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.
Extremal charged rotating dilaton black holes in odd dimensions
Allahverdizadeh, Masoud; Kunz, Jutta; Navarro-Lerida, Francisco
2010-09-15
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.
Stationary scalar clouds around maximally rotating linear dilaton black holes
NASA Astrophysics Data System (ADS)
Tokgoz, G.; Sakalli, I.
2017-06-01
We investigate the wave dynamics of a charged massive scalar field propagating in a maximally rotating (extremal) linear dilaton black hole geometry. We prove the existence of a discrete and infinite family of resonances describing non-decaying stationary scalar configurations (clouds) enclosing these rapidly rotating black holes. The results obtained signal the potential stationary scalar field distributions (dark matter) around the extremal linear dilaton black holes. In particular, we analytically compute the effective heights of those clouds above the center of the black hole.
Slowly rotating dilaton black hole in anti-de Sitter spacetime
Ghosh, Tanwi; SenGupta, Soumitra
2007-10-15
A rotating dilaton black hole solution for asymptotically anti-de Sitter spacetime is obtained in the small angular momentum limit with an appropriate combination of three Liouville-type dilaton potentials. The angular momentum, magnetic dipole moment, and the gyromagnetic ratio of such a black hole are determined for arbitrary values of the dilaton-electromagnetic coupling parameter.
Charged rotating dilaton black strings in (A)dS spaces
Sheykhi, Ahmad
2008-09-15
We derive a class of charged rotating dilaton black string solutions in the background of anti-de Sitter spaces with an appropriate combination of three Liouville-type dilaton potentials. We also present the suitable counterterm which removes the divergences of the action in the presence of dilaton potential. The solutions are analyzed and their thermodynamics are discussed by using the counterterm method.
Rotating black holes in dilatonic Einstein-Gauss-Bonnet theory.
Kleihaus, Burkhard; Kunz, Jutta; Radu, Eugen
2011-04-15
We construct generalizations of the Kerr black holes by including higher-curvature corrections in the form of the Gauss-Bonnet density coupled to the dilaton. We show that the domain of existence of these Einstein-Gauss-Bonnet-dilaton (EGBD) black holes is bounded by the Kerr black holes, the critical EGBD black holes, and the singular extremal EGBD solutions. The angular momentum of the EGBD black holes can exceed the Kerr bound. The EGBD black holes satisfy a generalized Smarr relation. We also compare their innermost stable circular orbits with those of the Kerr black holes and show the existence of differences which might be observable in astrophysical systems.
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.
NASA Astrophysics Data System (ADS)
Sakalli, I.
2016-10-01
Charged massive scalar field perturbations are studied in the gravitational, electromagnetic, dilaton, and axion fields of rotating linear dilaton black holes. In this geometry, we separate the covariant Klein-Gordon equation into radial and angular parts and obtain the exact solutions of both the equations in terms of the confluent Heun functions. Using the radial solution, we study the problems of resonant frequencies, entropy/area quantization, and greybody factor. We also analyze the behavior of the wave solutions near the event horizon of the rotating linear dilaton black hole and derive its Hawking temperature via the Damour-Ruffini-Sannan method.
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.
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.
Fermions tunnelling from the charged dilatonic black holes
NASA Astrophysics Data System (ADS)
Chen, De-You; Jiang, Qing-Quan; Zu, Xiao-Tao
2008-10-01
Kerner and Mann's recent work shows that for an uncharged and non-rotating black hole its Hawking temperature can be correctly derived by fermions tunnelling from its horizons. In this paper, our main work is to improve the analysis to deal with charged fermion tunnelling from the general dilatonic black holes, specifically including the charged, spherically symmetric dilatonic black hole, the rotating Einstein Maxwell dilaton axion (EMDA) black hole and the rotating Kaluza Klein (KK) black hole. As a result, the correct Hawking temperatures are well recovered by charged fermions tunnelling from these black holes.
Rotating black holes in Einstein-dilaton-Gauss-Bonnet gravity with finite coupling
NASA Astrophysics Data System (ADS)
Maselli, Andrea; Pani, Paolo; Gualtieri, Leonardo; Ferrari, Valeria
2015-10-01
Among various strong-curvature extensions of general relativity, Einstein-dilaton-Gauss-Bonnet gravity stands out as the only nontrivial theory containing quadratic curvature corrections while being free from the Ostrogradsky instability to any order in the coupling parameter. We derive an approximate stationary and axisymmetric black hole solution of this gravitational theory in closed form, which is of fifth order in the black hole spin and of seventh order in the coupling parameter of the theory. This extends previous work that obtained the corrections to the metric only to second order in the spin and at the leading order in the coupling parameter, and allows us to consider values of the coupling parameter close to the maximum permitted by theoretical constraints. We compute some quantities which characterize this solution, such as the dilaton charge, the moment of inertia, and the quadrupole moment, and its geodesic structure, including the innermost stable circular orbit and the epicyclic frequencies for massive particles. The latter provides a valuable tool to test general relativity against strong-curvature corrections through observations of the electromagnetic spectrum of accreting black holes.
Extremal Einstein-Born-Infeld black holes in dilaton gravity
NASA Astrophysics Data System (ADS)
Rad, Masoud Sepehri; Hendi, Seyed Hossein; Matsuno, Ken; Sheykhi, Ahmad
2015-12-01
Motivated by considerable interests of Myers-Perry black holes, we employ the perturbative method to obtain a family of extremal charged rotating black hole solutions in odd dimensional Einstein-Born-Infeld-dilaton gravity. We start with an extremal Myers-Perry black hole with equal angular momenta, and then by adding the dilaton field and the nonlinear Born-Infeld electrodynamics, we find an extremal nonlinearly charged rotating black holes. The perturbative parameter is assumed to be the electric charge q and the perturbations are performed up to the third order. We then study the physical properties of these Born-Infeld-dilaton black holes. In particular, we show that the perturbative parameter, q, the dilaton coupling constant, α, and the Born-Infeld parameter, β, modify the Smarr formula and the values of the gyromagnetic ratio of the extremal charged rotating black holes.
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
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.
Dilaton field released under collision of dilatonic black holes with Gauss-Bonnet term
NASA Astrophysics Data System (ADS)
Gwak, Bogeun; Ro, Daeho
2017-08-01
We investigate the upper limit of the gravitational radiation released upon the collision of two dilatonic black holes by analyzing the Gauss-Bonnet term. Dilatonic black holes have a dilaton hair coupled with this term. Using the laws of thermodynamics, the upper limit of the radiation is obtained, which reflected the effects of the dilaton hair. The amount of radiation released is greater than that emitted by a Schwarzschild black hole due to the contribution from the dilaton hair. In the collision, most of the dilaton hair can be released through radiation, where the energy radiated by the dilaton hair is maximized when the horizon of one black hole is minimized for a fixed second black hole.
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.
Acceleration of particles in Einstein-Maxwell-dilaton black holes
NASA Astrophysics Data System (ADS)
Mao, Pu-Jian; Li, Ran; Jia, Lin-Yu; Ren, Ji-Rong
2017-06-01
It has recently been pointed out that, under certain conditions, the energy of particles accelerated by black holes in the center-of-mass frame can become arbitrarily high. In this paper, we study the collision of two particles in the case of four-dimensional charged nonrotating, extremal charged rotating and near-extremal charged rotating Kaluza-Klein black holes as well as the naked singularity case in Einstein-Maxwell-dilaton theory. We find that the center-of-mass energy for a pair of colliding particles is unlimited at the horizon of charged nonrotating Kaluza-Klein black holes, extremal charged rotating Kaluza-Klein black holes and in the naked singularity case. Supported by NSFC (11575202, 11205048), Foundation for Young Key Teacher of Henan Normal University and Cuiying Programme of Lanzhou University (225000-582404) and Fundamental Research Fund for Physics and Mathematic of Lanzhou University (LZULL200911)
Hawking radiation from dilatonic black holes via anomalies
Jiang Qingquan; Cai Xu; Wu Shuangqing
2007-03-15
Recently, Hawking radiation from a Schwarzschild-type black hole via a gravitational anomaly at the horizon has been derived by Robinson and Wilczek. Their result shows that, in order to demand general coordinate covariance at the quantum level to hold in the effective theory, the flux of the energy-momentum tensor required to cancel the gravitational anomaly at the horizon of the black hole is exactly equal to that of (1+1)-dimensional blackbody radiation at the Hawking temperature. In this paper, we attempt to apply the analysis to derive Hawking radiation from the event horizons of static, spherically symmetric dilatonic black holes with arbitrary coupling constant {alpha}, and that from the rotating Kaluza-Klein ({alpha}={radical}(3)) as well as the Kerr-Sen ({alpha}=1) black holes via an anomalous point of view. Our results support Robinson and Wilczek's opinion. In addition, the properties of the obtained physical quantities near the extreme limit are qualitatively discussed.
Testing Einstein-dilaton-Gauss-Bonnet gravity with the reflection spectrum of accreting black holes
NASA Astrophysics Data System (ADS)
Zhang, Hao; Zhou, Menglei; Bambi, Cosimo; Kleihaus, Burkhard; Kunz, Jutta; Radu, Eugen
2017-05-01
Einstein-dilaton-Gauss-Bonnet gravity is a theoretically well-motivated alternative theory of gravity emerging as a low-energy four-dimensional model from heterotic string theory. Its rotating black hole solutions are known numerically and can have macroscopic deviations from the Kerr black holes of Einstein's gravity. Einstein-dilaton-Gauss-Bonnet gravity can thus be tested with observations of astrophysical black holes. In the present paper, we simulate observations of the reflection spectrum of thin accretion disks with present and future x-ray facilities to understand whether x-ray reflection spectroscopy can distinguish the black holes in Einstein-dilaton-Gauss-Bonnet gravity from those in Einstein's gravity. We find that this is definitively out of reach for present x-ray missions, but it may be achieved with the next generation of facilities.
Transmission Probability for Charged Dilatonic Black Holes in Various Dimensions
NASA Astrophysics Data System (ADS)
Ngampitipan, Tritos; Boonserm, Petarpa
A dilaton is a theoretical particle, which results from the Plank mass raised to a dynamical field. In this paper, the rigorous bounds on the transmission probabilities for charged black holes, coupled to a dilaton field in various dimensions, are calculated. The results show that in the absence of the cosmological constant, the black holes in (2 + 1) dimensions have only one event horizon. Moreover, the charges of the black holes can increase the transmission probabilities. However, for the black holes in (3 + 1) dimensions, the charges of the black holes can filter Hawking radiation.
Black Hole in a Model with Dilaton and Monopole Fields
NASA Astrophysics Data System (ADS)
Kyriakopoulos, E.
We present an exact black hole solution in a model having besides gravity a dilaton and a monopole field. The solution has three free parameters, which can be identified with the monopole charge, the ADM mass, and the dilaton charge. The metric is asymptotically flat and has two horizons and irremovable singularity only at r = 0. The dilaton field is singular only at r = 0. The dominant and the strong energy condition are satisfied outside and on the external horizon. According to a formulation of the no hair conjecture, the solution is "hairy." Also the well-known GHS-GM solution is obtained from our solution for certain values of its parameters.
Mass formulae of four-dimensional dilaton black holes
NASA Astrophysics Data System (ADS)
Okai, Tadashi
1994-02-01
Integral and differential mass formulae of 4-dimensional stationary and axisymmetric Einstein-Maxwell-dilaton systems are derived. The total mass (energy) of these systems are expressed in terms of other physical quantities such as electric charge of the black hole suitably modified due to the existence of the dilaton field. It is shown that when we vary slightly the fields (metric of the spacetime $g_{\\mu\
Quasinormal modes of Einstein-Gauss-Bonnet-dilaton black holes
NASA Astrophysics Data System (ADS)
Blázquez-Salcedo, Jose Luis; Khoo, Fech Scen; Kunz, Jutta
2017-09-01
We study quasinormal modes of static Einstein-Gauss-Bonnet-dilaton black holes. Both axial and polar perturbations are considered and studied from l =0 to l =3 . We emphasize the difference in the spectrum between the Schwarzschild solutions and dilatonic black holes. At large Gauss-Bonnet coupling constant, a small secondary branch of black holes is present, when the dilaton coupling is sufficiently strong. The modes of the primary branch can differ from the Schwarzschild modes up to 10%. The secondary branch is unstable and possesses long-lived modes. We address the possible effects of these modes on future observations of gravitational waves emitted during the ringdown phase of astrophysical black holes.
Letter: Dilatonic Black Hole Entropy Without Brick Walls
NASA Astrophysics Data System (ADS)
Ren, Zhao; Sheng-Li, Zhang
2004-09-01
The properties of the thermal radiation are discussed by using the new equation of state density motivated by the generalized uncertainty relation in the quantum gravity. There is no burst at the last stage of the emission of dilatonic black hole. When the new equation of state density is utilized to investigate the entropy of a bosonic field and fermionic field outside the horizon of a static dilatonic black hole, the divergence appearing in the brick wall model is removed, without any cutoff. It is derived from the contribution of the vicinity of the horizon that the entropy is proportional to the horizon area.
Heat engines for dilatonic Born-Infeld black holes
NASA Astrophysics Data System (ADS)
Bhamidipati, Chandrasekhar; Yerra, Pavan Kumar
2017-08-01
In the context of dilaton coupled Einstein gravity with a negative cosmological constant and a Born-Infeld field, we study heat engines where a charged black hole is the working substance. Using the existence of a notion of thermodynamic mass and volume (which depend on the dilaton coupling), the mechanical work takes place via the pdV terms present in the first law of extended gravitational thermodynamics. The efficiency is analyzed as a function of dilaton and Born-Infeld couplings, and the results are compared with analogous computations in the related conformal solutions in the Brans-Dicke-Born-Infeld theory and black holes in anti-de Sitter space-time.
Thermodynamics of novel charged dilatonic BTZ black holes
NASA Astrophysics Data System (ADS)
Dehghani, M.
2017-10-01
In this paper, the three-dimensional Einstein-Maxwell theory in the presence of a dilatonic scalar field has been studied. It has been shown that the dilatonic potential must be considered as the linear combination of two Liouville-type potentials. Two new classes of charged dilatonic BTZ black holes, as the exact solutions to the coupled scalar, vector and tensor field equations, have been obtained and their properties have been studied. The conserved charge and mass of the new black holes have been calculated, making use of the Gauss's law and Abbott-Deser proposal, respectively. Through comparison of the thermodynamical extensive quantities (i.e. temperature and entropy) obtained from both, the geometrical and the thermodynamical methods, the validity of the first law of black hole thermodynamics has been confirmed for both of the new black holes we just obtained. A black hole thermal stability or phase transition analysis has been performed, making use of the canonical ensemble method. Regarding the black hole heat capacity, it has been found that for either of the new black hole solutions there are some specific ranges in such a way that the black holes with the horizon radius in these ranges are locally stable. The points of type one and type two phase transitions have been determined. The black holes, with the horizon radius equal to the transition points are unstable. They undergo type one or type two phase transitions to be stabilized.
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.
Shadows of Einstein-dilaton-Gauss-Bonnet black holes
NASA Astrophysics Data System (ADS)
Cunha, Pedro V. P.; Herdeiro, Carlos A. R.; Kleihaus, Burkhard; Kunz, Jutta; Radu, Eugen
2017-05-01
We study the shadows of the fully non-linear, asymptotically flat Einstein-dilaton-Gauss-Bonnet (EdGB) black holes (BHs), for both static and rotating solutions. We find that, in all cases, these shadows are smaller than for comparable Kerr BHs, i.e. with the same total mass and angular momentum under similar observation conditions. In order to compare both cases we provide quantitative shadow parameters, observing in particular that the differences in the shadows mean radii are never larger than the percent level. Therefore, generically, EdGB BHs cannot be excluded by (near future) shadow observations alone. On the theoretical side, we find no clear signature of some exotic features of EdGB BHs on the corresponding shadows, such as the regions of negative (Komar, say) energy density outside the horizon. We speculate that this is due to the fact that the Komar energy interior to the light rings (or more precisely, the surfaces of constant radial coordinate that intersect the light rings in the equatorial plane) is always smaller than the ADM mass, and consequently the corresponding shadows are smaller than those of comparable Kerr BHs. The analysis herein provides a clear example that it is the light ring impact parameter, rather than its ;size;, that determines a BH shadow.
