Charged rotating dilaton black strings
Dehghani, M.H.; Farhangkhah, N.
2005-02-15
In this paper we, first, present a class of charged rotating solutions in four-dimensional Einstein-Maxwell-dilaton gravity with zero and Liouville-type potentials. We find that these solutions can present a black hole/string with two regular horizons, an extreme black hole or a naked singularity provided the parameters of the solutions are chosen suitable. We also compute the conserved and thermodynamic quantities, and show that they satisfy the first law of thermodynamics. Second, we obtain the (n+1)-dimensional rotating solutions in Einstein-dilaton gravity with Liouville-type potential. We find that these solutions can present black branes, naked singularities or spacetimes with cosmological horizon if one chooses the parameters of the solutions correctly. Again, we find that the thermodynamic quantities of these solutions satisfy the first law of thermodynamics.
Charged rotating Kaluza-Klein black holes in dilaton gravity
Allahverdizadeh, Masoud; Matsuno, Ken; Sheykhi, Ahmad
2010-02-15
We obtain a class of slowly rotating charged Kaluza-Klein black hole solutions of the five-dimensional Einstein-Maxwell-dilaton theory with arbitrary dilaton coupling constant. At infinity, the spacetime is effectively four dimensional. In the absence of the squashing function, our solution reduces to the five-dimensional asymptotically flat slowly rotating charged dilaton black hole solution with two equal angular momenta. We calculate the mass, the angular momentum, and the gyromagnetic ratio of these rotating Kaluza-Klein dilaton black holes. It is shown that the dilaton field and the nontrivial asymptotic structure of the solutions modify the gyromagnetic ratio of the black holes. We also find that the gyromagnetic ratio crucially depends on the dilaton coupling constant, {alpha}, and decreases with increasing {alpha} for any size of the compact extra dimension.
Extremal charged rotating dilaton black holes in odd dimensions
NASA Astrophysics Data System (ADS)
Allahverdizadeh, Masoud; Kunz, Jutta; Navarro-Lérida, Francisco
2010-09-01
Employing higher-order perturbation theory, we find a new class of charged rotating black hole solutions of Einstein-Maxwell-dilaton theory with general dilaton coupling constant. Starting from the Myers-Perry solutions, we use the electric charge as the perturbative parameter, and focus on extremal black holes with equal-magnitude angular momenta in odd dimensions. We perform the perturbations up to 4th order for black holes in 5 dimensions and up to 3rd order in higher odd dimensions. We calculate the physical properties of these black holes and study their dependence on the charge and the dilaton coupling constant.
Charged rotating dilaton black strings with logarithmic nonlinear source
NASA Astrophysics Data System (ADS)
Sheykhi, A.; Naeimipour, F.; Zebarjad, S. M.
2016-03-01
We find a new class of charged rotating dilaton black string solutions in the presence of logarithmic nonlinear electrodynamics. The dilaton potential is chosen in the form of the Liouville-type. We also present the suitable counterterm which removes the divergences of the action in the presence of dilaton potential. We find the conserved and thermodynamic quantities and check that the first law of thermodynamics holds on the black string horizon. We also address some theoretical implications of the nonlinear black hole/string solutions.
Charged rotating dilaton black holes with Kaluza-Klein asymptotics
NASA Astrophysics Data System (ADS)
Knoll, Christian; Nedkova, Petya
2016-03-01
We construct a class of stationary and axisymmetric solutions to the five-dimensional Einstein-Maxwell-dilaton gravity, which describe configurations of charged rotating black objects with Kaluza-Klein asymptotics. The solutions are constructed by uplifting a vacuum seed solution to six dimensions, performing a boost and a subsequent circle reduction. We investigate the physical properties of the charged solutions and obtain their general relations to the properties of the vacuum seed. We also derive the gyromagnetic ratio and the Smarr-like relations. As particular cases, we study three solutions, which describe a charged rotating black string, a charged rotating black ring on Kaluza-Klein bubbles, and a superposition of two black holes and a Kaluza-Klein bubble.
Nonlinear electrodynamics and thermodynamic geometry of rotating dilaton black branes
NASA Astrophysics Data System (ADS)
Sheykhi, A.; Naeimipour, F.; Zebarjad, S. M.
2016-07-01
We construct a new class of rotating dilaton solutions in the presence of logarithmic nonlinear electrodynamics. These solutions represent black branes with flat horizon and contain k=[(n-1)/2] rotation parameters in n-dimensional spacetime where [ x] is the integer part of x. We study the causal structure of the spacetime and calculate thermodynamic and conserved quantities and show that these quantities satisfy the first law of thermodynamics on the black brane horizon, { dM}={ TdS}+{{{sum _{i=1}k}}}Ω id{J}i+{ Ud}{Q}. Then, we study geometrical approach towards thermodynamics by choosing an appropriate geometrical metric. We show that the singularity of the Ricci scalar coincides exactly with the phase transition points. We observe that our system encounters two types of phase transitions depending on the metric parameters. For the first one the heat capacity is zero and for the second one the heat capacity diverges. In the first kind of phase transition, the brane has a transition from an unstable non-physical to a stable physical state. In the second type of phase transition the brane moves from a stable to an unstable state. Finally, we comment on the dynamical stability of the obtained solutions under perturbations in four dimensions.
Slowly rotating dilatonic black holes with exponential form of nonlinear electrodynamics
NASA Astrophysics Data System (ADS)
Hendi, S. H.; Sheykhi, A.; Sepehri Rad, M.; Matsuno, K.
2015-10-01
The generalization of the four-dimensional Kerr-Newman black holes to include the nonlinear electrodynamics has been one of the famous problems in black hole physics. In this paper, we address the effects of the small rotation parameter on the exact black hole solutions of Einstein-dilaton gravity coupled to the exponential nonlinear electrodynamics. We find a new stationary black hole solutions of this theory, in the limit of small angular momentum, and in the presence of Liouville-type potential for the dilaton field and an arbitrary value of the dilaton coupling constant. We compute the angular momentum and the gyromagnetic ratio of these rotating dilaton black holes. Interestingly enough, we find that the nonlinearity of the electrodynamics do not affect the angular momentum and the gyromagnetic ratio of the spacetime, while in contrast, the dilaton field can modify the angular momentum as well as the gyromagnetic ratio of the rotating black holes. We find the gyromagnetic ratio as , where is the coupling constant of the dilaton and the electrodynamic fields. For , we arrive at , which is the gyromagnetic ratio of the Kerr-Newman black holes in four dimensions.
Quantum (in)stability of 2D charged dilaton black holes and 3D rotating black holes
NASA Astrophysics Data System (ADS)
Nojiri, Shin'ichi; Odintsov, Sergei D.
1999-02-01
The quantum properties of charged black holes (BHs) in two-dimensional (2D) dilaton-Maxwell gravity (spontaneously compactified from heterotic string) with N dilaton coupled scalars are studied. We first investigate 2D BHs found by McGuigan, Nappi, and Yost. Kaluza-Klein reduction of 3D gravity with minimal scalars leads also to 2D dilaton-Maxwell gravity with dilaton coupled scalars and the rotating BH solution found by Bañados, Teitelboim, and Zanelli, which can be also described by 2D charged dilatonic BHs. Evaluating the one-loop effective action for dilaton coupled scalars in large N (and the s-wave approximation for the Bañados-Teitelboim-Zanelli case), we show that quantum-corrected BHs may evaporate or else antievaporate similarly to 4D Nariai BHs as is observed by Bousso and Hawking. Higher modes may cause the disintegration of BHs in accordance with recent observation by Bousso.
NASA Astrophysics Data System (ADS)
Soroushfar, Saheb; Saffari, Reza; Sahami, Ehsan
2016-07-01
In this paper, we consider the timelike and null geodesics around the static (GMGHS, magnetically charged GMGHS, electrically charged GMGHS) and the rotating (Kerr-Sen dilaton-axion) dilaton black holes. The geodesic equations are solved in terms of Weierstrass elliptic functions. To classify the trajectories around the black holes, we use the analytical solution and effective potential techniques and then characterize the different types of the resulting orbits in terms of the conserved energy and angular momentum. Also, using the obtained results we study astrophysical applications.
Bifurcation of the quasinormal spectrum and zero damped modes for rotating dilatonic black holes
NASA Astrophysics Data System (ADS)
Kokkotas, K. D.; Konoplya, R. A.; Zhidenko, A.
2015-09-01
It has been recently found that for the near extremal Kerr black holes appearing of zero damped modes (accompanied by quasinormal mode branching) signifies about inapplicability of the regime of small perturbations and the onset of turbulence. Here we show that this phenomenon is not limited by Kerr or Kerr-Newman solutions only, but also takes place for rotating dilatonic black holes for which we have found zero damped modes both numerically and analytically. We have also shown that, contrary to recent claims, there is no instability of a charged massive scalar field in the background of the rotating dilatonic black hole under physically adequate boundary conditions. Analytic expression for dominant quasinormal frequencies is deduced in the regime of large coupling q Q , where q and Q are the field and black hole charges, respectively.
Absorption cross-section and decay rate of rotating linear dilaton black holes
NASA Astrophysics Data System (ADS)
Sakalli, I.; Aslan, O. A.
2016-02-01
We analytically study the scalar perturbation of non-asymptotically flat (NAF) rotating linear dilaton black holes (RLDBHs) in 4-dimensions. We show that both radial and angular wave equations can be solved in terms of the hypergeometric functions. The exact greybody factor (GF), the absorption cross-section (ACS), and the decay rate (DR) for the massless scalar waves are computed for these black holes (BHs). The results obtained for ACS and DR are discussed through graphs.
Thermodynamics of charged rotating dilaton black branes with power-law Maxwell field
NASA Astrophysics Data System (ADS)
Zangeneh, M. Kord; Sheykhi, A.; Dehghani, M. H.
2015-10-01
In this paper, we construct a new class of charged rotating dilaton black brane solutions, with a complete set of rotation parameters, which is coupled to a nonlinear Maxwell field. The Lagrangian of the matter field has the form of the power-law Maxwell field. We study the causal structure of the spacetime and its physical properties in ample details. We also compute thermodynamic and conserved quantities of the spacetime, such as the temperature, entropy, mass, charge, and angular momentum. We find a Smarr-formula for the mass and verify the validity of the first law of thermodynamics on the black brane horizon. Finally, we investigate the thermal stability of solutions in both the canonical and the grand-canonical ensembles and disclose the effects of dilaton field and nonlinearity of the Maxwell field on the thermal stability of the solutions. We find that, for α ≤ 1, charged rotating black brane solutions are thermally stable independent of the values of the other parameters. For α >1, the solutions can encounter an unstable phase depending on the metric parameters.
Slowly-Rotating Black Hole Solution in Einstein-Dilaton-Gauss-Bonnet Gravity
NASA Astrophysics Data System (ADS)
Ayzenberg, Dimitry; Yunes, Nicolas
2015-04-01
We present a stationary and axisymmetric black hole solution in Einstein-Dilaton-Gauss-Bonnet gravity to quadratic order in the ratio of the spin angular momentum to the black hole mass squared. This solution introduces new corrections to previously found nonspinning and linear-in-spin solutions. The location of the event horizon and the ergosphere are modified, as well as the quadrupole moment. The new solution is of Petrov type I, although lower order in spin solutions are of Petrov type D. There are no closed timelike curves or spacetime regions that violate causality outside of the event horizon in the new solution. We calculate the modifications to the binding energy, Kepler's third law, and properties of the innermost stable circular orbit. These modifications are important for determining how the electromagnetic properties of accretion disks around supermassive black holes are changed from those expected in general relativity.
Tunneling Radiation of Massive Vector Bosons from Dilaton Black Holes
NASA Astrophysics Data System (ADS)
Li, Ran; Zhao, Jun-Kun; Wu, Xing-Hua
2016-07-01
It is well known that Hawking radiation can be treated as a quantum tunneling process of particles from the event horizon of black hole. In this paper, we attempt to apply the massive vector bosons tunneling method to study the Hawking radiation from the non-rotating and rotating dilaton black holes. Starting with the Proca field equation that govern the dynamics of massive vector bosons, we derive the tunneling probabilities and radiation spectrums of the emitted vector bosons from the static spherical symmetric dilatonic black hole, the rotating Kaluza—Klein black hole, and the rotating Kerr—Sen black hole. Comparing the results with the blackbody spectrum, we satisfactorily reproduce the Hawking temperatures of these dilaton black holes, which are consistent with the previous results in the literature. Supported by National Natural Science Foundation of China under Grant No. 11205048
Scalar field radiation from dilatonic black holes
NASA Astrophysics Data System (ADS)
Gohar, H.; Saifullah, K.
2012-12-01
We study radiation of scalar particles from charged dilaton black holes. The Hamilton-Jacobi method has been used to work out the tunneling probability of outgoing particles from the event horizon of dilaton black holes. For this purpose we use WKB approximation to solve the charged Klein-Gordon equation. The procedure gives Hawking temperature for these black holes as well.
Hawking Temperature of Dilaton Black Holes from Tunneling
NASA Astrophysics Data System (ADS)
Ren, Ji-Rong; Li, Ran; Liu, Fei-Hu
Recently, it has been suggested that Hawking radiation can be derived from quantum tunneling methods. Here, we calculated Hawking temperature of dilatonic black holes from tunneling formalism. The two semiclassical methods adopted here are: the null-geodesic method proposed by Parikh and Wilczek and the Hamilton-Jacobi method proposed by Angheben et al. We apply the two methods to analyze the Hawking temperature of the static spherical symmetric dilatonic black hole, the rotating Kaluza-Klein black hole, and the rotating Kerr-Sen black hole.
Hawking radiation of massive vector particles from the linear dilaton black holes
NASA Astrophysics Data System (ADS)
Li, Ran; Zhao, Junkun
2016-07-01
By using the tunneling formalism, we calculated the massive vector particles' Hawking radiation from the non-rotating and rotating linear dilaton black holes. By applying the WKB approximation to the Proca field equation that govern the dynamics of massive vector bosons, we derive the tunneling probabilities and radiation spectrums of the emitted vector particles from the linear dilaton black holes. The Hawking temperatures of the linear dilaton black holes have been recovered, which are consistent with the previous results in the literature. This means that the vector particles' tunneling method can also be used in studying the Hawking radiation of asymptotically non-flat and non-AdS black holes.
Charged dilatonic black holes in gravity's rainbow
NASA Astrophysics Data System (ADS)
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.
Effect of thermal fluctuations on a charged dilatonic black Saturn
NASA Astrophysics Data System (ADS)
Pourhassan, Behnam; Faizal, Mir
2016-04-01
In this paper, we will analyze the effect of thermal fluctuations on the thermodynamics of a charged dilatonic black Saturn. These thermal fluctuations will correct the thermodynamics of the charged dilatonic black Saturn. We will analyze the corrections to the thermodynamics of this system by first relating the fluctuations in the entropy to the fluctuations in the energy. Then, we will use the relation between entropy and a conformal field theory to analyze the fluctuations in the entropy. We will demonstrate that similar physical results are obtained from both these approaches. We will also study the effect of thermal fluctuations on the phase transition in this charged dilatonic black Saturn.
Decay of Dirac hair around a dilaton black hole
Gibbons, Gary W.; Rogatko, Marek
2008-02-15
The intermediate and late-time behavior of a massive Dirac field in the background of static spherically symmetric dilaton black hole solutions is investigated. The intermediate asymptotic behavior of a massive Dirac field depends on the mass parameter as well as the wave number of the mode, while the late-time behavior has a power-law decay rate independent of both.
Critical behavior of Born-Infeld dilaton black holes
NASA Astrophysics Data System (ADS)
Dehghani, M. H.; Sheykhi, A.; Dayyani, Z.
2016-01-01
We explore the critical behavior of (n +1 )-dimensional topological Born-Infeld-dilaton black holes in an extended phase space. We treat the cosmological constant and the Born-Infeld (BI) parameter as the thermodynamic pressure and BI vacuum polarization which can vary. We obtain thermodynamic quantities of the system such as pressure, temperature, Gibbs free energy, and investigate the behavior of these quantities. We also study the analogy of the van der Waals liquid-gas system with the Born-Infeld-dilaton black holes in canonical ensemble in which we can treat the black hole charge as a fixed external parameter. Moreover, we show that the critical values of pressure, temperature and volume are physical provided the coupling constant of dilaton gravity is less than 1 and the horizon is sphere. Finally, we calculate the critical exponents and show that although thermodynamic quantities depend on the dilaton coupling constant, BI parameter and the dimension of the spacetime, they are universal and are independent of metric parameters.
Observing the shadow of Einstein-Maxwell-Dilaton-Axion black hole
Wei, Shao-Wen; Liu, Yu-Xiao E-mail: liuyx@lzu.edu.cn
2013-11-01
In this paper, the shadows cast by Einstein-Maxwell-Dilaton-Axion black hole and naked singularity are studied. The shadow of a rotating black hole is found to be a dark zone covered by a deformed circle. For a fixed value of the spin a, the size of the shadow decreases with the dilaton parameter b. The distortion of the shadow monotonically increases with b and takes its maximal when the black hole approaches to the extremal case. Due to the optical properties, the area of the black hole shadow is supposed to equal to the high-energy absorption cross section. Based on this assumption, the energy emission rate is investigated. For a naked singularity, the shadow has a dark arc and a dark spot or straight, and the corresponding observables are obtained. These results show that there is a significant effect of the spin a and dilaton parameter b on these shadows. Moreover, we examine the observables of the shadow cast by the supermassive black hole at the center of the Milky Way, which is very useful for us to probe the nature of the black hole through the astronomical observations in the near future.
Penrose process in a charged axion-dilaton coupled black hole
NASA Astrophysics Data System (ADS)
Ganguly, Chandrima; SenGupta, Soumitra
2016-04-01
Using the Newman-Janis method to construct the axion-dilaton coupled charged rotating black holes, we show that the energy extraction from such black holes via the Penrose process takes place from the axion/Kalb-Ramond field energy responsible for rendering the angular momentum to the black hole. Determining the explicit form for the Kalb-Ramond field strength, which is argued to be equivalent to spacetime torsion, we demonstrate that at the end of the energy extraction process, the spacetime becomes torsion free with a spherically symmetric non-rotating black hole remnant. In this context, applications to physical phenomena, such as the emission of neutral particles in astrophysical jets, are also discussed. It is seen that the infalling matter gains energy from the rotation of the black hole, or equivalently from the axion field, and that it is ejected as a highly collimated astrophysical jet.
Hawking radiation of non-asymptotically flat rotating black holes
NASA Astrophysics Data System (ADS)
Sakalli, Izzet; Aslan, Onur Atilla
2016-04-01
We study the Hawking radiation of non-asymptotically flat rotating linear dilaton black holes, which are the solutions to the 4D Einstein-Maxwell-dilaton-axion action by using the semi-classical radiation spectrum method. Using scalar perturbations, we show that both angular and radial equations produce exact analytical solutions. Thus, we obtain a precise radiation spectrum for the rotating linear dilaton black hole. The high-frequency regime does not yield the standard Hawking temperature of this black hole computed from the surface gravity. However, we show in detail that the specific low-frequency band of the radiation spectrum allows for the original Hawking temperature of the rotating linear dilaton black hole. The computations are also exhibited graphically.
Thermodynamics of rotating solutions in (n+1)-dimensional Einstein-Maxwell-dilaton gravity
Sheykhi, A.; Riazi, N.; Pakravan, J.; Dehghani, M. H.
2006-10-15
We construct a class of charged, rotating solutions of (n+1)-dimensional Einstein-Maxwell-dilaton gravity with cylindrical or toroidal horizons in the presence of Liouville-type potentials and investigate their properties. These solutions are neither asymptotically flat nor (anti)-de Sitter. We find that these solutions can represent black brane, with inner and outer event horizons, an extreme black brane or a naked singularity provided the parameters of the solutions are chosen suitably. We also compute temperature, entropy, charge, electric potential, mass and angular momentum of the black brane solutions, and find that these quantities satisfy the first law of thermodynamics. We find a Smarr-type formula and perform a stability analysis by computing the heat capacity in the canonical ensemble. We find that the system is thermally stable when the coupling constant between the dilaton and matter field {alpha}{<=}1, while for {alpha}>1 the system has an unstable phase. This shows that the dilaton field makes the solution unstable, while it is stable even in Lovelock gravity.
Dilaton gravity, charged dust, and (quasi-) black holes
NASA Astrophysics Data System (ADS)
Bronnikov, K. A.; Fabris, J. C.; Silveira, R.; Zaslavskii, O. B.
2014-05-01
We consider Einstein-Maxwell-dilaton gravity with charged dust and interaction of the form P(χ)FμνFμν, where P(χ) is an arbitrary function of the dilaton field χ that can be normal or phantom. For any regular P(χ), static configurations are possible with arbitrary functions g00=exp(2γ(xi)) (i =1, 2, 3) and χ=χ(γ), without any assumption of spatial symmetry. The classical Majumdar-Papapetrou system is restored by putting χ =const. Among possible solutions are black-hole (BH) and quasi-black-hole (QBH) ones. Some general results on BH and QBH properties are deduced and confirmed by examples. It is found, in particular, that asymptotically flat BHs and QBHs can exist with positive energy densities of matter and both scalar and electromagnetic fields.
Dilaton gravity, (quasi-) black holes, and scalar charge
NASA Astrophysics Data System (ADS)
Bronnikov, K. A.; Fabris, J. C.; Silveira, R.; Zaslavskii, O. B.
2014-09-01
We consider static electrically charged dust configurations in the framework of Einstein-Maxwell-dilaton gravity with the interaction term P(\\chi) F_{mn} F^{mn} in the Lagrangian, where P(\\chi) is an arbitrary function of the dilaton field \\chi, and the latter is allowed to be normal or phantom. It is shown that, for any regular P(\\chi), static configurations are possible with arbitrary functions g_{00} = e^{2\\gamma(x^i)} (i=1,2,3) and \\chi = \\chi(\\gamma), without any assumption of spatial symmetry. The corresponding matter, electric charge and scalar charge densities are found from the field equations. Meanwhile, configurations with nontrivial \\chi(x^i) generically require a nonzero scalar charge density distribution. The classical Majumdar-Papapetrou (MP) system is obtained as a special case where \\chi = const; there is its scalar analogue in the case F_{mn} = 0, but only with a phantom \\chi field. Among possible solutions are black-hole (BH) and quasi-black-hole (QBH) ones. Some general results on QBH properties obtained previously for the MP system are here extended to systems with the dilaton. Particular examples of asymptotically flat spherically symmetric BH and QBH solutions are found, some of them being phantom-free, that is, exist with positive energy densities of matter and both scalar and electromagnetic fields.
Topology, entropy, and Witten index of dilaton black holes
Gibbons, G.W.; Kallosh, R.E. )
1995-03-15
We have found that for extreme dilaton black holes an inner boundary must be introduced in addition to the outer boundary to give an integer value to the Euler number. The resulting manifolds have (if one identifies imaginary time) a topology [ital S][sup 1][times][ital R][times][ital S][sup 2] and Euler number [chi]=0 in contrast with the nonextreme case with [chi]=2. The entropy of extreme U(1) dilaton black holes is already known to be zero. We include a review of some recent ideas due to Hawking on the Reissner-Nordstroem case. By regarding all extreme black holes as having an inner boundary, we conclude that the entropy of [ital all] extreme black holes, including [U(1)][sup 2] black holes, vanishes. We discuss the relevance of this to the vanishing of quantum corrections and the idea that the functional integral for extreme holes gives a Witten index. We have studied also the topology of moduli space'' of multi-black-holes. The quantum mechanics on black hole moduli spaces is expected to be supersymmetric despite the fact that they are not hyper-Kaehler since the corresponding geometry has a torsion unlike the BPS monopole case. Finally, we describe the possibility of extreme black hole fission for states with an energy gap. The energy released, as a proportion of the initial rest mass, during the decay of an electromagnetic black hole is 300 times greater than that released by the fission of a [sup 235]U nucleus.
Conformally invariant thermodynamics of a Maxwell-Dilaton black hole
NASA Astrophysics Data System (ADS)
Lopez-Monsalvo, C. S.; Nettel, F.; Quevedo, H.
2013-12-01
The thermodynamics of Maxwell-Dilaton black holes has been extensively studied. It has served as a fertile ground to test ideas about temperature through various definitions of surface gravity. In this paper, we make an independent analysis of this black hole solution in both, Einstein and Jordan, frames. We explore a set of definitions for the surface gravity and observe the different predictions they make for the near extremal configuration of this black hole. Finally, motivated by the singularity structure in the interior of the event horizon, we use a holographic argument to remove the micro-states from the disconnected region of this solution. In this manner, we construct a frame independent entropy from which we obtain a temperature which agrees with the standard results in the non-extremal regime, and has a desirable behaviour around the extremal configurations according to the third law of black hole mechanics.
Pani, Paolo; Cardoso, Vitor
2009-04-15
It is generally accepted that Einstein's theory will get some as yet unknown corrections, possibly large in the strong-field regime. An ideal place to look for these modifications is in the vicinities of compact objects such as black holes. Here, we study dilatonic black holes, which arise in the framework of Gauss-Bonnet couplings and one-loop corrected four-dimensional effective theory of heterotic superstrings at low energies. These are interesting objects as a prototype for alternative, yet well-behaved gravity theories: they evade the 'no-hair' theorem of general relativity but were proven to be stable against radial perturbations. We investigate the viability of these black holes as astrophysical objects and try to provide some means to distinguish them from black holes in general relativity. We start by extending previous works and establishing the stability of these black holes against axial perturbations. We then look for solutions of the field equations describing slowly rotating black holes and study geodesic motion around this geometry. Depending on the values of mass, dilaton charge, and angular momentum of the solution, one can have differences in the innermost-stable-circular-orbit location and orbital frequency, relative to black holes in general relativity. In the most favorable cases, the difference amounts to a few percent. Given the current state-of-the-art, we discuss the difficulty of distinguishing the correct theory of gravity from electromagnetic observations or even with gravitational-wave detectors.
NASA Astrophysics Data System (ADS)
Rogatko, Marek
2016-03-01
The uniqueness of a static asymptotically flat photon sphere for a static black hole solution in the Einstein-Maxwell-dilaton theory with an arbitrary coupling constant is proposed. Using the conformal positive energy theorem, we show that the dilaton photon sphere subject to the nonextremality condition constitutes a cylinder over a topological sphere.
Thermodynamics of Gauss-Bonnet-dilaton Lifshitz black branes
NASA Astrophysics Data System (ADS)
Zangeneh, M. Kord; Dehghani, M. H.; Sheykhi, A.
