deprince et al. 2018b).
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