Fermions tunneling from the Horowitz-Strominger Dilaton black hole
NASA Astrophysics Data System (ADS)
Li, Qiang; Zeng, Xiaoxiong
2009-06-01
Based on the work of Kerner and Mann, fermions tunneling from the Horowitz-Strominger Dilaton black hole on the membrane is studied. Owing to the coupling among electromagnetic field, matter field and gravity field, the Dirac equation of charged particles is introduced, and according to that, the expected emission temperature is obtained. After the self-gravitational interaction is considered, it is found that the tunneling rate of fermions also satisfies the underlying Unitary theory as the case of scalar particles.
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.
Dilatonic BTZ black holes with power-law field
NASA Astrophysics Data System (ADS)
Hendi, S. H.; Eslam Panah, B.; Panahiyan, S.; Sheykhi, A.
2017-04-01
Motivated by low energy effective action of string theory and numerous applications of BTZ black holes, we will consider minimal coupling between dilaton and nonlinear electromagnetic fields in three dimensions. The main goal is studying thermodynamical structure of black holes in this set up. Temperature and heat capacity of these black holes are investigated and a picture regarding their phase transitions is given. In addition, the role and importance of studying the mass of black holes is highlighted. We will see how different parameters modify thermodynamical quantities, hence thermodynamical structure of these black holes. In addition, geometrical thermodynamics is used to investigate thermodynamical properties of these black holes. In this regard, the successful method is presented and the nature of interaction around bound and phase transition points is studied.
NASA Astrophysics Data System (ADS)
Dayyani, Z.; Sheykhi, A.; Dehghani, M. H.
2017-04-01
We investigate the critical behavior of a (n +1 )-dimensional topological dilaton black holes in an extended phase space in both canonical and grand-canonical ensembles, when the gauge field is in the form of a power-Maxwell field. In order to do this, we introduce for the first time the counterterms that remove the divergences of the action in dilaton gravity for the solutions with curved boundary. Using the counterterm method, we calculate the conserved quantities and the action and, therefore, the Gibbs free energy in both the canonical and grand-canonical ensembles. We treat the cosmological constant as a thermodynamic pressure, and its conjugate quantity as a thermodynamic volume. In the presence of the power-Maxwell field, we find an analogy between the topological dilaton black holes with a van der Walls liquid-gas system in all dimensions provided the dilaton coupling constant α and the power parameter p are chosen properly. Interestingly enough, we observe that the power-Maxwell dilaton black holes admit the phase transition in both canonical and grand-canonical ensembles. This is in contrast to RN-AdS, Einstein-Maxwell-dilaton and Born-Infeld-dilaton black holes, which only admit the phase transition in the canonical ensemble. In addition, we calculate the critical quantities and show that they depend on α , n and p . Finally, we obtain the critical exponents in the two ensembles and show that they are independent of the model parameters and have the same values as in the mean-field theory.
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.
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.
Einstein-Maxwell-dilaton phantom black holes: Thermodynamics and geometrothermodynamics
NASA Astrophysics Data System (ADS)
Quevedo, Hernando; Quevedo, María N.; Sánchez, Alberto
2016-07-01
We use the Legendre-invariant formalism of geometrothermodynamics to investigate the geometric properties of the equilibrium space of a spherically symmetric phantom black hole with electric charge and dilaton. We find that at certain points of the equilibrium space the thermodynamic curvature is characterized by the presence of singularities that are interpreted as phase transitions. We also investigate the phase transition structure by using the standard approach of black hole thermodynamics based upon the analysis of the heat capacity and response functions. We show compatibility between the two approaches. In addition, a new type of phase transition is found, which is due to the presence of phantom energy and corresponds to a transition between black hole states with different stability properties.
Hamiltonian thermodynamics of three-dimensional dilatonic black holes
NASA Astrophysics Data System (ADS)
Dias, Gonçalo A. S.; Lemos, José P. S.
2008-08-01
The action for a class of three-dimensional dilaton-gravity theories with a negative cosmological constant can be recast in a Brans-Dicke type action, with its free ω parameter. These theories have static spherically symmetric black holes. Those with well formulated asymptotics are studied through a Hamiltonian formalism, and their thermodynamical properties are found out. The theories studied are general relativity (ω→∞), a dimensionally reduced cylindrical four-dimensional general relativity theory (ω=0), and a theory representing a class of theories (ω=-3). 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 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 one pair of canonical coordinates {M,PM}, M being the mass parameter and PM its conjugate momenta The resulting Hamiltonian is a sum of boundary terms only. A quantization of the theory is performed. The Schrödinger evolution operator is constructed, the trace is taken, and the partition function of the canonical ensemble is obtained. The black hole entropies differ, in general, from the usual quarter of the horizon area due to the dilaton.
Hamiltonian thermodynamics of charged three-dimensional dilatonic black holes
NASA Astrophysics Data System (ADS)
Dias, Gonçalo A. S.; Lemos, José P. S.
2008-10-01
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 ω 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 (ω→±∞), a dimensionally reduced cylindrical four-dimensional general relativity theory (ω=0), and a theory representing a class of theories (ω=-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,PM;Q,PQ}, where M is the mass parameter, which for ω<-(3)/(2) and for ω=±∞ needs a careful renormalization, PM is the conjugate momenta of M, Q is the charge parameter, and PQ is its conjugate momentum. The resulting Hamiltonian is a sum of boundary terms only. A quantization of the theory is performed. The Schrödinger 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 ϕ¯. Like the uncharged cases studied previously, the charged black hole entropies differ, in general, from the usual quarter of the horizon area due to the dilaton.
NASA Astrophysics Data System (ADS)
Sheykhi, A.; Naeimipour, F.; Zebarjad, S. M.
2015-06-01
Considering the Lagrangian of the logarithmic nonlinear electrodynamics in the presence of a scalar dilaton field, we obtain a new class of topological black hole solutions of Einstein-dilaton gravity with two Liouville-type dilaton potentials. Black hole horizons and cosmological horizons, in these spacetimes, can be a two-dimensional positive, zero, or negative constant curvature surface. We find that the behavior of the electric field crucially depends on the dilaton coupling constant α . For small α , the electric field diverges near the origin, although its divergency is weaker than the linear Maxwell field. However, with increasing α , the behavior of the electric field, near the origin, approaches to that of the Maxwell field. We also study casual structure, asymptotic behavior, and physical properties of the solutions. We find that, depending on the model parameters, the topological dilaton black holes may have one or two horizons, and even in some cases we encounter a naked singularity without horizon. We compute the conserved and thermodynamic quantities of the spacetime and investigate that these quantities satisfy the first law of thermodynamics. We also probe thermal stability in the canonical and grand canonical ensembles and disclose the effects of the dilaton field as well as nonlinear parameter on the thermal stability of the solutions. Finally, we investigate thermodynamical geometry of the obtained solutions by introducing a new metric and studying the phase transition points due to the divergency of the Ricci scalar. We find that the dilaton field affects the phase transition points of the system.
An alternative perspective to observe the critical phenomena of dilaton black holes
NASA Astrophysics Data System (ADS)
Mo, Jie-Xiong
2017-08-01
The critical phenomena of dilaton black holes are probed from a totally different perspective other than the P- v criticality and the q- U criticality discussed in former literature. We investigate not only the two point correlation function but also the entanglement entropy of dilaton black holes. For both the two point correlation function and the entanglement entropy we consider 4× 2× 2=16 cases due to different choices of parameters. The van der Waals-like behavior can be clearly witnessed from all the T-δ L ( T-δ S) graphs for q
Rotating black holes with non-Abelian hair
NASA Astrophysics Data System (ADS)
Kleihaus, Burkhard; Kunz, Jutta; Navarro-Lérida, Francisco
2016-12-01
We here review asymptotically flat rotating black holes in the presence of non-Abelian gauge fields. Like their static counterparts these black holes are no longer uniquely determined by their global charges. In the case of pure SU(2) Yang-Mills fields, the rotation generically induces an electric charge, while the black holes do not carry a magnetic charge. When a Higgs field is coupled, rotating black holes with monopole hair arise in the case of a Higgs triplet, while in the presence of a complex Higgs doublet the black holes carry sphaleron hair. The inclusion of a dilaton allows for Smarr type mass formulae.
NASA Astrophysics Data System (ADS)
Sheykhi, A.; Hajkhalili, S.
2015-11-01
We study topological dilaton black holes of Einstein gravity in the presence of exponential nonlinear electrodynamics. The event horizons of these black holes can be a two-dimensional positive, zero or negative constant curvature surface. We analyze thermodynamics of these solutions by calculating all conserved and thermodynamic quantities and showing that the first law holds on the black hole horizon. Then, we perform the stability analysis in both canonical and grand canonical ensemble and disclose the effects of the dilaton and nonlinear electrodynamics on the thermal stability of the solutions. Finally, we study the phase transition points of these black holes in the thermodynamic geometry approach.
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.
Thermodynamics of (2 +1 )-dimensional black holes in Einstein-Maxwell-dilaton gravity
NASA Astrophysics Data System (ADS)
Dehghani, M.
2017-08-01
In this paper, the linearly charged three-dimensional Einstein's theory coupled to a dilatonic field has been considered. It has been shown that the dilatonic potential must be considered in a form of generalized Liouville-type potential. Two new classes of charged dilatonic black hole solutions, as the exact solutions to the Einstein-Maxwell-dilaton (EMd) gravity, have been obtained and their properties have been studied. The conserved charge and mass related to both of the new EMd black holes have been calculated. Through comparison of the thermodynamical extensive quantities (i.e., temperature and entropy) obtained from both, the geometrical and the thermodynamical methods, the validity of first law of black hole thermodynamics has been investigated for both of the new black holes we just obtained. At the final stage, making use of the canonical ensemble method and regarding the black hole heat capacity, the thermal stability or phase transition of the new black hole solutions have been analyzed. It has been shown that there is a specific range for the horizon radius in such a way that the black holes with the horizon radius in that range are locally stable. Otherwise, they are unstable and may undergo type one or type two phase transitions to be stabilized.
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.
Modeling of non-rotating neutron stars in minimal dilatonic gravity
NASA Astrophysics Data System (ADS)
Fiziev, P.; Marinov, K.
2017-01-01
The model of minimal dilatonic gravity (MDG), called also the massive Branse-Dicke model with ω =0, is an alternative model of gravitation, which uses one Branse-Dicke gravitation-dilaton field Φ and offers a simultaneous explanation of the effects of dark energy (DE) and dark matter (DM). Here we present an extensive research of non-rotating neutron star models in MDG with four different realistic equations of state (EOS), which are in agreement with the latest observational data. The equations describing static spherically symmetric stars in MDG are solved numerically. The effects corresponding to DE and DM are clearly seen and discussed.
Spinning dilaton black hole in 2 + 1 dimensions as a particle accelerator
NASA Astrophysics Data System (ADS)
Fernando, Sharmanthie
2017-04-01
In this paper, we have studied particle collision around a spinning dilaton black hole in 2 + 1 dimensions. This black hole is a solution to the low-energy string theory in 2 + 1 dimensions. Time-like geodesics are presented in detail and the center-of-mass (CM) energy of two-particle collision at the horizon of a spinning black hole is considered. We noticed that there is a possibility of the two masses to create infinite CM energy.
AdS black hole solutions in dilatonic Einstein-Gauss-Bonnet gravity
Maeda, Kei-ichi; Ohta, Nobuyoshi; Sasagawa, Yukinori
2011-02-15
We find that anti-de Sitter (AdS) spacetime with a nontrivial linear dilaton field is an exact solution in the effective action of the string theory, which is described by gravity with the Gauss-Bonnet curvature terms coupled to a dilaton field in the string frame without a cosmological constant. The AdS radius is determined by the spacetime dimensions and the coupling constants of curvature corrections. We also construct the asymptotically AdS black hole solutions with a linear dilaton field numerically. We find these AdS black holes for hyperbolic topology and in dimensions higher than four. We discuss the thermodynamical properties of those solutions. Extending the model to the case with the even-order higher Lovelock curvature terms, we also find the exact AdS spacetime with a nontrivial dilaton. We further find a cosmological solution with a bounce of three-dimensional space and a solitonic solution with a nontrivial dilaton field, which is regular everywhere and approaches an asymptotically AdS spacetime.
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.
Kleihaus, B; Kunz, J
2001-04-23
We construct stationary black-hole solutions in SU(2) Einstein-Yang-Mills theory which carry angular momentum and electric charge. Possessing nontrivial non-Abelian magnetic fields outside their regular event horizon, they represent nonperturbative rotating hairy black holes.
Phase transition for black holes in dilatonic Einstein-Gauss-Bonnet theory of gravitation
NASA Astrophysics Data System (ADS)
Khimphun, Sunly; Lee, Bum-Hoon; Lee, Wonwoo
2016-11-01
We study the thermodynamic properties of a black hole and the Hawking-Page phase transition in the asymptotically anti-de Sitter spacetime in the dilatonic Einstein-Gauss-Bonnet theory of gravitation. We show how the higher-order curvature terms can influence both the thermodynamic properties and the phase transition. We evaluate both heat capacity and free energy difference to determine the local and global thermodynamic stabilities, respectively. We find that the phase transition occurs from the thermal anti-de Sitter to a small spherical black hole geometry and occurs to a hyperbolic black hole geometry in the (dilatonic) Einstein-Gauss-Bonnet theory of gravitation unlike those in Einstein's theory of gravitation.
Analytical approximation for the Einstein-dilaton-Gauss-Bonnet black hole metric
NASA Astrophysics Data System (ADS)
Kokkotas, K. D.; Konoplya, R. A.; Zhidenko, A.
2017-09-01
We construct an analytical approximation for the numerical black hole metric of P. Kanti et al. [Phys. Rev. D 54, 5049 (1996), 10.1103/PhysRevD.54.5049] in the four-dimensional Einstein-dilaton-Gauss-Bonnet (EdGB) theory. The continued fraction expansion in terms of a compactified radial coordinate, used here, converges slowly when the dilaton coupling approaches its extremal values, but for a black hole far from the extremal state, the analytical formula has a maximal relative error of a fraction of one percent already within the third order of the continued fraction expansion. The suggested analytical representation of the numerical black hole metric is relatively compact and a good approximation in the whole space outside the black hole event horizon. Therefore, it can serve in the same way as an exact solution when analyzing particles' motion, perturbations, quasinormal modes, Hawking radiation, accreting disks, and many other problems in the vicinity of a black hole. In addition, we construct the approximate analytical expression for the dilaton field.
Redundant and physical black hole parameters: Is there an independent physical dilaton charge?
NASA Astrophysics Data System (ADS)
Hajian, K.; Sheikh-Jabbari, M. M.
2017-05-01
Black holes as solutions to gravity theories, are generically identified by a set of parameters. Some of these parameters are associated with black hole physical conserved charges, like ADM charges. There can also be some ;redundant parameters.; We propose necessary conditions for a parameter to be physical. The conditions are essentially integrability and non-triviality of the charge variations arising from ;parametric variations,; variation of the solution with respect to the chosen parameters. In addition, we prove that variation of the redundant parameters which do not meet our criteria do not appear in the first law of thermodynamics. As an interesting application, we show that dilaton moduli are redundant parameters for black hole solutions to Einstein-Maxwell-(Axion)-Dilaton theories, because variations in dilaton moduli would render entropy, mass, electric charges or angular momenta non-integrable. Our results are in contrast with modification of the first law due to scalar charges suggested in Gibbons-Kallosh-Kol paper [1] and its follow-ups. We also briefly discuss implications of our results for the attractor behavior of extremal black holes.