2015-09-01
We explore an effective supergravity action in the presence of a massless gauge field which contains a Gauss-Bonnet term as well as a dilaton field. We construct a new class of black brane solutions of this theory with a Lifshitz asymptotic by fixing the parameters of the model such that the asymptotic Lifshitz behavior can be supported. Then we construct the well-defined finite action through the use of the counterterm method. We also obtain two independent constants along the radial coordinate by combining the equations of motion. Calculations of these two constants at infinity through the use of the large-r behavior of the metric functions show that our solution respects the no-hair theorem. Furthermore, we combine these two constants in order to get a constant C which is proportional to the energy of the black brane. We calculate this constant at the horizon in terms of the temperature and entropy and at large-r in terms of the geometrical mass. By calculating the value of the energy density through the use of the counterterm method, we obtain the relation between the energy density, the temperature, and the entropy. This relation is the generalization of the well-known Smarr formula for AdS black holes. Finally, we study the thermal stability of our black brane solution and show that it is stable under thermal perturbations.
Hamiltonian thermodynamics of charged three-dimensional dilatonic black holes
Dias, Goncalo A. S.; Lemos, Jose P. S.
2008-10-15
The action for a class of three-dimensional dilaton-gravity theories, with an electromagnetic Maxwell field and a cosmological constant, can be recast in a Brans-Dicke-Maxwell type action, with its free {omega} parameter. For a negative cosmological constant, these theories have static, electrically charged, and spherically symmetric black hole solutions. Those theories with well formulated asymptotics are studied through a Hamiltonian formalism, and their thermodynamical properties are found out. The theories studied are general relativity ({omega}{yields}{+-}{infinity}), a dimensionally reduced cylindrical four-dimensional general relativity theory ({omega}=0), and a theory representing a class of theories ({omega}=-3), all with a Maxwell term. The Hamiltonian formalism is set up in three dimensions through foliations on the right region of the Carter-Penrose diagram, with the bifurcation 1-sphere as the left boundary, and anti-de Sitter infinity as the right boundary. The metric functions on the foliated hypersurfaces and the radial component of the vector potential one-form are the canonical coordinates. The Hamiltonian action is written, the Hamiltonian being a sum of constraints. One finds a new action which yields an unconstrained theory with two pairs of canonical coordinates (M,P{sub M};Q,P{sub Q}), where M is the mass parameter, which for {omega}<-(3/2) and for {omega}={+-}{infinity} needs a careful renormalization, P{sub M} is the conjugate momenta of M, Q is the charge parameter, and P{sub Q} is its conjugate momentum. The resulting Hamiltonian is a sum of boundary terms only. A quantization of the theory is performed. The Schroedinger evolution operator is constructed, the trace is taken, and the partition function of the grand canonical ensemble is obtained, where the chemical potential is the scalar electric field {phi}. Like the uncharged cases studied previously, the charged black hole entropies differ, in general, from the usual quarter of the
Solitons and black holes in a generalized Skyrme model with dilaton-quarkonium field
Doneva, Daniela D.; Stefanov, Ivan Zh.; Yazadjiev, Stoytcho S.
2011-06-15
Skyrme theory is among the viable effective theories which emerge from the low-energy limit of quantum chromodynamics. Many of its generalizations include also a dilaton. Here we find new self-gravitating solutions, both solitons and black holes, in a generalized Skyrme model in which a dilaton is present. The investigation of the properties of the solutions is done numerically. We find that the introduction of the dilaton in the theory does not change the picture qualitatively, only quantitatively. The model considered here has one free parameter more than the Einstein-Skyrme model which comes from the potential of the dilaton. We have applied also the turning point method to establish that one of the black-hole branches of solutions is unstable. The turning point method here is based on the first law of black-hole thermodynamics a detailed derivation of which is given in the Appendix of the paper.
Thermodynamic instability of charged dilaton black holes in AdS spaces
Sheykhi, A.; Dehghani, M. H.; Hendi, S. H.
2010-04-15
We study thermodynamic instability of a class of (n+1)-dimensional charged dilatonic spherically symmetric black holes in the background of the anti-de Sitter universe. We calculate the quasilocal mass of the anti-de Sitter dilaton black hole through the use of the subtraction method of Brown and York. We find a Smarr-type formula and perform a stability analysis in the canonical ensemble and disclose the effect of the dilaton field on the thermal stability of the solutions. Our study shows that the solutions are thermally stable for small {alpha}, while for large {alpha} the system has an unstable phase, where {alpha} is a coupling constant between the dilaton and matter field.
Thermodynamics of black holes in (n+1)-dimensional Einstein-Born-Infeld-dilaton gravity
Sheykhi, A.; Riazi, N.
2007-01-15
We construct a new class of (n+1)-dimensional (n{>=}3) black hole solutions in Einstein-Born-Infeld-dilaton gravity with Liouville-type potential for the dilaton field and investigate their properties. These solutions are neither asymptotically flat nor (anti)-de Sitter. We find that these solutions can represent black holes, with inner and outer event horizons, an extreme black hole, or a naked singularity provided the parameters of the solutions are chosen suitably. We compute the thermodynamic quantities of the black hole solutions and find that these quantities satisfy the first law of thermodynamics. We also perform a stability analysis and investigate the effect of dilaton on the stability of the solutions.
Magnetic Dilaton Rotating Strings in the Presence of Exponential Nonlinear Electrodynamics
NASA Astrophysics Data System (ADS)
Sheykhi, A.; Mahmoudi, Z.
2016-09-01
In this paper, we construct a new class of four-dimensional spinning magnetic dilaton string solutions which produces a longitudinal nonlinear electromagnetic field. The Lagrangian of the matter field has the exponential form. We study the physical properties of the solution in ample details. Geometrical, causal and geodisical structures of the solutions are investigated, separately. We confirm that the spacetime is both null and geodesically complete. We find that these solutions have no curvature singularity and no horizon, but have a conic geometry. We investigate the effects of variation of charge and the intensity of the dilaton field, on the deficit angle. Due to the presence of the dilaton field, the asymptotic behavior of the solutions are neither flat nor (anti-) de Sitter [(A)dS]. Furthermore, we extend our study to the higher dimensions and obtain the ( n+1)-dimensional magnetic rotating dilaton strings with k≤[ n/2] rotation parameters and calculate conserved quantities of the solutions. Although these solutions are not asymptotically (A)dS, we use counterterm method to calculate conserved quantities. We also calculate electric charge and show that the net electric charge of the spinning string is proportional to the rotating parameter and the electric field only exists when the rotation parameter does not vanish.
Magnetic Dilaton Rotating Strings in the Presence of Exponential Nonlinear Electrodynamics
NASA Astrophysics Data System (ADS)
Sheykhi, A.; Mahmoudi, Z.
2016-04-01
In this paper, we construct a new class of four-dimensional spinning magnetic dilaton string solutions which produces a longitudinal nonlinear electromagnetic field. The Lagrangian of the matter field has the exponential form. We study the physical properties of the solution in ample details. Geometrical, causal and geodisical structures of the solutions are investigated, separately. We confirm that the spacetime is both null and geodesically complete. We find that these solutions have no curvature singularity and no horizon, but have a conic geometry. We investigate the effects of variation of charge and the intensity of the dilaton field, on the deficit angle. Due to the presence of the dilaton field, the asymptotic behavior of the solutions are neither flat nor (anti-) de Sitter [(A)dS]. Furthermore, we extend our study to the higher dimensions and obtain the (n+1)-dimensional magnetic rotating dilaton strings with k≤[n/2] rotation parameters and calculate conserved quantities of the solutions. Although these solutions are not asymptotically (A)dS, we use counterterm method to calculate conserved quantities. We also calculate electric charge and show that the net electric charge of the spinning string is proportional to the rotating parameter and the electric field only exists when the rotation parameter does not vanish.
Late-time evolution of a charged massless scalar field in the spacetime of a dilaton black hole
NASA Astrophysics Data System (ADS)
Moderski, Rafał; Rogatko, Marek
2001-04-01
We investigate the power-law tails in the evolution of a charged massless scalar field around a fixed background of a dilaton black hole. Using both analytical and numerical methods we find the inverse power-law relaxation of charged fields at future timelike infinity, future null infinity, and along the outer horizon of the considered black hole. We envisage that a charged hair decays slower than neutral ones. The oscillatory inverse power law along the outer horizon of the dilaton black hole is of great importance for a mass inflation scenario along the Cauchy horizon of a dynamically formed dilaton black hole.
Quantum Gravity Effects on the Tunneling Radiation of the Einstein-Maxwell-Dilaton-Axion Black Hole
NASA Astrophysics Data System (ADS)
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.
NASA Astrophysics Data System (ADS)
Lin, Kai; Yang, Shu-Zheng
2009-10-01
Fermions tunneling of the non-stationary Dilaton-Maxwell black hole is investigated with general tortoise coordinate transformation. The Dirac equation is simplified by semiclassical approximation so that the Hamilton-Jacobi equation is generated. Finally the tunneling rate and the Hawking temperature is calculated.
Rapidly rotating neutron stars in dilatonic Einstein-Gauss-Bonnet theory
NASA Astrophysics Data System (ADS)
Kleihaus, Burkhard; Kunz, Jutta; Mojica, Sindy; Zagermann, Marco
2016-03-01
We construct sequences of rapidly rotating neutron stars in dilatonic Einstein-Gauss-Bonnet theory, employing two equations of state for the nuclear matter. We analyze the dependence of the physical properties of these neutron stars on the Gauss-Bonnet coupling strength. For a given equation of state we determine the physically relevant domain of rapidly rotating neutron stars, which is delimited by the set of neutron stars rotating at the Kepler limit, the set of neutron stars along the secular instability line, and the set of static neutron stars. As compared to Einstein gravity, the presence of the Gauss-Bonnet term decreases this domain, leading to lower values for the maximum mass as well as to smaller central densities. The quadrupole moment is decreased by the Gauss-Bonnet term for rapidly rotating neutron stars, while it is increased for slowly rotating neutron stars. The universal relation between the quadrupole moment and the moment of inertia found in general relativity appears to extend to dilatonic Einstein-Gauss-Bonnet theory with very little dependence on the coupling strength of the Gauss-Bonnet term. The neutron stars carry a small dilaton charge.
Information Loss and Tunneling Radiation of the Non-Stationary Dilaton-Maxwell Black Hole
NASA Astrophysics Data System (ADS)
Chen, Deyou; Yang, Shuzheng
Taking the self-gravitational interaction and unfixed background space-time into account, we discuss the tunneling radiation of the Dilaton-Maxwell black hole by the Hamilton-Jacobi method. The result shows that the tunneling rate is related not only to the change of Bekenstein-Hawking entropy, but also to a subtle integral about the black hole mass, which does not satisfy the unitary theory and is different from Parikh and Wilczek's result. This implies that information loss in black hole evaporation is possible.
García-Diaz, Alberto A.
2014-01-14
Using the Schwarzschild coordinate frame for a static cyclic symmetric metric in 2+1 gravity coupled minimally to a dilaton logarithmically depending on the radial coordinate in the presence of an exponential potential, by solving first order linear Einstein equations, the general solution is derived and it is identified with the Chan–Mann dilaton solution. In these coordinates, a new stationary dilaton solution is obtained; it does not allow for a de Sitter–Anti-de Sitter limit at spatial infinity, where its structural functions increase indefinitely. On the other hand, it is horizonless and allows for a naked singularity at the origin of coordinates; moreover, one can identify at a large radial coordinate a (quasi-local) mass parameter and in the whole space a constant angular momentum. Via a general SL(2,R)–transformation, applied on the static cyclic symmetric metric, a family of stationary dilaton solutions has been generated. A particular SL(2,R)–transformation is identified, which gives rise to the rotating Chan–Mann dilaton solution. All the exhibited solutions have been characterized by their quasi-local energy, mass, and momentum through their series expansions at spatial infinity. The algebraic structure of the Ricci–energy-momentum, and Cotton tensors is given explicitly.
Analytic solutions of the geodesic equation for Einstein-Maxwell-dilaton-axion black holes
NASA Astrophysics Data System (ADS)
Flathmann, Kai; Grunau, Saskia
2015-11-01
In this article we study the geodesic motion of test particles and light in the Einstein-Maxwell-dilaton-axion black hole spacetime. We derive the equations of motion and present their solutions in terms of the Weierstraß ℘, σ and ζ functions. With the help of parametric diagrams and effective potentials we analyze the geodesic motion and give a list of all possible orbit types.
Radiating black holes in Einstein-Maxwell-dilaton theory and cosmic censorship violation
NASA Astrophysics Data System (ADS)
Aniceto, Pedro; Pani, Paolo; Rocha, Jorge V.
2016-05-01
We construct exact, time-dependent, black hole solutions of Einstein-Maxwell-dilaton theory with arbitrary dilaton coupling, a. For a = 1 this theory arises as the four-dimensional low-energy effective description of heterotic string theory. These solutions represent electrically charged, spherically symmetric black holes emitting or absorbing charged null fluids and generalize the Vaidya and Bonnor-Vaidya solutions of general relativity and of Einstein-Maxwell theory, respectively. The a = 1 case stands out as special, in the sense that it is the only choice of the coupling that allows for a time-dependent dilaton field in this class of solutions. As a by-product, when a = 1 we show that an electrically charged black hole in this theory can be overcharged by bombarding it with a stream of electrically charged null fluid, resulting in the formation of a naked singularity. This provides an example of cosmic censorship violation in an exact dynamical solution to low-energy effective string theory and in a case in which the total stress-energy tensor satisfies all energy conditions. When a ≠ 1, our solutions necessarily have a time-independent scalar field and consequently cannot be overcharged.
NASA Astrophysics Data System (ADS)
Sheykhi, A.; Naeimipour, F.; Zebarjad, S. M.
2015-12-01
In this paper, we construct a new class of black hole solutions which is coupled to the logarithmic nonlinear electrodynamics in the context of dilaton gravity. We consider an n -dimensional action in which gravity is coupled to the logarithmic nonlinear electrodynamics field and a scalar dilaton field to obtain the equations of motion of the gravitational, dilaton and electromagnetic fields. This leads to finding a new class of n -dimensional static and spherically symmetric black hole solutions in the presence of two Liouville-type dilaton potentials. The asymptotic behavior of these solutions is neither flat nor (anti-)de Sitter [(A)dS], and in the limiting case where the nonlinear parameter β goes to infinity, our solutions reduce to the black holes of Einstein-Maxwell-dilaton gravity in higher dimensions. Thermodynamic quantities such as mass, temperature, electric potential and entropy are also computed, and it is shown that they agree with the first law of thermodynamics. Furthermore, we find that for small values of the electric charge parameter q , and the dilaton coupling constant α , as well as small dimension n , the solutions are thermally stable. By increasing n , the region of stability stands for smaller values of α independent of q . Finally, we use the method of thermodynamical geometry and find the phase transition points by calculating the Ricci scalar of a thermodynamic metric.
NASA Astrophysics Data System (ADS)
Lan, Xiao-Gang
2013-05-01
By introducing a new tortoise coordinate transformation, we apply Damour-Ruffini-Sannan method to study the Hawking radiation of massive scalar particles in a dynamic Dilaton-Maxwell black hole. We find that Hawking radiation spectrum shows still the blackbody one, while the Hawking temperature is significantly changed. Additionally, by adopting the thin film method, we calculate the entropy of a dynamic Dilaton-Maxwell black hole. The result indicates that the entropy for such a black hole is still in proportional to the area of its event horizon.
Quasinormal modes for single horizon black holes in generic 2D dilaton gravity
NASA Astrophysics Data System (ADS)
Kettner, Joanne; Kunstatter, Gabor; Medved, A. J. M.
2004-12-01
There has been some recent speculation that a connection may exist between the quasinormal-mode spectra of highly damped black holes and the fundamental theory of quantum gravity. This notion follows from a conjecture by Hod that the real part of the highly damped mode frequencies can be used to calibrate the semi-classical level spacing in the black-hole quantum area spectrum. However, even if the level spacing can be fixed in this manner, it still remains unclear whether this implies a physically significant 'duality' or merely a numerical coincidence. This tapestry of ideas serves as the motivation for the current paper. We utilize the 'monodromy approach' to calculate the quasinormal-mode spectra for a generic class of black holes in two-dimensional dilatonic gravity. Our results agree with the prior literature whenever a direct comparison is possible and provide the analysis of a much more diverse class of black-hole models than previously considered.
Kerr-Sen dilaton-axion black hole lensing in the strong deflection limit
Gyulchev, Galin N.; Yazadjiev, Stoytcho S.
2007-01-15
In the present work we study numerically quasiequatorial lensing by the charged, stationary, axially symmetric Kerr-Sen dilaton-axion black hole in the strong deflection limit. In this approximation we compute the magnification and the positions of the relativistic images. The most outstanding effect is that the Kerr-Sen black hole caustics drift away from the optical axis and shift in the clockwise direction with respect to the Kerr caustics. The intersections of the critical curves on the equatorial plane as a function of the black hole angular momentum are found, and it is shown that they decrease with the increase of the parameter Q{sup 2}/M. All of the lensing quantities are compared to particular cases as Schwarzschild, Kerr, and Gibbons-Maeda black holes.
Peculiar properties of a charged dilatonic black hole in AdS{sub 5}
Gubser, Steven S.; Rocha, Fabio D.
2010-02-15
We study a charged dilatonic black hole in AdS{sub 5}, derived from a Lagrangian involving a gauge field whose kinetic term is modified by the exponential of a neutral scalar. This black hole has two properties which one might reasonably demand of the dual of a Fermi liquid: Its entropy is proportional to temperature at low temperature, and its extremal limit supports normal modes of massless, charged bulk fermions. The black hole we study has a simple analytic form because it can be embedded in type IIB string theory as the near-horizon limit of D3-branes with equal spins in two of the three independent transverse planes. Two further properties can be deduced from this embedding: There is a thermodynamic instability, reminiscent of ferromagnetism, at low temperatures; and there is an AdS{sub 3} factor in the extremal near-horizon geometry which accounts for the linear dependence of entropy on temperature. Altogether, it is plausible that the dilatonic black hole we study, or a relative of it with similar behavior in the infrared, is the dual of a Fermi liquid; however, the particular embedding in string theory that we consider is unlikely to have such a dual description, unless through some unexpected boson-fermion equivalence at large N.
New 2D dilaton gravity for nonsingular black holes
NASA Astrophysics Data System (ADS)
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.
NASA Astrophysics Data System (ADS)
Nashed, Gamal G. L.
2013-03-01
Two different charged dilaton black holes in 4-dimension, within teleparallel equivalent of general relativity (TEGR), are derived. These solutions are related through local Lorentz transformation. The total energy of these black holes, using three different methods, the Hamiltonian method, the translational momentum 2-form and the Euclidean continuation method given by Gibbons and Hawking, is calculated. It is shown that the three methods give the same results. The value of energy is shown to depend on the mass M and charge q. The verification of the first law of thermodynamics is proved. Finally, it is shown that if the charge q is vanishing then, the total energy reduced to that of Schwarzschild's black hole.
Rotating black hole and quintessence
NASA Astrophysics Data System (ADS)
Ghosh, Sushant G.
2016-04-01
We discuss spherically symmetric exact solutions of the Einstein equations for quintessential matter surrounding a black hole, which has an additional parameter (ω ) due to the quintessential matter, apart from the mass ( M). In turn, we employ the Newman-Janis complex transformation to this spherical quintessence black hole solution and present a rotating counterpart that is identified, for α =-e^2 ne 0 and ω =1/3, exactly as the Kerr-Newman black hole, and as the Kerr black hole when α =0. Interestingly, for a given value of parameter ω , there exists a critical rotation parameter (a=aE), which corresponds to an extremal black hole with degenerate horizons, while for a
Analytical Kerr-Sen dilaton-axion black hole lensing in the weak deflection limit
Gyulchev, Galin N.; Yazadjiev, Stoytcho S.
2010-01-15
We investigate analytical gravitational lensing by charged, stationary, axially symmetric Kerr-Sen dilaton-axion black holes in the weak-deflection limit. Approximate solutions to the lightlike equations of motion are present up to and including third-order terms in M/b, a/b, and r{sub {alpha}/}b, where M is the black hole mass, a is the angular momentum, r{sub {alpha}=}Q{sup 2}/M, Q being the charge and b is the impact parameter of the light ray. We compute the positions of the two weak field images, the corresponding signed and absolute magnifications up to post-Newtonian order. It is shown that there are static post-Newtonian corrections to the signed magnification and their sum as well as to the critical curves, which are functions of the charge. The shift of the critical curves as a function of the lens angular momentum is found, and it is shown that they decrease slightly with the increase of the charge. The pointlike caustics drift away from the optical axis and do not depend on the charge. All of the lensing quantities are compared to particular cases as Schwarzschild and Kerr black holes as well as the Gibbons-Maeda-Garfinkle-Horowitz-Strominger black hole.
Gravitational Lensing by Kerr-Sen Dilaton-Axion Black Hole in the Weak Deflection Limit
Gyulchev, G. N.; Yazadjiev, S. S.
2010-11-25
We investigate analytically gravitational lensing by charged, stationary, axially symmetric Kerr-Sen dilaton-axion black hole in the weak deflection limit. Approximate solutions to the lightlike equations of motion are present up to and including third-order terms in M/b, a/b and r{sub {alpha}}/b, where M is the black hole mass, a is the angular momentum, r{sub {alpha}}= Q{sup 2}/M,Q being the charge and b is the impact parameter of the light ray. We compute the positions of the two weak field images up to post-Newtonian order. The shift of the critical curves as a function of the lens angular momentum is found, and it is shown that they decrease slightly with the increase of the charge. The lensing observables are compared to these characteristics for particular cases as Schwarzschild and Kerr black holes as well as the Gibbons-Maeda-Garfinkle-Horowitz-Strominger black hole.
A nonsingular rotating black hole
NASA Astrophysics Data System (ADS)
Ghosh, Sushant G.
2015-11-01
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 well-defined 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.
Late-time evolution of a self-interacting scalar field in the spacetime of a dilaton black hole
Moderski, Rafal; Rogatko, Marek
2001-08-15
We investigate the late-time tails of self-interacting (massive) scalar fields in the spacetime of a dilaton black hole. Following the no hair theorem we examine the mechanism by which self-interacting scalar hair decays. We reveal that the intermediate asymptotic behavior of the considered field perturbations is dominated by an oscillatory inverse power-law decaying tail. The numerical simulations show that at very late time, massive self-interacting scalar hair decays slower than any power law.
NASA Astrophysics Data System (ADS)
Gabach-Clement, Maria E.; Reiris, Martin
2013-08-01
We give a thorough description of the shape of rotating axisymmetric stable black-hole (apparent) horizons applicable in dynamical or stationary regimes. It is found that rotation manifests in the widening of their central regions (rotational thickening), limits their global shapes to the extent that stable holes of a given area A and angular momentum J≠0 form a precompact family (rotational stabilization) and enforces their whole geometry to be close to the extreme-Kerr horizon geometry at almost maximal rotational speed (enforced shaping). The results, which are based on the stability inequality, depend only on A and J. In particular they are entirely independent of the surrounding geometry of the space-time and of the presence of matter satisfying the strong energy condition. A complete set of relations between A, J, the length L of the meridians and the length R of the greatest axisymmetric circle, is given. We also provide concrete estimations for the distance between the geometry of horizons and that of the extreme Kerr, in terms only of A and J. Besides its own interest, the work has applications to the Hoop conjecture as formulated by Gibbons in terms of the Birkhoff invariant, to the Bekenstein-Hod entropy bounds and to the study of the compactness of classes of stationary black-hole space-times.
Cosmological rotating black holes in five-dimensional fake supergravity
Nozawa, Masato; Maeda, Kei-ichi
2011-01-15
In recent series of papers, we found an arbitrary dimensional, time-evolving, and spatially inhomogeneous solution in Einstein-Maxwell-dilaton gravity with particular couplings. Similar to the supersymmetric case, the solution can be arbitrarily superposed in spite of nontrivial time-dependence, since the metric is specified by a set of harmonic functions. When each harmonic has a single point source at the center, the solution describes a spherically symmetric black hole with regular Killing horizons and the spacetime approaches asymptotically to the Friedmann-Lemaitre-Robertson-Walker (FLRW) cosmology. We discuss in this paper that in 5 dimensions, this equilibrium condition traces back to the first-order 'Killing spinor' equation in 'fake supergravity' coupled to arbitrary U(1) gauge fields and scalars. We present a five-dimensional, asymptotically FLRW, rotating black-hole solution admitting a nontrivial 'Killing spinor', which is a spinning generalization of our previous solution. We argue that the solution admits nondegenerate and rotating Killing horizons in contrast with the supersymmetric solutions. It is shown that the present pseudo-supersymmetric solution admits closed timelike curves around the central singularities. When only one harmonic is time-dependent, the solution oxidizes to 11 dimensions and realizes the dynamically intersecting M2/M2/M2-branes in a rotating Kasner universe. The Kaluza-Klein-type black holes are also discussed.
NASA Astrophysics Data System (ADS)
Zeng, Xiao-Xiong; Liu, Xiong-Wei; Yang, Shu-Zheng
2008-12-01
Hawking radiation of particles with electric and magnetic charges from the Einstein Maxwell-Dilaton Axion black hole is derived via the anomaly cancellation method, initiated by Robinson and Wilczek and elaborated by Banerjee and Kulkarni recently. We reconstruct the electromagnetic field tensor to redefine the gauge potential and equivalent charge corresponding to the source with electric and magnetic charges. We only adopt the covariant gauge and gravitational anomalies to discuss the near-horizon quantum anomaly in the dragging coordinate frame. Our result shows that Hawking radiation in this case also can be reproduced from the viewpoint of anomaly.
Rotating black branes in Brans-Dicke-Born-Infeld theory
NASA Astrophysics Data System (ADS)
Hendi, S. H.
2008-08-01
In this paper, we present a new class of charged rotating black brane solutions in the higher dimensional Brans-Dicke-Born-Infeld theory and investigate their properties. Solving the field equations directly is a nontrivial task because they include the second derivatives of the scalar field. We remove this difficulty through a conformal transformation. Also, we find that the suitable Lagrangian of Einstein-Born-Infeld-dilaton gravity is not the same as presented by Dehghani et al. [J. Cosmol. Astropart. Phys. 0702, 020 (2007)]. We show that the given solutions can present black brane, with inner and outer event horizons, an extreme black brane, or a naked singularity provided the parameters of the solutions are chosen suitably. These black brane solutions are neither asymptotically flat nor (anti-)de Sitter. Then we calculate finite Euclidean action, the conserved, and thermodynamic quantities through the use of counterterm method. Finally, we argue that these quantities satisfy the first law of thermodynamics, and the entropy does not follow the area law.
NASA Astrophysics Data System (ADS)
Mo, Jie-Xiong; Li, Gu-Qiang; Xu, Xiao-Bao
2016-04-01
The effects of a power-law Maxwell field on the critical phenomena of higher dimensional dilaton black holes are probed in detail. We successfully derive the analytic solutions of the critical point and carry out some checks to ensure that these critical quantities are positive. It is shown that the constraint on the parameter α describing the strength of the coupling of the electromagnetic field and the scalar field turns out to be 0 <α2<1 , which is tighter than that in the nonextended phase space. It is also shown that these critical quantities and the ratio Pcvc/Tc are affected by the power-law Maxwell field. Moreover, critical exponents are found to coincide with those of other anti-de Sitter black holes, showing the powerful influence of mean field theory.
NASA Astrophysics Data System (ADS)
Hendi, S. H.; Tad, R. Moradi; Armanfard, Z.; Talezadeh, M. S.
2016-05-01
Motivated by a thermodynamic analogy of black holes and Van der Waals liquid/gas systems, in this paper, we study P- V criticality of both dilatonic Born-Infeld black holes and their conformal solutions, Brans-Dicke-Born-Infeld solutions. Due to the conformal constraint, we have to neglect the old Lagrangian of dilatonic Born-Infeld theory and its black hole solutions, and introduce a new one. We obtain spherically symmetric nonlinearly charged black hole solutions in both Einstein and Jordan frames and then we calculate the related conserved and thermodynamic quantities. After that, we extend the phase space by considering the proportionality of the cosmological constant and thermodynamical pressure. We obtain critical values of the thermodynamic coordinates through numerical methods and plot the relevant P- V and G- T diagrams. Investigation of the mentioned diagrams helps us to study the thermodynamical phase transition. We also analyze the effects of varying different parameters on the phase transition of black holes.
NASA Astrophysics Data System (ADS)
Sakalli, I.
2011-08-01
We show in detail that the entropic force of the static spherically symmetric spacetimes with unusual asymptotics can be calculated through the Verlinde's arguments. We introduce three different holographic screen candidates, which are first employed thoroughly by Myung and Kim [Phys. Rev. D 81, 105012 (2010)] for Schwarzschild black hole solutions, in order to identify the entropic force arising between a charged dilaton black hole and a test particle. The significance of the dilaton parameter on the entropic force is highlighted, and shown graphically.
BLACK HOLE AURORA POWERED BY A ROTATING BLACK HOLE
Takahashi, Masaaki; Takahashi, Rohta
2010-05-15
We present a model for high-energy emission sources generated by a standing magnetohydrodynamical (MHD) shock in a black hole magnetosphere. The black hole magnetosphere would be constructed around a black hole with an accretion disk, where a global magnetic field could be originated by currents in the accretion disk and its corona. Such a black hole magnetosphere may be considered as a model for the central engine of active galactic nuclei, some compact X-ray sources, and gamma-ray bursts. The energy sources of the emission from the magnetosphere are the gravitational and electromagnetic energies of magnetized accreting matters and the rotational energy of a rotating black hole. When the MHD shock generates in MHD accretion flows onto the black hole, the plasma's kinetic energy and the black hole's rotational energy can convert to radiative energy. In this Letter, we demonstrate the huge energy output at the shock front by showing negative energy postshock accreting MHD flows for a rapidly rotating black hole. This means that the extracted energy from the black hole can convert to the radiative energy at the MHD shock front. When an axisymmetric shock front is formed, we expect a ring-shaped region with very hot plasma near the black hole; this would look like an 'aurora'. The high-energy radiation generated from there would carry to us the information for the curved spacetime due to the strong gravity.
"Triangular" extremal dilatonic dyons
NASA Astrophysics Data System (ADS)
Gal'tsov, Dmitri; Khramtsov, Mikhail; Orlov, Dmitri
2015-04-01
Explicit dyonic solutions in four-dimensional Einstein-Maxwell-dilaton theory are known only for three particular values of the dilaton coupling constant: a = 0 , 1 ,√{ 3}. However, numerical evidence was presented on existence of dyons admitting an extremal limit in theories with more general sequence of dilaton couplings a =√{ n (n + 1) / 2 } labeled by an integer n. Apart from the lower members n = 0 , 1 , 2, this family of theories does not have motivation from supergravity/string theory, and analytical origin of the above sequence remained unclear so far. We fill the gap showing that this formula follows from analyticity of the dilaton function at the AdS2 ×S2 event horizon of the extremal dyonic black hole, with n being the leading dilaton power in the Taylor expansion. We also derive generalization of this rule for asymptotically anti-de Sitter dyonic black holes with spherical, planar and hyperbolic topology of the horizon.
Renormalized vacuum polarization of rotating black holes
NASA Astrophysics Data System (ADS)
Ferreira, Hugo R. C.
2015-04-01
Quantum field theory on rotating black hole spacetimes is plagued with technical difficulties. Here, we describe a general method to renormalize and compute the vacuum polarization of a quantum field in the Hartle-Hawking state on rotating black holes. We exemplify the technique with a massive scalar field on the warped AdS3 black hole solution to topologically massive gravity, a deformation of (2 + 1)-dimensional Einstein gravity. We use a "quasi-Euclidean" technique, which generalizes the Euclidean techniques used for static spacetimes, and we subtract the divergences by matching to a sum over mode solutions on Minkowski spacetime. This allows us, for the first time, to have a general method to compute the renormalized vacuum polarization, for a given quantum state, on a rotating black hole, such as the physically relevant case of the Kerr black hole in four dimensions.
Rotating black rings on Taub-NUT
NASA Astrophysics Data System (ADS)
Chen, Yu; Teo, Edward
2012-06-01
In this paper, we construct new solutions describing rotating black rings on Taub-NUT using the inverse-scattering method. These are five-dimensional vacuum spacetimes, generalising the Emparan-Reall and extremal Pomeransky-Sen'kov black rings to a Taub-NUT background space. When reduced to four dimensions in Kaluza-Klein theory, these solutions describe (possibly rotating) electrically charged black holes in superposition with a finitely separated magnetic monopole. Various properties of these solutions are studied, from both a five- and four-dimensional perspective.
Shadow of rotating regular black holes
NASA Astrophysics Data System (ADS)
Abdujabbarov, Ahmadjon; Amir, Muhammed; Ahmedov, Bobomurat; Ghosh, Sushant G.
2016-05-01
We study the shadows cast by the different types of rotating regular black holes viz. Ayón-Beato-García (ABG), Hayward, and Bardeen. These black holes have in addition to the total mass (M ) and rotation parameter (a ), different parameters as electric charge (Q ), deviation parameter (g ), and magnetic charge (g*). Interestingly, the size of the shadow is affected by these parameters in addition to the rotation parameter. We found that the radius of the shadow in each case decreases monotonically, and the distortion parameter increases when the values of these parameters increase. A comparison with the standard Kerr case is also investigated. We have also studied the influence of the plasma environment around regular black holes to discuss its shadow. The presence of the plasma affects the apparent size of the regular black hole's shadow to be increased due to two effects: (i) gravitational redshift of the photons and (ii) radial dependence of plasma density.
Charged rotating noncommutative black holes
Modesto, Leonardo; Nicolini, Piero
2010-11-15
In this paper we complete the program of the noncomutative geometry inspired black holes, providing the richest possible solution, endowed with mass, charge and angular momentum. After providing a prescription for employing the Newman-Janis algorithm in the case of nonvanishing stress tensors, we find regular axisymmetric charged black holes in the presence of a minimal length. We study also the new thermodynamics and we determine the corresponding higher-dimensional solutions. As a conclusion we make some consideration about possible applications.
Charged rotating noncommutative black holes
NASA Astrophysics Data System (ADS)
Modesto, Leonardo; Nicolini, Piero
2010-11-01
In this paper we complete the program of the noncomutative geometry inspired black holes, providing the richest possible solution, endowed with mass, charge and angular momentum. After providing a prescription for employing the Newman-Janis algorithm in the case of nonvanishing stress tensors, we find regular axisymmetric charged black holes in the presence of a minimal length. We study also the new thermodynamics and we determine the corresponding higher-dimensional solutions. As a conclusion we make some consideration about possible applications.
Ultraspinning instability of rotating black holes
Dias, Oscar J. C.; Figueras, Pau; Monteiro, Ricardo; Santos, Jorge E.
2010-11-15
Rapidly rotating Myers-Perry black holes in d{>=}6 dimensions were conjectured to be unstable by Emparan and Myers. In a previous publication, we found numerically the onset of the axisymmetric ultraspinning instability in the singly spinning Myers-Perry black hole in d=7, 8, 9. This threshold also signals a bifurcation to new branches of axisymmetric solutions with pinched horizons that are conjectured to connect to the black ring, black Saturn and other families in the phase diagram of stationary solutions. We firmly establish that this instability is also present in d=6 and in d=10, 11. The boundary conditions of the perturbations are discussed in detail for the first time, and we prove that they preserve the angular velocity and temperature of the original Myers-Perry black hole. This property is fundamental to establishing a thermodynamic necessary condition for the existence of this instability in general rotating backgrounds. We also prove a previous claim that the ultraspinning modes cannot be pure gauge modes. Finally we find new ultraspinning Gregory-Laflamme instabilities of rotating black strings and branes that appear exactly at the critical rotation predicted by the aforementioned thermodynamic criterium. The latter is a refinement of the Gubser-Mitra conjecture.
Twisting of light around rotating black holes
NASA Astrophysics Data System (ADS)
Tamburini, Fabrizio; Thidé, Bo; Molina-Terriza, Gabriel; Anzolin, Gabriele
2011-03-01
Kerr black holes are among the most intriguing predictions of Einstein's general relativity theory. These rotating massive astrophysical objects drag and intermix their surrounding space and time, deflecting and phase-modifying light emitted near them. We have found that this leads to a new relativistic effect that imprints orbital angular momentum on such light. Numerical experiments, based on the integration of the null geodesic equations of light from orbiting point-like sources in the Kerr black hole equatorial plane to an asymptotic observer, indeed identify the phase change and wavefront warping and predict the associated light-beam orbital angular momentum spectra. Setting up the best existing telescopes properly, it should be possible to detect and measure this twisted light, thus allowing a direct observational demonstration of the existence of rotating black holes. As non-rotating objects are more an exception than a rule in the Universe, our findings are of fundamental importance.
Rotating black holes can have short bristles
NASA Astrophysics Data System (ADS)
Hod, Shahar
2014-12-01
The elegant 'no short hair' theorem states that, if a spherically-symmetric static black hole has hair, then this hair must extend beyond 3/2 the horizon radius. In the present paper we provide evidence for the failure of this theorem beyond the regime of spherically-symmetric static black holes. In particular, we show that rotating black holes can support extremely short-range stationary scalar configurations (linearized scalar 'clouds') in their exterior regions. To that end, we solve analytically the Klein-Gordon-Kerr-Newman wave equation for a linearized massive scalar field in the regime of large scalar masses.
Stringy stability of charged dilaton black holes with flat event horizon
Ong, Yen Chin; Chen, Pisin
2015-01-15
Electrically charged black holes with flat event horizon in anti-de Sitter space have received much attention due to various applications in Anti-de Sitter/Conformal Field Theory (AdS/CFT) correspondence, from modeling the behavior of quark-gluon plasma to superconductor. Critical to the physics on the dual field theory is the fact that when embedded in string theory, black holes in the bulk may become vulnerable to instability caused by brane pair-production. Since dilation arises naturally in the context of string theory, we study the effect of coupling dilation to Maxwell field on the stability of flat charged AdS black holes.
Three-charge doubly rotating black ring
Gal'tsov, Dmitri V.; Scherbluk, Nikolai G.
2010-02-15
Using the recently proposed new solution generating technique, we construct the charged version of the Pomeranski-Senkov doubly rotating black ring in the U(1){sup 3} five-dimensional supergravity. For arbitrary values of charges the solution is unbalanced, but the Dirac-Misner string is removed when two of the charges are set to zero. In this particular case our solution can be uplifted to some solutions of six-dimensional vacuum gravity.
Noncommutative geometry-inspired rotating black hole in three dimensions
NASA Astrophysics Data System (ADS)
Tejeiro, Juan Manuel; Larrañaga, Alexis
2012-01-01
We find a new rotating black hole in three-dimensional anti-de Sitter space using an anisotropic perfect fluid inspired by the noncommutative black hole. We deduce the thermodynamical quantities of this black hole and compare them with those of a rotating BTZ solution.
Rotating black string with nonlinear source
Hendi, S. H.
2010-09-15
In this paper, we derive rotating black string solutions in the presence of two kinds of nonlinear electromagnetic fields, so-called Born-Infeld and power Maxwell invariant. Investigation of the solutions show that for the Born-Infeld black string the singularity is timelike and the asymptotic behavior of the solutions is anti-de Sitter, but for power Maxwell invariant solutions, depending on the values of nonlinearity parameter, the singularity may be timelike as well as spacelike and the solutions are not asymptotically anti-de Sitter for all values of the nonlinearity parameter. Next, we calculate the conserved quantities of the solutions by using the counterterm method, and find that these quantities do not depend on the nonlinearity parameter. We also compute the entropy, temperature, the angular velocity, the electric charge, and the electric potential of the solutions, in which the conserved and thermodynamics quantities satisfy the first law of thermodynamics.
CFTs in rotating black hole backgrounds
NASA Astrophysics Data System (ADS)
Figueras, Pau; Tunyasuvunakool, Saran
2013-06-01
We use AdS/CFT to construct the gravitational dual of a 5D CFT in the background of a non-extremal rotating black hole. Our boundary conditions are such that the vacuum state of the dual CFT corresponds to the Unruh state. We extract the expectation value of the stress tensor of the dual CFT using holographic renormalization and show that it is stationary and regular on both the future and the past event horizons. The energy density of the CFT is found to be negative everywhere in our domain and we argue that this can be understood as a vacuum polarization effect. We construct the solutions by numerically solving the elliptic Einstein-DeTurck equation for stationary Lorentzian spacetimes with Killing horizons. Communicated by H Reall
Nonaxisymmetric instability of rapidly rotating black hole in five dimensions
Shibata, Masaru; Yoshino, Hirotaka
2010-01-15
We present results from numerical solution of Einstein's equation in five dimensions describing evolution of rapidly rotating black holes. We show, for the first time, that the rapidly rotating black holes in higher dimensions are unstable against nonaxisymmetric deformation; for the five-dimensional case, the critical value of spin parameter for onset of the instability is {approx_equal}0.87.
Charged fermions tunneling from accelerating and rotating black holes
Rehman, Mudassar; Saifullah, K. E-mail: saifullah@qau.edu.pk
2011-03-01
We study Hawking radiation of charged fermions from accelerating and rotating black holes with electric and magnetic charges. We calculate the tunneling probabilities of incoming and outgoing fermionic particles and find the Hawking temperature of these black holes. We also provide an explicit expression of the classical action for the massive and massless particles in the background of these black holes.
Scalar emission in a rotating Goedel black hole
Chen Songbai; Wang Bin; Jing Jiliang
2008-09-15
We study the absorption probability and Hawking radiation of the scalar field in the rotating Goedel black hole in minimal five-dimensional gauged supergravity. We find that Goedel parameter j imprints in the greybody factor and Hawking radiation. It plays a different role from the angular momentum of the black hole in the Hawking radiation and super-radiance. This information can help us know more about rotating Goedel black holes in minimal five-dimensional gauged supergravity.
Particle motion and Penrose processes around rotating regular black hole
NASA Astrophysics Data System (ADS)
Abdujabbarov, Ahmadjon
2016-07-01
The neutral particle motion around rotating regular black hole that was derived from the Ayón-Beato-García (ABG) black hole solution by the Newman-Janis algorithm in the preceding paper (Toshmatov et al., Phys. Rev. D, 89:104017, 2014) has been studied. The dependencies of the ISCO (innermost stable circular orbits along geodesics) and unstable orbits on the value of the electric charge of the rotating regular black hole have been shown. Energy extraction from the rotating regular black hole through various processes has been examined. We have found expression of the center of mass energy for the colliding neutral particles coming from infinity, based on the BSW (Baňados-Silk-West) mechanism. The electric charge Q of rotating regular black hole decreases the potential of the gravitational field as compared to the Kerr black hole and the particles demonstrate less bound energy at the circular geodesics. This causes an increase of efficiency of the energy extraction through BSW process in the presence of the electric charge Q from rotating regular black hole. Furthermore, we have studied the particle emission due to the BSW effect assuming that two neutral particles collide near the horizon of the rotating regular extremal black hole and produce another two particles. We have shown that efficiency of the energy extraction is less than the value 146.6 % being valid for the Kerr black hole. It has been also demonstrated that the efficiency of the energy extraction from the rotating regular black hole via the Penrose process decreases with the increase of the electric charge Q and is smaller in comparison to 20.7 % which is the value for the extreme Kerr black hole with the specific angular momentum a= M.
Rotating black hole thermodynamics with a particle probe
Gwak, Bogeun; Lee, Bum-Hoon
2011-10-15
The thermodynamics of Myers-Perry black holes in general dimensions are studied using a particle probe. When undergoing particle absorption, the changes of the entropy and irreducible mass are shown to be dependent on the particle radial momentum. The black hole thermodynamic behaviors are dependent on dimensionality for specific rotations. For a 4-dimensional Kerr black hole, its black hole properties are maintained for any particle absorption. 5-dimensional black holes can avoid a naked ring singularity by absorbing a particle in specific momenta ranges. Black holes over 6 dimensions become ultraspinning black holes through a specific form of particle absorption. The microscopical changes are interpreted in limited cases of Myers-Perry black holes using Kerr/CFT correspondence. We systematically describe the black hole properties changed by particle absorption in all dimensions.
Charged rotating Kaluza-Klein black holes in five dimensions
Nakagawa, Toshiharu; Ishihara, Hideki; Matsuno, Ken; Tomizawa, Shinya
2008-02-15
We construct a new charged rotating Kaluza-Klein black hole solution in the five-dimensional Einstein-Maxwell theory with a Chern-Simon term. The features of the solutions are also investigated. The spacetime is asymptotically locally flat, i.e., it asymptotes to a twisted S{sup 1} bundle over the four-dimensional Minkowski spacetime. The solution describe a non-BPS black hole rotating in the direction of the extra dimension. The solutions have the limits to the supersymmetric black hole solutions, a new extreme non-BPS black hole solution and a new rotating non-BPS black hole solution with a constant twisted S{sup 1} fiber.
Quantum tunneling from scalar fields in rotating black strings
NASA Astrophysics Data System (ADS)
Gohar, H.; Saifullah, K.
2013-08-01
Using the Hamilton-Jacobi method of quantum tunneling and complex path integration, we study Hawking radiation of scalar particles from rotating black strings. We discuss tunneling of both charged and uncharged scalar particles from the event horizons. For this purpose, we use the Klein-Gordon equation and find the tunneling probability of outgoing scalar particles. The procedure gives Hawking temperature for rotating charged black strings as well.
Cosmic censorship of rotating Anti-de Sitter black hole
NASA Astrophysics Data System (ADS)
Gwak, Bogeun; Lee, Bum-Hoon
2016-02-01
We test the validity of cosmic censorship in the rotating anti-de Sitter black hole. For this purpose, we investigate whether the extremal black hole can be overspun by the particle absorption. The particle absorption will change the mass and angular momentum of the black hole, which is analyzed using the Hamilton-Jacobi equations consistent with the laws of thermodynamics. We have found that the mass of the extremal black hole increases more than the angular momentum. Therefore, the outer horizon of the black hole still exists, and cosmic censorship is valid.
NASA Astrophysics Data System (ADS)
Brax, Philippe; van de Bruck, Carsten; Davis, Anne-Christine; Shaw, Douglas
2010-09-01
We consider the dilaton in the strong string-coupling limit and elaborate on the original idea of Damour and Polyakov whereby the dilaton coupling to matter is minimized and vanishes at a finite value of the dilaton field. Combining this type of coupling with an exponential potential, the effective potential of the dilaton becomes matter density dependent. We study the background cosmology, showing that the dilaton can play the role of dark energy. We also analyze the constraints imposed by the absence of violation of the equivalence principle. Imposing these constraints and assuming that the dilaton plays the role of dark energy, we consider the consequences of the dilaton on large scale structures and, in particular, the behavior of the slip functions and the growth index at low redshift.
Gamma rays from accretion onto rotating black holes
NASA Technical Reports Server (NTRS)
Collins, M. S.
1978-01-01
Ionized matter falling onto an isolated, rotating black hole will be heated sufficiently that proton-proton collisions will produce mesons, including neutral pions, which decay into gamma rays. For massive (1000 M sub circled dot), black holes, the resulting gamma-ray luminosity may exceed 10 to the 36th power engs/s, with a spectrum peaked near 20 MeV.
Gamma rays from accretion onto rotating black holes
NASA Technical Reports Server (NTRS)
Collins, M. S.
1979-01-01
Ionized matter falling onto an isolated rotating black hole will be heated sufficiently that proton-proton collisions will produce mesons, including neutral pions, which decay into gamma rays. For massive (1000-solar mass) black holes, the resulting gamma-ray luminosity may exceed 10 to the 36th erg/s with a spectrum peaked near 20 MeV.
Shapes of rotating nonsingular black hole shadows
NASA Astrophysics Data System (ADS)
Amir, Muhammed; Ghosh, Sushant G.
2016-07-01
It is believed that curvature singularities are a creation of general relativity and, hence, in the absence of a quantum gravity, models of nonsingular black holes have received significant attention. We study the shadow (apparent shape), an optical appearance because of its strong gravitational field, cast by a nonsingular black hole which is characterized by three parameters, i.e., mass (M ), spin (a ), and a deviation parameter (k ). The nonsingular black hole under consideration is a generalization of the Kerr black hole that can be recognized asymptotically (r ≫k ,k >0 ) explicitly as the Kerr-Newman black hole, and in the limit k →0 as the Kerr black hole. It turns out that the shadow of a nonsingular black hole is a dark zone covered by a deformed circle. Interestingly, it is seen that the shadow of a black hole is affected due to the parameter k . Indeed, for a given a , the size of a shadow reduces as the parameter k increases, and the shadow becomes more distorted as we increase the value of the parameter k when compared with the analogous Kerr black hole shadow. We also investigate, in detail, how the ergoregion of a black hole is changed due to the deviation parameter k .
Hawking temperature of rotating charged black strings from tunneling
NASA Astrophysics Data System (ADS)
Ahmed, Jamil; Saifullah, K.
2011-11-01
Thermal radiations from spherically symmetric black holes have been studied from the point of view of quantum tunneling. In this paper we extend this approach to study radiation of fermions from charged and rotating black strings. Using WKB approximation and Hamilton-Jacobi method we work out the tunneling probabilities of incoming and outgoing fermions and find the correct Hawking temperature for these objects. We show that in appropriate limits the results reduce to those for the uncharged and non-rotating black strings.
Rotating black lens solution in five dimensions
Chen Yu; Teo, Edward
2008-09-15
It has recently been shown that a stationary, asymptotically flat vacuum black hole in five space-time dimensions with two commuting axial symmetries must have an event horizon with either a spherical, ring or lens-space topology. In this paper, we study the third possibility, a so-called black lens with L(n,1) horizon topology. Using the inverse scattering method, we construct a black-lens solution with the simplest possible rod structure, and possessing a single asymptotic angular momentum. Its properties are then analyzed; in particular, it is shown that there must either be a conical singularity or a naked curvature singularity present in the space-time.
Instabilities of Extremal Rotating Black Holes in Higher Dimensions
NASA Astrophysics Data System (ADS)
Hollands, Stefan; Ishibashi, Akihiro
2015-11-01
Recently, Durkee and Reall have conjectured a criterion for linear instability of rotating, extremal, asymptotically Minkowskian black holes in dimensions, such as the Myers-Perry black holes. They considered a certain elliptic operator, , acting on symmetric trace-free tensors intrinsic to the horizon. Based in part on numerical evidence, they suggested that if the lowest eigenvalue of this operator is less than the critical value -1/4 ( called "effective BF-bound"), then the black hole is linearly unstable. In this paper, we prove an extended version of their conjecture. Our proof uses a combination of methods such as (1) the "canonical energy method" of Hollands-Wald, (2) algebraically special properties of the near horizon geometries associated with the black hole, (3) the Corvino-Schoen technique, and (4) semiclassical analysis. Our method of proof is also applicable to rotating, extremal asymptotically Anti-deSitter black holes. In that case, we find additional instabilities for ultra-spinning black holes. Although we explicitly discuss in this paper only extremal black holes, we argue that our results can be generalized to near extremal black holes.
Slowly rotating black holes with nonlinear electrodynamics in five dimensions
NASA Astrophysics Data System (ADS)
Hendi, S. H.; Sepehri Rad, M.
2014-10-01
Employing linear order perturbation theory with the rotation parameter as the perturbative parameter, we obtain asymptotically AdS slowly rotating black hole solutions in the Einstein gravity with Born-Infeld (BI) type nonlinear electrodynamics (NED). We start from asymptotically AdS static black hole solutions coupled to BI type NED in five dimensions. Then, we consider the effect of adding a small amount of angular momenta to the seed solutions. Finally, we investigate the geometry and thermodynamic properties of the solutions.
A strongly coupled anisotropic fluid from dilaton driven holography
NASA Astrophysics Data System (ADS)
Jain, Sachin; Kundu, Nilay; Sen, Kallol; Sinha, Aninda; Trivedi, Sandip P.
2015-01-01
We consider a system consisting of 5 dimensional gravity with a negative cosmological constant coupled to a massless scalar, the dilaton. We construct a black brane solution which arises when the dilaton satisfies linearly varying boundary conditions in the asymptotically AdS 5 region. The geometry of this black brane breaks rotational symmetry while preserving translational invariance and corresponds to an anisotropic phase of the system. Close to extremality, where the anisotropy is big compared to the temperature, some components of the viscosity tensor become parametrically small compared to the entropy density. We study the quasi normal modes in considerable detail and find no instability close to extremality. We also obtain the equations for fluid mechanics for an anisotropic driven system in general, working upto first order in the derivative expansion for the stress tensor, and identify additional transport coefficients which appear in the constitutive relation. For the fluid of interest we find that the parametrically small viscosity can result in a very small force of friction, when the fluid is enclosed between appropriately oriented parallel plates moving with a relative velocity.
Hawking radiation of a high-dimensional rotating black hole
NASA Astrophysics Data System (ADS)
Ren, Zhao; Lichun, Zhang; Huaifan, Li; Yueqin, Wu
2010-01-01
We extend the classical Damour-Ruffini method and discuss Hawking radiation spectrum of high-dimensional rotating black hole using Tortoise coordinate transformation defined by taking the reaction of the radiation to the spacetime into consideration. Under the condition that the energy and angular momentum are conservative, taking self-gravitation action into account, we derive Hawking radiation spectrums which satisfy unitary principle in quantum mechanics. It is shown that the process that the black hole radiates particles with energy ω is a continuous tunneling process. We provide a theoretical basis for further studying the physical mechanism of black-hole radiation.