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.
Asymptotically nonflat Einstein-Born-Infeld-dilaton black holes with Liouville-type potential
Sheykhi, A.; Riazi, N.; Mahzoon, M. H.
2006-08-15
We construct some classes of electrically charged, static and spherically symmetric black hole solutions of the four-dimensional Einstein-Born-Infeld-dilaton gravity in the absence and presence of Liouville-type potential for the dilaton field and investigate their properties. These solutions are neither asymptotically flat nor (anti)-de Sitter. We show that in the presence of the Liouville-type potential, there exist two classes of solutions. We also compute temperature, entropy, charge and mass of the black hole solutions, and find that these quantities satisfy the first law of thermodynamics. We find that in order to fully satisfy all the field equations consistently, there must be a relation between the electric charge and other parameters of the system.
Quasinormal Modes of Charged Dilaton Black Holes and Their Entropy Spectra
NASA Astrophysics Data System (ADS)
Sakalli, I.
2013-08-01
In this study, we employ the scalar perturbations of the charged dilaton black hole (CDBH) found by Chan, Horne and Mann (CHM), and described with an action which emerges in the low-energy limit of the string theory. A CDBH is neither asymptotically flat (AF) nor non-asymptotically flat (NAF) spacetime. Depending on the value of its dilaton parameter a, it has both Schwarzschild and linear dilaton black hole (LDBH) limits. We compute the complex frequencies of the quasinormal modes (QNMs) of the CDBH by considering small perturbations around its horizon. By using the highly damped QNM in the process prescribed by Maggiore, we obtain the quantum entropy and area spectra of these black holes (BHs). Although the QNM frequencies are tuned by a, we show that the quantum spectra do not depend on a, and they are equally spaced. On the other hand, the obtained value of undetermined dimensionless constant ɛ is the double of Bekenstein's result. The possible reason of this discrepancy is also discussed.
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)
Gregory, Ruth; Kubizňák, David; Wills, Danielle
2013-06-01
A Kerr black hole sporting cosmic string hair is studied in the context of the abelian Higgs model vortex. It is shown that such a system displays much richer phenomenology than its static Schwarzschild or Reissner-Nordstrom cousins, for example, the rotation generates a near horizon `electric' field. In the case of an extremal rotating black hole, two phases of the Higgs hair are possible: large black holes exhibit standard hair, with the vortex piercing the event horizon. Small black holes on the other hand, exhibit a flux-expelled solution, with the gauge and scalar field remaining identically in their false vacuum state on the event horizon. This solution however is extremely sensitive to confirm numerically, and we conjecture that it is unstable due to a supperradiant mechanism similar to the Kerr-adS instability. Finally, we compute the gravitational back reaction of the vortex, which turns out to be far more nuanced than a simple conical deficit. While the string produces a conical effect, it is conical with respect to a local co-rotating frame, not with respect to the static frame at infinity.
(Anti)evaporation of dyonic black holes in string-inspired dilaton f(R)-gravity
NASA Astrophysics Data System (ADS)
Addazi, Andrea
2017-06-01
We discuss dyonic black hole solutions in the case of f(R)-gravity coupled with a dilaton and two gauge bosons. The study of such a model is highly motivated from string theory. Our black hole solutions are extensions of the one firstly studied by Kallosh, Linde, Ortín, Peet and Van Proeyen (KLOPV) in arXiv:hep-th/9205027. We will show that extreme solutions are unstable. In particular, these solutions have Bousso-Hawking-Nojiri-Odintsov (anti)evaporation instabilities.
Black hole merger estimates in Einstein-Maxwell and Einstein-Maxwell-dilaton gravity
NASA Astrophysics Data System (ADS)
Jai-akson, Puttarak; Chatrabhuti, Auttakit; Evnin, Oleg; Lehner, Luis
2017-08-01
The recent birth of gravitational wave astronomy invites a new generation of precision tests of general relativity. Signatures of black hole (BH) mergers must be systematically explored in a wide spectrum of modified gravity theories. Here, we turn to one such theory in which the initial value problem for BH mergers is well posed, the Einstein-Maxwell-dilaton system. We present conservative estimates for the merger parameters (final spins, quasinormal modes) based on techniques that have worked well for ordinary gravity mergers and utilize information extracted from test particle motion in the final BH metric. The computation is developed in parallel for the modified gravity BHs (we specifically focus on the Kaluza-Klein value of the dilaton coupling, for which analytic BH solutions are known) and ordinary Kerr-Newman BHs. We comment on the possibility of obtaining final BHs with spins consistent with current observations.
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.
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.
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.
Quantizing dilatonic black holes. Towards nonperturbative canonical quantization of the CGHS model.
NASA Astrophysics Data System (ADS)
Varadarajan, M.
Motivated by the search for a nonperturbative quantization, the author casts the Callan-Giddings-Harvey-Strominger (CGHS) model of dilatonic black holes into a Hamiltonian framework. By making transformations to new "embedding" variables, he maps the model into that of a parametrized scalar field propagating on a fixed flat 1+1 background spacetime. The description in terms of the new variables is thus more amenable to quantization. Issues of asymptotics and boundary terms are dealt with systematically. This work has been done in collaboration with K. Kuchař (Univ of Utah) and J. Romano (Univ of Wisconsin-Milwaukee).
Holographic aspects of two-charged dilatonic black hole in AdS5
NASA Astrophysics Data System (ADS)
Alishahiha, Mohsen; Mohammadi Mozaffar, M. Reza; Mollabashi, Ali
2012-10-01
We study certain features of a strongly coupled theory whose gravitational dual is given by two-charge dilatonic black hole in AdS5 which has recently been used to study holographic Fermi liquids. By making use of the gravity description, we have studied conductivity, holographic entanglement entropy and dynamics of a charged scalar field. In particular at low energy we find that the temperature dependence of the real part of the conductivity goes as T 3 and the background is stable against scalar condensations.
Thermodynamics of phantom black holes in Einstein-Maxwell-dilaton theory
NASA Astrophysics Data System (ADS)
Rodrigues, Manuel E.; Oporto, Zui A. A.
2012-05-01
A thermodynamic analysis of the black hole solutions coming from the Einstein-Maxwell-dilaton theory in 4D is done. By considering the canonical and grand-canonical ensemble, we apply standard method as well as a recent method known as geometrothermodynamics. We are particularly interested in the characteristics of the so called phantom black hole solutions. We will analyze the thermodynamics of these solutions, the points of phase transition and their extremal limit. The thermodynamic stability is also analyzed. We obtain a mismatch between the results of the geometrothermodynamics method when compared with the ones obtained by the specific heat, revealing a weakness of the method, as well as possible limitations of its applicability to very pathological thermodynamic systems. We also found that normal and phantom solutions are locally and globally unstable, except for certain values of the coupled constant of the Einstein-Maxwell-dilaton action. We also show that the anti-Reissner-Nordstrom solution does not possess extremal limit nor phase transition points, contrary to the Reissner-Nordstrom case.
Black holes in models with dilaton field and electric or electric and magnetic charges
NASA Astrophysics Data System (ADS)
Kyriakopoulos, E.
2006-12-01
Exact static spherically symmetric charged black holes in four dimensions are presented. One of them has only electric charge and another electric and magnetic charges. In these solutions the metric is asymptotically flat, has two horizons, irremovable singularity only at r = 0, and the dilaton field is singular only at r = 0. The solution with electric charge only is characterized by three free parameters, the ADM mass, the electric charge and an additional free parameter. It can be considered as a modification of the GHS-GM solution obtained by changing the coupling between dilaton and electromagnetic field. The general dyonic solution is again characterized by three free parameters, the ADM mass, the magnetic charge and an additional free parameter, which is not the electric charge. According to a definition of the no-hair conjecture the solutions are 'hairy'. A very interesting special case of the dyonic solution is characterized by three free parameters, the ADM mass and the electric and magnetic charges. The solutions satisfy the dominant as well as the strong energy condition outside and on the external horizon.
Rotating regular black hole solution
NASA Astrophysics Data System (ADS)
Abdujabbarov, Ahmadjon
2016-07-01
Based on the Newman-Janis algorithm, the Ayón-Beato-García spacetime metric [Phys. Rev. Lett. 80, 5056 (1998)] of the regular spherically symmetric, static, and charged black hole has been converted into rotational form. It is shown that the derived solution for rotating a regular black hole is regular and the critical value of the electric charge for which two horizons merge into one sufficiently decreases in the presence of the nonvanishing rotation parameter a of the black hole.
On regular rotating black holes
NASA Astrophysics Data System (ADS)
Torres, R.; Fayos, F.
2017-01-01
Different proposals for regular rotating black hole spacetimes have appeared recently in the literature. However, a rigorous analysis and proof of the regularity of this kind of spacetimes is still lacking. In this note we analyze rotating Kerr-like black hole spacetimes and find the necessary and sufficient conditions for the regularity of all their second order scalar invariants polynomial in the Riemann tensor. We also show that the regularity is linked to a violation of the weak energy conditions around the core of the rotating black hole.
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.
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)
Hendi, S. H.; Talezadeh, M. S.
2017-01-01
Regarding the wide applications of dilaton gravity in the presence of electrodynamics, we introduce a suitable Lagrangian for the coupling of dilaton with gauge field. There are various Lagrangians which show the coupling between scalar fields and electrodynamics with correct special situations. In this paper, taking into account conformal transformation of Brans-Dicke theory with an electrodynamics Lagrangian, we show that how scalar field should couple with electrodynamics in dilaton gravity. In other words, in order to introduce a correct Lagrangian of dilaton gravity, one should check at least two requirements: compatibility with Brans-Dicke theory and appropriate special situations. Finally, we apply the mentioned method to obtain analytical solutions of dilaton-Born-Infeld and Brans-Dicke-Born-Infeld theories with energy dependent spacetime.
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)
Blázquez-Salcedo, Jose Luis; Macedo, Caio F. B.; Cardoso, Vitor; Ferrari, Valeria; Gualtieri, Leonardo; Khoo, Fech Scen; Kunz, Jutta; Pani, Paolo
2016-11-01
Gravitational waves emitted by distorted black holes—such as those arising from the coalescence of two neutron stars or black holes—carry not only information about the corresponding spacetime but also about the underlying theory of gravity. Although general relativity remains the simplest, most elegant, and viable theory of gravitation, there are generic and robust arguments indicating that it is not the ultimate description of the gravitational universe. Here, we focus on a particularly appealing extension of general relativity, which corrects Einstein's theory through the addition of terms which are second order in curvature: the topological Gauss-Bonnet invariant coupled to a dilaton. We study gravitational-wave emission from black holes in this theory and (i) find strong evidence that black holes are linearly (mode) stable against both axial and polar perturbations, (ii) discuss how the quasinormal modes of black holes can be excited during collisions involving black holes, and finally (iii) show that future ringdown detections with a large signal-to-noise ratio would improve current constraints on the coupling parameter of the theory.
Rotating black holes and Coriolis effect
NASA Astrophysics Data System (ADS)
Chou, Chia-Jui; Wu, Xiaoning; Yang, Yi; Yuan, Pei-Hung
2016-10-01
In this work, we consider the fluid/gravity correspondence for general rotating black holes. By using the suitable boundary condition in near horizon limit, we study the correspondence between gravitational perturbation and fluid equation. We find that the dual fluid equation for rotating black holes contains a Coriolis force term, which is closely related to the angular velocity of the black hole horizon. This can be seen as a dual effect for the frame-dragging effect of rotating black hole under the holographic picture.
NASA Astrophysics Data System (ADS)
Maselli, Andrea; Gualtieri, Leonardo; Pani, Paolo; Stella, Luigi; Ferrari, Valeria
2015-03-01
Quasi-periodic oscillations (QPOs) observed in the X-ray flux emitted by accreting black holes are associated with phenomena occurring near the horizon. Future very large area X-ray instruments will be able to measure QPO frequencies with very high precision, thus probing this strong-field region. Using the relativistic precession model, we show the way in which QPO frequencies could be used to test general relativity (GR) against those alternative theories of gravity which predict deviations from the classical theory in the strong-field and high-curvature regimes. We consider one of the best-motivated high-curvature corrections to GR, namely, the Einstein-Dilaton-Gauss-Bonnet theory, and show that a detection of QPOs with the expected sensitivity of the proposed ESA M-class mission LOFT would set the most stringent constraints on the parameter space of this theory.
NASA Astrophysics Data System (ADS)
Rogatko, Marek
2014-02-01
Mass, angular momentum, and charge inequalities for axisymmetric maximal time-symmetric initial data invariant under an action of U(1) group, in Einstein-Maxwell-axion-dilaton gravity being the low-energy limit of the heterotic string theory, is established. We assume that a data set with two asymptotically flat regions is given on a smooth simply connected manifold. We also pay attention to the area momentum charge inequalities for a closed orientable two-dimensional spacelike surface embedded in the spacetime of the considered theory.
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.
Relativistic Magnetic Reconnection around rotating black holes
NASA Astrophysics Data System (ADS)
Asenjo, Felipe; Comisso, Luca
2016-10-01
In recent years, the classical Sweet-Parker and Petschek models have been extended in the special relativistic regime, both for MHD plasmas and two-fluid electron-positron plasmas. Nevertheless, there could be situations, like in the vicinity of black holes, where also general relativistic effects can become important. Here, we calculate analytically the reconnection rate and other relevant quantities in a magnetic reconnection process around a rotating black hole. A striking result is that the black hole rotation is capable to produce an enhancement of the rate at which magnetic reconnection proceeds. This work is supported by Fondecyt-Chile, Grant No. 11140025.
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.
Global charges of stationary non-Abelian black holes.
Kleihaus, Burkhard; Kunz, Jutta; Navarro-Lérida, Francisco
2003-05-02
We consider stationary axially symmetric black holes in SU(2) Einstein-Yang-Mills-dilaton theory. We present a mass formula for these stationary non-Abelian black holes, which also holds for Abelian black holes. The presence of the dilaton field allows for rotating black holes, which possess nontrivial electric and magnetic gauge fields, but do not carry a non-Abelian charge. We further present a new uniqueness conjecture.
Collision of two rotating Hayward black holes
NASA Astrophysics Data System (ADS)
Gwak, Bogeun
2017-07-01
We investigate the spin interaction and the gravitational radiation thermally allowed in a head-on collision of two rotating Hayward black holes. The Hayward black hole is a regular black hole in a modified Einstein equation, and hence it can be an appropriate model to describe the extent to which the regularity effect in the near-horizon region affects the interaction and the radiation. If one black hole is assumed to be considerably smaller than the other, the potential of the spin interaction can be analytically obtained and is dependent on the alignment of angular momenta of the black holes. For the collision of massive black holes, the gravitational radiation is numerically obtained as the upper bound by using the laws of thermodynamics. The effect of the Hayward black hole tends to increase the radiation energy, but we can limit the effect by comparing the radiation energy with the gravitational waves GW150914 and GW151226.
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.
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.