Radiation spectrum of a high-dimensional rotating black hole
NASA Astrophysics Data System (ADS)
Zhao, Ren; Li, Huaifan; Zhang, Lichun; Wu, Yueqin
2010-03-01
This study extends the classical Damour-Ruffini method and discusses Hawking radiation in a ( n + 4)-dimensional rotating black hole. Under the condition that the total energy and angular momentum of spacetime are conservative, but angular momentum a = J/ M of unit mass of the black hole is variable, taking into consideration the reaction of the radiation of the particle to the spacetime, a new Tortoise coordinate transformation and discuss the black hole radiation spectrum is discussed. The radiation spectrum that satisfies the unitary principle in the general case is derived.
Entropy of a radiating rotating charged black hole
NASA Astrophysics Data System (ADS)
Wu, Yue-Jiang; Zhao, Zheng; Yang, Xue-Jun
2004-06-01
The Hawking radiation temperature and the entropy of a radiating rotating charged black hole are calculated by employing the method of tortoise coordinate transformation and the improved brick-wall model. A new tortoise coordinate transformation is introduced which simplifies the cut-off factor and more satisfying results are obtained. The results show that the temperature of the event horizon depends on time and angle, and the entropy of a non-stationary black hole is exactly proportional to its horizon area as in the case of a stationary black hole.
ROTATING NON-KERR BLACK HOLE AND ENERGY EXTRACTION
Liu Changqing; Chen Songbai; Jing Jiliang
2012-06-01
The properties of the ergosphere and energy extraction by the Penrose process in a rotating non-Kerr black hole are investigated. It is shown that the ergosphere is sensitive to the deformation parameter {epsilon} and the shape of the ergosphere becomes thick as parameter {epsilon} increases. It is of interest to note that, compared with the Kerr black hole, the deformation parameter {epsilon} can enhance the maximum efficiency of the energy extraction process greatly. Especially for the case of a > M, the non-Kerr metric describes a superspinning compact object and the maximum efficiency can exceed 60%, while it is only 20.7% for the extremal Kerr black hole.
Magnetic strings in dilaton gravity
Dehghani, M.H.
2005-03-15
First, I present two new classes of magnetic rotating solutions in four-dimensional Einstein-Maxwell-dilaton gravity with Liouville-type potential. The first class of solutions yields a four-dimensional spacetime with a longitudinal magnetic field generated by a static or spinning magnetic string. I find that these solutions have no curvature singularity and no horizons, but have a conic geometry. In these spacetimes, when the rotation parameter does not vanish, there exists an electric field, and therefore the spinning string has a net electric charge which is proportional to the rotation parameter. The second class of solutions yields a spacetime with an angular magnetic field. These solutions have no curvature singularity, no horizon, and no conical singularity. The net electric charge of the strings in these spacetimes is proportional to their velocities. Second, I obtain the (n+1)-dimensional rotating solutions in Einstein-dilaton gravity with Liouville-type potential. I argue that these solutions can present horizonless spacetimes with conic singularity, if one chooses the parameters of the solutions suitable. I also use the counterterm method and compute the conserved quantities of these spacetimes.
Thermodynamics of 5D dilaton-gravity
Megias, E.
2011-05-23
We calculate the free energy, spatial string tension and Polyakov loop of the gluon plasma using the dilaton potential of Ref. [1] in the dilaton-gravity theory of AdS/QCD. The free energy is computed from the Black Hole solutions of the Einstein equations in two ways: first, from the Bekenstein-Hawking proportionality of the entropy with the area of the horizon, and secondly from the Page-Hawking computation of the free energy. The finite temperature behaviour of the spatial string tension and Polyakov loop follow from the corresponding string theory in AdS{sub 5}. Comparison with lattice data is made.
Particles Generation and Bose Instability in Primordial Rotating Black Holes
NASA Astrophysics Data System (ADS)
Gaina, Alex
The author makes a connection between the Kepler's laws of motion for planets in the gravitational field of the Sun with the motion of test particles in classical mechanics. Subsequently He discusses the quantum problem, or the motion of scalar particles described by Klein-Gordon equation in the gravitational field of a black hole, when the Particle's Energy is less than the Rest Energy of the Particle: E< mc^2. It is mentioned that the spectrum of energies will be discrete one as in the case of the Hydrogen atom. But, due to very fast decreasing of the Potential energy of the particle near the horizon of the Black Hole, or the Black Hole itself, the spectrum will be a quasidiscrete one. The imaginary part of the Energy describes the fall of the particle into Black Hole. There are two features, which could complicate the problem: 1) The rotation of the Black Hole 2) The spin of the Particles. The first circumstance will lead, as is shown by author, to superradiation (the Imaginary part of the Energy will change the sign) as in the case of Particles scattering (E>mc^2). As in that case detailed calculations show that the black Hole will drop the angular momentum very fast if the black Hole is highly rotating. Electrically charged particles cannot develop such a process due to very fast ionization of bosonic levels by electromagnetic radiation. Meanwhile, neutral particles produces Gamma-bursts of energies 67.5, 274.5, 932 Mev correspondingly. The duration of bursts is 1.26* 10^-17 s (for neutral pion), 2.99*10^-18 s (for Eta meson), 8.55*10^-19 s (for D^0 meson). The radiated energies are 1.2 * 10^35 erg, 8.67*10^34 erg, 8.55*10^33 erg, corresponding to very great powers of the order of magnitude 10^52 erg/s. The second circumstance does stops the superradiative decay due to Pauli exclussion principle. The imaginary part of the Energy will not change the sign, and the particles levels are decaying only. For this reason the superradiative bound levels decay of the
Rotating black holes at future colliders. III. Determination of black hole evolution
Ida, Daisuke; Oda, Kin-ya; Park, Seong Chan
2006-06-15
TeV scale gravity scenario predicts that the black hole production dominates over all other interactions above the scale and that the Large Hadron Collider will be a black hole factory. Such higher-dimensional black holes mainly decay into the standard model fields via the Hawking radiation whose spectrum can be computed from the greybody factor. Here we complete the series of our work by showing the greybody factors and the resultant spectra for the brane-localized spinor and vector field emissions for arbitrary frequencies. Combining these results with the previous works, we determine the complete radiation spectra and the subsequent time evolution of the black hole. We find that, for a typical event, well more than half a black hole mass is emitted when the hole is still highly rotating, confirming our previous claim that it is important to take into account the angular momentum of black holes.
Perturbative charged rotating 5D Einstein-Maxwell black holes
NASA Astrophysics Data System (ADS)
Navarro-Lérida, Francisco
2010-12-01
We present perturbative charged rotating 5D Einstein-Maxwell black holes with spherical horizon topology. The electric charge Q is the perturbative parameter, the perturbations being performed up to 4th order. The expressions for the relevant physical properties of these black holes are given. The gyromagnetic ratio g, in particular, is explicitly shown to be non-constant in higher order, and thus to deviate from its lowest order value, g = 3. Comparison of the perturbative analytical solutions with their non-perturbative numerical counterparts shows remarkable agreement.
Corrected Entropy Law for Charged and Rotating Black Strings
NASA Astrophysics Data System (ADS)
Rizwan, Muhammad
2016-08-01
The primary objective in this work is to study the corrected entropy law for charged and rotating black strings in asymptotically anti-de Sitter spacetime. By employing, the Hamilton-Jacobi approach, fermions tunneling beyond semiclassical approximation is investigated. The correction has been done by taking the proportionality parameters of quantum correction of action I i to the semiclassical action I 0 as 2 π times the inverse of the black string horizon area. Moreover, with the aid of corrected Hawking temperature we finally compute the corrected area law, which includes the logarithmic term and inverse area terms.
Exact solution for two unequal counter-rotating black holes
NASA Astrophysics Data System (ADS)
Cabrera-Munguia, I.; Macías, Alfredo
2013-07-01
The full analytical form of the metric describing two unequal counter-rotating black holes with a massless strut (conical singularity) in between is derived explicitly. It is characterized by means of physical parameters like the two Komar masses M1 and M2, Komar angular momenta J1 and J2 (having J1 and J2 opposite sign) and the separation distance R between the centers of the black hole horizons. This solution belongs to a 4-parameter subclass of the double-Kerr-NUT problem, in which the five physical parameters satisfy an algebraic relationship and the interaction force can be observed as Schwarzschild type.
Rotating black holes in the teleparallel equivalent of general relativity
NASA Astrophysics Data System (ADS)
Nashed, Gamal G. L.
2016-05-01
We derive set of solutions with flat transverse sections in the framework of a teleparallel equivalent of general relativity which describes rotating black holes. The singularities supported from the invariants of torsion and curvature are explained. We investigate that there appear more singularities in the torsion scalars than in the curvature ones. The conserved quantities are discussed using Einstein-Cartan geometry. The physics of the constants of integration is explained through the calculations of conserved quantities. These calculations show that there is a unique solution that may describe true physical black hole.
Rotating and accelerating black holes with a cosmological constant
NASA Astrophysics Data System (ADS)
Chen, Yu; Ng, Cheryl; Teo, Edward
2016-08-01
We propose a new form of the rotating C-metric with cosmological constant, which generalizes the form found by Hong and Teo for the Ricci-flat case. This solution describes the entire class of spherical black holes undergoing rotation and acceleration in dS or AdS space-time. The new form allows us to identify the complete ranges of coordinates and parameters of this solution. We perform a systematic study of its geometrical and physical properties, and of the various limiting cases that arise from it.
Electrically charged matter rotating around magnetized black holes
NASA Astrophysics Data System (ADS)
Kovar, Jiri; Slany, Petr; Stuchlik, Zdenek; Karas, Vladimir
2015-08-01
We present results of our study of charged-fluid toroidal structures surrounding a non-rotating black hole surrounded by a dipole and large-scale, asymptotically uniform magnetic fields. In continuation of our former study of electrically charged matter in approximation of zero conductivity, we demonstrate the existence of orbiting structures in the equatorial plane, levitating above it and those hovering near the symmetry axis. We constrain the range of black-hole, magnetic fields and matter parameters that allow stable configurations of the fluid structures and derive the geometrical shape of equi-pressure surfaces, characterizing the temperature and other astrophysical characteristic profiles. Our simplified analytical study suggests that these regions of stability may be relevant for trapping electrically charged particles and dust grains in some areas of the black hole magnetosphere, being thus important in some astrophysical situations.
Hidden Symmetries of Higher-Dimensional Rotating Black Holes
NASA Astrophysics Data System (ADS)
Kubiznak, David
2008-09-01
In this thesis we study higher-dimensional rotating black holes. Such black holes are widely discussed in string theory and brane-world models at present. We demonstrate that even the most general known Kerr-NUT-(A)dS spacetime, describing the general rotating higher-dimensional asymptotically (anti) de Sitter black hole with NUT parameters, is in many aspects similar to its four-dimensional counterpart. Namely, we show that it admits a fundamental hidden symmetry associated with the principal conformal Killing-Yano tensor. Such a tensor generates towers of hidden and explicit symmetries. The tower of Killing tensors is responsible for the existence of irreducible, quadratic in momenta, conserved integrals of geodesic motion. These integrals, together with the integrals corresponding to the tower of explicit symmetries, make geodesic equations in the Kerr-NUT-(A)dS spacetime completely integrable. We further demonstrate that in this spacetime the Hamilton-Jacobi, Klein-Gordon, and stationary string equations allow complete separation of variables and the problem of finding parallel-propagated frames reduces to the set of the first order ordinary differential equations. Moreover, we show that the Kerr-NUT-(A)dS spacetime is the most general Einstein space which possesses all these properties. We also explicitly derive the most general (off-shell) canonical metric admitting the principal conformal Killing-Yano tensor and demonstrate that such a metric is necessarily of the special algebraic type D of the higher-dimensional algebraic classification. The results presented in this thesis describe the new and complete picture of the relationship of hidden symmetries and rotating black holes in higher dimensions.
Rotating black holes in an expanding Universe from fake supergravity
NASA Astrophysics Data System (ADS)
Chimento, Samuele; Klemm, Dietmar
2015-02-01
Using the recipe of Meessen and Palomo-Lozano (2009 J. High Energy Phys. JHEP05(2009)042), where all fake supersymmetric backgrounds of matter-coupled fake N = 2, d = 4 gauged supergravity were classified, we construct dynamical rotating black holes in an expanding FLRW Universe. This is done for two different prepotentials that are both truncations of the stu model and correspond to just one vector multiplet. In this scenario, the cosmic expansion is driven by two U(1) gauge fields and by a complex scalar that rolls down its potential. Generically, the solutions of Meessen and Palomo-Lozano are fibrations over a Gauduchon-Tod base space, and we make three different choices for this base, namely flat space, the three-sphere and the Berger sphere. In the first two cases, the black holes are determined by harmonic functions on the base, while in the last case they obey a deformed Laplace equation that contains the squashing parameter of the Berger sphere. This is the generalization to a cosmological context of the usual recipe in ungauged supergravity, where black holes are given in terms of harmonic functions on three-dimensional Euclidean space. The constructed solutions may be instrumental in addressing analytically certain aspects of black hole physics in a dynamical context.
Slowly rotating black holes in alternative theories of gravity
Pani, Paolo; Macedo, Caio F. B.; Crispino, Luis C. B.; Cardoso, Vitor
2011-10-15
We present, in closed analytic form, a general stationary, slowly rotating black hole, which is a solution to a large class of alternative theories of gravity in four dimensions. In these theories, the Einstein-Hilbert action is supplemented by all possible quadratic, algebraic curvature invariants coupled to a scalar field. The solution is found as a deformation of the Schwarzschild metric in general relativity. We explicitly derive the changes to the orbital frequency at the innermost stable circular orbit and at the light ring in closed form. These results could be useful when comparing general relativity against alternative theories by (say) measurements of x-ray emission in accretion disks, or by stellar motion around supermassive black holes. When gravitational-wave astronomy comes into force, strong constraints on the coupling parameters can in principle be made.
Slowly rotating black holes in Einstein-æther theory
NASA Astrophysics Data System (ADS)
Barausse, Enrico; Sotiriou, Thomas P.; Vega, Ian
2016-02-01
We study slowly rotating, asymptotically flat black holes in Einstein-æther theory and show that solutions that are free from naked finite area singularities form a two-parameter family. These parameters can be thought of as the mass and angular momentum of the black hole, while there are no independent æ ther charges. We also show that the æ ther has nonvanishing vorticity throughout the spacetime, as a result of which there is no hypersurface that resembles the universal horizon found in static, spherically symmetric solutions. Moreover, for experimentally viable choices of the coupling constants, the frame-dragging potential of our solutions only shows percent-level deviations from the corresponding quantities in General Relativity and Hořava gravity. Finally, we uncover and discuss several subtleties in the correspondence between Einstein-æther theory and Hořava gravity solutions in the cω→∞ limit.
5D extremal rotating black holes and CFT duals
NASA Astrophysics Data System (ADS)
Loran, Farhang; Soltanpanahi, Hesam
2009-08-01
Kerr/CFT correspondence has been recently applied to various types of 5D extremal rotating black holes. A common feature of all such examples is the existence of two chiral CFT duals corresponding to the U(1) symmetries of the near horizon geometry. In this paper, by studying the moduli space of the near horizon metric of five-dimensional extremal black holes which are asymptotically flat or AdS, we realize an SL(2, {\\mathbb Z} ) modular group which is a symmetry of the near horizon geometry. We show that there is a lattice of chiral CFT duals corresponding to the moduli points identified under the action of the modular group. The microscopic entropy corresponding to all such CFTs is equivalent and is in agreement with the Bekenstein-Hawking entropy.
Tunneling of massive vector particles from rotating charged black strings
NASA Astrophysics Data System (ADS)
Jusufi, Kimet; Övgün, Ali
2016-07-01
We study the quantum tunneling of charged massive vector bosons from a charged static and a rotating black string. We apply the standard methods, first we use the WKB approximation and the Hamilton-Jacobi equation, and then we end up with a set of four linear equations. Finally, solving for the radial part by using the determinant of the metric equals zero, the corresponding tunneling rate and the Hawking temperature is recovered in both cases. The tunneling rate deviates from pure thermality and is consistent with an underlying unitary theory.
Structure of the singularity inside a realistic rotating black hole
NASA Astrophysics Data System (ADS)
Ori, Amos
1992-04-01
The structure and results of an analysis of the asymptotic behavior of nonlinear, asymmetric, metric perturbations near the Cauchy horizon inside a Kerr black hole are presented. This analysis suggests that metric perturbations, to all orders in the perturbation expansion, are finite and small at the Cauchy horizon, even though their gradients (and the curvature) diverge there. Accordingly, objects which fall into a realistic rotating blackhole a longtime after the collapse will not be crushed by a tidal gravitational deformations as they approach the curvature singularity.
Accretion of radiation and rotating primordial black holes
NASA Astrophysics Data System (ADS)
Mahapatra, S.; Nayak, B.
2016-02-01
We consider rotating primordial black holes (PBHs) and study the effect of accretion of radiation in the radiation-dominated era. The central part of our analysis deals with the role of the angular momentum parameter on the evolution of PBHs. We find that both the accretion and evaporation rates decrease with an increase in the angular momentum parameter, but the rate of evaporation decreases more rapidly than the rate of accretion. This shows that the evaporation time of PBHs is prolonged with an increase in the angular momentum parameter. We also note that the lifetime of rotating PBHs increases with an increase in the accretion efficiency of radiation as in the case of nonrotating PBHs.
Joint Evolution of Spinning Supermassive Black Holes and Rotating Nuclei
NASA Astrophysics Data System (ADS)
Merritt, David; Vasiliev, Eugene
2015-01-01
A rotating supermassive black hole (SBH) interacts with stars in a galactic nucleus via torques due to dragging of inertial frames. If the stars orbit preferentially about an axis that is misaligned with the SBH's spin, the SBH will experience a net torque and its spin vector will precess; individual stellar orbits also precess about the instantaneous SBH spin vector, although at different rates depending on their orbital elements. Solution of the coupled, post-Newtonian equations describing this interaction reveals two evolutionary modes: sustained precession of the SBH; and damped precession, leading to alignment of the SBH spin with the nuclear angular momentum. Beyond a certain radius, stars interact gravitationally with each other in a time shorter than the Lense-Thirring time. Long-term evolution in this case is well described as uniform precession of the SBH about the cluster's rotational axis, with a stochastic contribution due to star-star interactions.
Relativistic Collapse of Rotating Supermassive Stars to Supermassive Black Holes
NASA Astrophysics Data System (ADS)
Shapiro, Stuart L.
2003-10-01
There is compelling evidence that supermassive black holes (SMBHs) exist. Yet the origin of these objects, or their seeds, is still unknown. We are performing general relativistic simulations of gravitational collapse to black holes in different scenarios to help reveal how SMBH seeds might arise in the universe. SMBHs with ~ 109 Msolar must have formed by z > 6, or within 109 yrs after the Big Bang, to power quasars. It may be difficult for gas accretion to build up such a SMBH by this time unless the initial seed black hole already has a substantial mass. One plausible progenitor of a massive seed black hole is a supermassive star (SMS). We have followed the collapse of a SMS to a SMBH by means of 3D hydrodynamic simulations in post-Newtonian gravity and axisymmetric simulations in full general relativity. The initial SMS of arbitrary mass M in these simulations rotates uniformly at the mass-shedding limit and is marginally unstable to radial collapse. The final black hole mass and spin are determined to be Mh/M ~ 0.9 and Jh/Mh2 ~ 0.75. The remaining mass goes into a disk of mass Mdisk/M ~ 0.1. This disk arises even though the total spin of the progenitor star, J/M2 = 0.97, is safely below the Kerr limit. The collapse generates a mild burst gravitational radiation. Nonaxisymmetric bars or one-armed spirals may arise during the quasi-stationary evolution of a SMS, during its collapse, or in the ambient disk about the hole, and are potential sources of quasi-periodic waves, detectable by LISA.
Collapse of differentially rotating supermassive stars: Post black hole formation
Saijo, Motoyuki; Hawke, Ian
2009-09-15
We investigate the collapse of differentially rotating supermassive stars (SMSs) by means of 3+1 hydrodynamic simulations in general relativity. We particularly focus on the onset of collapse to understand the final outcome of collapsing SMSs. We find that the estimated ratio of the mass between the black hole and the surrounding disk from the equilibrium star is roughly the same as the results from numerical simulation. This suggests that the picture of axisymmetric collapse is adequate, in the absence of nonaxisymmetric instabilities, to illustrate the final state of the collapse. We also find that quasiperiodic gravitational waves continue to be emitted after the quasinormal mode frequency has decayed. We furthermore have found that when the newly formed black hole is almost extreme Kerr, the amplitude of the quasiperiodic oscillation is enhanced during the late stages of the evolution. Geometrical features, shock waves, and instabilities of the fluid are suggested as a cause of this amplification behavior. This alternative scenario for the collapse of differentially rotating SMSs might be observable by the Laser Interferometer Space Antenna.
Instability and new phases of higher-dimensional rotating black holes
Dias, Oscar J. C.; Monteiro, Ricardo; Santos, Jorge E.; Figueras, Pau; Emparan, Roberto
2009-12-01
It has been conjectured that higher-dimensional rotating black holes become unstable at a sufficiently large value of the rotation, and that new black holes with pinched horizons appear at the threshold of the instability. We search numerically and find the stationary axisymmetric perturbations of Myers-Perry black holes with a single spin that mark the onset of the instability and the appearance of the new black hole phases. We also find new ultraspinning Gregory-Laflamme instabilities of rotating black strings and branes.
Rotating (A)dS black holes in bigravity
NASA Astrophysics Data System (ADS)
Ayón-Beato, Eloy; Higuita-Borja, Daniel; Méndez-Zavaleta, Julio A.
2016-01-01
In this paper we explore the advantage of using the Kerr-Schild Ansatz in the search for analytic configurations to bigravity. It turns out that it plays a crucial role by providing means to straightforwardly calculate the square root matrix encoding the interaction terms between both gravities. In this spirit, we rederive the Babichev-Fabbri family of asymptotically flat rotating black holes with the aid of an emerging circularity theorem. Taking into account that the interaction terms contain by default two cosmological constants, we repeat our approach starting from the more natural seeds for the Kerr-Schild Ansatz in this context: the (A)dS spacetimes. As a result, we show that a couple of Kerr-(A)dS black holes constitute an exact solution to ghost-free bigravity. Similar to the asymptotically flat case, these black holes share the same angular momentum and (A)dS radius, but their masses are not constrained to be equal.
Accelerating black diholes and static black dirings
Teo, Edward
2006-01-15
We show how a recently discovered black-ring solution with a rotating 2-sphere can be turned into two new solutions of Einstein-Maxwell-dilaton theory. The first is a four-dimensional solution describing a pair of oppositely charged, extremal black holes--known as a black dihole--undergoing uniform acceleration. The second is a five-dimensional solution describing a pair of concentric, static extremal black rings carrying opposite dipole charges--a so-called black diring. The properties of both solutions, which turn out to be formally very similar, are analyzed in detail. We also present, in an appendix, an accelerating version of the Zipoy-Voorhees solution in four-dimensional Einstein gravity.
Non-conformal hydrodynamics in Einstein-dilaton theory
NASA Astrophysics Data System (ADS)
Kulkarni, Shailesh; Lee, Bum-Hoon; Park, Chanyong; Roychowdhury, Raju
2012-09-01
In the Einestein-dilaton theory with a Liouville potential parameterized by η, we find a Schwarzschild-type black hole solution. This black hole solution, whose asymptotic geometry is described by the warped metric, is thermodynamically stable only for 0 ≤ η < 2. Applying the gauge/gravity duality, we find that the dual gauge theory represents a non-conformal thermal system with the equation of state depending on η. After turning on the bulk vector fluctuations with and without a dilaton coupling, we calculate the charge diffusion constant, which indicates that the life time of the quasi normal mode decreases with η. Interestingly, the vector fluctuation with the dilaton coupling shows that the DC conductivity increases with temperature, a feature commonly found in electrolytes.
The missing asymptotic sector of rotating black-hole spectroscopy
NASA Astrophysics Data System (ADS)
Keshet, Uri; Ben-Meir, Arnon
2014-10-01
The rotation of a Kerr black hole splits its low-frequency spectrum in two, so it was so far unclear why the known highly-damped resonances show no splitting. We find the missing, split sector, with spin s quasinormal modes approaching the total reflection frequencies ω (n ∈ N) = - ΩΔJ - iκ (n - s), where Ω, κ and ΔJ are the horizon's angular velocity, surface gravity, and induced change in angular momentum. Surprisingly, the new sector is at least partly polar, and corresponds to reversible J transitions. Its fundamental branch converges quickly, possibly affecting gravitational wave signals. A simple interpretation of the Carter constant of motion is proposed.
High energy physics in the vicinity of rotating black holes
NASA Astrophysics Data System (ADS)
Grib, A. A.; Pavlov, Yu. V.
2015-10-01
We consider particle collisions in the vicinity of the horizon of rotating black holes. We show that the existence of geodesics for both massive and massless particles coming from inside the gravitational radius leads to different possibilities for an unboundedly high collision energy to appear in the center-of-mass frame of two particles. We give a classification of such geodesics in the general case based on a proved theorem for extremal spherical orbits. We analyze the case of the unbounded energy increase in the situation where one (critical) particle moves along the "white hole" geodesic with an angular momentum close to the bound while the other particle falls along an ordinary geodesic and the case of an unbounded negative angular momentum of the first particle.
Scaling symmetry and scalar hairy rotating AdS3 black holes
NASA Astrophysics Data System (ADS)
Ahn, Byoungjoon; Hyun, Seungjoon; Park, Sang-A.; Yi, Sang-Heon
2016-01-01
By using the scaling symmetry in the reduced action formalism, we derive the novel Smarr relation which holds even for the hairy rotating AdS3 black holes. Then, by using the Smarr relation we argue that the hairy rotating AdS3 black holes are stable thermodynamically, compared to the nonhairy ones.
Hawking radiation of scalar particles from accelerating and rotating black holes
Gillani, Usman A.; Rehman, Mudassar; Saifullah, K. E-mail: mudassar051@yahoo.com
2011-06-01
Hawking radiation of uncharged and charged scalar particles from accelerating and rotating black holes is studied. We calculate the tunneling probabilities of these particles from the rotation and acceleration horizons of these black holes. Using this method we recover the correct Hawking temperature as well.
Quasars: a supermassive rotating toroidal black hole interpretation
NASA Astrophysics Data System (ADS)
Spivey, R. J.
2000-08-01
A supermassive rotating toroidal black hole (TBH) is proposed as the fundamental structure of quasars and other jet-producing active galactic nuclei. Rotating protogalaxies gather matter from the central gaseous region leading to the birth of massive toroidal stars, the internal nuclear reactions of which proceed very rapidly. Once the nuclear fuel is spent, gravitational collapse produces a slender ring-shaped TBH remnant. Transitory electron and neutron degeneracy stabilized collapse phases, although possible, are unlikely owing to the large masses involved thus these events are typically the first supernovae of the host galaxies. Given time, the TBH mass increases through continued accretion by several orders of magnitude, the event horizon swells whilst the central aperture shrinks. The difference in angular velocities between the accreting matter and the TBH induces a magnetic field that is strongest in the region of the central aperture and innermost ergoregion. Owing to the presence of negative energy states when such a gravitational vortex is immersed in an electromagnetic field, circumstances are near ideal for energy extraction via non-thermal radiation including the Penrose process and superradiant scattering. This establishes a self-sustaining mechanism whereby the transport of angular momentum away from the quasar by relativistic bi-directional jets reinforces both the modulating magnetic field and the TBH/accretion disc angular velocity differential. Continued mass-capture by the TBH results in contraction of the central aperture until the TBH topology transitions to being spheroidal, extinguishing quasar behaviour. Similar mechanisms may be operating in microquasars, supernovae and sources of repeating gamma-ray bursts when neutron density or black hole tori arise. Long-term TBH stability seems to require either a negative cosmological constant, a non-stationary space-time resulting from the presence of accreting matter or the intervention of quantum
ROTATING ACCRETION FLOWS: FROM INFINITY TO THE BLACK HOLE
Li, Jason; Ostriker, Jeremiah; Sunyaev, Rashid
2013-04-20
Accretion onto a supermassive black hole of a rotating inflow is a particularly difficult problem to study because of the wide range of length scales involved. There have been broadly utilized analytic and numerical treatments of the global properties of accretion flows, but detailed numerical simulations are required to address certain critical aspects. We use the ZEUS code to run hydrodynamical simulations of rotating, axisymmetric accretion flows with Bremsstrahlung cooling, considering solutions for which the centrifugal balance radius significantly exceeds the Schwarzschild radius, with and without viscous angular momentum transport. Infalling gas is followed from well beyond the Bondi radius down to the vicinity of the black hole. We produce a continuum of solutions with respect to the single parameter M-dot{sub B}/ M-dot{sub Edd}, and there is a sharp transition between two general classes of solutions at an Eddington ratio of M-dot{sub B}/M-dot{sub Edd}{approx}few Multiplication-Sign 10{sup -2}. Our high inflow solutions are very similar to the standard Shakura and Sunyaev results. But our low inflow results are to zeroth order the stationary Papaloizou and Pringle solution, which has no accretion. To next order in the small, assumed viscosity they show circulation, with disk and conical wind outflows almost balancing inflow. These solutions are characterized by hot, vertically extended disks, and net accretion proceeds at an extremely low rate, only of order {alpha} times the inflow rate. Our simulations have converged with respect to spatial resolution and temporal duration, and they do not depend strongly on our choice of boundary conditions.
Lifespan of rotating black hole in the frame of generalized uncertainty principle
NASA Astrophysics Data System (ADS)
He, Tangmei; Zhang, Jingyi; Yang, Jinbo; Tan, Hongwei
2016-01-01
In this paper, the lifespan under the generalized uncertainty principle (GUP) of rotating black hole is derived through the corrected radiation energy flux and the first law of the thermodynamics of black hole. The radiation energy flux indicates that there exist the highest temperature and the minimum mass both of which are relevant to the initial mass of the black hole in the final stage of the radiation. The lifespan of rotating black hole includes three terms: the dominant term is just the lifespan in the flat spacetime; the other two terms are individually induced by the rotation and the GUP.
Estimation of the mass outflow rates around rotating black holes
NASA Astrophysics Data System (ADS)
Aktar, Ramiz; Das, Santabrata
We consider steady, advective, rotating, inviscid accretion disc around the spinning black holes to compute the mass outflow rate (R_{dot{m}}) defined as the ratio of mass flux of outflowing to the inflowing matter. Due to centrifugal barrier, accreting matter suffers discontinuous shock transition and because of shock compression, the post-shock matter becomes hot and denser than the pre-shock matter. We call the post-shock disc as Post Shock Corona (PSC). During accretion, a part of the inflowing matter deflects as bipolar outflows due to the presence of excess thermal gradient force at PSC. We find that R_{dot{m}}is directly correlated with the spin of the black hole (a_{k}) for the same set of inflow parameter, namely specific energy (E) and specific angular momentum (λ). We observe that the maximum outflow rate(R_{dot{m}}^{max}) weakly depends on spin (a_{k}) that lies in the range˜ 17% - 18% of the inflow rate.
Adiabatic growth of a black hole in a rotating stellar system
NASA Technical Reports Server (NTRS)
Lee, Man Hoi; Goodman, Jeremy
1989-01-01
The consequences of slowly adding a massive black hole to the center of a rotating stellar system are considered. Although both the rotation velocity V and the velocity dispersion sigma increase when the black hole is added, the rotation velocity increases faster. The effect goes in the right direction but is too gradual to explain the V/sigma profiles recently observed in several galactic nuclei.
Where are the BTZ black hole degrees of freedom? The rotating case
NASA Astrophysics Data System (ADS)
Mitchell, Joseph M.
2016-07-01
Recent work has shown that the entropy of the non-rotating BTZ black hole can be derived from a dual conformal description at any spatial location. In this followup it is shown that a dual conformal description exists at any spatial location for the rotating BTZ black hole as well. As in the non-rotating case, two copies of the central charge {c}+/- =3{\\ell }/2G are recovered and the microcanonical Cardy formula yields the correct Bekenstein–Hawking entropy.
Trace anomaly of dilaton-coupled scalars in two dimensions
NASA Astrophysics Data System (ADS)
Bousso, Raphael; Hawking, Stephen
1997-12-01
Conformal scalar fields coupled to the dilaton appear naturally in two-dimensional models of black hole evaporation. We show that their trace anomaly is (1/24π)[R-6(∇φ)2-2□φ]. It follows that a Russo-Susskind-Thorlacius-type counterterm appears naturally in the one-loop effective action.
Powerful, Rotating Disk Winds from Stellar-mass Black Holes
NASA Astrophysics Data System (ADS)
Miller, J. M.; Fabian, A. C.; Kaastra, J.; Kallman, T.; King, A. L.; Proga, D.; Raymond, J.; Reynolds, C. S.
2015-12-01
We present an analysis of ionized X-ray disk winds found in the Fe K band of four stellar-mass black holes observed with Chandra, including 4U 1630-47, GRO J1655-40, H 1743-322, and GRS 1915+105. High-resolution photoionization grids were generated in order to model the data. Third-order gratings spectra were used to resolve complex absorption profiles into atomic effects and multiple velocity components. The Fe xxv line is found to be shaped by contributions from the intercombination line (in absorption), and the Fe xxvi line is detected as a spin-orbit doublet. The data require 2-3 absorption zones, depending on the source. The fastest components have velocities approaching or exceeding 0.01c, increasing mass outflow rates and wind kinetic power by orders of magnitude over prior single-zone models. The first-order spectra require re-emission from the wind, broadened by a degree that is loosely consistent with Keplerian orbital velocities at the photoionization radius. This suggests that disk winds are rotating with the orbital velocity of the underlying disk, and provides a new means of estimating launching radii—crucial to understanding wind driving mechanisms. Some aspects of the wind velocities and radii correspond well to the broad-line region in active galactic nuclei (AGNs), suggesting a physical connection. We discuss these results in terms of prevalent models for disk wind production and disk accretion itself, and implications for massive black holes in AGNs.
BlackMax: A black-hole event generator with rotation, recoil, split branes, and brane tension
Dai Dechang; Starkman, Glenn; Stojkovic, Dejan; Issever, Cigdem; Tseng, Jeff; Rizvi, Eram
2008-04-01
We present a comprehensive black-hole event generator, BlackMax, which simulates the experimental signatures of microscopic and Planckian black-hole production and evolution at the LHC in the context of brane world models with low-scale quantum gravity. The generator is based on phenomenologically realistic models free of serious problems that plague low-scale gravity, thus offering more realistic predictions for hadron-hadron colliders. The generator includes all of the black-hole gray-body factors known to date and incorporates the effects of black-hole rotation, splitting between the fermions, nonzero brane tension, and black-hole recoil due to Hawking radiation (although not all simultaneously). The generator can be interfaced with Herwig and Pythia. The main code can be downloaded from http://www-pnp.physics.ox.ac.uk/{approx}issever/BlackMax/blackmax.html.
No hair theorem in quasi-dilaton massive gravity
NASA Astrophysics Data System (ADS)
Wu, De-Jun; Zhou, Shuang-Yong
2016-06-01
We investigate the static, spherically symmetric black hole solutions in the quasi-dilaton model and its generalizations, which are scalar extended dRGT massive gravity with a shift symmetry. We show that, unlike generic scalar extended massive gravity models, these theories do not admit static, spherically symmetric black hole solutions until the theory parameters in the dRGT potential are fine-tuned. When fine-tuned, the geometry of the static, spherically symmetric black hole is necessarily that of general relativity and the quasi-dilaton field is constant across the spacetime. The fine-tuning and the no hair theorem apply to black holes with flat, anti-de Sitter or de Sitter asymptotics.
Mirror effect induced by the dilaton field on the Hawking radiation
Maeda, Kengo; Okamura, Takashi
2006-11-03
A ''stringy particle'' action is naturally derived from Kaluza-Klein compactification of a test string action coupled to the dilaton field in a conformally invariant manner. According to the standard procedure, we perform the second quantization of the stringy particle. As an interesting application, we consider evaporation of a near-extremal dilatonic black hole by Hawking radiation via the stringy particles. We show that a mirror surface which reflects them is induced by the dilaton field outside the the horizon when the size of the black hole is comparable to the Planck scale. As a result, the energy flux does not propagate across the surface, and hence the evaporation of the dilatonic black hole stops just before the naked singularity at the extremal state appears even though the surface gravity is non-zero in the extremal limit.
General Nonextremal Rotating Black Holes in Minimal Five-Dimensional Gauged Supergravity
Chong, Z.-W.; Lue, H.; Pope, C.N.; Cvetic, M.
2005-10-14
We construct the general solution for nonextremal charged rotating black holes in five-dimensional minimal gauged supergravity. They are characterized by four nontrivial parameters: namely, the mass, the charge, and the two independent rotation parameters. The metrics in general describe regular rotating black holes, providing the parameters lie in appropriate ranges so that naked singularities and closed timelike curves (CTCs) are avoided. We calculate the conserved energy, angular momenta, and charge for the solutions, and show how supersymmetric solutions arise in a Bogomol'nyi-Prasad-Sommerfield limit. These have naked CTCs in general, but for special choices of the parameters we obtain new regular supersymmetric black holes or smooth topological solitons.
5D Einstein-Maxwell solitons and concentric rotating dipole black rings
Yazadjiev, Stoytcho S.
2008-09-15
We discuss the application of the solitonic techniques to the 5D Einstein-Maxwell gravity. As an illustration we construct a new exact solution describing two concentric rotating dipole black rings. The properties of the solution are investigated.
Floating and sinking: the imprint of massive scalars around rotating black holes.
Cardoso, Vitor; Chakrabarti, Sayan; Pani, Paolo; Berti, Emanuele; Gualtieri, Leonardo
2011-12-01
We study the coupling of massive scalar fields to matter in orbit around rotating black holes. It is generally expected that orbiting bodies will lose energy in gravitational waves, slowly inspiraling into the black hole. Instead, we show that the coupling of the field to matter leads to a surprising effect: because of superradiance, matter can hover into "floating orbits" for which the net gravitational energy loss at infinity is entirely provided by the black hole's rotational energy. Orbiting bodies remain floating until they extract sufficient angular momentum from the black hole, or until perturbations or nonlinear effects disrupt the orbit. For slowly rotating and nonrotating black holes floating orbits are unlikely to exist, but resonances at orbital frequencies corresponding to quasibound states of the scalar field can speed up the inspiral, so that the orbiting body sinks. These effects could be a smoking gun of deviations from general relativity. PMID:22242985
Hawking radiation of spin-1 particles from a three-dimensional rotating hairy black hole
Sakalli, I.; Ovgun, A.
2015-09-15
We study the Hawking radiation of spin-1 particles (so-called vector particles) from a three-dimensional rotating black hole with scalar hair using a Hamilton–Jacobi ansatz. Using the Proca equation in the WKB approximation, we obtain the tunneling spectrum of vector particles. We recover the standard Hawking temperature corresponding to the emission of these particles from a rotating black hole with scalar hair.
Hawking radiation of spin-1 particles from a three-dimensional rotating hairy black hole
NASA Astrophysics Data System (ADS)
Sakalli, I.; Ovgun, A.
2015-09-01
We study the Hawking radiation of spin-1 particles (so-called vector particles) from a three-dimensional rotating black hole with scalar hair using a Hamilton-Jacobi ansatz. Using the Proca equation in the WKB approximation, we obtain the tunneling spectrum of vector particles. We recover the standard Hawking temperature corresponding to the emission of these particles from a rotating black hole with scalar hair.
Faraday rotation of plasmas in the vicinity of a Schwarzschild black hole
NASA Astrophysics Data System (ADS)
Asenjo, Felipe; Bhattacharjee, Chinmoy; Mahajan, Swadesh
2015-11-01
The propagation of an electromagnetic wave in a multi-specie plasmas (ion-electron and ion-electron-positron), embedded in the gravitational field of a Schwarzschild black hole, is investigated with particular emphasis on studying the Faraday rotation (rotation of the phase angle of the right and left-handed components of wave). In order to appropriately deal with the strong gravitational field (affecting the plasma in the proximity of the black hole horizon), we employ Rindler coordinates in the 3 +1 decomposition of general relativity. The rather complex dispersion relation for high-frequency electromagnetic waves reveals the dependence of Faraday rotation on the number density of different constituents of the multi-specie plasma, the background magnetic field, and the mass of the black hole. Amongst other things, the expression for the Faraday rotation allows us to determine the black hole mass if the number density and magnetic field strength are estimated, and the rotation of the phase angle is measured. It is also shown how Faraday rotation could be harnessed to infer black hole features in a more complete theory that pertains, for example, to Kerr black holes. Different astrophysical implications are pointed out. Felipe Asenjo thanks CONICyT for funding No. 79130002.
Acceleration of particles as a universal property of rotating black holes
Zaslavskii, Oleg B.
2010-10-15
We argue that the possibility of having infinite energy in the center-of-mass frame of colliding particles is a generic property of rotating black holes. We suggest a general model-independent derivation valid for dirty black holes. The earlier observations for the Kerr or Kerr-Newman metrics are confirmed and generalized.
Fermions tunnelling from 5D general rotating charged Gödel black hole
NASA Astrophysics Data System (ADS)
Song, Shi-Xiong; Huang, Jiang; Ren, Ji-Rong
2011-01-01
Using the tunneling method we derive the Hawking temperature of the nonextremal rotating charged black hole in the Gödel universe of five-dimensional minimal supergravity theory found by Wu. We successfully recovered the tunneling probability of charged Dirac particles and the expected Hawking temperature of the black hole, which is exactly consistent with that obtained by other methods.
Energy loss of a heavy particle near 3D charged rotating hairy black hole
NASA Astrophysics Data System (ADS)
Naji, Jalil
2014-01-01
In this paper we consider a charged rotating black hole in three dimensions with a scalar charge and discuss the energy loss of a heavy particle moving near the black-hole horizon. We also study quasi-normal modes and find the dispersion relations. We find that the effect of scalar charge and electric charge increases the energy loss.
Doukas, Jason; Cho, H. T.; Cornell, A. S.; Naylor, Wade
2009-08-15
In this article we present results for tensor graviton modes (in seven dimensions and greater, n{>=}3) for gray-body factors of Kerr-de Sitter black holes and for Hawking radiation from simply rotating (n+4)-dimensional Kerr black holes. Although there is some subtlety with defining the Hawking temperature of a Kerr-de Sitter black hole, we present some preliminary results for emissions assuming the standard Hawking normalization and a Bousso-Hawking-like normalization.
Hawking radiation of scalars from accelerating and rotating black holes with NUT parameter
NASA Astrophysics Data System (ADS)
Jan, Khush; Gohar, H.
2014-03-01
We study the quantum tunneling of scalars from charged accelerating and rotating black hole with NUT parameter. For this purpose we use the charged Klein-Gordon equation. We apply WKB approximation and the Hamilton-Jacobi method to solve charged Klein-Gordon equation. We find the tunneling probability of outgoing charged scalars from the event horizon of this black hole, and hence the Hawking temperature for this black hole
Wu, Shuang-Qing
2008-03-28
I present the general exact solutions for nonextremal rotating charged black holes in the Gödel universe of five-dimensional minimal supergravity theory. They are uniquely characterized by four nontrivial parameters: namely, the mass m, the charge q, the Kerr equal rotation parameter a, and the Gödel parameter j. I calculate the conserved energy, angular momenta, and charge for the solutions and show that they completely satisfy the first law of black hole thermodynamics. I also study the symmetry and separability of the Hamilton-Jacobi and the massive Klein-Gordon equations in these Einstein-Maxwell-Chern-Simons-Gödel black hole backgrounds. PMID:18517852
NASA Astrophysics Data System (ADS)
Wu, Shuang-Qing
2008-03-01
I present the general exact solutions for nonextremal rotating charged black holes in the Gödel universe of five-dimensional minimal supergravity theory. They are uniquely characterized by four nontrivial parameters: namely, the mass m, the charge q, the Kerr equal rotation parameter a, and the Gödel parameter j. I calculate the conserved energy, angular momenta, and charge for the solutions and show that they completely satisfy the first law of black hole thermodynamics. I also study the symmetry and separability of the Hamilton-Jacobi and the massive Klein-Gordon equations in these Einstein-Maxwell-Chern-Simons-Gödel black hole backgrounds.
NASA Astrophysics Data System (ADS)
Shibata, Masaru; Shapiro, Stuart L.
2002-06-01
We follow the collapse in axisymmetry of a uniformly rotating, supermassive star (SMS) to a supermassive black hole in full general relativity. The initial SMS of arbitrary mass M is marginally unstable to radial collapse and rotates at the mass-shedding limit. The collapse proceeds homologously early on and results in the appearance of an apparent horizon at the center. Although our integration terminates before final equilibrium is achieved, we determine that the final black hole will contain about 90% of the total mass of the system and will have a spin parameter J/M2~0.75. The remaining gas forms a rotating disk about the nascent hole.
Causal extraction of black hole rotational energy by various kinds of electromagnetic fields
Koide, Shinji; Baba, Tamon
2014-09-10
Recent general relativistic magnetohydrodynamics (MHD) simulations have suggested that relativistic jets from active galactic nuclei (AGNs) have been powered by the rotational energy of central black holes. Some mechanisms for extraction of black hole rotational energy have been proposed, like the Penrose process, Blandford-Znajek mechanism, MHD Penrose process, and superradiance. The Blandford-Znajek mechanism is the most promising mechanism for the engines of the relativistic jets from AGNs. However, an intuitive interpretation of this mechanism with causality is not yet clarified, while the Penrose process has a clear interpretation for causal energy extraction from a black hole with negative energy. In this paper, we present a formula to build physical intuition so that in the Blandford-Znajek mechanism, as well as in other electromagnetic processes, negative electromagnetic energy plays an important role in causal extraction of the rotational energy of black holes.
The Klein-Gordon equation of a rotating charged hairy black hole in (2 + 1) dimensions
NASA Astrophysics Data System (ADS)
Pourhassan, B.
2016-03-01
In this paper, we consider the Klein-Gordon equation in a 3D charged rotating hairy black hole background to study behavior of a massive scalar field. In the general case, we find periodic-like behavior for the scalar field which may vanish at the black hole horizon or far from the black hole horizon. For the special cases of non-rotating or near horizon approximation, we find radial solution of Klein-Gordon equation in terms of hypergeometric and Kummer functions. Also for the case of uncharged black hole, we find numerical solution of the Klein-Gordon equation as periodic function which may enhance out of the black hole or vanish at horizon. We find allowed boundary conditions which may yield to the identical bosons described by scalar field.
NASA Astrophysics Data System (ADS)
Shapiro, Stuart L.; Shibata, Masaru
2002-10-01
The collapse of a uniformly rotating, supermassive star (SMS) to a supermassive black hole (SMBH) has been followed recently by means of hydrodynamic simulations in full general relativity. The initial SMS of arbitrary mass M in these simulations rotates uniformly at the mass-shedding limit and is marginally unstable to radial collapse. The final black hole mass and spin have been determined to be Mh/M~0.9 and Jh/M2h~0.75. The remaining mass goes into a disk of mass Mdisk/M~0.1. Here we show that these black hole and disk parameters can be calculated analytically from the initial stellar density and angular momentum distribution. The analytic calculation thereby corroborates and provides a simple physical explanation for the computational discovery that SMS collapse inevitably terminates in the simultaneous formation of a SMBH and a rather substantial ambient disk. This disk arises even though the total spin of the progenitor star, J/M2=0.97, is safely below the Kerr limit. The calculation performed here applies to any marginally unstable n=3 polytrope uniformly rotating at the breakup speed, independent of stellar mass or the source of internal pressure. It illustrates how the black hole and disk parameters can be determined for the collapse of other types of stars with different initial density and rotation profiles.
Horizon structure and shadow of rotating Einstein-Born-Infeld black holes
NASA Astrophysics Data System (ADS)
Atamurotov, Farruh
2016-07-01
We investigate the horizon structure of the rotating Einstein-Born-Infeld solution which goes over to the Einstein-Maxwell's Kerr-Newman solution as the Born-Infeld parameter goes to innity ( ! 1). We nd that for a given , mass M and charge Q, there exist critical spinning parameter aE and rEH, which corresponds to an extremal Einstein-Born-Infeld black hole with degenerate horizons, and aE decreases and rEH increases with increase in the Born-Infeld parameter . While a < aE describe a non-extremal Einstein-Born- Infeld black hole with outer and inner horizons. Similarly, the effect of on innite redshift surface and in turn on ergoregion is also included. It is well known that a black hole can cast a shadow as an optical appearance due to its strong gravitational eld. We also investigate the shadow cast by the rotating Einstein- Born-Infeld black hole and demonstrate that the null geodesic equations can be integrated that allows us to investigate the shadow cast by a black hole which is found to be a dark zone covered by a circle. Interestingly, the shadows of Einstein-Born-Infeld black hole is slightly smaller than for the Reissner-Nordstrom black hole which are concentric circles, for different values of the Born-Infeld parameter , whose radius decreases with increase in the value of parameter . The shadows for the rotating Einstein-Born-Infeld solution are also included.
Radionic nonuniform black strings
NASA Astrophysics Data System (ADS)
Tamaki, Takashi; Kanno, Sugumi; Soda, Jiro
2004-01-01
Nonuniform black strings in the two-brane system are investigated using the effective action approach. It is shown that the radion acts as a nontrivial hair of the black strings. From the brane point of view, the black string appears as the deformed dilatonic black hole which becomes a dilatonic black hole in the single brane limit and reduces to the Reissner-Nordström black hole in the close limit of two-branes. The stability of solutions is demonstrated using catastrophe theory. From the bulk point of view, the black strings are proved to be nonuniform. Nevertheless, the zeroth law of black hole thermodynamics still holds.
The quantum emission spectra of rapidly-rotating Kerr black holes: Discrete or continuous?
NASA Astrophysics Data System (ADS)
Hod, Shahar
2015-10-01
Bekenstein and Mukhanov (BM) have suggested that, in a quantum theory of gravity, black holes may have discrete emission spectra. Using the time-energy uncertainty principle they have also shown that, for a (non-rotating) Schwarzschild black hole, the natural broadening δω of the black-hole emission lines is expected to be small on the scale set by the characteristic frequency spacing Δω of the spectral lines: ζSch ≡ δω / Δω ≪ 1. BM have therefore concluded that the expected discrete emission lines of the quantized Schwarzschild black hole are unlikely to overlap. In this paper we calculate the characteristic dimensionless ratio ζ (a bar) ≡ δω / Δω for the predicted BM emission spectra of rapidly-rotating Kerr black holes (here a bar ≡ J /M2 is the dimensionless angular momentum of the black hole). It is shown that ζ (a bar) is an increasing function of the black-hole angular momentum. In particular, we find that the quantum emission lines of Kerr black holes in the regime a bar ≳ 0.9 are characterized by the dimensionless ratio ζ (a bar) ≳ 1 and are therefore effectively blended together. Our results thus suggest that, even if the underlying mass (energy) spectrum of these rapidly-rotating Kerr black holes is fundamentally discrete as suggested by Bekenstein and Mukhanov, the natural broadening phenomenon (associated with the time-energy uncertainty principle) is expected to smear the black-hole radiation spectrum into a continuum.
Entropy bound of horizons for accelerating, rotating and charged Plebanski-Demianski black hole
NASA Astrophysics Data System (ADS)
Debnath, Ujjal
2016-09-01
We first review the accelerating, rotating and charged Plebanski-Demianski (PD) black hole, which includes the Kerr-Newman rotating black hole and the Taub-NUT spacetime. The main feature of this black hole is that it has 4 horizons like event horizon, Cauchy horizon and two accelerating horizons. In the non-extremal case, the surface area, entropy, surface gravity, temperature, angular velocity, Komar energy and irreducible mass on the event horizon and Cauchy horizon are presented for PD black hole. The entropy product, temperature product, Komar energy product and irreducible mass product have been found for event horizon and Cauchy horizon. Also their sums are found for both horizons. All these relations are dependent on the mass of the PD black hole and other parameters. So all the products are not universal for PD black hole. The entropy and area bounds for two horizons have been investigated. Also we found the Christodoulou-Ruffini mass for extremal PD black hole. Finally, using first law of thermodynamics, we also found the Smarr relation for PD black hole.
Rotating black holes in a draining bathtub: Superradiant scattering of gravity waves
NASA Astrophysics Data System (ADS)
Richartz, Maurício; Prain, Angus; Liberati, Stefano; Weinfurtner, Silke
2015-06-01
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.
Holographic conductivity for logarithmic charged dilaton-Lifshitz solutions
NASA Astrophysics Data System (ADS)
Dehyadegari, A.; Sheykhi, A.; Kord Zangeneh, M.