Rotating black hole solutions with quintessential energy
NASA Astrophysics Data System (ADS)
Toshmatov, Bobir; Stuchlík, Zdeněk; Ahmedov, Bobomurat
2017-02-01
Quintessential dark energy with density ρ and pressure p is governed by an equation of state of the form p=ωqρ with the quintessential parameter ω_qin (-1;-1/3). We derive the geometry of quintessential rotating black holes, generalizing thus the Kerr spacetimes. Then we study the quintessential rotating black hole spacetimes with the special value of ωq = -2/3 when the resulting formulae are simple and easily tractable. We show that such special spacetimes can exist for the dimensionless quintessential parameter c < 1/6 and determine the critical rotational parameter a0 separating the black hole and naked singularity spacetime in dependence on the quintessential parameter c . For the spacetimes with ωq = -2/3 we give all the black hole characteristics and demonstrate local thermodynamical stability. We present the integrated geodesic equations in separated form and study in details the circular geodetical orbits. We give radii and parameters of the photon circular orbits, marginally bound and marginally stable orbits. We stress that the outer boundary on the existence of circular geodesics, given by the so-called static radius where the gravitational attraction of the black hole is balanced by the cosmic repulsion, does not depend on the dimensionless spin of the rotating black hole, similarly to the case of the Kerr-de Sitter spacetimes with vacuum dark energy. We also give restrictions on the dimensionless parameters c and a of the spacetimes allowing for existence of stable circular geodesics. Finally, using numerical methods we generalize the discussion of the circular geodesics to the black holes with arbitrary quintessential parameter ωq.
Magnetic field generation by rotating black holes
NASA Technical Reports Server (NTRS)
Leahy, D. A.; Vilenkin, A.
1981-01-01
A new mechanism of cosmic magnetic field generation is discussed. Neutrinos asymmetrically emitted by rotating black holes scatter on protons and produce a proton current which generates the magnetic field. It is shown that this mechanism can in principle produce a seed field sufficiently strong to account for present galactic fields.
Horizon quantum mechanics of rotating black holes
NASA Astrophysics Data System (ADS)
Casadio, Roberto; Giugno, Andrea; Giusti, Andrea; Micu, Octavian
2017-05-01
The horizon quantum mechanics is an approach that was previously introduced in order to analyze the gravitational radius of spherically symmetric systems and compute the probability that a given quantum state is a black hole. In this work, we first extend the formalism to general space-times with asymptotic (ADM) mass and angular momentum. We then apply the extended horizon quantum mechanics to a harmonic model of rotating corpuscular black holes. We find that simple configurations of this model naturally suppress the appearance of the inner horizon and seem to disfavor extremal (macroscopic) geometries.
No-hair conjecture in two-dimensional dilaton supergravity
NASA Astrophysics Data System (ADS)
Gamboa, J.; Georgelin, Y.
1993-11-01
We study two-dimensional (2D) dilaton gravity and supergravity following Hamiltonian methods. First, we consider the structure of constraints of 2D dilaton gravity, and then the 2D dilaton supergravity theory is obtained taking the square root of the bosonic constraints. We integrate exactly the equations of motion in both cases, and we show that the solutions of the equation of motion of 2D dilaton supergravity differ from the solutions of 2D dilaton gravity only by boundary conditions on the fermionic variables; i.e., the black holes of 2D dilaton supergravity theory are exactly the same black holes of 2D bosonic dilaton gravity modulo supersymmetry transformations. This result is the two-dimensional analogue of the no-hair theorem for supergravity.
Rotating black ring on Kaluza-Klein bubbles
Nedkova, Petya G.; Yazadjiev, Stoytcho S.
2010-08-15
We construct a new exact solution to the 5D Einstein equations describing a rotating black ring with a single angular momentum surrounded by two Kaluza-Klein bubbles. The solution is generated by two-soliton Baecklund transformation. Its physical properties are computed and analyzed. The corresponding static solution, the rotating black string, and the boosted black string are reproduced as limits.
Simulations of jets driven by black hole rotation.
Semenov, Vladimir; Dyadechkin, Sergey; Punsly, Brian
2004-08-13
The origin of jets emitted from black holes is not well understood; however, there are two possible energy sources: the accretion disk or the rotating black hole. Magnetohydrodynamic simulations show a well-defined jet that extracts energy from a black hole. If plasma near the black hole is threaded by large-scale magnetic flux, it will rotate with respect to asymptotic infinity, creating large magnetic stresses. These stresses are released as a relativistic jet at the expense of black hole rotational energy. The physics of the jet initiation in the simulations is described by the theory of black hole gravitohydromagnetics.
Rotating black holes on codimension 2 branes
Kiley, Derrick
2007-12-15
It has recently been demonstrated that certain types of nontensional stress-energy can live on tensional codimension-2 branes, including gravitational shockwaves and small Schwarzschild black holes. In this paper we generalize the earlier Schwarzschild results, and construct the exact gravitational fields of small rotating black holes on a codimension-2 brane. We focus on the phenomenologically interesting case of a three-brane embedded in a spacetime with two compactified extra dimensions. For a nonzero tension on the brane, we verify that these solutions also show the ''lightning rod'' effect found in the Schwarzschild solutions, the net effect of which is to rescale the fundamental Planck mass. This allows for larger black hole parameters, such as the event horizon, angular momentum, and lifetime than would be naively expected for a tensionless brane. It is also found that a black hole with angular momentum pointing purely along the brane directions has a smaller horizon angular velocity than the corresponding tensionless case, while a hole with bulk components of angular momentum has a larger angular velocity.
Black holes surrounded by uniformly rotating rings
NASA Astrophysics Data System (ADS)
Ansorg, Marcus; Petroff, David
2005-07-01
Highly accurate numerical solutions to the problem of black holes surrounded by uniformly rotating rings in axially symmetric, stationary spacetimes are presented. The numerical methods developed to handle the problem are discussed in some detail. Related Newtonian problems are described and numerical results provided, which show that configurations can reach an inner mass-shedding limit as the mass of the central object increases. Exemplary results for the full relativistic problem for rings of constant density are given and the deformation of the event horizon due to the presence of the ring is demonstrated. Finally, we provide an example of a system for which the angular momentum of the central black hole divided by the square of its mass exceeds one (Jc/M2c>1).
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.
NASA Astrophysics Data System (ADS)
Zangeneh, M. Kord; Dehyadegari, A.; Mehdizadeh, M. R.; Wang, B.; Sheykhi, A.
2017-06-01
In this paper, we first obtain the higher-dimen-sional dilaton-Lifshitz black hole solutions in the presence of Born-Infeld (BI) electrodynamics. We find that there are two different solutions for the cases of z=n+1 and z≠ n+1 where z is the dynamical critical exponent and n is the number of spatial dimensions. Calculating the conserved and thermodynamical quantities, we show that the first law of thermodynamics is satisfied for both cases. Then we turn to the study of different phase transitions for our Lifshitz black holes. We start with the Hawking-Page phase transition and explore the effects of different parameters of our model on it for both linearly and BI charged cases. After that, we discuss the phase transitions inside the black holes. We present the improved Davies quantities and prove that the phase transition points shown by them are coincident with the Ruppeiner ones. We show that the zero temperature phase transitions are transitions in the radiance properties of black holes by using the Landau-Lifshitz theory of thermodynamic fluctuations. Next, we turn to the study of the Ruppeiner geometry (thermodynamic geometry) for our solutions. We investigate thermal stability, interaction type of possible black hole molecules and phase transitions of our solutions for linearly and BI charged cases separately. For the linearly charged case, we show that there are no phase transitions at finite temperature for the case z≥ 2. For z<2, it is found that the number of finite temperature phase transition points depends on the value of the black hole charge and there are not more than two. When we have two finite temperature phase transition points, there is no thermally stable black hole between these two points and we have discontinuous small/large black hole phase transitions. As expected, for small black holes, we observe finite magnitude for the Ruppeiner invariant, which shows the finite correlation between possible black hole molecules, while for large
Horizon dynamics of distorted rotating black holes
Chu, Tony; Cohen, Michael I.; Pfeiffer, Harald P.
2011-05-15
We present numerical simulations of a rotating black hole distorted by a pulse of ingoing gravitational radiation. For strong pulses, we find up to five concentric marginally outer trapped surfaces. These trapped surfaces appear and disappear in pairs, so that the total number of such surfaces at any given time is odd. The world tubes traced out by the marginally outer trapped surfaces are found to be spacelike during the highly dynamical regime, approaching a null hypersurface at early and late times. We analyze the structure of these marginally trapped tubes in the context of the dynamical horizon formalism, computing the expansion of outgoing and incoming null geodesics, as well as evaluating the dynamical horizon flux law and the angular momentum flux law. Finally, we compute the event horizon. The event horizon is well-behaved and approaches the apparent horizon before and after the highly dynamical regime. No new generators enter the event horizon during the simulation.
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.
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.
Brax, Philippe; Davis, Anne-Christine; Shaw, Douglas
2010-09-15
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.
GENERAL: Canonical Entropy and Phase Transition of Rotating Black Hole
NASA Astrophysics Data System (ADS)
Zhao, Ren; Wu, Yue-Qin; Zhang, Li-Chun
2008-07-01
Recently, the Hawking radiation of a black hole has been studied using the tunnel effect method. The radiation spectrum of a black hole is derived. By discussing the correction to spectrum of the rotating black hole, we obtain the canonical entropy. The derived canonical entropy is equal to the sum of Bekenstein-Hawking entropy and correction term. The correction term near the critical point is different from the one near others. This difference plays an important role in studying the phase transition of the black hole. The black hole thermal capacity diverges at the critical point. However, the canonical entropy is not a complex number at this point. Thus we think that the phase transition created by this critical point is the second order phase transition. The discussed black hole is a five-dimensional Kerr-AdS black hole. We provide a basis for discussing thermodynamic properties of a higher-dimensional rotating black hole.
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.
Eikonal particle scattering and dilaton gravity
Das, S.; Majumdar, P.
1997-02-01
Approximating light charged pointlike particles in terms of (nonextremal) dilatonic black holes is shown to lead to certain pathologies in Planckian scattering in the eikonal approximation, which are traced to the presence of a (naked) curvature singularity in the metric of these black holes. The existence of such pathologies is confirmed by analyzing the problem in an {open_quotes}external metric{close_quote}{close_quote} formulation where an ultrarelativistic point particle scatters off a dilatonic black hole geometry at large impact parameters. The maladies disappear almost trivially upon imposing the extremal limit. Attempts to derive an effective three-dimensional {open_quotes}boundary{close_quote}{close_quote} field theory in the eikonal limit are stymied by four-dimensional (bulk) terms proportional to the light-cone derivatives of the dilaton field, leading to nontrivial mixing of electromagnetic and gravitational effects, in contrast with the case of general relativity. An eikonal scattering amplitude, showing decoupling of these effects, is shown to be derivable by resummation of graviton, dilaton, and photon exchange ladder diagrams in a linearized version of the theory for an asymptotic value of the dilaton field which makes the string coupling constant nonperturbative. {copyright} {ital 1997} {ital The American Physical Society}
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.
Black hole physics from two-dimensional dilaton gravity based on the SL(2,[ital R])/U(1) coset model
Nojiri, S. ); Oda, I. Faculty of Science, Department of Physics, Ochanomizu University, 1-1, Otsuka 2, Bunkyo-ku, Tokyo 112 )
1994-04-15
We analyze the quantum two-dimensional dilaton gravity model, which is described by the SL(2,[ital R])/U(1) gauged Wess-Zumino-Witten model deformed by a (1,1) operator. We show that the curvature singularity does not appear when the central charge [ital c][sub matter] of the matter fields is given by 22[lt][ital c][sub matter][lt]24. When 22[lt][ital c][sub matter][lt]24, the matter shock waves, whose energy-momentum tensors are given by [ital T][sub matter][proportional to][delta]([ital x][sup +][minus][ital x][sub 0][sup +]), create a kind of wormholes, i.e., causally disconnected regions. Most of the quantum information in past null infinity is lost in future null infinity but the lost information would be carried by the wormholes. We also discuss the problem of defining the mass of quantum black holes. On the basis of the argument by Regge and Teitelboim, we show that the ADM mass measured by the observer who lives in one of the asymptotically flat regions is finite and does not vanish in general. On the other hand, the Bondi mass is ill defined in this model. Instead of the Bondi mass, we consider the mass measured by observers who live in an asymptotically flat region at first. A class of observers finds the mass of the black hole created by a shock wave changes as the observers' proper time goes by, i.e., they observe Hawking radiation. The measured mass vanishes after the infinite proper time and the black hole evaporates completely. Therefore the total Hawking radiation is positive even when [ital N][lt]24.
Cosmic censorship of rotating Anti-de Sitter black hole
Gwak, Bogeun; Lee, Bum-Hoon E-mail: bhl@sogang.ac.kr
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.
Hawking temperature of rotating charged black strings from tunneling
Ahmed, Jamil; Saifullah, K. E-mail: saifullah@qau.edu.pk
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.
Dynamical Evolution of Rotating Globular Clusters with Embedded Black Holes
NASA Astrophysics Data System (ADS)
Fiestas, J.; Porth, O.; Spurzem, R.
2008-05-01
Evolution of self-gravitating rotating dense stellar systems (e.g. globular clusters) with embedded black holes is investigated. The interplay between velocity diffusion due to relaxation and black hole star accretion is followed together with cluster differential rotation using 2D+1 Fokker Planck numerical methods. The models can reproduce the Bahcall-Wolf f E1/4 ( r-7/4) cusp inside the zone of influence of the black hole. Angular momentum transport and star accretion processes support the development of central rotation in relaxation time scales, before re-expansion and cluster dissolution due to mass loss in the tidal field of a parent galaxy. Gravogyro and gravothermal instabilities conduce the system to a faster evolution leading to shorter collapse times with respect to models without black hole.
Interaction of higher-dimensional rotating black holes with branes
NASA Astrophysics Data System (ADS)
Frolov, Valeri P.; Fursaev, Dmitri V.; Stojkovic, Dejan
2004-07-01
We study interaction of rotating higher-dimensional black holes with a brane in spacetimes with large extra dimensions. We demonstrate that in a general case a rotating black hole attached to a brane can lose bulk components of its angular momenta. A stationary black hole can have only those components of the angular momenta which are connected with Killing vectors generating transformations preserving a position of the brane. In a final stationary state the null Killing vector generating the black hole horizon is tangent to the brane. We discuss first the interaction of a cosmic string and a domain wall with the 4D Kerr black hole. We then prove the general result for slowly rotating higher-dimensional black holes interacting with branes. The characteristic time when a rotating black hole with gravitational radius r0 reaches this final stationary state is T ~ rp-10/(Gσ), where G is the higher-dimensional gravitational coupling constant, σ is the brane tension and p is the number of extra dimensions.
Energy extraction from Kerr black holes by rigidly rotating strings
NASA Astrophysics Data System (ADS)
Kinoshita, Shunichiro; Igata, Takahisa; Tanabe, Kentaro
2016-12-01
In this paper, we show that a rigidly rotating string can extract the rotational energy from a rotating black hole. We consider Nambu-Goto strings stationary with respect to a corotating Killing vector with an uniform angular velocity ω in the Kerr spacetime. We show that a necessary condition of the energy-extraction process is that an effective horizon on the string world sheet, which corresponds to the inner light surface, is inside the ergosphere of the Kerr black hole and the angular velocity ω is less than that of the black hole Ωh . Furthermore, we discuss global configurations of such strings in both of a slow-rotation limit and the extremal Kerr case.
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.
Charged rotating black holes on a 3-brane
Aliev, A.N.; Guemruekcueoglu, A.E.
2005-05-15
We study exact stationary and axisymmetric solutions describing charged rotating black holes localized on a 3-brane in the Randall-Sundrum braneworld. The charges of the black holes are considered to be of two types, the first being an induced tidal charge that appears as an imprint of nonlocal gravitational effects from the bulk space and the second is a usual electric charge arising due to a Maxwell field trapped on the brane. We assume a special ansatz for the metric on the brane taking it to be of the Kerr-Schild form and show that the Kerr-Newman solution of ordinary general relativity in which the electric charge is superseded by a tidal charge satisfies a closed system of the effective gravitational field equations on the brane. It turns out that the negative tidal charge may provide a mechanism for spinning up the black hole so that its rotation parameter exceeds its mass. This is not allowed in the framework of general relativity. We also find a new solution that represents a rotating black hole on the brane carrying both charges. We show that for a rapid enough rotation the combined influence of the rotational dynamics and the local bulk effects of the 'squared' energy-momentum tensor on the brane distort the horizon structure of the black hole in such a way that it can be thought of as composed of nonuniformly rotating null circles with growing radii from the equatorial plane to the poles. We finally study the geodesic motion of test particles in the equatorial plane of a rotating black hole with tidal charge. We show that the effects of negative tidal charge tend to increase the horizon radius, as well as the radii of the limiting photon orbit, the innermost bound and the innermost stable circular orbits for both direct and retrograde motions of the particles.
Rotating Hayward's regular black hole as particle accelerator
NASA Astrophysics Data System (ADS)
Amir, Muhammed; Ghosh, Sushant G.
2015-07-01
Recently, Bañados, Silk and West (BSW) demonstrated that the extremal Kerr black hole can act as a particle accelerator with arbitrarily high center-of-mass energy ( E CM) when the collision takes place near the horizon. The rotating Hayward's regular black hole, apart from Mass ( M) and angular momentum ( a), has a new parameter g ( g > 0 is a constant) that provides a deviation from the Kerr black hole. We demonstrate that for each g, with M = 1, there exist critical a E and r {/H E }, which corresponds to a regular extremal black hole with degenerate horizons, and a E decreases whereas r {/H E } increases with increase in g. While a < a E describe a regular non-extremal black hole with outer and inner horizons. We apply the BSW process to the rotating Hayward's regular black hole, for different g, and demonstrate numerically that the E CM diverges in the vicinity of the horizon for the extremal cases thereby suggesting that a rotating regular black hole can also act as a particle accelerator and thus in turn provide a suitable framework for Plank-scale physics. For a non-extremal case, there always exist a finite upper bound for the E CM, which increases with the deviation parameter g.
Marginally bound (critical) geodesics of rapidly rotating black holes
NASA Astrophysics Data System (ADS)
Hod, Shahar
2013-10-01
One of the most important geodesics in a black hole spacetime is the marginally bound spherical orbit. This critical geodesic represents the innermost spherical orbit which is bound to the central black hole. The radii rmb(a¯) of the marginally bound equatorial circular geodesics of rotating Kerr black holes were found analytically by Bardeen et al. more than four decades ago (here a¯≡J/M2 is the dimensionless angular momentum of the black hole). On the other hand, no closed-form formula exists in the literature for the radii of generic (nonequatorial) marginally bound geodesics of the rotating Kerr spacetime. In the present study, we analyze the critical (marginally bound) orbits of rapidly rotating Kerr black holes. In particular, we derive a simple analytical formula for the radii rmb(a¯≃1;cosi) of the marginally bound spherical orbits, where cosi is an effective inclination angle (with respect to the black hole equatorial plane) of the geodesic. We find that the marginally bound spherical orbits of rapidly rotating black holes are characterized by a critical inclination angle, cosi=2/3, above which the coordinate radii of the geodesics approach the black hole radius in the extremal a¯→1 limit. It is shown that this critical inclination angle signals a transition in the physical properties of the orbits: in particular, it separates marginally bound spherical geodesics which lie a finite proper distance from the black hole horizon from marginally bound geodesics which lie an infinite proper distance from the horizon.
Physics of rotating and expanding black hole universe (PREBHU)
NASA Astrophysics Data System (ADS)
Seshavatharam, U. V. Satya
Throughout its journey universe follows strong gravity. By unifying general theory of relativity and quantum mechanics a simple derivation is given for rotating black hole's temperature. It is shown that when the rotation speed approaches light speed temperature approaches Hawking's black hole temperature. Applying this idea to the cosmic black hole it is noticed that there is ``no cosmic temperature" if there is ``no cosmic rotation". Starting from the Planck scale it is assumed that - universe is a rotating and expanding black hole. Another key assumption is that at any time cosmic black hole rotates with light speed. For this cosmic sphere as a whole while in light speed rotation ``rate of decrease" in temperature or ``rate of increase" in cosmic redshift is a measure of ``rate of cosmic expansion". Since 1992, measured CMBR data indicates that, present CMB is same in all directions equal to 2.7260 kelvin smooth to 1 part in 100000 and there is no continuous decrease! This directly indicates that, at present rate of decrease in temperature is practically zero and rate of expansion is practically zero. Universe is isotropic and hence static and is rotating as a rigid sphere with light speed. At present galaxies are revolving with speeds proportional to their distances from the cosmic axis of rotation. If present CMBR temperature is 2.7260 kelvin, present value of obtained angular velocity is 2.17× 10^{-18} rad/sec = 67 Km/sec/Mpc. Present cosmic mass density and cosmic time are fitted with natural logarithmic ratio of cosmic volume and planck particle's volume. Finally it can be suggested that dark matter and dark energy are ad-hoc and misleading concepts. (Planck particle can be considered as the baby universe).
Entropy product of rotating black holes in three-dimensions
NASA Astrophysics Data System (ADS)
Mahdavian Yekta, Davood
2017-03-01
It has been shown that the product of the entropies of the inner Cauchy and outer event horizon of the charged axisymmetric and stationary black holes is a universal formula, which is independent of the black hole's mass. In this paper, we investigate this universality for the two kinds of rotating black holes in the three-dimensional gravity models. In fact, we study the spacelike warped anti-de Sitter black hole in the new massive gravity and the Bañados, Teitelboim, and Zanelli black hole in the minimal massive gravity. We show that this rule is held in the first theory. By contrast, in the latter case which includes a holographic gravitational anomalous term, we obtain that the universality does not work and the product depends on the mass. As a complement to the above verification, we also study the thermodynamic properties of these black holes.
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.
GUP assisted Hawking radiation of rotating acoustic black holes
NASA Astrophysics Data System (ADS)
Sakalli, I.; Övgün, A.; Jusufi, K.
2016-10-01
Recent studies (Steinhauer in Nat. Phys. 10:864, 2014, Phys. Rev. D 92:024043, 2015) provide compelling evidences that Hawking radiation could be experimentally proven by using an analogue black hole. In this paper, taking this situation into account we study the quantum gravitational effects on the Hawking radiation of rotating acoustic black holes. For this purpose, we consider the generalized uncertainty principle (GUP) in the phenomenon of quantum tunneling. We firstly take the modified commutation relations into account to compute the GUP modified Hawking temperature when the massive scalar particles tunnel from this black hole. Then, we find a remarkably instructive expression for the GUP entropy to derive the quantum gravity corrected Hawking temperature of the rotating acoustic black hole.
Holographic heat engines: general considerations and rotating black holes
NASA Astrophysics Data System (ADS)
Hennigar, Robie A.; McCarthy, Fiona; Ballon, Alvaro; Mann, Robert B.
2017-09-01
We perform the first study of holographic heat engines where the working material is a rotating black hole, obtaining exact results for the efficiency of a rectangular engine cycle. We also make general considerations in the context of benchmarking these engines on circular cycles. We find an exact expression that is valid for black holes with vanishing specific heat at constant volume and derive an upper bound, below the Carnot efficiency and independent of spacetime dimension, which holds for any black hole of this kind. We illustrate our results with applications to a variety of black holes, noting the effects of spacetime dimension, rotation, and higher curvature corrections on the efficiency of the cycle.
Spherical null geodesics of rotating Kerr black holes
NASA Astrophysics Data System (ADS)
Hod, Shahar
2013-01-01
The non-equatorial spherical null geodesics of rotating Kerr black holes are studied analytically. Unlike the extensively studied equatorial circular orbits whose radii are known analytically, no closed-form formula exists in the literature for the radii of generic (non-equatorial) spherical geodesics. We provide here an approximate formula for the radii rph (a / M ; cos i) of these spherical null geodesics, where a / M is the dimensionless angular momentum of the black hole and cos i is an effective inclination angle (with respect to the black-hole equatorial plane) of the orbit. It is well-known that the equatorial circular geodesics of the Kerr spacetime (the prograde and the retrograde orbits with cos i = ± 1) are characterized by a monotonic dependence of their radii rph (a / M ; cos i = ± 1) on the dimensionless spin-parameter a / M of the black hole. We use here our novel analytical formula to reveal that this well-known property of the equatorial circular geodesics is actually not a generic property of the Kerr spacetime. In particular, we find that counter-rotating spherical null orbits in the range (3√{ 3} -√{ 59}) / 4 ≲ cos i < 0 are characterized by a non-monotonic dependence of rph (a / M ; cos i =const) on the dimensionless rotation-parameter a / M of the black hole. Furthermore, it is shown that spherical photon orbits of rapidly-rotating black holes are characterized by a critical inclination angle, cos i =√{ 4 / 7 }, above which the coordinate radii of the orbits approach the black-hole radius in the extremal limit. We prove that this critical inclination angle signals a transition in the physical properties of the spherical null geodesics: in particular, it separates orbits which are characterized by finite proper distances to the black-hole horizon from orbits which are characterized by infinite proper distances to the horizon.
Dynamical evolution of rotating globular clusters with embedded black holes
NASA Astrophysics Data System (ADS)
Fiestas, José
2006-02-01
In this dissertation evolution of self-gravitating dense stellar systems (e.g. globular clusters, galactic nuclei) with embedded black holes is investigated, motivated by observational evidences of the existence of central dark objects in these systems. The interaction between the stellar and black hole component is followed in a way, different from most other investigations in this field, as flattening of the system due to differential rotation is allowed. The axisymmetric system is modelled using 2-dimensional, in energy and z-component of angular momentum, Fokker Planck numerical methods. The interplay between velocity diffusion due to relaxation and black hole star accretion is followed together with cluster rotation. The results show how angular momentum transport and star accretion support the development of central rotation in relaxation time scales. Gravogyro and gravothermal instabilities conduce the system to a faster evolution leading to shorter collapse times with respect to models without black hole, and a faster cluster dissolution in the galactic tidal field of a parent galaxy. As a further application, two-dimensional distribution (in the meridional plane) of kinematical and structural parameters (density, dispersions, rotation) are reproduced, covering a wide range of ages, rotation, concentrations and ellipticities, with the aim to enable the use of set of models for comparison with observational data.
Rotating black hole solutions in relativistic analogue gravity
NASA Astrophysics Data System (ADS)
Giacomelli, Luca; Liberati, Stefano
2017-09-01
Simulation and experimental realization of acoustic black holes in analogue gravity systems have lead to a novel understanding of relevant phenomena such as Hawking radiation or superradiance. We explore here the possibility of using relativistic systems for simulating rotating black hole solutions and possibly get an acoustic analogue of a Kerr black hole. In doing so, we demonstrate a precise relation between nonrelativistic and relativistic solutions and provide a new class of vortex solutions for relativistic systems. Such solutions might be used in the future as a test bed in numerical simulations as well as concrete experiments.
Hawking radiation from rotating black holes and gravitational anomalies
Murata, Keiju; Soda, Jiro
2006-08-15
We study the Hawking radiation from Rotating black holes from the gravitational anomalies point of view. First, we show that the scalar field theory near the Kerr black hole horizon can be reduced to the 2-dimensional effective theory. Then, following Robinson and Wilczek, we derive the Hawking flux by requiring the cancellation of gravitational anomalies. We also apply this method to Hawking radiation from higher dimensional Myers-Perry black holes. In the appendix, we present the trace anomaly derivation of Hawking radiation to argue the validity of the boundary condition at the horizon.
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.
On the simplest binary system of rotating black holes
Manko, V. S.; Rodchenko, E. D.; Sadovnikov, B. I.; Ruiz, E.
2009-05-01
Exact axisymmetric stationary solution of the Einstein equations describing a system of two counter-rotating identical Kerr black holes is worked out in a physical parametrization within the framework of the Ernst formalism and analytically extended double-Kerr solution. The derivation of the limiting case of extreme constituents is also discussed.
Rotating Black Holes and the Kerr Metric
NASA Astrophysics Data System (ADS)
Kerr, Roy Patrick
2008-10-01
Since it was first discovered in 1963 the Kerr metric has been used by relativists as a test-bed for conjectures on worm-holes, time travel, closed time-like loops, and the existence or otherwise of global Cauchy surfaces. More importantly, it has also used by astrophysicists to investigate the effects of collapsed objects on their local environments. These two groups of applications should not be confused. Astrophysical Black Holes are not the same as the Kruskal solution and its generalisations.
Analytic continuation of the rotating black hole state counting
NASA Astrophysics Data System (ADS)
Achour, Jibril Ben; Noui, Karim; Perez, Alejandro
2016-08-01
In loop quantum gravity, a spherical black hole can be described in terms of a Chern-Simons theory on a punctured 2-sphere. The sphere represents the horizon. The punctures are the edges of spin-networks in the bulk which cross the horizon and carry quanta of area. One can generalize this construction and model a rotating black hole by adding an extra puncture colored with the angular momentum J in the 2-sphere. We compute the entropy of rotating black holes in this model and study its semi-classical limit. After performing an analytic continuation which sends the Barbero-Immirzi parameter to γ = ± i,weshowthattheleadingorderterminthesemi-classicalexpansionoftheentropy reproduces the Bekenstein-Hawking law independently of the value of J.
Extremal charged rotating black holes in odd dimensions
Allahverdizadeh, Masoud; Kunz, Jutta; Navarro-Lerida, Francisco
2010-07-15
Employing higher order perturbation theory, we obtain charged rotating black holes in odd dimensions, where the Einstein-Maxwell Lagrangian may be supplemented with a Chern-Simons term. 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. For Einstein-Maxwell-Chern-Simons theory with arbitrary Chern-Simons coupling constant, we perform the perturbations up to 3rd order for any odd dimension. We discuss the physical properties of these black holes and study their dependence on the charge. In particular, we show that the gyromagnetic ratio g of Einstein-Maxwell black holes differs from the lowest order perturbative value D-2, and that the first correction term to g/(D-2) is universal.
Anomalies, Hawking radiations, and regularity in rotating black holes
Iso, Satoshi; Umetsu, Hiroshi; Wilczek, Frank
2006-08-15
This is an extended version of our previous letter [S. Iso, H. Umetsu, and F. Wilczek, Phys. Rev. Lett. 96, 151302 (2006).]. In this paper we consider rotating black holes and show that the flux of Hawking radiation can be determined by anomaly cancellation conditions and regularity requirement at the horizon. By using a dimensional reduction technique, each partial wave of quantum fields in a d=4 rotating black hole background can be interpreted as a (1+1)-dimensional charged field with a charge proportional to the azimuthal angular momentum m. From this and the analysis [S. P. Robinson and F. Wilczek, Phys. Rev. Lett. 95, 011303 (2005), S. Iso, H. Umetsu, and F. Wilczek, Phys. Rev. Lett. 96, 151302 (2006).] on Hawking radiation from charged black holes, we show that the total flux of Hawking radiation from rotating black holes can be universally determined in terms of the values of anomalies at the horizon by demanding gauge invariance and general coordinate covariance at the quantum level. We also clarify our choice of boundary conditions and show that our results are consistent with the effective action approach where regularity at the future horizon and vanishing of ingoing modes at r={infinity} are imposed (i.e. Unruh vacuum)
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 black holes in higher dimensions with a cosmological constant.