2016-07-01
We disclose the effects of the logarithmic nonlinear electrodynamics on the holographic conductivity of Lifshitz dilaton black holes/branes. We analyze thermodynamics of these solutions as a necessary requirement for applying gauge/gravity duality, by calculating conserved and thermodynamic quantities such as the temperature, entropy, electric potential and mass of the black holes/branes. We calculate the holographic conductivity for a (2 + 1)-dimensional brane boundary and study its behavior in terms of the frequency per temperature. Interestingly enough, we find out that, in contrast to the Lifshitz-Maxwell-dilaton black branes which have conductivity for all z, here in the presence of nonlinear gauge field, the holographic conductivity does exist provided z ≤ 3 and vanishes for z > 3. It is shown that independent of the nonlinear parameter β, the real part of the conductivity is the same for a specific value of frequency per temperature in both AdS and Lifshitz cases. Besides, the behavior of real part of conductivity for large frequencies has a positive slope with respect to large frequencies for a system with Lifshitz symmetry whereas it tends to a constant for a system with AdS symmetry. This behavior may be interpreted as existence of an additional charge carrier rather than the AdS case, and is due to the presence of the scalar dilaton field in model. Similar behavior for optical conductivity of single-layer graphene induced by mild oxygen plasma exposure has been reported.
Black branes as piezoelectrics.
Armas, Jay; Gath, Jakob; Obers, Niels A
2012-12-14
We find a realization of linear electroelasticity theory in gravitational physics by uncovering a new response coefficient of charged black branes, exhibiting their piezoelectric behavior. Taking charged dilatonic black strings as an example and using the blackfold approach we measure their elastic and piezolectric moduli. We also use our results to draw predictions about the equilibrium condition of charged dilatonic black rings in dimensions higher than six. PMID:23368298
FAST TRACK COMMUNICATION Single-charge rotating black holes in four-dimensional gauged supergravity
NASA Astrophysics Data System (ADS)
Chow, David D. K.
2011-02-01
We consider four-dimensional U(1)4 gauged supergravity, and obtain asymptotically AdS4, non-extremal, charged, rotating black holes with one non-zero U(1) charge. The thermodynamic quantities are computed. We obtain a generalization that includes a NUT parameter. The general solution has a discrete symmetry involving inversion of the rotation parameter, and has a string frame metric that admits a rank-2 Killing-Stäckel tensor.
Rotating black holes in a Randall-Sundrum brane with a cosmological constant
NASA Astrophysics Data System (ADS)
Neves, J. C. S.; Molina, C.
2012-12-01
In this work we have constructed axially symmetric vacuum solutions of the gravitational field equations in a Randall-Sundrum brane. A non-null effective cosmological constant is considered, and asymptotically de Sitter and anti-de Sitter spacetimes are obtained. The solutions describe rotating black holes in a four-dimensional brane. Optical features of the solutions are treated, emphasizing the rotation of the polarization vector along null congruences.
Rotating Kaluza-Klein multi-black holes with Goedel parameter
Matsuno, Ken; Ishihara, Hideki; Nakagawa, Toshiharu; Tomizawa, Shinya
2008-09-15
We obtain new five-dimensional supersymmetric rotating multi-Kaluza-Klein black hole solutions with the Goedel parameter in the Einstein-Maxwell system with a Chern-Simons term. These solutions have no closed timelike curve outside the black hole horizons. At infinity, the space-time is effectively four-dimensional. Each horizon admits various lens space topologies L(n;1)=S{sup 3}/Z{sub n} in addition to a round S{sup 3}. The space-time can have outer ergoregions disjointed from the black hole horizons, as well as inner ergoregions attached to each horizon. We discuss the rich structures of ergoregions.
Supersymmetry in the spacetime of higher-dimensional rotating black holes
Ahmedov, Haji; Aliev, Alikram N.
2009-04-15
General higher-dimensional rotating black hole spacetimes of any dimensions admit the Killing and Killing-Yano tensors, which generate the hidden symmetries just as in four-dimensional Kerr spacetime. We study these properties of the black holes using the formalism of supersymmetric mechanics of pseudoclassical spinning point particles. We present two nontrivial supercharges, corresponding to the Killing-Yano and conformal Killing-Yano tensors of the second rank. We demonstrate that an unusual extended Poisson-Dirac algebra of these supercharges results in two independent Killing tensors in spacetime dimensions D{>=}6, giving explicit examples for the Myers-Perry black holes in D=6 dimensions.
Equatorial gravitational lensing by accelerating and rotating black hole with NUT parameter
NASA Astrophysics Data System (ADS)
Sharif, M.; Iftikhar, Sehrish
2016-01-01
This paper is devoted to study equatorial gravitational lensing in accelerating and rotating black hole with a NUT parameter in the strong field limit. For this purpose, we first calculate null geodesic equation using the Hamilton-Jacobi separation method. We then numerically obtain deflection angle and deflection coefficients which depend on acceleration and spin parameter of the black hole. We also investigate observables in the strong field limit by taking the example of a black hole in the center of galaxy. It is concluded that acceleration parameter has a significant effect on the strong field lensing in the equatorial plane.
Supersymmetric rotating black hole spacetime tested by geodesics
NASA Astrophysics Data System (ADS)
Diemer, Valeria; Kunz, Jutta
2014-04-01
We present the complete analytical solution of the geodesics equations in the supersymmetric [Breckenridge-Myers-Peet-Vafa (BMPV)] spacetime J. C. Breckenridge et al. Phys. Lett. B 391, 93 (1997). We study systematically the properties of massive and massless test particle motion. We analyze the trajectories with analytical methods based on the theory of elliptic functions. Since the nature of the effective potential depends strongly on the rotation parameter ω, one has to distinguish between the under-rotating case, the critical case, and the over-rotating case, as discussed by Gibbons and Herdeiro in their pioneering study G. W. Gibbons and C. A. R. Herdeiro, Classical Quantum Gravity 16, 3619 (1999). We discuss various properties that distinguish this spacetime from the classical relativistic spacetimes like Schwarzschild, Reissner-Nordström, Kerr, or Myers-Perry. The over-rotating BMPV spacetime allows, for instance, for planetary bound orbits for massive and massless particles. We also address causality violation, as analyzed in G. W. Gibbons and C. A. R. Herdeiro, Classical Quantum Gravity 16, 3619 (1999).
Vector potential and metric perturbations of a rotating black hole
NASA Technical Reports Server (NTRS)
Chrzanowski, P. L.
1975-01-01
The assumption of factorized Green's functions together with the inhomogeneous Teukolsky equations are used to derive analytic expressions for homogeneous metric (and vector potential) perturbations of a Kerr black hole. These homogeneous solutions are used to construct solutions to the perturbation equations when sources are present. What one finds are particularly simple formulas for the energy and angular momentum flux in the asymptotic regions at plus or minus infinity.-
Comparing initial data for rapidly rotating, merging black holes
NASA Astrophysics Data System (ADS)
Khan, Haroon; SXS Collaboration
2015-04-01
Detecting gravitational waves (ripples of curved spacetime) requires accurate predictions of the expected waveforms. Only numerical simulations can predict the waveforms near the time of merger, because then all analytical approximations fail. These numerical simulations must begin with initial data that satisfy the Einstein constraint equations while yielding a pair of merging black holes of the desired physical configuration. Different methods of constructing initial data yield physically different systems, which lead to different initial bursts of spurious ``junk'' gravitational radiation as the system relaxes to equilibrium. By extending work by to the case of rapidly spinning black holes, I am using the Spectral Einstein Code (SpEC) to test whether such physically different initial data are nevertheless astrophysically equivalent (i.e., whether the waveforms agree after the initial relaxation). Specifically, extending the work of, I am using two different initial data methods to simulate merging black holes with equal masses and equal spins aligned with the orbital angular momentum of the system.
Horizon structure of rotating Einstein-Born-Infeld black holes and shadow
NASA Astrophysics Data System (ADS)
Atamurotov, Farruh; Ghosh, Sushant G.; Ahmedov, Bobomurat
2016-05-01
We investigate the horizon structure of the rotating Einstein-Born-Infeld solution which goes over to the Einstein-Maxwell's Kerr-Newman solution as the Born-Infeld parameter goes to infinity (β → ∞). We find that for a given β , mass M, and charge Q, there exist a critical spinning parameter aE and rHE, which corresponds to an extremal Einstein-Born-Infeld black hole with degenerate horizons, and aE decreases and rHE increases with increase of the Born-Infeld parameter β , while a
NASA Astrophysics Data System (ADS)
Stein, Leo C.
2014-08-01
Rapidly rotating black holes are a prime arena for understanding corrections to Einstein's theory of general relativity (GR). We construct solutions for rapidly rotating black holes in dynamical Chern-Simons (dCS) gravity, a useful and motivated example of a post-GR correction. We treat dCS as an effective theory and thus work in the decoupling limit, where we apply a perturbation scheme using the Kerr metric as the background solution. Using the solutions to the scalar field and the trace of the metric perturbation, we determine the regime of validity of our perturbative approach. We find that the maximal spin limit may be divergent, and the decoupling limit is strongly restricted for rapid rotation. Rapidly rotating stellar-mass black holes can potentially be used to place strong bounds on the coupling parameter ℓ of dCS. In order for the black hole observed in GRO J1655-40 to be within the decoupling limit, we need ℓ≲22 km, a value 7 orders of magnitude smaller than present Solar System bounds on dynamical Chern-Simons gravity.
Regular rotating de Sitter–Kerr black holes and solitons
NASA Astrophysics Data System (ADS)
Dymnikova, Irina; Galaktionov, Evgeny
2016-07-01
We study the basic generic properties of the class of regular rotating solutions asymptotically Kerr for a distant observer, obtained with using the Gürses–Gürsey algorithm from regular spherically symmetric solutions specified by {T}tt={T}rr which belong to the Kerr–Schild metrics. All regular solutions obtained with the Newman–Janis complex translation from the known spherical solutions, belong to this class. Spherical solutions with {T}tt={T}rr satisfying the weak energy condition (WEC), have obligatory de Sitter center. Rotation transforms the de Sitter center into the interior de Sitter vacuum disk. Regular de Sitter–Kerr solutions have at most two horizons and two ergospheres, and two different kinds of interiors. In the case when an original spherical solution satisfies the dominant energy condition, there can exist the interior de Sitter vacuum { S }-surface which contains the de Sitter disk as a bridge. The WEC is violated in the internal cavities between the { S }-surface and the disk, which are filled thus with a phantom fluid. In the case when a related spherical solution violates the dominant energy condition, vacuum interior of a rotating solution reduces to the de Sitter disk only.
The critical phenomena of charged rotating de Sitter black holes
NASA Astrophysics Data System (ADS)
Guo, Xiongying; Li, Huaifan; Zhang, Lichun; Zhao, Ren
2016-07-01
In this paper, we investigate the effective thermodynamic quantities in Kerr–Newman–de Sitter spacetime by considering the relations between the black hole event horizon and the cosmological event horizon. We find the effect of the critical point of Kerr–Newman–de Sitter spacetime for the different state parameters. We study the critical phenomena of the system taking different state parameters. This result is consistent with the nature of a liquid–gas phase transition at the critical point, hence deepening the understanding of the analogy of charged de Sitter spacetime and liquid–gas systems.
Absorption of massless scalar field by rotating black holes
NASA Astrophysics Data System (ADS)
Leite, Luiz C. S.; Crispino, Luís C. B.; de Oliveira, Ednilton S.; Macedo, Caio F. B.; Dolan, Sam R.
2016-07-01
We compute the absorption cross-section of the Kerr black holes (BH) for the massless scalar field, and present a selection of numerical results, to complement the results of Ref.[C. F. B. Macedo, L. C. S. Leite, E. S. Oliveria, S. R. Dolan and L. C. B. Crispino, Phys. Rev. D 88 (2013) 064033.] We show that, in the high-frequency regime, the cross-section approaches the geodesic capture cross-section. We split the absorption cross-section into corotating and counterrotating contributions, and we show that the counterrotating contribution exceeds the corotating one.
On the black hole limit of rotating discs of charged dust
NASA Astrophysics Data System (ADS)
Breithaupt, Martin; Liu, Yu-Chun; Meinel, Reinhard; Palenta, Stefan
2015-07-01
Investigating the rigidly rotating disc of dust with constant specific charge, we find that it leads to an extreme Kerr-Newman black hole in the ultra-relativistic limit. A necessary and sufficient condition for a black hole limit is, that the electric potential in the co-rotating frame is constant on the disc. In that case certain other relations follow. These relations are reviewed with a highly accurate post-Newtonian expansion. Remarkably it is possible to survey the leading order behaviour close to the black hole limit with the post-Newtonian expansion. We find that the disc solution close to that limit can be approximated very well by a ‘hyperextreme’ Kerr-Newman solution with the same gravitational mass, angular momentum and charge.
Thermodynamics and Hawking radiation of five-dimensional rotating charged Goedel black holes
Wu Shuangqing; Peng Junjin
2011-02-15
We study the thermodynamics of Goedel-type rotating charged black holes in five-dimensional minimal supergravity. These black holes exhibit some peculiar features such as the presence of closed timelike curves and the absence of a globally spatial-like Cauchy surface. We explicitly compute their energies, angular momenta, and electric charges that are consistent with the first law of thermodynamics. Besides, we extend the covariant anomaly cancellation method, as well as the approach of the effective action, to derive their Hawking fluxes. Both the methods of the anomaly cancellation and the effective action give the same Hawking fluxes as those from the Planck distribution for blackbody radiation in the background of the charged rotating Goedel black holes. Our results further support that Hawking radiation is a quantum phenomenon arising at the event horizon.
Statistical Entropy of Four-Dimensional Rotating Black Holes from Near-Horizon Geometry
Cvetic, M.; Larsen, F.; Cvetic, M.
1999-01-01
We show that a class of four-dimensional rotating black holes allow five-dimensional embeddings as black rotating strings. Their near-horizon geometry factorizes locally as a product of the three-dimensional anti{endash}de Sitter space-time and a two-dimensional sphere (AdS{sub 3}{times}S{sup 2} ), with angular momentum encoded in the global space-time structure. Following the observation that the isometries on the AdS{sub 3} space induce a two-dimensional (super)conformal field theory on the boundary, we reproduce the microscopic entropy with the correct dependence on the black hole angular momentum. {copyright} {ital 1999} {ital The American Physical Society }
Phenomenology of Rotating Extra-Dimensional Black Holes at Hadron Colliders
Frost, James A.
2010-02-10
Results are presented from CHARYBDIS2, a new Monte Carlo simulation of black hole production and decay at hadron colliders. The main new features of CHARYBDIS2 are a full treatment of the spin-down phase of the decay process using the angular and energy distributions of the associated Hawking radiation, improved modelling of the loss of angular momentum and energy in the production process as well as a wider range of options for the Planck-scale termination of the decay. The new features allow the study of the effects of black hole rotation and the feasibility of its observation. We present results, with emphasis on the consequences and experimental signatures of black hole rotation at the LHC. The effects of rotation are found to be large, with substantial changes to particle energies and distributions. Rotation persists throughout evaporation, invalidating the approximation of a rapid spin-down followed by isotropic emission in a non-rotating Schwarzschild phase. A selection of results are presented from the original article, arXiv:0904:0979.
Oscillating supertubes and neutral rotating black hole microstates
NASA Astrophysics Data System (ADS)
Mathur, Samir D.; Turton, David
2014-04-01
The construction of neutral black hole microstates is an important problem, with implications for the information paradox. In this paper we conjecture a construction of non-supersymmetric supergravity solutions describing D-brane configurations which carry mass and angular momentum, but no other conserved charges. We first study a classical string solution which locally carries dipole winding and momentum charges in two compact directions, but globally carries no net winding or momentum charge. We investigate its backreaction in the D1-D5 duality frame, where this object becomes a supertube which locally carries oscillating dipole D1-D5 and NS1-NS5 charges, and again carries no net charge. In the limit of an infinite straight supertube, we find an exact supergravity solution describing this object. We conjecture that a similar construction may be carried out based on a class of two-charge non-supersymmetric D1-D5 solutions. These results are a step towards demonstrating how neutral black hole microstates may be constructed in string theory.
The formation of supermassive black holes in rapidly rotating disks
NASA Astrophysics Data System (ADS)
Latif, M. A.; Schleicher, D. R. G.
2015-06-01
Massive primordial halos exposed to moderate UV backgrounds are the potential birthplaces of supermassive black holes. In these halos, an initially isothermal collapse will occur, leading to high accretion rates of ~0.1 M⊙ yr-1. During the collapse, the gas in the interior will turn into a molecular state, and will form accretion disk in order to conserve angular momentum. We consider here the structure of such an accretion disk and the role of viscous heating in the presence of high accretion rates for a central star of 10, 100, and 104 M⊙. Our results show that the temperature in the disk increases considerably due to viscous heating, leading to a transition from the molecular to the atomic cooling phase. We found that the atomic cooling regime may extend out to several 100 AU for a 104 M⊙ central star and that it provides substantial support to stabilize the disk. It therefore favors the formation of a massive central object. The comparison of clump migration and contraction time scales shows that stellar feedback from these clumps may occur during the later stages of the evolution. Overall, viscous heating provides an important pathway to obtain an atomic gas phase within the center of the halo, and helps in the formation of very massive objects. The massive object may collapse to form a massive black hole of about ≥104 M⊙.
Gravitational radiation and angular momentum flux from a slowly rotating dynamical black hole
Wu, Yu-Huei; Wang, Chih-Hung
2011-04-15
A four-dimensional asymptotic expansion scheme is used to study the next-order effects of the nonlinearity near a spinning dynamical black hole. The angular-momentum flux and energy flux formula are then obtained by constructing the reference frame in terms of the compatible constant spinors and the compatibility of the coupling leading-order Newman-Penrose equations. By using the slow rotation and small-tide approximation for a spinning black hole, the horizon cross-section we chose is spherical symmetric. It turns out the flux formula is rather simple and can be compared with the known results. Directly from the energy flux formula of the slow-rotating dynamical horizon, we find that the physically reasonable condition on requiring the positivity of the gravitational energy flux yields that the shear will monotonically decrease with time. Thus a slow-rotating dynamical horizon will asymptotically approach an isolated horizon during late time.
Renormalized vacuum polarization on rotating warped AdS3 black holes
NASA Astrophysics Data System (ADS)
Ferreira, Hugo R. C.; Louko, Jorma
2015-01-01
We compute the renormalized vacuum polarization of a massive scalar field in the Hartle-Hawking state on (2 +1 )-dimensional rotating, spacelike stretched black hole solutions to topologically massive gravity, surrounded by a Dirichlet mirror that makes the state well defined. The Feynman propagator is written as a mode sum on the complex Riemannian section of the spacetime, and a Hadamard renormalization procedure is implemented by matching to a mode sum on the complex Riemannian section of a rotating Minkowski spacetime. No analytic continuation in the angular momentum parameter is invoked. Selected numerical results are given, demonstrating the numerical efficacy of the method. We anticipate that this method can be extended to wider classes of rotating black hole spacetimes, in particular to the Kerr spacetime in four dimensions.
Intersecting nonextreme p-branes and linear dilaton background
Chen, C.-M.; Gal'tsov, Dmitri V.; Ohta, Nobuyoshi
2005-08-15
We construct the general static solution to the supergravity action containing gravity, the dilaton and a set of antisymmetric forms describing the intersecting branes delocalized in the relative transverse dimensions. The solution is obtained by reducing the system to a set of separate Liouville equations (the intersection rules implying the separability); it contains the maximal number of free parameters corresponding to the rank of the differential equations. Imposing the requirement of the absence of naked singularities, we show that the general configurations are restricted to two and only two classes: the usual asymptotically flat intersecting branes, and the intersecting branes some of which are asymptotically flat and some approach the linear dilaton background at infinity. In both cases the configurations are black. These are supposed to be relevant for the description of the thermal phase of the QFT's in the corresponding Domain-Wall/QFT duality.
Sequences of extremal radially excited rotating black holes.
Blázquez-Salcedo, Jose Luis; Kunz, Jutta; Navarro-Lérida, Francisco; Radu, Eugen
2014-01-10
In the Einstein-Maxwell-Chern-Simons theory the extremal Reissner-Nordström solution is no longer the single extremal solution with vanishing angular momentum, when the Chern-Simons coupling constant reaches a critical value. Instead a whole sequence of rotating extremal J=0 solutions arises, labeled by the node number of the magnetic U(1) potential. Associated with the same near horizon solution, the mass of these radially excited extremal solutions converges to the mass of the extremal Reissner-Nordström solution. On the other hand, not all near horizon solutions are also realized as global solutions. PMID:24483880
Phantom black holes and sigma models
Azreg-Aienou, Mustapha; Clement, Gerard; Fabris, Julio C.; Rodrigues, Manuel E.
2011-06-15
We construct static multicenter solutions of phantom Einstein-Maxwell-dilaton theory from null geodesics of the target space, leading to regular black holes without spatial symmetry for certain discrete values of the dilaton coupling constant. We also discuss the three-dimensional gravitating sigma models obtained by reduction of phantom Einstein-Maxwell, phantom Kaluza-Klein and phantom Einstein-Maxwell-dilaton-axion theories. In each case, we generate by group transformations phantom charged black hole solutions from a neutral seed.
Horizon structure and shadow of rotating Einstein-Born-Infeld black holes
NASA Astrophysics Data System (ADS)
Atamurotov, Farruh
2016-07-01
We investigate the horizon structure of the rotating Einstein-Born-Infeld solution which goes over to the Einstein-Maxwell's Kerr-Newman solution as the Born-Infeld parameter goes to innity ( ! 1). We nd that for a given , mass M and charge Q, there exist critical spinning parameter aE and rEH, which corresponds to an extremal Einstein-Born-Infeld black hole with degenerate horizons, and aE decreases and rEH increases with increase in the Born-Infeld parameter . While a < aE describe a non-extremal Einstein-Born- Infeld black hole with outer and inner horizons. Similarly, the e ect of on innite redshift surface and in turn on ergoregion is also included. It is well known that a black hole can cast a shadow as an optical appearance due to its strong gravitational eld. We also investigate the shadow cast by the rotating Einstein- Born-Infeld black hole and demonstrate that the null geodesic equations can be integrated that allows us to investigate the shadow cast by a black hole which is found to be a dark zone covered by a circle. Interestingly, the shadows of Einstein-Born-Infeld black hole is slightly smaller than for the Reissner-Nordstrom black hole which are concentric circles, for di erent values of the Born-Infeld parameter , whose radius decreases with increase in the value of parameter . The shadows for the rotating Einstein-Born-Infeld solution are also included.
NASA Astrophysics Data System (ADS)
Morozova, Viktoriya; Ahmedov, Bobomurat; Rezzolla, Luciano
2016-07-01
We extend the Wald solution for magnetic field to a black hole that is also moving at constant velocity. In particular, we derive analytic solutions for the Maxwell equations for a rotating black hole moving at constant speed in an asymptotically uniform magnetic test field. By adopting Kerr-Schild coordinates we avoid singular behaviors at the horizon and obtain a complete description of the charge and current distributions in terms of the black-hole spin and velocity. Using this solution, we compute the energy losses expected when charged particles are accelerated along the magnetic field lines, improving previous estimates that had to cope with singular electromagnetic fields on the horizon. When used to approximate the emission from binary black holes in a uniform magnetic field, our estimates match reasonably well those from numericalrelativity calculations in the force-free approximation.
Seed for general rotating non-extremal black holes of {N}= 8 supergravity
NASA Astrophysics Data System (ADS)
Chow, David D. K.; Compère, Geoffrey
2014-01-01
We describe the most general asymptotically flat, stationary, non-extremal, dyonic black hole of the four-dimensional {N}= 2 supergravity coupled to three vector multiplets that describes the low-energy regime of the STU model. Under U-dualities, this can be used as a seed to generate all single-centered stationary black holes of {N}= 8 supergravity. The independent conserved charges are the mass, angular momentum, four electric charges and four magnetic charges; an independent NUT charge can also be added. Several aspects of the black hole are presented, including thermodynamics, the BPS limit, the near-horizon limit in the extremal fast and slow rotating cases, properties of black hole horizons, the existence of Killing tensors and the separability of probe scalars.
On dilatons and the LHC diphoton excess
NASA Astrophysics Data System (ADS)
Megías, Eugenio; Pujolàs, Oriol; Quirós, Mariano
2016-05-01
We study soft wall models that can embed the Standard Model and a naturally light dilaton. Exploiting the full capabilities of these models we identify the parameter space that allows to pass Electroweak Precision Tests with a moderate Kaluza-Klein scale, around 2 TeV. We analyze the coupling of the dilaton with Standard Model (SM) fields in the bulk, and discuss two applications: i) Models with a light dilaton as the first particle beyond the SM pass quite easily all observational tests even with a dilaton lighter than the Higgs. However the possibility of a 125 GeV dilaton as a Higgs impostor is essentially disfavored; ii) We show how to extend the soft wall models to realize a 750 GeV dilaton that could explain the recently reported diphoton excess at the LHC.
Mass-loss from advective accretion disc around rotating black holes
NASA Astrophysics Data System (ADS)
Aktar, Ramiz; Das, Santabrata; Nandi, Anuj
2015-11-01
We examine the properties of the outflowing matter from an advective accretion disc around a spinning black hole. During accretion, rotating matter experiences centrifugal pressure-supported shock transition that effectively produces a virtual barrier around the black hole in the form of post-shock corona (hereafter PSC). Due to shock compression, PSC becomes hot and dense that eventually deflects a part of the inflowing matter as bipolar outflows because of the presence of extra thermal gradient force. In our approach, we study the outflow properties in terms of the inflow parameters, namely specific energy (E) and specific angular momentum (λ) considering the realistic outflow geometry around the rotating black holes. We find that spin of the black hole (ak) plays an important role in deciding the outflow rate R_{dot{m}} (ratio of mass flux of outflow to inflow); in particular, R_{dot{m}} is directly correlated with ak for the same set of inflow parameters. It is found that a large range of the inflow parameters allows global accretion-ejection solutions, and the effective area of the parameter space (E, λ) with and without outflow decreases with black hole spin (ak). We compute the maximum outflow rate (R^{max}_{dot{m}}) as a function of black hole spin (ak) and observe that R^{max}_{dot{m}} weakly depends on ak that lies in the range ˜10-18 per cent of the inflow rate for the adiabatic index (γ) with 1.5 ≥ γ ≥ 4/3. We present the observational implication of our approach while studying the steady/persistent jet activities based on the accretion states of black holes. We discuss that our formalism seems to have the potential to explain the observed jet kinetic power for several Galactic black hole sources and active galactic nuclei.
Superradiance and instability of small rotating charged AdS black holes in all dimensions
NASA Astrophysics Data System (ADS)
Aliev, Alikram N.