Gibbons, G W; Lü, H; Page, Don N; Pope, C N
2004-10-22
We present the metric for a rotating black hole with a cosmological constant and with arbitrary angular momenta in all higher dimensions. The metric is given in both Kerr-Schild and the Boyer-Lindquist form. In the Euclidean-signature case, we also obtain smooth compact Einstein spaces on associated S(D-2) bundles over S2, infinitely many for each odd D>/=5. Applications to string theory and M-theory are indicated.
Mechanics of rotating isolated horizons
Ashtekar, Abhay; Beetle, Christopher; Lewandowski, Jerzy
2001-08-15
Black hole mechanics was recently extended by replacing the more commonly used event horizons in stationary space-times with isolated horizons in more general space-times (which may admit radiation arbitrarily close to black holes). However, so far the detailed analysis has been restricted to nonrotating black holes (although it incorporated arbitrary distortion, as well as electromagnetic, Yang-Mills, and dilatonic charges). We now fill this gap by first introducing the notion of isolated horizon angular momentum and then extending the first law to the rotating case.
Galaxy rotation and supermassive black hole binary evolution
NASA Astrophysics Data System (ADS)
Mirza, M. A.; Tahir, A.; Khan, F. M.; Holley-Bockelmann, H.; Baig, A. M.; Berczik, P.; Chishtie, F.
2017-09-01
Supermassive black hole (SMBH) binaries residing at the core of merging galaxies are recently found to be strongly affected by the rotation of their host galaxies. The highly eccentric orbits that form when the host is counterrotating emit strong bursts of gravitational waves that propel rapid SMBH binary coalescence. Most prior work, however, focused on planar orbits and a uniform rotation profile, an unlikely interaction configuration. However, the coupling between rotation and SMBH binary evolution appears to be such a strong dynamical process that it warrants further investigation. This study uses direct N-body simulations to isolate the effect of galaxy rotation in more realistic interactions. In particular, we systematically vary the SMBH orbital plane with respect to the galaxy rotation axis, the radial extent of the rotating component, and the initial eccentricity of the SMBH binary orbit. We find that the initial orbital plane orientation and eccentricity alone can change the inspiral time by an order of magnitude. Because SMBH binary inspiral and merger is such a loud gravitational wave source, these studies are critical for the future gravitational wave detector, Laser Interferometer Space Antenna, an ESA/NASA mission currently set to launch by 2034.
Rotating Charged Hairy Black Hole in (2+1) Dimensions and Particle Acceleration
NASA Astrophysics Data System (ADS)
Sadeghi, J.; Pourhassan, B.; Farahani, H.
2014-09-01
In this paper, we construct rotating charged hairy black hole in (2+1) dimensions for infinitesimal black hole charge and rotation parameters. Then we consider this black hole as particle accelerator and calculate the center-of-mass energy of two colliding test particles near the rotating charged hairy black hole in (2+1) dimensions. As we expected, the center-of-mass energy has infinite value.
Featured Image: Making a Rapidly Rotating Black Hole
NASA Astrophysics Data System (ADS)
Kohler, Susanna
2017-10-01
These stills from a simulation show the evolution (from left to right and top to bottom) of a high-mass X-ray binary over 1.1 days, starting after the star on the right fails to explode as a supernova and then collapses into a black hole. Many high-mass X-ray binaries like the well-known Cygnus X-1, the first source widely accepted to be a black hole host rapidly spinning black holes. Despite our observations of these systems, however, were still not sure how these objects end up with such high rotation speeds. Using simulations like that shown above, a team of scientists led by Aldo Batta (UC Santa Cruz) has demonstrated how a failed supernova explosion can result in such a rapidly spinning black hole. The authors work shows that in a binary where one star attempts to explode as a supernova and fails it doesnt succeed in unbinding the star the large amount of fallback material can interact with the companion star and then accrete onto the black hole, spinning it up in the process. You can read more about the authors simulations and conclusions in the paper below.CitationAldo Batta et al 2017 ApJL 846 L15. doi:10.3847/2041-8213/aa8506
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.
Gravitational stability of simply rotating Myers-Perry black holes: Tensorial perturbations
Kodama, Hideo; Konoplya, R. A.; Zhidenko, Alexander
2010-02-15
We study the stability of D{>=}7 asymptotically flat black holes rotating in a single two-plane against tensor-type gravitational perturbations. The extensive search of quasinormal modes for these black holes did not indicate any presence of growing modes, implying the stability of simply rotating Myers-Perry black holes against tensor-type perturbations.
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 hole solutions to Horava-Lifshitz gravity
Aliev, Alikram N.; Sentuerk, Cetin
2010-11-15
We present a new stationary solution to the field equations of Horava-Lifshitz gravity with the detailed balance condition and for any value of the coupling constant {lambda}>1/3. This is the generalization of the corresponding spherically symmetric solution earlier found by Lue, Mei, and Pope to include a small amount of angular momentum. For the relativistic value {lambda}=1, the solution describes slowly rotating AdS type black holes. With a soft violation of the detailed balance condition and for {lambda}=1, we also find such a generalization for the Schwarzschild type black hole solution of the theory. Finally, using the canonical Hamiltonian approach, we calculate the mass and the angular momentum of these solutions.
Standing shocks in adiabatic black hole accretion of rotating matter
Abramowicz, M.A.; Chakrabarti, S.K. International Centre for Theoretical Physics, Trieste )
1990-02-01
This paper discusses the solutions for stationary, axisymmetric, transonic, adiabatic flows with polytropic, rotating fluid configurations of small transverse thickness in an arbitrarily chosen potential. Special attention is paid to the formation of the standing shocks in the case of black hole accretion and winds. The possibility of three types of shocks depending upon three extreme physical conditions at the shocks is pointed out. These are Rankine-Hugoniot shocks, isentropic compression waves, and isothermal shocks. The shock conditions for these three cases are written down, and the physical situations under which they may form are discussed. 21 refs.
Accretion of radiation and rotating primordial black holes
Mahapatra, S. Nayak, B.
2016-02-15
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.
Chaotic cold accretion on to black holes in rotating atmospheres
NASA Astrophysics Data System (ADS)
Gaspari, M.; Brighenti, F.; Temi, P.
2015-07-01
The fueling of black holes is one key problem in the evolution of baryons in the universe. Chaotic cold accretion (CCA) profoundly differs from classic accretion models, as Bondi and thin disc theories. Using 3D high-resolution hydrodynamic simulations, we now probe the impact of rotation on the hot and cold accretion flow in a typical massive galaxy. In the hot mode, with or without turbulence, the pressure-dominated flow forms a geometrically thick rotational barrier, suppressing the black hole accretion rate to ~1/3 of the spherical case value. When radiative cooling is dominant, the gas loses pressure support and quickly circularizes in a cold thin disk; the accretion rate is decoupled from the cooling rate, although it is higher than that of the hot mode. In the more common state of a turbulent and heated atmosphere, CCA drives the dynamics if the gas velocity dispersion exceeds the rotational velocity, i.e., turbulent Taylor number Tat< 1. Extended multiphase filaments condense out of the hot phase via thermal instability (TI) and rain toward the black hole, boosting the accretion rate up to 100 times the Bondi rate (Ṁ• ~ Ṁcool). Initially, turbulence broadens the angular momentum distribution of the hot gas, allowing the cold phase to condense with prograde or retrograde motion. Subsequent chaotic collisions between the cold filaments, clouds, and a clumpy variable torus promote the cancellation of angular momentum, leading to high accretion rates. As turbulence weakens (Tat > 1), the broadening of the distribution and the efficiency of collisions diminish, damping the accretion rate ∝ Tat-1, until the cold disk drives the dynamics. This is exacerbated by the increased difficulty to grow TI in a rotating halo. The simulated sub-Eddington accretion rates cover the range inferred from AGN cavity observations. CCA predicts inner flat X-ray temperature and r-1 density profiles, as recently discovered in M 87 and NGC 3115. The synthetic Hα images
Scattering of circularly polarized light by a rotating black hole
NASA Astrophysics Data System (ADS)
Frolov, Valeri P.; Shoom, Andrey A.
2012-07-01
We study scattering of polarized light by a rotating (Kerr) black hole of mass M and angular momentum J. In order to keep trace of the polarization dependence of photon trajectories one can use the following dimensionless parameter: ɛ=±(ωM)-1, where ω is the photon frequency and the sign + (-) corresponds to the right (left) circular polarization. We assume that |ɛ|≪1 and use the modified geometric optics approximation developed in [Phys. Rev. D 84, 044026 (2011)]; that is, we include the first order in ɛ polarization-dependent terms into the eikonal equation. These corrections modify late-time behavior of photons. We demonstrate that the photon moves along a null curve, which in the limit ɛ=0 becomes a null geodesic. We focus on the scattering problem for polarized light. Namely, we consider the following problems: (i) How does the photon’s bending angle depend on its polarization? (ii) How does the position of the image of a pointlike source depend on its polarization? (iii) How does the arrival time of photons depend on their polarization? We perform the numerical calculations that illustrate these effects for an extremely rotating black hole and discuss their possible applications.
Evolution of Binary Supermassive Black Holes in Rotating Nuclei
NASA Astrophysics Data System (ADS)
Rasskazov, Alexander; Merritt, David
2017-03-01
The interaction of a binary supermassive black hole with stars in a galactic nucleus can result in changes to all the elements of the binary’s orbit, including the angles that define its orientation. If the nucleus is rotating, the orientation changes can be large, causing large changes in the binary’s orbital eccentricity as well. We present a general treatment of this problem based on the Fokker–Planck equation for f, defined as the probability distribution for the binary’s orbital elements. First- and second-order diffusion coefficients are derived for the orbital elements of the binary using numerical scattering experiments, and analytic approximations are presented for some of these coefficients. Solutions of the Fokker–Planck equation are then derived under various assumptions about the initial rotational state of the nucleus and the binary hardening rate. We find that the evolution of the orbital elements can become qualitatively different when we introduce nuclear rotation: (1) the orientation of the binary’s orbit evolves toward alignment with the plane of rotation of the nucleus and (2) binary orbital eccentricity decreases for aligned binaries and increases for counteraligned ones. We find that the diffusive (random-walk) component of a binary’s evolution is small in nuclei with non-negligible rotation, and we derive the time-evolution equations for the semimajor axis, eccentricity, and inclination in that approximation. The aforementioned effects could influence gravitational wave production as well as the relative orientation of host galaxies and radio jets.
Bulk viscosity of accretion disks around non rotating black holes
NASA Astrophysics Data System (ADS)
Moeen Moghaddas, M.
2017-01-01
In this paper, we study the Keplerian, relativistic accretion disks around the non rotating black holes with the bulk viscosity. Many of authors studied the relativistic accretion disks around the black holes, but they ignored the bulk viscosity. We introduce a simple method to calculate the bulk in these disks. We use the simple form for the radial component of the four velocity in the Schwarzschild metric, then the other components of the four velocity and the components of the shear and the bulk tensor are calculated. Also all components of the bulk viscosity, the shear viscosity and stress tensor are calculated. It is seen that some components of the bulk tensor are comparable with the shear tensor. We calculate some of the thermodynamic quantities of the relativistic disks. Comparison of thermodynamic quantities shows that in some states influences of the bulk viscosity are important, especially in the inner radiuses. All calculations are done analytically and we do not use the boundary conditions. Finally, we find that in the relativistic disks around the black holes, the bulk viscosity is non-negligible in all the states.
Dirac particle tunneling from black rings
Jiang Qingquan
2008-08-15
Recent research shows that Hawking radiation can be treated as a quantum tunneling process, and Hawking temperatures of Dirac particles across the horizon of a black hole can be correctly recovered via the fermion tunneling method. In this paper, motivated by the fermion tunneling method, we attempt to apply the analysis to derive Hawking radiation of Dirac particles via tunneling from black ring solutions of 5-dimensional Einstein-Maxwell-dilaton gravity theory. Finally, it is interesting to find that, as in the black hole case, fermion tunneling can also result in correct Hawking temperatures for the rotating neutral, dipole, and charged black rings.
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.
Rotating black hole surrounded by self-gravitating torus in the puncture framework
Shibata, Masaru
2007-09-15
We present a formulation for computing equilibria composed of a rotating black hole and a massive self-gravitating torus in general relativity. Such a system is a plausible outcome formed after stellar core collapse of massive and supermassive stars as well as after a merger of a black hole-neutron star binary. In our formulation, the black hole is modeled in the puncture framework. The numerical solutions for equilibria are computed for rapidly rotating black holes and for a wide range of mass ratio of the black hole and torus. The equilibria obtained in this paper can be used for studying nonaxisymmetric instabilities, runaway instability, and magnetorotational instability of a self-gravitating accretion torus around a rotating black hole in numerical relativity. We also remark that the relation among the area, mass, and spin of rotating black holes are slightly modified by the torus.
NASA Astrophysics Data System (ADS)
Song, Yoogeun; Pu, Hung-Yi; Hirotani, Kouichi; Matsushita, Satoki; Kong, Albert K. H.; Chang, Hsiang-Kuang
2017-10-01
We investigate the acceleration of electrons and positrons by magnetic-field-aligned electric fields in the polar funnel of an accreting black hole (BH). Applying the pulsar outer-gap theory to BH magnetospheres, we find that such a lepton accelerator arises in the immediate vicinity of the event horizon due to frame-dragging, and that their gamma-ray luminosity increases with decreasing accretion rate. Furthermore, we demonstrate that the gamma-ray flux is enhanced along the rotation axis by more than an order of magnitude if the BH spin increases from $a=0.90M$ to $a=0.9999M$. As a result, if a ten-solar-mass, almost-maximally rotating BH is located within 3 kpc, when its accretion rate is between 0.005% and 0.01% of the Eddington rate, its high-energy flare becomes detectable with the Fermi/Large Area Telescope, provided that the flare lasts longer than 1.2 months and that we view the source nearly along the rotation axis. In addition, its very-high-energy flux is marginally detectable with the Cherenkov Telescope Array, provided that the flare lasts longer than a night and that our viewing angle is about 45 degrees with respect to the rotation axis.
Three-dimensional dilatonic gravity's rainbow: Exact solutions
NASA Astrophysics Data System (ADS)
Hossein Hendi, Seyed; Eslam Panah, Behzad; Panahiyan, Shahram
2016-10-01
Deep relations of dark energy scenario and string theory results into dilaton gravity, on the one hand, and the connection between quantum gravity and gravity's rainbow, on the other hand, motivate us to consider three-dimensional dilatonic black hole solutions in gravity's rainbow. We obtain two classes of the solutions, which are polynomial and logarithmic forms. We also calculate conserved and thermodynamic quantities, and examine the first law of thermodynamics for both classes. In addition, we study thermal stability and show that one of the classes is thermally stable while the other one is unstable.
Three-dimensional dilatonic gravity's rainbow: Exact solutions
NASA Astrophysics Data System (ADS)
Hossein Hendi, Seyed; Eslam Panah, Behzad; Panahiyan, Shahram
2016-10-01
Deep relations of dark energy scenario and string theory results into dilaton gravity, on the one hand, and the connection between quantum gravity and gravity's rainbow, on the other hand, motivate us to consider three-dimensional dilatonic black hole solutions in gravity's rainbow. We obtain two classes of the solutions, which are polynomial and logarithmic forms. We also calculate conserved and thermodynamic quantities, and examine the first law of thermodynamics for both classes. In addition, we study thermal stability and show that one of the classes is thermally stable while the other one is unstable.
A rotating black hole solution for shape dynamics
NASA Astrophysics Data System (ADS)
Gomes, Henrique; Herczeg, Gabriel
2014-09-01
Shape dynamics is a classical theory of gravity which agrees with general relativity in many important aspects, but which possesses different gauge symmetries and can present some fundamental global differences with respect to Einstein space-times. Here, we present a general procedure for (locally) mapping stationary, axisymmetric general relativity solutions onto their shape dynamic counterparts. We focus in particular on the rotating black hole solution for shape dynamics and show that many of the properties of the spherically symmetric solution are preserved in the extension to the axisymmetric case: it is also free of physical singularities, it does not form a space-time at the horizon, and it possesses an inversion symmetry about the horizon which leads to us to interpret the solution as a wormhole.