2016-02-01
Rotating small AdS black holes exhibit the superradiant instability to low-frequency scalar perturbations, which is amenable to a complete analytic description in four dimensions. In this paper, we extend this description to all higher dimensions, focusing on slowly rotating charged AdS black holes with a single angular momentum. We divide the spacetime of these black holes into the near-horizon and far regions and find solutions to the scalar wave equation in each of these regions. Next, we perform the matching of these solutions in the overlap between the regions, by employing the idea that the orbital quantum number ℓ can be thought of as an approximate integer. Thus, we obtain the complete low-frequency solution that allows us to calculate the complex frequency spectrum of quasinormal modes, whose imaginary part is determined by a small damping parameter. Finally, we find a remarkably instructive expression for the damping parameter, which appears to be a complex quantity in general. We show that the real part of the damping parameter can be used to give a universal analytic description of the superradiant instability for slowly rotating charged AdS black holes in all spacetime dimensions.
Dehghani, M.H.; Mann, R.B.
2006-05-15
We generalize the quasilocal definition of the stress-energy tensor of Einstein gravity to the case of third order Lovelock gravity, by introducing the surface terms that make the action well-defined. We also introduce the boundary counterterm that removes the divergences of the action and the conserved quantities of the solutions of third order Lovelock gravity with zero curvature boundary at constant t and r. Then, we compute the charged rotating solutions of this theory in n+1 dimensions with a complete set of allowed rotation parameters. These charged rotating solutions present black hole solutions with two inner and outer event horizons, extreme black holes or naked singularities provided the parameters of the solutions are suitably chosen. We compute temperature, entropy, charge, electric potential, mass and angular momenta of the black hole solutions, and find that these quantities satisfy the first law of thermodynamics. We find a Smarr-type formula and perform a stability analysis by computing the heat capacity and the determinant of Hessian matrix of mass with respect to its thermodynamic variables in both the canonical and the grand-canonical ensembles, and show that the system is thermally stable. This is commensurate with the fact that there is no Hawking-Page phase transition for black objects with zero curvature horizon.
General relativistic x ray (UV) polarization rotations as a quantitative test for black holes
NASA Technical Reports Server (NTRS)
Stark, Richard F.
1989-01-01
It is now 11 years since a potentially easily observable and quantitative test for black holes using general relativistic polarization rotations was proposed (Stark and Connors 1977, and Connors and Stark 1977). General relativistic rotations of the x ray polarization plane of 10 to 100 degrees with x ray energy (between 1 and 100 keV) are predicted for black hole x ray binaries. (Classically, by symmetry, there is no rotation.) Unfortunately, x ray polarimetry has not been taken sufficiently seriously during this period, and this test has not yet been performed. A similar (though probably less clean) effect is expected in the UV for supermassive black holes in some quasars active galactic nuclei. Summarizing: (1) a quantitative test (proposed in 1977) for black holes exists; (2) x ray polarimetry of galactic x ray binaries sensitive to at least 1/2 percent between 1 keV and 100 keV is needed (polarimetry in the UV of quasars and AGN will also be of interest); and (3) proportional counters using timerise discrimination were shown in laboratory experiments able to perform x ray polarimetry and this and other methods need to be developed.
Energy extraction and particle acceleration around a rotating black hole in quintessence
NASA Astrophysics Data System (ADS)
Oteev, Tursinbay; Abdujabbarov, Ahmadjon; Stuchlík, Zdeněk; Ahmedov, Bobomurat
2016-08-01
We study motion and collision of particles in the gravitational field of rotating black hole immersed in quintessential dark energy characterized with the quintessential parameter ωqin(-1;-1/3) governing the equation of state of the dark energy, and the dimensionless quintessential field parameter tilde{c}. We focus on the acceleration of particles due to collisional processes and show how the center of mass energy depends on the quintessential field parameter tilde{c}. We also make comparison of the obtained results to the collisional energetics of quintessential static black holes demonstrating the crucial role of the rotation parameter a in the particle acceleration. Finally we study the dependence of the maximal value of the efficiency of energy extraction through Penrose process for rotating black hole with quintessential field parameter tilde{c}. It is found that quintessence field decreases the energy extraction efficiency through Penrose process and when the parameter tilde{c} vanishes one can get the standard value of the efficiency coefficient for the Kerr black hole as η˜ 21 %.
Non-singular rotating black hole with a time delay in the center
NASA Astrophysics Data System (ADS)
Lorenzo, Tommaso De; Giusti, Andrea; Speziale, Simone
2016-03-01
As proposed by Bambi and Modesto, rotating non-singular black holes can be constructed via the Newman-Janis algorithm. Here we show that if one starts with a modified Hayward black hole with a time delay in the centre, the algorithm succeeds in producing a rotating metric, but curvature divergences reappear. To preserve finiteness, the time delay must be introduced directly at the level of the non-singular rotating metric. This is possible thanks to the deformation of the inner stationarity limit surface caused by the regularisation, and in more than one way. We outline three different possibilities, distinguished by the angular velocity of the event horizon. Along the way, we provide additional results on the Bambi-Modesto rotating Hayward metric, such as the structure of the regularisation occurring at the centre, the behaviour of the quantum gravity scale alike an electric charge in decreasing the angular momentum of the extremal black hole configuration, or details on the deformation of the ergosphere.
Erratum: Erratum to: Non-singular rotating black hole with a time delay in the center
NASA Astrophysics Data System (ADS)
De Lorenzo, Tommaso; Giusti, Andrea; Speziale, Simone
2016-08-01
As proposed by Bambi and Modesto, rotating non-singular black holes can be constructed via the Newman-Janis algorithm. Here we show that if one starts with a modified Hayward black hole with a time delay in the centre, the algorithm succeeds in producing a rotating metric, but curvature divergences reappear. To preserve finiteness, the time delay must be introduced directly at the level of the non-singular rotating metric. This is possible thanks to the deformation of the inner stationarity limit surface caused by the regularisation, and in more than one way. We outline three different possibilities, distinguished by the angular velocity of the event horizon. Along the way, we provide additional results on the Bambi-Modesto rotating Hayward metric, such as the structure of the regularisation occurring at the centre, the behaviour of the quantum gravity scale alike an electric charge in decreasing the angular momentum of the extremal black hole configuration, or details on the deformation of the ergosphere.
Charged and rotating AdS black holes and their CFT duals
NASA Astrophysics Data System (ADS)
Hawking, S. W.; Reall, H. S.
2000-01-01
Black hole solutions that are asymptotic to AdS5×S5 or AdS4×S7 can rotate in two different ways. If the internal sphere rotates, then one can obtain a Reissner-Nordström-AdS black hole. If the asymptotically AdS space rotates, then one can obtain a Kerr-AdS hole. One might expect superradiant scattering to be possible in either of these cases. Superradiant modes reflected off the potential barrier outside the hole would be reamplified at the horizon, and a classical instability would result. We point out that the existence of a Killing vector field timelike everywhere outside the horizon prevents this from occurring for black holes with negative action. Such black holes are also thermodynamically stable in the grand canonical ensemble. The CFT duals of these black holes correspond to a theory in an Einstein universe with a chemical potential and a theory in a rotating Einstein universe. We study these CFTs in the zero coupling limit. In the first case, Bose-Einstein condensation occurs on the boundary at a critical value of the chemical potential. However, the supergravity calculation demonstrates that this is not to be expected at strong coupling. In the second case, we investigate the limit in which the angular velocity of the Einstein universe approaches the speed of light at finite temperature. This is a new limit in which to compare the CFT at strong and weak coupling. We find that the free CFT partition function and supergravity action have the same type of divergence but the usual factor of 4/3 is modified at finite temperature.
THE FORCE-FREE MAGNETOSPHERE OF A ROTATING BLACK HOLE
Contopoulos, Ioannis; Kazanas, Demosthenes
2013-03-10
We revisit the Blandford-Znajek process and solve the fundamental equation that governs the structure of the steady-state force-free magnetosphere around a Kerr black hole. The solution depends on the distributions of the magnetic field angular velocity {omega} and the poloidal electric current I. These are not arbitrary. They are determined self-consistently by requiring that magnetic field lines cross smoothly the two singular surfaces of the problem: the inner ''light surface'' located inside the ergosphere and the outer ''light surface'' which is the generalization of the pulsar light cylinder. We find the solution for the simplest possible magnetic field configuration, the split monopole, through a numerical iterative relaxation method analogous to the one that yields the structure of the steady-state axisymmetric force-free pulsar magnetosphere. We obtain the rate of electromagnetic extraction of energy and confirm the results of Blandford and Znajek and of previous time-dependent simulations. Furthermore, we discuss the physical applicability of magnetic field configurations that do not cross both ''light surfaces''.
The Force-Free Magnetosphere of a Rotating Black Hole
NASA Technical Reports Server (NTRS)
Contopoulos, Ioannis; Kazanas, Demosthenes; Papadopoulos, Demetrios B.
2013-01-01
We revisit the Blandford-Znajek process and solve the fundamental equation that governs the structure of the steady-state force-free magnetosphere around a Kerr black hole. The solution depends on the distributions of the magnetic field angular velocity and the poloidal electric current. These are not arbitrary. They are determined self-consistently by requiring that magnetic field lines cross smoothly the two singular surfaces of the problem: the inner "light surface" located inside the ergosphere and the outer "light surface" which is the generalization of the pulsar light cylinder.We find the solution for the simplest possible magnetic field configuration, the split monopole, through a numerical iterative relaxation method analogous to the one that yields the structure of the steady-state axisymmetric force-free pulsar magnetosphere. We obtain the rate of electromagnetic extraction of energy and confirm the results of Blandford and Znajek and of previous time-dependent simulations. Furthermore, we discuss the physical applicability of magnetic field configurations that do not cross both "light surfaces."
NASA Astrophysics Data System (ADS)
Lin, Kai; Satheeshkumar, V. H.; Wang, Anzhong
2016-06-01
In this paper, we show the existence of static and rotating universal horizons and black holes in gravitational theories with broken Lorentz invariance. We pay particular attention to the ultraviolet regime, and show that universal horizons and black holes exist not only in the low energy limit but also at the ultraviolet energy scales. This is realized by presenting various static and stationary exact solutions of the full theory of the projectable Hořava gravity with an extra U(1) symmetry in (2 +1 )-dimensions, which, by construction, is power-counting renormalizable.
Surface terms of quasitopological gravity and thermodynamics of charged rotating black branes
Dehghani, M. H.; Vahidinia, M. H.
2011-10-15
We introduce the surface term for quasitopological gravity in order to make the variational principle of the action well defined. We also introduce the charged black branes of quasitopological gravity and calculate the finite action through the use of the counterterm method. Then we compute the thermodynamic quantities of the black brane solution by use of Gibbs free energy and investigate the first law of thermodynamics by introducing a Smarr-type formula. Finally, we generalize our solutions to the case of rotating charged solutions.
Hidden conformal symmetry of rotating black holes in minimal five-dimensional gauged supergravity
Setare, M. R.; Kamali, V.
2010-10-15
In the present paper we show that for a low frequency limit the wave equation of a massless scalar field in the background of nonextremal charged rotating black holes in five-dimensional minimal gauged and ungauged supergravity can be written as the Casimir of an SL(2,R) symmetry. Our result shows that the entropy of the black hole is reproduced by the Cardy formula. Also the absorption cross section is consistent with the finite temperature absorption cross section for a two-dimensional conformal field theory.
Tunnelling of scalar and Dirac particles from squashed charged rotating Kaluza-Klein black holes
NASA Astrophysics Data System (ADS)
Stetsko, M. M.
2016-02-01
The thermal radiation of scalar particles and Dirac fermions from squashed charged rotating five-dimensional black holes is considered. To obtain the temperature of the black holes we use the tunnelling method. In the case of scalar particles we make use of the Hamilton-Jacobi equation. To consider tunnelling of fermions the Dirac equation was investigated. The examination shows that the radial parts of the action for scalar particles and fermions in the quasi-classical limit in the vicinity of horizon are almost the same and as a consequence it gives rise to identical expressions for the temperature in the two cases.
Fluid/gravity correspondence for general non-rotating black holes
NASA Astrophysics Data System (ADS)
Wu, Xiaoning; Ling, Yi; Tian, Yu; Zhang, Chengyong
2013-07-01
In this paper, we investigate the fluid/gravity correspondence in spacetime with general non-rotating weakly isolated horizon. With the help of a Petrov-like boundary condition and large mean curvature limit, we show that the dual hydrodynamical system is described by a generalized forced incompressible Navier-Stokes equation. Specially, for stationary black holes or those spacetime with some asymptotically stationary conditions, such a system reduces to a standard forced Navier-Stokes system.
Separable wave equations for gravitoelectromagnetic perturbations of rotating charged black strings
NASA Astrophysics Data System (ADS)
Miranda, Alex S.; Morgan, Jaqueline; Kandus, Alejandra; Zanchin, Vilson T.
2015-12-01
Rotating charged black strings are exact solutions of four-dimensional Einstein-Maxwell equations with a negative cosmological constant and a non-trivial spacetime topology. According to the AdS/CFT correspondence, these black strings are dual to rotating thermal states of a strongly interacting quantum field theory with nonzero chemical potential that lives in a cylinder. The dynamics of linear fluctuations in the dual field theory can be studied from the perturbation equations for classical fields in a black-string spacetime. With this motivation in mind, we develop here a completely gauge and tetrad invariant perturbation approach to deal with the gravitoelectromagnetic fluctuations of rotating charged black strings in the presence of sources. As usual, for any charged black hole, a perturbation in the background electromagnetic field induces a metric perturbation and vice versa. In spite of this coupling and the non-vanishing angular momentum, we show that linearization of equations of the Newman-Penrose formalism leads to four separated second-order complex equations for suitable combinations of the spin coefficients, the Weyl and the Maxwell scalars. Then, we generalize the Chandrasekhar transformation theory by the inclusion of sources and apply it to reduce the perturbation problem to four decoupled inhomogeneous wave equations—a pair for each sector of perturbations. The radial part of such wave equations can be put into Schrödinger-like forms after Fourier transforming them with respect to time. We find that the resulting effective potentials form two pairs of supersymmetric partner potentials and, as a consequence, the fundamental variables of one perturbation sector are related to the variables of the other sector. The relevance of such a symmetry in connection to the AdS/CFT correspondence is discussed, and future applications of the pertubation theory developed here are outlined.
QPOs from Random X-ray Bursts around Rotating Black Holes
NASA Technical Reports Server (NTRS)
Kukumura, Keigo; Kazanas, Demosthenes; Stephenson, Gordon
2009-01-01
We continue our earlier studies of quasi-periodic oscillations (QPOs) in the power spectra of accreting, rapidly-rotating black holes that originate from the geometric 'light echoes' of X-ray flares occurring within the black hole ergosphere. Our present work extends our previous treatment to three-dimensional photon emission and orbits to allow for arbitrary latitudes in the positions of the distant observers and the X-ray sources in place of the mainly equatorial positions and photon orbits of the earlier consideration. Following the trajectories of a large number of photons we calculate the response functions of a given geometry and use them to produce model light curves which we subsequently analyze to compute their power spectra and autocorrelation functions. In the case of an optically-thin environment, relevant to advection-dominated accretion flows, we consistently find QPOs at frequencies of order of approximately kHz for stellar-mass black hole candidates while order of approximately mHz for typical active galactic nuclei (approximately equal to 10(exp 7) solar mass) for a wide range of viewing angles (30 degrees to 80 degrees) from X-ray sources predominantly concentrated toward the equator within the ergosphere. As in out previous treatment, here too, the QPO signal is produced by the frame-dragging of the photons by the rapidly-rotating black hole, which results in photon 'bunches' separated by constant time-lags, the result of multiple photon orbits around the hole. Our model predicts for various source/observer configurations the robust presence of a new class of QPOs, which is inevitably generic to curved spacetime structure in rotating black hole systems.
Koide, Shinji
2010-01-10
To study phenomena of plasmas around rotating black holes, we have derived a set of 3+1 formalism of generalized general relativistic magnetohydrodynamic (GRMHD) equations. In particular, we investigated general relativistic phenomena with respect to the Ohm's law. We confirmed the electromotive force due to the gravitation, centrifugal force, and frame-dragging effect in plasmas near the black holes. These effects are significant only in the local small-scale phenomena compared to the scale of astrophysical objects. We discuss the possibility of magnetic reconnection, which is triggered by one of these effects in a small-scale region and influences the plasmas globally. We clarify the conditions of applicability of the generalized GRMHD, standard resistive GRMHD, and ideal GRMHD for plasmas in black hole magnetospheres.
Buoyancy and the Penrose process produce jets from rotating black holes
NASA Astrophysics Data System (ADS)
Semenov, V. S.; Dyadechkin, S. A.; Heyn, M. F.
2014-04-01
The exact mechanism by which astrophysical jets are formed is still unknown. It is believed that the necessary elements consist of a rotating (Kerr) black hole and a magnetized accreting plasma. We model the accreting plasma as a collection of magnetic flux tubes/strings. If such a tube falls into a Kerr black hole, then the leading portion loses angular momentum and energy as the string brakes. To compensate for this loss, momentum and energy is redistributed to the trailing portion of the tube. We found that buoyancy creates a pronounced helical magnetic field structure aligned with the spin axis. Along the field lines, the plasma is centrifugally accelerated close to the speed of light. This process leads to unlimited stretching of the flux tube since one part of the tube continues to fall into the black hole and, simultaneously, the other part of the string is pushed outward. Eventually, reconnection cuts the tube. The inner part is filled with new material and the outer part forms a collimated bubble-structured relativistic jet. Each plasmoid can be considered as an outgoing particle in the Penrose mechanism: it carries extracted rotational energy away from the black hole while the falling part, with corresponding negative energy, is left inside the ergosphere.
Superradiance from a charged dilation black hole
Shiraishi, K. )
1992-12-07
In this paper, the authors study the behavior of the wave function of charged Klein-Gordon field around a charge dilaton black hole. The rate of spontaneous charge loss is estimated for large black hole case.
Near-horizon circular orbits and extremal limit for dirty rotating black holes
NASA Astrophysics Data System (ADS)
Zaslavskii, O. B.
2015-08-01
We consider generic rotating axially symmetric "dirty" (surrounded by matter) black holes. Near-horizon circular equatorial orbits are examined in two different cases of near-extremal (small surface gravity κ ) and exactly extremal black holes. This has a number of qualitative distinctions. In the first case, it is shown that such orbits can lie as close to the horizon as one wishes on suitably chosen slices of space-time when κ →0 . This generalizes the observation of T. Jacobson [Classical Quantum Gravity 28, 187001 (2011), 10.1088/0264-9381/28/18/187001] made for the Kerr metric. If a black hole is extremal (κ =0 ), circular on-horizon orbits are impossible for massive particles but, in general, are possible in its vicinity. The corresponding black hole parameters determine also the rate with which a fine-tuned particle on the noncircular near-horizon orbit asymptotically approaches the horizon. Properties of orbits under discussion are also related to the Bañados-Silk-West effect of high energy collisions near black holes. Impossibility of the on-horizon orbits in question is manifestation of kinematic censorship that forbids infinite energies in collisions.
Solitons of axion-dilaton gravity
Bakas, I. |
1996-11-01
We use soliton techniques of the two-dimensional reduced {beta}-function equations to obtain nontrivial string backgrounds from flat space. These solutions are characterized by two integers ({ital n},{ital m}) referring to the soliton numbers of the metric and axion-dilaton sectors, respectively. We show that the Nappi-Witten universe associated with the SL(2){times}SU(2)/SO(1,1){times}U(1) CFT coset arises as a (1,1) soliton in this fashion for certain values of the moduli parameters, while for other values of the soliton moduli we arrive at the SL(2)/SO(1,1){times}SO(1,1){sup 2} background. Ordinary four-dimensional black holes arise as two-dimensional (2,0) solitons, while the Euclidean wormhole background is described as a (0,2) soliton on flat space. The soliton transformations correspond to specific elements of the string Geroch group. These could be used as a starting point for exploring the role of {ital U} dualities in string compactifications to two dimensions. {copyright} {ital 1996 The American Physical Society.}
Can the slow-rotation approximation be used in electromagnetic observations of black holes?
NASA Astrophysics Data System (ADS)
Ayzenberg, Dimitry; Yagi, Kent; Yunes, Nicolás
2016-05-01
Future electromagnetic observations of black holes (BHs) may allow us to test general relativity (GR) in the strong-field regime. Such tests, however, require knowledge of rotating BH solutions in modified gravity theories, a class of which does not admit the Kerr metric as a solution. Several rotating BH solutions in modified theories have only been found in the slow-rotation approximation (i.e. assuming the spin angular momentum is much smaller than the mass squared). We here investigate whether the systematic error due to the approximate nature of these BH metrics is small enough relative to the observational error to allow their use in electromagnetic observations to constrain deviations from GR. We address this by considering whether electromagnetic observables constructed from a slow-rotation approximation to the Kerr metric can fit observables constructed from the full Kerr metric with systematic errors smaller than current observational errors. We focus on BH shadow and continuum spectrum observations, as these are the least influenced by accretion disk physics, with current observational errors of about 10%. We find that the fractional systematic error introduced by using a second-order, slowly rotating Kerr metric is at most 2% for shadows created by BHs with dimensionless spins χ ≤slant 0.6. We also find that the systematic error introduced by using the slowly rotating Kerr metric as an exact metric when constructing continuum spectrum observables is negligible for BHs with dimensionless spins of χ ≲ 0.9. Our results suggest that the modified gravity solutions found in the slow-rotation approximation may be used to constrain realistic deviations from GR with continuum spectrum and BH shadow observations.
NASA Astrophysics Data System (ADS)
Peng, Jun-Jin; Wu, Shuang-Qing
2008-03-01
Motivated by the success of the recently proposed method of anomaly cancellation to derive Hawking fluxes from black hole horizons of spacetimes in various dimensions, we have further extended the covariant anomaly cancellation method shortly simplified by Banerjee and Kulkarni to explore the Hawking radiation of the (3 + 1)-dimensional charged rotating black strings and their higher dimensional extensions in anti-de Sitter spacetimes, whose horizons are not spherical but can be toroidal, cylindrical or planar, according to their global identifications. It should be emphasized that our analysis presented here is very general in the sense that the determinant of the reduced (1 + 1)-dimensional effective metric from these black strings need not be equal to one (√{ - g } ≠ 1). Our results indicate that the gauge and energy-momentum fluxes needed to cancel the (1 + 1)-dimensional covariant gauge and gravitational anomalies are compatible with the Hawking fluxes. Besides, thermodynamics of these black strings are studied in the case of a variable cosmological constant.
Ahmedov, Haji; Aliev, Alikram N.
2008-09-15
We examine the separability properties of the equation of motion for a stationary string near a rotating charged black hole with two independent angular momenta in five-dimensional minimal gauged supergravity. It is known that the separability problem for the stationary string in a general stationary spacetime is reduced to that for the usual Hamilton-Jacobi equation for geodesics of its quotient space with one dimension fewer. Using this fact, we show that the 'effective metric' of the quotient space does not allow the complete separability for the Hamilton-Jacobi equation, albeit such a separability occurs in the original spacetime of the black hole. We also show that only for two special cases of interest the Hamilton-Jacobi equation admits the complete separation of variables and therefore the integrability for the stationary string motion in the original background, namely, when the black hole has zero electric charge or it has an arbitrary electric charge but two equal angular momenta. We give the explicit expressions for the Killing tensors corresponding to these cases. However, for the general black hole spacetime the effective metric of the quotient space admits a conformal Killing tensor. We construct the explicit expression for this tensor.
Null geodesics and shadow of a rotating black hole in extended Chern-Simons modified gravity
Amarilla, Leonardo; Eiroa, Ernesto F.; Giribet, Gaston
2010-06-15
The Chern-Simons modification to general relativity in four dimensions consists of adding to the Einstein-Hilbert term a scalar field that couples to the first-class Pontryagin density. In this theory, which has attracted considerable attention recently, the Schwarzschild metric persists as an exact solution, and this is why this model resists several observational constraints. In contrast, the spinning black hole solution of the theory is not given by the Kerr metric but by a modification of it, so far only known for slow rotation and small coupling constant. In the present paper, we show that, in this approximation, the null geodesic equation can be integrated, and this allows us to investigate the shadow cast by a black hole. We discuss how, in addition to the angular momentum of the solution, the coupling to the Chern-Simons term deforms the shape of the shadow.
Integrability of spinning particle motion in higher-dimensional rotating black hole spacetimes.
Kubizňák, David; Cariglia, Marco
2012-02-01
We study the motion of a classical spinning particle (with spin degrees of freedom described by a vector of Grassmann variables) in higher-dimensional general rotating black hole spacetimes with a cosmological constant. In all dimensions n we exhibit n bosonic functionally independent integrals of spinning particle motion, corresponding to explicit and hidden symmetries generated from the principal conformal Killing-Yano tensor. Moreover, we demonstrate that in 4-, 5-, 6-, and 7-dimensional black hole spacetimes such integrals are in involution, proving the bosonic part of the motion integrable. We conjecture that the same conclusion remains valid in all higher dimensions. Our result generalizes the result of Page et al. [Phys. Rev. Lett. 98, 061102 (2007)] on complete integrability of geodesic motion in these spacetimes. PMID:22400922
Dehghani, M. H.; Pakravan, J.; Hendi, S. H.
2006-11-15
We construct a class of charged rotating solutions in (n+1)-dimensional Maxwell-Brans-Dicke theory with flat horizon in the presence of a quadratic potential and investigate their properties. These solutions are neither asymptotically flat nor (anti)-de Sitter. We find that these solutions can present black brane, with inner and outer event horizons, an extreme black brane or a naked singularity provided the parameters of the solutions are chosen suitably. We compute the finite Euclidean action through the use of counterterm method, and obtain the conserved and thermodynamic quantities by using the relation between the action and free energy in grand-canonical ensemble. We find that these quantities satisfy the first law of thermodynamics, and the entropy does not follow the area law.
Extracting Energy-Momentum from Rotating Black Holes Using the Penrose Mechanism
NASA Astrophysics Data System (ADS)
Williams, Reva Kay
1999-11-01
Over the past three decays, since the discovery of quasars, mounting observational evidence has accumulated that black holes indeed exist in nature. In this paper, we present a theoretical and numerical (Monte Carlo) analysis of Penrose scattering processes (Compton and γ-γ e*+e^- production) in the ergosphere of Kerr (rotating) black holes. These model calculations surprising reveal that the high energies and luminosities, the collimated jets about the polar axis, and the asymmetrical jets (which can be enhanced by relativistic Doopler beaming effects), all, are inherent properties of rotation black holes. When we assume that the accretion disk is a two-temperature bistable thin disk/ion corona, recently referred to as an advection dominated accretion flow (ADAF), energies as high as 54 GeV can be attained by these Perose processes along; and when relativistic beaming is included, energies in the TeV range can be achieved, agreeing with observations of some BL Lac objects. We show that the scattered escaping particles exhibit tightly wounded coil-like cone distributions (i.e. highly collimated jet distributions) about the polar axis, with helical polar angles of escape varying from 0.5^o to 30^o for the highest to lowest energy particles, respectively. We show also that the gravitomagnetic (GM) field, which causes the dragging of inertial frames, exerts a force acting on the momentum vectors of the incident and scattered particles, causing the particle emission to be asymmetrical above and below the equatorial plane. This Penrose energy extraction model can be applied to any size black hole irrespective of the mass. Also it is reemphasized why the Blandford and Znajek model is not tenable, as pointed out by Punsly and Coroniti (1989, 1990a, 1990b).