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.
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.
Superradiance instability of small rotating AdS black holes in arbitrary dimensions
NASA Astrophysics Data System (ADS)
Delice, Ã.-zgür; Durǧut, Türküler
2015-07-01
We investigate the stability of D dimensional singly rotating Myers-Perry-AdS black holes under superradiance against scalar field perturbations. It is well known that small four dimensional rotating or charged Anti-de Sitter (AdS) black holes are unstable against superradiance instability of a scalar field. Recent works extended the existence of this instability to five dimensional rotating charged AdS black holes or static charged AdS black holes in arbitrary dimensions. In this paper we analytically prove that rotating small AdS black holes in arbitrary dimensions also shows superradiance instability irrespective of the value of the (positive) angular momentum quantum number. To do this we solve the Klein-Gordon equation in the slow rotation, low frequency limit. By using the asymptotic matching technique, we are able to calculate the real and imaginary parts of the correction terms to the frequency of the scalar field due to the presence of the black hole, confirming the presence of superradiance instability. We see that, unlike in the case of static AdS black holes, the analytical method is valid for rotating AdS black holes for any value of angular momentum number and spacetime dimensions. For comparison we derive the corresponding correction terms for Myers-Perry black holes in the black hole bomb formalism in the Appendix and see that the results are in agreement.
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.
No hair theorem in quasi-dilaton massive gravity
Wu, De-Jun; Zhou, Shuang-Yong
2016-04-11
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 ormore » de Sitter asymptotics. (C) 2016 The Authors. Published by Elsevier B.V. This is an open access article under the CC BY license (http://creativecommons.org/licenses/by/4.0/). Funded by SCOAP(3).« less
ENERGETIC GAMMA RADIATION FROM RAPIDLY ROTATING BLACK HOLES
Hirotani, Kouichi; Pu, Hung-Yi
2016-02-10
Supermassive black holes (BHs) are believed to be the central powerhouse of active galactic nuclei. Applying the pulsar outer-magnetospheric particle accelerator theory to BH magnetospheres, we demonstrate that an electric field is exerted along the magnetic field lines near the event horizon of a rotating BH. In this particle accelerator (or a gap), electrons and positrons are created by photon–photon collisions and accelerated in the opposite directions by this electric field, efficiently emitting gamma-rays via curvature and inverse-Compton processes. It is shown that a gap arises around the null-charge surface formed by the frame-dragging effect, provided that there is no current injection across the gap boundaries. The gap is dissipating a part of the hole’s rotational energy, and the resultant gamma-ray luminosity increases with decreasing plasma accretion from the surroundings. Considering an extremely rotating supermassive BH, we show that such a gap reproduces the significant very-high-energy (VHE) gamma-ray flux observed from the radio galaxy IC 310, provided that the accretion rate becomes much less than the Eddington rate particularly during its flare phase. It is found that the curvature process dominates the inverse-Compton process in the magnetosphere of IC 310, and that the observed power-law-like spectrum in VHE gamma-rays can be explained to some extent by a superposition of the curvature emissions with varying curvature radius. It is predicted that the VHE spectrum extends into higher energies with increasing VHE photon flux.
Thermodynamics of a 3 — D charged rotating hairy black hole
NASA Astrophysics Data System (ADS)
Naji, Jalil; Heydari, Saba; Amjadi, Ali
2014-09-01
In this paper, we consider a charged rotating black hole in three dimensions with a scalar charge, and discuss thermodynamics quantities. We find effects of the black hole parameters on the temperature, entropy, free energy, total energy and specific heat. We also investigate the stability of the black hole and study phase transition. We consider the first law of thermodynamics and find that satisfied.
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.
Angular Momentum-Free of the Entropy Relations for Rotating Kaluza-Klein Black Holes
NASA Astrophysics Data System (ADS)
Liu, Hang; Meng, Xin-he
2016-11-01
Based on a mathematical lemma related to the Vandermonde determinant and two theorems derived from the first law of black hole thermodynamics, we investigate the angular momentum independence of the entropy sum as well as the entropy product of general rotating Kaluza-Klein black holes in higher dimensions. We show that for both non-charged rotating Kaluza-Klein black holes and non-charged rotating Kaluza-Klein-AdS black holes, the angular momentum of the black holes will not be present in entropy sum relation in dimensions d≥4, while the independence of angular momentum of the entropy product holds provided that the black holes possess at least one zero rotation parameter a j = 0 in higher dimensions d≥5, which means that the cosmological constant does not affect the angular momentum-free property of entropy sum and entropy product under the circumstances that charge δ=0. For the reason that the entropy relations of charged rotating Kaluza-Klein black holes as well as the non-charged rotating Kaluza-Klein black holes in asymptotically flat spacetime act the same way, it is found that the charge has no effect in the angular momentum-independence of entropy sum and product in asymptotically flat spactime.
Angular Momentum-Free of the Entropy Relations for Rotating Kaluza-Klein Black Holes
NASA Astrophysics Data System (ADS)
Liu, Hang; Meng, Xin-he
2017-02-01
Based on a mathematical lemma related to the Vandermonde determinant and two theorems derived from the first law of black hole thermodynamics, we investigate the angular momentum independence of the entropy sum as well as the entropy product of general rotating Kaluza-Klein black holes in higher dimensions. We show that for both non-charged rotating Kaluza-Klein black holes and non-charged rotating Kaluza-Klein-AdS black holes, the angular momentum of the black holes will not be present in entropy sum relation in dimensions d≥4, while the independence of angular momentum of the entropy product holds provided that the black holes possess at least one zero rotation parameter a j = 0 in higher dimensions d≥5, which means that the cosmological constant does not affect the angular momentum-free property of entropy sum and entropy product under the circumstances that charge δ=0. For the reason that the entropy relations of charged rotating Kaluza-Klein black holes as well as the non-charged rotating Kaluza-Klein black holes in asymptotically flat spacetime act the same way, it is found that the charge has no effect in the angular momentum-independence of entropy sum and product in asymptotically flat spactime.
Shadow of the rotating black hole with quintessential energy in the presence of plasma
NASA Astrophysics Data System (ADS)
Abdujabbarov, Ahmadjon; Toshmatov, Bobir; Stuchlík, Zdeněk; Ahmedov, Bobomurat
We study the shadow of the rotating black hole with quintessential energy (i) in vacuum, (ii) in the presence of plasma with radial power-law density. For the vacuum case, the quintessential field parameter of the rotating black hole significantly changes the shape of the shadow. With increasing quintessential field parameter, the radius of the shadow also increases. With the increase of the radius of the shadow of the rotating black hole, the quintessential field parameter causes decrease of the distortion of the shadow shape: in the presence of the quintessential field parameter, the shadow of the fast rotating black hole becomes too close to the circle. We assume the distant observer of the black hole shadow to be located near the so-called static radius where the gravitational attraction of the black hole is just balanced by the cosmic repulsion. The shape and size of the shadow of quintessential rotating black hole surrounded by plasma depends on (i) plasma parameters, (ii) black hole spin and (iii) quintessential field parameter. With the increase of the plasma refraction index, the apparent radius of the shadow increases. However, for the large values of the quintessential field parameter, the change of the black hole shadow shape due to the presence of plasma is not significant, i.e. the effect of the quintessential field parameter dominates over the plasma effect.
Charged rotating AdS black holes with Chern-Simons coupling
NASA Astrophysics Data System (ADS)
Mir, Mozhgan; Mann, Robert B.
2017-01-01
We obtain a perturbative solution for rotating charged black holes in five-dimensional Einstein-Maxwell-Chern-Simons theory with a negative cosmological constant. We start from a small undeformed Kerr-AdS solution and use the electric charge as a perturbative parameter to build up black holes with equal-magnitude angular momenta up to fourth order. These black hole solutions are described by three parameters, the charge, horizon radius and horizon angular velocity. We determine the physical quantities of these black holes and study their dependence on the parameters of black holes and arbitrary Chern-Simons coefficient. In particular, for values of the CS coupling constant beyond its supergravity value, due to a rotational instability, counterrotating black holes arise. Also the rotating solutions appear to have vanishing angular momenta and are not manifest uniquely by their global charges.
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.
BlackMax: A black-hole event generator with rotation, recoil, split branes, and brane tension
NASA Astrophysics Data System (ADS)
Dai, De-Chang; Starkman, Glenn; Stojkovic, Dejan; Issever, Cigdem; Rizvi, Eram; Tseng, Jeff
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/~issever/BlackMax/blackmax.html.
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.
Generic rotating regular black holes in general relativity coupled to nonlinear electrodynamics
NASA Astrophysics Data System (ADS)
Toshmatov, Bobir; Stuchlík, Zdeněk; Ahmedov, Bobomurat
2017-04-01
We construct regular rotating black hole and no-horizon spacetimes based on the recently introduced spherically symmetric generic regular black hole spacetimes related to electric or magnetic charge under nonlinear electrodynamics coupled to general relativity that for special values of the spacetime parameters reduce to the Bardeen and Hayward spacetimes. We show that the weak and strong energy conditions are violated inside the Cauchy horizons of these generic rotating black holes. We give the boundary between the rotating black hole and no-horizon spacetimes and determine the black hole horizons and the boundary of the ergosphere. We introduce the separated Carter equations for the geodesic motion in these rotating spacetimes. For the most interesting new class of the regular spacetimes, corresponding for magnetic charges to the Maxwell field in the weak field limit of the nonlinear electrodynamics, we determine the structure of the circular geodesics and discuss their properties. We study the epicyclic motion of a neutral particle moving along the stable circular orbits around the "Maxwellian" rotating regular black holes. We show that epicyclic frequencies measured by the distant observers and related to the oscillatory motion of the neutral test particle along the stable circular orbits around the rotating singular and regular Maxwellian black holes are always smaller than ones in the Kerr spacetime.
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
NASA Astrophysics Data System (ADS)
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.
Floating and sinking: the imprint of massive scalars around rotating black holes.
Cardoso, Vitor; Chakrabarti, Sayan; Pani, Paolo; Berti, Emanuele; Gualtieri, Leonardo
2011-12-09
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.
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.
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.
No-go theorem for slowly rotating black holes in Hořava-Lifshitz gravity.
Barausse, Enrico; Sotiriou, Thomas P
2012-11-02
We consider slowly rotating, stationary, axisymmetric black holes in the infrared limit of Hořava-Lifshitz gravity. We show that such solutions do not exist, provided that they are regular everywhere apart from the central singularity. This has profound implications for the viability of the theory, considering the astrophysical evidence for the existence of black holes with nonzero spin.
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.
Thermodynamics of rotating Kaluza-Klein black holes in gravity's rainbow
NASA Astrophysics Data System (ADS)
Alsaleh, Salwa
2017-04-01
In this paper, a four-dimensional rotating Kaluza Klien (K-K) black hole was deformed using rainbow functions derived from loop quantum gravity and non-commutative geometry. We studied the thermodynamic properties and critical phenomena of this deformed black hole. The deformed temperature and entropy showed the existence of a Planckian remnant. The calculation of Gibbs free energy G for the ordinary and deformed black holes showed that both share a similar critical behaviour.
Jet-quenching parameter in 3D rotating hairy black hole background
NASA Astrophysics Data System (ADS)
Naji, Jalil
2015-07-01
In this paper, we consider rotating black hole in three dimensions with a scalar charge and discuss about the jet-quenching parameter. We find that the effect of scalar charge is decreasing and rotation parameter is increasing the value of the jet-quenching parameter.
Hawking radiation in a rotating Kaluza-Klein black hole with squashed horizons
Chen Songbai; Wang Bin; Su Rukeng
2008-01-15
We explore the signature of the extra dimension in the Hawking radiation in a rotating Kaluza-Klein black hole with squashed horizons. Comparing with the spherical case, we find that the rotating parameter brings richer physics. We obtain the appropriate size of the extra dimension which can enhance the Hawking radiation and may open a window to detect the extra dimensions.
Binary compact object mergers in Einstein-Maxwell-Dilaton theories
NASA Astrophysics Data System (ADS)
Hirschmann, Eric; Lehner, Luis; Liebling, Steve; Palenzuela, Carlos
2017-01-01
We present work on the dynamics and gravitational wae emission of binary black holes in a modified theory of gravity. Our particular model is inspired by low energy string theory and includes additional matter fields, such as a dilaton, not necessarily present in vacuum general relativity. We consider deviations from standard predictions for gravitational wave signatures and examine alternative scalar and electromagnetic channels for emission.
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.
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.
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.
A scalar field condensation instability of rotating Anti-de Sitter black holes
NASA Astrophysics Data System (ADS)
Dias, Óscar J. C.; Monteiro, Ricardo; Reall, Harvey S.; Santos, Jorge E.
2010-11-01
Near-extreme Reissner-Nordström-anti-de Sitter black holes are unstable against the condensation of an uncharged scalar field with mass close to the Breitenlöhner-Freedman bound. It is shown that a similar instability afflicts near-extreme large rotating AdS black holes, and near-extreme hyperbolic Schwarzschild-AdS black holes. The resulting nonlinear hairy black hole solutions are determined numerically. Some stability results for (possibly charged) scalar fields in black hole backgrounds are proved. For most of the extreme black holes we consider, these demonstrate stability if the “effective mass” respects the near-horizon BF bound. Small spherical Reissner-Nordström-AdS black holes are an interesting exception to this result.
Energetics and optical properties of 6-dimensional rotating black hole in pure Gauss-Bonnet gravity
NASA Astrophysics Data System (ADS)
Abdujabbarov, Ahmadjon; Atamurotov, Farruh; Dadhich, Naresh; Ahmedov, Bobomurat; Stuchlík, Zdeněk
2015-08-01
We study physical processes around a rotating black hole in pure Gauss-Bonnet (GB) gravity. In pure GB gravity, the gravitational potential has a slower fall-off as compared to the corresponding Einstein potential in the same dimension. It is therefore expected that the energetics of a pure GB black hole would be weaker, and our analysis bears out that the efficiency of energy extraction by the Penroseprocess is increased to 25.8 % and the particle acceleration is increased to 55.28 %; the optical shadow of the black hole is decreased. These are in principle distinguishing observable features of a pure GB black hole.
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.
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.
Stealths on (1+1)-dimensional dilatonic gravity
NASA Astrophysics Data System (ADS)
Alvarez, Abigail; Campuzano, Cuauhtemoc; Cruz, Miguel; Rojas, Efraín; Saavedra, Joel
2016-12-01
We study gravitational stealth configurations emerging on a charged dilatonic (1+1)-D black hole spacetime. We accomplish this by considering the coupling of a non-minimally scalar field φ and a self-interacting scalar field Ψ living in a (1+1)-D charged black hole background. In addition, the self-interacting potential for Ψ is obtained which exhibits transitions for some specific values of the non-minimal parameter. Atypically, we found that the solutions for these stealth scalar fields do not have a dependence on the temporal coordinate.
Entropy bound of horizons for accelerating, rotating and charged Plebanski–Demianski black hole
Debnath, Ujjal
2016-09-15
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.
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.
An extremization principle for the entropy of rotating BPS black holes in AdS5
NASA Astrophysics Data System (ADS)
Hosseini, Seyed Morteza; Hristov, Kiril; Zaffaroni, Alberto
2017-07-01
We show that the Bekenstein-Hawking entropy of a class of BPS electrically charged rotating black holes in AdS5 × S 5 can be obtained by a simple extremization principle. We expect that this extremization corresponds to the attractor mechanism for BPS rotating black holes in five-dimensional gauged supergravity, which is still unknown. The expression to be extremized has a suggestive resemblance to anomaly polynomials and the supersymmetric Casimir energy recently studied for N=4 super Yang-Mills.