Quantum tunneling from rotating black holes with scalar hair in three dimensions
NASA Astrophysics Data System (ADS)
Sakalli, I.; Gursel, H.
2016-06-01
We study the Hawking radiation of scalar and Dirac particles (fermions) emitted from a rotating scalar hair black hole (RSHBH) within the context of three dimensional (3 D) Einstein gravity using non-minimally coupled scalar field theory. Amalgamating the quantum tunneling approach with the Wentzel-Kramers-Brillouin approximation, we obtain the tunneling rates of the outgoing particles across the event horizon. Inserting the resultant tunneling rates into the Boltzmann formula, we then obtain the Hawking temperature (T_H) of the 3 D RSHBH.
Two-charge rotating black holes in four-dimensional gauged supergravity
NASA Astrophysics Data System (ADS)
Chow, David D. K.
2011-09-01
We obtain an asymptotically AdS, non-extremal, electrically charged and rotating black hole solution of four-dimensional U(1)4 gauged supergravity with two non-zero and independent U(1) charges. The thermodynamical quantities are computed. We find BPS solutions that are nakedly singular. The solution is generalized to include a NUT parameter and dyonic gauge fields. The string frame metric has a rank-2 Killing-Stäckel tensor and has completely integrable geodesic motion, and the massless Klein-Gordon equation separates for the Einstein frame metric.
Thermodynamics of Einstein-Born-Infeld black holes in three dimensions
Myung, Yun Soo; Kim, Yong-Wan; Park, Young-Jai
2008-08-15
We show that all thermodynamic quantities of the Einstein-Born-Infeld black holes in three dimensions can be obtained from the dilaton and its potential of two-dimensional dilaton gravity through dimensional reduction. These are all between nonrotating uncharged BTZ (Banados-Teitelboim-Zanelli) black hole (NBTZ) and charged BTZ black hole (CBTZ)
Thermodynamics of rotating black branes in (n+1)-dimensional Einstein-Born-Infeld gravity
Dehghani, M. H.; Sedehi, H. R. Rastegar
2006-12-15
We construct a new class of charged rotating solutions of (n+1)-dimensional Einstein-Born-Infeld gravity with cylindrical or toroidal horizons in the presence of cosmological constant and investigate their properties. These solutions are asymptotically (anti)-de Sitter and reduce to the solutions of Einstein-Maxwell gravity as the Born-Infeld parameters goes to infinity. We find that these solutions can represent black branes, with inner and outer event horizons, an extreme black brane or a naked singularity provided the parameters of the solutions are chosen suitably. We compute temperature, mass, angular momentum, entropy, charge and electric potential of the black brane solutions. We obtain a Smarr-type formula and show that these quantities satisfy the first law of thermodynamics. We also perform a stability analysis by computing the heat capacity and the determinant of Hessian matrix of mass of the system with infinite boundary with respect to its thermodynamic variables in both the canonical and the grand-canonical ensembles, and show that the system is thermally stable in the whole phase space. Also, we find that there exists an unstable phase when the finite size effect is taken into account.
NASA Astrophysics Data System (ADS)
Tursunov, Arman; Stuchlík, Zdeněk; Kološ, Martin
2016-04-01
We study the motion of charged particles in the field of a rotating black hole immersed into an external asymptotically uniform magnetic field, focusing on the epicyclic quasicircular orbits near the equatorial plane. Separating the circular orbits into four qualitatively different classes according to the sign of the canonical angular momentum of the motion and the orientation of the Lorentz force, we analyze the circular orbits using the so-called force formalism. We find the analytical solutions for the radial profiles of velocity, specific angular momentum, and specific energy of the circular orbits in dependence on the black-hole dimensionless spin and the magnetic field strength. The innermost stable circular orbits are determined for all four classes of the circular orbits. The stable circular orbits with an outward-oriented Lorentz force can extend to radii lower than the radius of the corresponding photon circular geodesic. We calculate the frequencies of the harmonic oscillatory motion of the charged particles in the radial and vertical directions related to the equatorial circular orbits and study the radial profiles of the radial, ωr; vertical, ωθ; and orbital, ωϕ, frequencies, finding significant differences in comparison to the epicyclic geodesic circular motion. The most important new phenomenon is the existence of toroidal charged particle epicyclic motion with ωr˜ωθ≫ωϕ that could occur around retrograde circular orbits with an outward-oriented Lorentz force. We demonstrate that for the rapidly rotating black holes the role of the "Wald induced charge" can be relevant.
Slowly varying dilaton cosmologies and their field theory duals
Awad, Adel; Das, Sumit R.; Ghosh, Archisman; Oh, Jae-Hyuk; Trivedi, Sandip P.
2009-12-15
We consider a deformation of the AdS{sub 5}xS{sup 5} solution of IIB supergravity obtained by taking the boundary value of the dilaton to be time dependent. The time dependence is taken to be slowly varying on the anti-de Sitter (AdS) scale thereby introducing a small parameter {epsilon}. The boundary dilaton has a profile which asymptotes to a constant in the far past and future and attains a minimum value at intermediate times. We construct the supergravity (sugra) solution to first nontrivial order in {epsilon}, and find that it is smooth, horizon-free, and asymptotically AdS{sub 5}xS{sup 5} in the far future. When the intermediate values of the dilaton becomes small enough the curvature becomes of order the string scale and the sugra approximation breaks down. The resulting dynamics is analyzed in the dual SU(N) gauge theory on S{sup 3} with a time dependent coupling constant which varies slowly. When N{epsilon}<<1, we find that a quantum adiabatic approximation is applicable, and use it to argue that at late times the geometry becomes smooth AdS{sub 5}xS{sup 5} again. When N{epsilon}>>1, we formulate a classical adiabatic perturbation theory based on coherent states which arises in the large N limit. For large values of the 't Hooft coupling this reproduces the supergravity results. For small 't Hooft coupling the coherent state calculations become involved and we cannot reach a definite conclusion. We argue that the final state should have a dual description which is mostly smooth AdS{sub 5} space with the possible presence of a small black hole.
Slowly Varying Dilaton Cosmologies and Their Field Theory Duals
Awad, Adel; Das, Sumit R.; Ghosh, Archisman; Oh, Jae-Hyuk; Trivedi, Sandip P.; /Tata Inst. /Stanford U., ITP /SLAC
2011-06-28
We consider a deformation of the AdS{sub 5} x S{sup 5} solution of IIB supergravity obtained by taking the boundary value of the dilaton to be time dependent. The time dependence is taken to be slowly varying on the AdS scale thereby introducing a small parameter {epsilon}. The boundary dilaton has a profile which asymptotes to a constant in the far past and future and attains a minimum value at intermediate times. We construct the sugra solution to first non-trivial order in {epsilon}, and find that it is smooth, horizon free, and asymptotically AdS{sub 5} x S{sup 5} in the far future. When the intermediate values of the dilaton becomes small enough the curvature becomes of order the string scale and the sugra approximation breaks down. The resulting dynamics is analysed in the dual SU(N) gauge theory on S{sup 3} with a time dependent coupling constant which varies slowly. When N{epsilon} << 1, we find that a quantum adiabatic approximation is applicable, and use it to argue that at late times the geometry becomes smooth AdS{sub 5} x S{sup 5} again. When N{epsilon} >> 1, we formulate a classical adiabatic perturbation theory based on coherent states which arises in the large N limit. For large values of the tHooft coupling this reproduces the supergravity results. For small 'tHooft coupling the coherent state calculations become involved and we cannot reach a definite conclusion. We argue that the final state should have a dual description which is mostly smooth AdS5 space with the possible presence of a small black hole.
Effects of turbulence and rotation on protostar formation as a precursor of massive black holes
NASA Astrophysics Data System (ADS)
Van Borm, C.; Bovino, S.; Latif, M. A.; Schleicher, D. R. G.; Spaans, M.; Grassi, T.
2014-12-01
Context. The seeds of the first supermassive black holes may have resulted from the direct collapse of hot primordial gas in ≳104 K haloes, forming a supermassive or quasi-star as an intermediate stage. Aims: We explore the formation of a protostar resulting from the collapse of primordial gas in the presence of a strong Lyman-Werner radiation background. Particularly, we investigate the impact of turbulence and rotation on the fragmentation behaviour of the gas cloud. We accomplish this goal by varying the initial turbulent and rotational velocities. Methods: We performed 3D adaptive mesh refinement simulations with a resolution of 64 cells per Jeans length using the ENZO code, simulating the formation of a protostar up to unprecedentedly high central densities of 1021 cm-3 and spatial scales of a few solar radii. To achieve this goal, we employed the KROME package to improve modelling of the chemical and thermal processes. Results: We find that the physical properties of the simulated gas clouds become similar on small scales, irrespective of the initial amount of turbulence and rotation. After the highest level of refinement was reached, the simulations have been evolved for an additional ~5 freefall times. A single bound clump with a radius of 2 × 10-2 AU and a mass of ~7 × 10-2 M⊙ is formed at the end of each simulation, marking the onset of protostar formation. No strong fragmentation is observed by the end of the simulations, regardless of the initial amount of turbulence or rotation, and high accretion rates of a few solar masses per year are found. Conclusions: Given such high accretion rates, a quasi-star of 105 M⊙ is expected to form within 105 years. Appendix A is available in electronic form at http://www.aanda.org
NASA Technical Reports Server (NTRS)
Kazanas, Demosthenes; Fukumura, K.
2009-01-01
We present detailed computations of photon orbits emitted by flares at the ISCO of accretion disks around rotating black holes. We show that for sufficiently large spin parameter, i.e. $a > 0.94 M$, following a flare at ISCO, a sufficient number of photons arrive at an observer after multiple orbits around the black hole, to produce an "photon echo" of constant lag, i.e. independent of the relative phase between the black hole and the observer, of $\\Delta T \\simeq 14 M$. This constant time delay, then, leads to the presence of a QPO in the source power spectrum at a frequency $\
NASA Astrophysics Data System (ADS)
Page, Don N.; Kubizňák, David; Vasudevan, Muraari; Krtouš, Pavel
2007-02-01
We explicitly exhibit n-1=[D/2]-1 constants of motion for geodesics in the general D-dimensional Kerr-NUT-AdS rotating black hole spacetime, arising from contractions of even powers of the 2-form obtained by contracting the geodesic velocity with the dual of the contraction of the velocity with the (D-2)-dimensional Killing-Yano tensor. These constants of motion are functionally independent of each other and of the D-n+1 constants of motion that arise from the metric and the D-n=[(D+1)/2] Killing vectors, making a total of D independent constants of motion in all dimensions D. The Poisson brackets of all pairs of these D constants are zero, so geodesic motion in these spacetimes is completely integrable.
Integrability of some charged rotating supergravity black hole solutions in four and five dimensions
NASA Astrophysics Data System (ADS)
Vasudevan, Muraari
2005-09-01
We study the integrability of geodesic flow in the background of some recently discovered charged rotating solutions of supergravity in four and five dimensions. Specifically, we work with the gauged multicharge Taub-NUT-Kerr-(anti-)de Sitter metric in four dimensions, and the U(1) 3 gauged charged-Kerr-(anti-)de Sitter black hole solution of N = 2 supergravity in five dimensions. We explicitly construct the nontrivial irreducible Killing tensors that permit separation of the Hamilton-Jacobi equation in these spacetimes. These results prove integrability for a large class of previously known supergravity solutions, including several BPS solitonic states. We also derive first-order equations of motion for particles in these backgrounds and examine some of their properties. Finally, we also examine the Klein-Gordon equation for a scalar field in these spacetimes and demonstrate separability.
Creation of a scalar potential in 2D dilaton gravity
Behrndt, K.
1994-09-01
The authors investigate quantum corrections of the 2-d dilaton gravity near the singularity. Their motivation comes from a s-wave reduced cosmological solution which is classically singular in the scalar fields (dilaton and moduli). As a result they find, that the singularity disappears and a dilaton/moduli potential is created.
New soft theorems for the gravity dilaton and the Nambu-Goldstone dilaton at subsubleading order
NASA Astrophysics Data System (ADS)
Di Vecchia, Paolo; Marotta, Raffaele; Mojaza, Matin; Nohle, Josh
2016-04-01
We study the soft behavior of two seemingly different particles that are both referred to as dilatons in the literature, namely the one that appears in theories of gravity and in string theory and the Nambu-Goldstone boson of spontaneously broken conformal invariance. Our primary result is the discovery of a soft theorem at subsubleading order for each dilaton, which in both cases contains the operator of special conformal transformations. Interesting similarities as well as differences between the dilaton soft theorems are discussed.
NASA Astrophysics Data System (ADS)
Wu, Shuang-Qing
2009-08-01
The aim of this paper is to investigate the separability of a spin-1/2 spinor field in a five-dimensional rotating, charged black hole constructed by Cvetič and Youm in string theory, in the case when three U(1) charges are set equal. This black hole solution represents a natural generalization of the famous four-dimensional Kerr-Newman solution to five dimensions with the inclusion of a Chern-Simons term to the Maxwell equation. It is shown that the usual Dirac equation cannot be separated by variables in this general spacetime with two independent angular momenta. However if one supplements an additional counterterm into the usual Dirac operator, then the modified Dirac equation for the spin-1/2 spinor particles is separable in this rotating, charged Einstein-Maxwell-Chern-Simons black hole background geometry. A first-order symmetry operator that commutes with the modified Dirac operator has exactly the same form as that previously found in the uncharged Myers-Perry black hole case. It is expressed in terms of a rank-three totally antisymmetric tensor and its covariant derivative. This tensor obeys a generalized Killing-Yano equation and its square is a second-order symmetric Stäckel-Killing tensor admitted by the five-dimensional rotating, charged black hole spacetime.
Wu Shuangqing
2009-08-15
The aim of this paper is to investigate the separability of a spin-1/2 spinor field in a five-dimensional rotating, charged black hole constructed by Cvetic and Youm in string theory, in the case when three U(1) charges are set equal. This black hole solution represents a natural generalization of the famous four-dimensional Kerr-Newman solution to five dimensions with the inclusion of a Chern-Simons term to the Maxwell equation. It is shown that the usual Dirac equation cannot be separated by variables in this general spacetime with two independent angular momenta. However if one supplements an additional counterterm into the usual Dirac operator, then the modified Dirac equation for the spin-1/2 spinor particles is separable in this rotating, charged Einstein-Maxwell-Chern-Simons black hole background geometry. A first-order symmetry operator that commutes with the modified Dirac operator has exactly the same form as that previously found in the uncharged Myers-Perry black hole case. It is expressed in terms of a rank-three totally antisymmetric tensor and its covariant derivative. This tensor obeys a generalized Killing-Yano equation and its square is a second-order symmetric Staeckel-Killing tensor admitted by the five-dimensional rotating, charged black hole spacetime.
The massive Dirac field on a rotating black hole spacetime: angular solutions
NASA Astrophysics Data System (ADS)
Dolan, Sam R.; Gair, Jonathan R.
2009-09-01
The massive Dirac equation on a Kerr-Newman background may be solved by the method of separation of variables. The radial and angular equations are coupled via an angular eigenvalue, which is determined from the Chandrasekhar-Page (CP) equation. Obtaining accurate angular eigenvalues is a key step in studying scattering, absorption and emission of the fermionic field. Here we introduce a new method for finding solutions of the CP equation. First, we introduce a novel representation for the spin-half spherical harmonics. Next, we decompose the angular solutions of the CP equation (the mass-dependent spin-half spheroidal harmonics) in the spherical basis. The method yields a three-term recurrence relation which may be solved numerically via continued-fraction methods, or perturbatively to obtain a series expansion for the eigenvalues. In the case μ = ±ω (where ω and μ are the frequency and mass of the fermion) we obtain eigenvalues and eigenfunctions in a closed form. We study the eigenvalue spectrum and the zeros of the maximally co-rotating mode. We compare our results with previous studies, and uncover and correct some errors in the literature. We provide series expansions, tables of eigenvalues and numerical fits across a wide parameter range and present plots of a selection of eigenfunctions. It is hoped that this study will be a useful resource for all researchers interested in the Dirac equation on a rotating black hole background.
Modulus stabilization in higher curvature dilaton gravity
NASA Astrophysics Data System (ADS)
Choudhury, Sayantan; Mitra, Joydip; SenGupta, Soumitra
2014-08-01
We propose a framework of modulus stabilization in two brane warped geometry scenario in presence of higher curvature gravity and dilaton in bulk space-time. In the prescribed setup we study various features of the stabilized potential for the modulus field, generated by a bulk scalar degrees of freedom with quartic interactions localized on the two 3-branes placed at the orbifold fixed points. We determine the parameter space for the gravidilaton and Gauss-Bonnet couplings required to stabilize the modulus in such higher curvature dilaton gravity setup.
Dilaton cosmology, noncommutativity, and generalized uncertainty principle
Vakili, Babak
2008-02-15
The effects of noncommutativity and of the existence of a minimal length on the phase space of a dilatonic cosmological model are investigated. The existence of a minimum length results in the generalized uncertainty principle (GUP), which is a deformed Heisenberg algebra between the minisuperspace variables and their momenta operators. I extend these deformed commutating relations to the corresponding deformed Poisson algebra. For an exponential dilaton potential, the exact classical and quantum solutions in the commutative and noncommutative cases, and some approximate analytical solutions in the case of GUP, are presented and compared.
Quantum naked singularities in 2D dilaton gravity
NASA Astrophysics Data System (ADS)
Vaz, Cenalo; Witten, Louis
1997-02-01
Roughly speaking, naked singularities are singularities that may be seen by timelike observers. The Cosmic Censorship conjecture forbids their existence by stating that a reasonable system of energy will not, under reasonable conditions, collapse into a naked singularity. There are however many (classical) counter-examples to this conjecture in the literature. We propose a defense of the conjecture through the quantum theory. We will show that the Hawking effect and the accompanying back reaction, when consistently applied to naked singularities in two-dimensional models of dilaton gravity with matter and a cosmological constant, prevent their formation by causing them to explode or to emit radiation catastrophically. This contrasts with black holes which radiate slowly. If this phenomenon is reproduced in the four-dimensional world, the radiation accompanying the formation of naked singularities should have observable consequences.
First law of black Saturn thermodynamics
Rogatko, Marek
2007-06-15
The physical process version and equilibrium state version of the first law of thermodynamics for a black object consisting of n-dimensional charged stationary axisymmetric black hole surrounded by a black rings, the so-called black Saturn, was derived. The general setting for our derivations is n-dimensional dilaton gravity with p+1 strength form fields.
Spherical and planar three-dimensional anti-de Sitter black holes
NASA Astrophysics Data System (ADS)
Zanchin, Vilson T.; Miranda, Alex S.
2004-02-01
The technique of dimensional reduction was used in a recent paper (Zanchin V T, Kleber A and Lemos J P S 2002 Phys. Rev. D 66 064022) where a three-dimensional (3D) Einstein Maxwell dilaton theory was built from the usual four-dimensional (4D) Einstein Maxwell Hilbert action for general relativity. Starting from a class of 4D toroidal black holes in asymptotically anti-de Sitter (AdS) spacetimes several 3D black holes were obtained and studied in such a context. In the present work we choose a particular case of the 3D action which presents Maxwell field, dilaton field and an extra scalar field, besides gravity field and a negative cosmological constant, and obtain new 3D static black hole solutions whose horizons may have spherical or planar topology. We show that there is a 3D static spherically symmetric solution analogous to the 4D Reissner Nordström AdS black hole, and obtain other new 3D black holes with planar topology. From the static spherical solutions, new rotating 3D black holes are also obtained and analysed in some detail.
NASA Astrophysics Data System (ADS)
Liu, Hang; Meng, Xin-he
2016-08-01
In this paper, we investigate the angular momentum independence of the entropy sum and product for AdS rotating black holes based on the first law of thermodynamics and a mathematical lemma related to Vandermonde determinant. The advantage of this method is that the explicit forms of the spacetime metric, black hole mass and charge are not needed but the Hawking temperature and entropy formula on the horizons are necessary for static black holes, while our calculations require the expressions of metric and angular velocity formula. We find that the entropy sum is always independent of angular momentum for all dimensions and the angular momentum-independence of entropy product only holds for the dimensions d > 4 with at least one rotation parameter ai = 0, while the mass-free of entropy sum and entropy product for rotating black holes only stand for higher dimensions (d > 4) and for all dimensions, respectively. On the other hand, we find that the introduction of a negative cosmological constant does not affect the angular momentum-free of entropy sum and product but the criterion for angular momentum-independence of entropy product will be affected.
NASA Astrophysics Data System (ADS)
Giri, K.; Chang, H.-K.
2015-12-01
In this paper, we present the time evolution of a rotationally axisymmetric gas ring around a non rotating black hole using two dimensional grid-based hydrodynamics simulations. We show the way in which angular momentum transport is included in simulations of non-selfgravitating accretion of matter towards a black hole. We use the Shakura-Sunyaev α viscosity prescription to estimate the turbulent viscosity for all major viscous stress tensors. We investigate how a gas ring which is initially assumed to rotate with Keplerian angular velocity is accreted onto a black hole and hence forms an accretion disc in the presence of turbulent viscosity. We show that a centrifugally pressure supported sub-Keplerian flow with shocks forms when the ring starts to disperse with inclusion of relatively small amount of viscosity. But, if the viscosity is above the critical value, the shock disappears altogether and the whole disc becomes Keplerian which is subsonic everywhere except in a region close to the horizon, where it supersonically enters to the black hole. We discovered a multiple valued Mach number solution and the corresponding density distributions that connect matter (a) from the initial Keplerian gas ring to a sub-Keplerian disc with shocks in presence of small amount of viscosity and (b) from the sub-Keplerian flow to a Keplerian disc in presence of huge amount of viscosity. We calculate the temporal variations of the magnitude of various time scales which ensure us about the stability of the flow.
Extended 2D generalized dilaton gravity theories
NASA Astrophysics Data System (ADS)
de Mello, R. O.
2008-09-01
We show that an anomaly-free description of matter in (1+1) dimensions requires a deformation of the 2D relativity principle, which introduces a non-trivial centre in the 2D Poincaré algebra. Then we work out the reduced phase space of the anomaly-free 2D relativistic particle, in order to show that it lives in a noncommutative 2D Minkowski space. Moreover, we build a Gaussian wave packet to show that a Planck length is well defined in two dimensions. In order to provide a gravitational interpretation for this noncommutativity, we propose to extend the usual 2D generalized dilaton gravity models by a specific Maxwell component, which guages the extra symmetry associated with the centre of the 2D Poincaré algebra. In addition, we show that this extension is a high energy correction to the unextended dilaton theories that can affect the topology of spacetime. Further, we couple a test particle to the general extended dilaton models with the purpose of showing that they predict a noncommutativity in curved spacetime, which is locally described by a Moyal star product in the low energy limit. We also conjecture a probable generalization of this result, which provides strong evidence that the noncommutativity is described by a certain star product which is not of the Moyal type at high energies. Finally, we prove that the extended dilaton theories can be formulated as Poisson Sigma models based on a nonlinear deformation of the extended Poincaré algebra.
Renormalized stress-energy tensor near the horizon of a slowly evolving, rotating black hole
NASA Astrophysics Data System (ADS)
Frolov, Valery P.; Thorne, Kip S.
1989-04-01
The renormalized expectation value of the stress-energy tensor
A Particle Probing Thermodynamics in Rotating AdS Black Hole
NASA Astrophysics Data System (ADS)
Gwak, Bogeun; Lee, Bum-Hoon
2016-07-01
We briefly review the thermodynamics of a probe particle absorption to a black hole in this proceeding. The particle energy has a relation to its momenta at the horizon of the black hole. Following this relation, the particle infinitesimally changes the black hole mass and momenta. Under these changes, the changes of properties of the black hole are consistent with the laws of thermodynamics.
NASA Astrophysics Data System (ADS)
Mantovani, D.; Veste, M.; Freese, D.
2012-04-01
The early successional tree species Robinia pseudoacacia L. demonstrates a high potential for biomass production in short rotation plantations and agroforestry systems. On marginal lands and recultivated areas, often characterized by poor edaphic conditions, black locust is already successfully cropped. In southern Brandenburg (East Germany), vast areas have been exploited for lignite open cast mining and the outcome is a drastic alteration of the top soil layer and subsurface geological structure, causing a radical change of the hydrologic cycle. Soil poor in nutrient and carbon, combined with low rainfall, limits the reclamation of these areas and their use for conventional agriculture. However, promising results have been obtained by the establishment of black locust for bioenergy production. For the evaluation of the black locust growth potential in southern Brandenburg with its sandy soils and low annual mean rainfall, detailed information about the link between growth, transpiration and soil water availability are needed. Therefore, we determined the biomass-transpiration relation and formulated the equation that describes the intertwined interaction between water use and biomass production. The equation will be integrated into mathematical tools. To reduce the numerous environmental variables involved in field experiments, we grew black locust under semi-controlled environmental conditions by using wick lysimeters. The lysimeters were filled with sandy loam soil and water was supplied solely by an automatic irrigation system in relation to the volumetric soil water content (7%, 10%, and 14%). Rainfall is excluded by a light transmissive roof. Water use efficiency (WUE) at whole plant level is evaluated by the ratio between the biomass produced during the vegetation period and the cumulative daily water use. The study encompasses ecophysiological investigations of the gas exchange (H2O and CO2) on single leaves, to evaluate the influence of the stomata
Extreme luminosities in ejecta produced by intermittent outflows around rotating black holes
NASA Astrophysics Data System (ADS)
van Putten, Maurice H. P. M.
2015-02-01
Extreme sources in the Transient Universe show evidence of relativistic outflows from intermittent inner engines, such as cosmological gamma-ray bursts (GRBs). They probably derive from rotating back holes interacting with surrounding matter. We show that these interactions are enhanced inversely proportional to the duty cycle in advection of magnetic flux, as may apply at high accretion rates. We demonstrate the morphology and ballistic propagation of relativistic ejecta from burst outflows by numerical simulations in relativistic magnetohydrodynamics. Applied to stellar mass black holes in core-collapse of massive stars, it provides a robust explosion mechanism as a function of total energy output. At breakout, these ejecta may produce a low-luminosity GRB. A long GRB may ensue from an additional ultrarelativistic baryon-poor inner jet from a sufficiently long-lived intermittent inner engine. The simulations demonstrate a complex geometry in mergers of successive ejecta, whose mixing and shocks provide a pathway to broad-band high-energy emission from magnetic reconnection and shocks.