Strong gravity effects of rotating black holes: quasi-periodic oscillations
NASA Astrophysics Data System (ADS)
Aliev, Alikram N.; Daylan Esmer, Göksel; Talazan, Pamir
2013-02-01
We explore strong gravity effects of the geodesic motion in the spacetime of rotating black holes in general relativity and braneworld gravity. We focus on the description of the motion in terms of three fundamental frequencies: the orbital frequency, the radial and vertical epicyclic frequencies. For a Kerr black hole, we perform a detailed numerical analysis of these frequencies at the innermost stable circular orbits and beyond them as well as at the characteristic stable orbits, at which the radial epicyclic frequency attains its highest value. We find that the values of the epicyclic frequencies for a class of stable orbits exhibit good qualitative agreement with the observed frequencies of the twin peaks quasi-periodic oscillations (QPOs) in some black hole binaries. We also find that at the characteristic stable circular orbits, where the radial (or the vertical) epicyclic frequency has maxima, the vertical and radial epicyclic frequencies exhibit an approximate 2:1 ratio even in the case of near-extreme rotation of the black hole. Next, we perform a similar analysis of the fundamental frequencies for a rotating braneworld black hole and argue that the existence of such a black hole with a negative tidal charge, whose angular momentum exceeds the Kerr bound in general relativity, does not confront with the observations of high-frequency QPOs.
Energetics of a rotating charged black hole in 5-dimensional supergravity
Prabhu, Kartik; Dadhich, Naresh
2010-01-15
We investigate the properties of the event horizon and static limit for a charged rotating black hole solution of minimal supergravity theory in (1+4) dimension. Unlike the four-dimensional case, there are in general two rotations, and they couple to both mass and charge. This gives rise to much richer structure to ergosphere leading to energy extraction even for axial fall. Another interesting feature is that the metric in this case is sensitive to the sign of the Maxwell charge.
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.
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.
Particle acceleration and curvature TeV emission by rotating, supermassive black holes
Levinson
2000-07-31
It is shown that particles accelerating near the event horizon of a spinning supermassive black hole that is threaded by externally supported magnetic field lines suffer severe curvature losses that limit the maximum energy they can attain to values well below that imposed by the maximum voltage drop induced by the black hole dynamo. It is further shown that the dominant fraction of the rotational energy extracted from the black hole is radiated in the TeV band. The implications for vacuum breakdown and the observational consequences are discussed.
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).
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.
Matter-antimatter separation in the early universe by rotating black holes
NASA Technical Reports Server (NTRS)
Leahy, D. A.
1981-01-01
Consideration of the effect of rotating black holes evaporating early in the universe shows that they would have produced oppositely directed neutrino and antineutrino currents, which push matter and antimatter apart. This separation mechanism is, however, too feeble to account for a present baryon-to-photon ratio of 10 to the -9th, and has no significant observational consequences.
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.
Quantum tunneling from the charged non-rotating BTZ black hole with GUP
NASA Astrophysics Data System (ADS)
Sadeghi, Jafar; Reza Shajiee, Vahid
2017-03-01
In the present paper, the quantum corrections to the temperature, entropy and specific heat capacity of the charged non-rotating BTZ black hole are studied by the generalized uncertainty principle in the tunneling formalism. It is shown that quantum corrected entropy would be of the form of predicted entropy in quantum gravity theories like string theory and loop quantum gravity.
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.
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.
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.
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.
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.
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.
NASA Astrophysics Data System (ADS)
Stein, Leo
2014-10-01
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 BHs 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.
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."
Integrability in conformally coupled gravity: Taub-NUT spacetimes and rotating black holes
NASA Astrophysics Data System (ADS)
Bardoux, Yannis; Caldarelli, Marco M.; Charmousis, Christos
2014-05-01
We consider four dimensional stationary and axially symmetric spacetimes for conformally coupled scalar-tensor theories. We show that, in analogy to the Lewis-Papapetrou problem in General Relativity (GR), the theory at hand can be recast in an analogous integrable form. We give the relevant rod formalism, introduced by Weyl for vacuum GR, explicitly giving the rod structure of the black hole of Bocharova et al. and Bekenstein (BBMB), in complete analogy to the Schwarzschild solution. The additional scalar field is shown to play the role of an extra Weyl potential. We then employ the Ernst method as a concrete solution generating example to obtain the Taub-NUT version of the BBMB hairy black hole. The solution is easily extended to include a cosmological constant. We show that the anti-de Sitter hyperbolic version of this solution is free of closed timelike curves that plague usual Taub-NUT metrics, and thus consists of a rotating, asymptotically locally anti-de Sitter black hole. This stationary solution has no curvature singularities whatsoever in the conformal frame, and the NUT charge is shown here to regularize the central curvature singularity of the corresponding static black hole. Given our findings we discuss the anti-de Sitter hyperbolic version of Taub-NUT in four dimensions, and show that the curvature singularity of the NUT-less solution is now replaced by a neighbouring chronological singularity screened by horizons. We argue that the properties of this rotating black hole are very similar to those of the rotating BTZ black hole in three dimensions.
Hawking Radiation via Damour-Ruffini Method in Squashed Charged Rotating Kaluza-Klein Black Holes
NASA Astrophysics Data System (ADS)
Hu, Ji-Wan; Wu, Jing-He; Liu, Xian-Ming
2016-12-01
Using the Damour-Ruffini method, Hawking radiation of charged particles from squashed charged rotating five-dimensional Kaluza-Klein black holes is investigated extensively. Under the generalized tortoise coordinate transformation, Hawking temperature of the black holes is calculated by using charged scalar particles and Dirac fermions respectively. We find that the obtained Hawking temperature for charged Dirac fermions is the same as for charged scalar particles. What's more, the spectrum of Hawking radiation contains the information of the size of the extra dimension, which could provide insight for further investigation of large extra dimensions in the future.
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.
Hawking Radiation via Damour-Ruffini Method in Squashed Charged Rotating Kaluza-Klein Black Holes
NASA Astrophysics Data System (ADS)
Hu, Ji-Wan; Wu, Jing-He; Liu, Xian-Ming
2017-02-01
Using the Damour-Ruffini method, Hawking radiation of charged particles from squashed charged rotating five-dimensional Kaluza-Klein black holes is investigated extensively. Under the generalized tortoise coordinate transformation, Hawking temperature of the black holes is calculated by using charged scalar particles and Dirac fermions respectively. We find that the obtained Hawking temperature for charged Dirac fermions is the same as for charged scalar particles. What's more, the spectrum of Hawking radiation contains the information of the size of the extra dimension, which could provide insight for further investigation of large extra dimensions in the future.
A simple accretion model of a rotating gas sphere onto a Schwarzschild black hole
NASA Astrophysics Data System (ADS)
Huerta, E. A.; Mendoza, S.
2007-04-01
We construct a simple accretion model of a rotating gas sphere onto a Schwarzschild black hole. We show how to build analytic solutions in terms of Jacobi elliptic functions. This construction represents a general relativistic generalisation of the Newtonian accretion model first proposed by Ulrich (1976). In exactly the same form as it occurs for the Newtonian case, the flow naturally predicts the existence of an equatorial rotating accretion disc about the hole. However, the radius of the disc increases monotonically without limit as the flow reaches its minimum allowed angular momentum for this particular model.
Hawking radiation from rotating AdS black holes in conformal gravity
NASA Astrophysics Data System (ADS)
Wu, Shuang-Qing; Deng, Gao-Ming; Wu, Di
2014-08-01
We extend to study Hawking radiation via tunneling in conformal gravity. We adopt Parikh-Wilczek's semi-classical tunneling method and the method of complex-path integral to investigate Hawking radiation from new rotating AdS black holes in conformal gravity. In this paper, the research on Hawking radiation from the rotating black holes is done in a general system, not limited in dragging coordinate systems any longer. Moreover, there existed some shortcomings in the previous derivation of geodesic equations. Different from the massless case, they used a different approach to derive the geodesic equation of the massive particles. Even the treatment was inconsistent with the variation principle of action. To remedy the shortcoming, we improve treatment to deduce the geodesic equations of massive and massless particles in a unified and self-consistent way. In addition, we also recover the Hawking temperature resorting to the complex-path integral method.
Gravitational instability of simply rotating AdS black holes in higher dimensions
Kodama, Hideo; Konoplya, R. A.; Zhidenko, Alexander
2009-02-15
We study the stability of AdS black holes rotating in a single two-plane for tensor-type gravitational perturbations in D>6 space-time dimensions. First, by an analytic method, we show that there exists no unstable mode when the magnitude a of the angular momentum is smaller than r{sub h}{sup 2}/R, where r{sub h} is the horizon radius and R is the AdS curvature radius. Then, by numerical calculations of quasinormal modes, using the separability of the relevant perturbation equations, we show that an instability occurs for rapidly rotating black holes with a>r{sub h}{sup 2}/R, although the growth rate is tiny (of order 10{sup -12} of the inverse horizon radius). We give numerical evidence indicating that this instability is caused by superradiance.
Perturbations of slowly rotating black holes: Massive vector fields in the Kerr metric
NASA Astrophysics Data System (ADS)
Pani, Paolo; Cardoso, Vitor; Gualtieri, Leonardo; Berti, Emanuele; Ishibashi, Akihiro
2012-11-01
We discuss a general method to study linear perturbations of slowly rotating black holes which is valid for any perturbation field, and particularly advantageous when the field equations are not separable. As an illustration of the method we investigate massive vector (Proca) perturbations in the Kerr metric, which do not appear to be separable in the standard Teukolsky formalism. Working in a perturbative scheme, we discuss two important effects induced by rotation: a Zeeman-like shift of nonaxisymmetric quasinormal modes and bound states with different azimuthal number m, and the coupling between axial and polar modes with different multipolar index ℓ. We explicitly compute the perturbation equations up to second order in rotation, but in principle the method can be extended to any order. Working at first order in rotation we show that polar and axial Proca modes can be computed by solving two decoupled sets of equations, and we derive a single master equation describing axial perturbations of spin s=0 and s=±1. By extending the calculation to second order we can study the superradiant regime of Proca perturbations in a self-consistent way. For the first time we show that Proca fields around Kerr black holes exhibit a superradiant instability, which is significantly stronger than for massive scalar fields. Because of this instability, astrophysical observations of spinning black holes provide the tightest upper limit on the mass of the photon: mγ≲4×10-20eV under our most conservative assumptions. Spin measurements for the largest black holes could reduce this bound to mγ≲10-22eV or lower.
Novel Rotating Hairy Black Hole in (2+1)-Dimensions and Shear Viscosity to Entropy Ratio
NASA Astrophysics Data System (ADS)
Naji, J.; Heshmatian, S.
2014-08-01
The novel rotating hairy black hole metric in (2 + 1) dimensions, which is an exact solution to the field equations of the Einstein-scalar AdS theory with a non-minimal coupling, considered in this paper and some hydrodynamics quantities such as diffusion constant and shear viscosity investigated. By using thermodynamics quantities such as temperature and entropy we can use diffusion constant to obtain shear viscosity and then calculate shear viscosity to entropy ratio.
A rotating hairy AdS3 black hole with the metric having only one Killing vector field
NASA Astrophysics Data System (ADS)
Iizuka, Norihiro; Ishibashi, Akihiro; Maeda, Kengo
2015-08-01
We perturbatively construct a three-dimensional rotating AdS black hole with a real scalar hair. We choose the mass of a scalar field slightly above the Breitenlohner-Freedman bound and impose a general boundary condition for the bulk scalar field at AdS infinity. We first show that rotating BTZ black holes are unstable against scalar field perturbations under our more general boundary condition. Next we construct a rotating hairy black hole perturbatively with respect to a small amplitude ɛ of the scalar field, up to O( ɛ 4). Our hairy black hole is stationary and exhibits no dissipation, but the lumps of the non-linearly perturbed geometry break axial symmetry, thus providing the first example of a rotating black hole whose metric admits only one Killing vector field. Furthermore, we numerically show that the entropy of our hairy black hole is larger than that of the BTZ black hole with the same energy and the angular momentum. We briefly discuss if our rotating hairy black hole in lumpy geometry could be the endpoint of the instability.
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.
Exact solutions for a system of two counter-rotating black holes
Manko, V. S.; Rodchenko, E. D.; Sadovnikov, B. I.; Ruiz, E.
2008-12-15
The full metric describing two counter-rotating identical Kerr black holes separated by a massless strut is derived in the explicit analytical form. It contains three arbitrary parameters which are the Komar mass M, Komar angular momentum per unit mass a of one of the black holes (the other has the same mass and equal but opposite angular momentum) and the coordinate distance R between the centers of the horizons. In the limit of extreme black holes, the metric becomes a special member of the Kinnersly-Chitre five-parameter family of vacuum solutions generalizing the Tomimatsu-Sato {delta}=2 spacetime, and we present the complete set of metrical fields defining this limit.
Secular evolution of very eccentric, inclined orbits around a supermassive rotating black hole
NASA Astrophysics Data System (ADS)
Will, Clifford; Maitra, Matthew
2017-01-01
We analyze the secular evolution of the highly eccentric, inclined orbit of a star or black hole in the field of a rotating massive Kerr black hole. Such orbits, with 1 - e ranging from 10-2 to 10-6 may be the end result of a process of stellar interactions in a dense nuclear star cluster surrounding the black hole, leading to extreme-mass ratio inspirals (EMRIs). The calculations are done in post-Newtonian (PN) theory, through 3PN order in the conservative sector, including spin-orbit, quadrupolar and (spin)2 terms from the Kerr geometry, and through 4.5PN order, including 4PN spin-orbit contributions, in the radiation reaction sector. We also incorporate an accurate criterion for capture of the body by the rotating black hole for arbitrary inclinations. For a range of initial values of the body's semi-major axis, eccentricity and inclination, we determine the time and number of orbits until plunge and the final orbital eccentricity. We also estimate the gravitational-wave frequency and energy flux at the final plunge, as a function of the orbital inclination. Supported in part by the National Science Foundation PHY 13-06069 & PHY 16-00188.
Hawking fluxes and anomalies in rotating regular black holes with a time-delay
NASA Astrophysics Data System (ADS)
Takeuchi, Shingo
2016-11-01
Based on the anomaly cancellation method we compute the Hawking fluxes (the Hawking thermal flux and the total flux of energy-momentum tensor) from a four-dimensional rotating regular black hole with a time-delay. To this purpose, in the three metrics proposed in [1], we try to perform the dimensional reduction in which the anomaly cancellation method is feasible at the near-horizon region in a general scalar field theory. As a result we can demonstrate that the dimensional reduction is possible in two of those metrics. Hence we perform the anomaly cancellation method and compute the Hawking fluxes in those two metrics. Our Hawking fluxes involve three effects: (1) quantum gravity effect regularizing the core of the black holes, (2) rotation of the black hole, (3) time-delay. Further in this paper toward the metric in which the dimensional could not be performed, we argue that it would be some problematic metric, and mention its cause. The Hawking fluxes we compute in this study could be considered to correspond to more realistic Hawking fluxes. Further what Hawking fluxes can be obtained from the anomaly cancellation method would be interesting in terms of the relation between a consistency of quantum field theories and black hole thermodynamics.
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.
Manko, V. S.; Sanchez-Mondragon, J.; Ruiz, E.
2009-05-01
In the present paper we enlarge the list of black dihole spacetimes by introducing the notion of asymmetric black diholes which describe configurations composed of two static charged black holes endowed with unequal masses and equal but opposite charges. The asymmetric dihole solutions are considered both in the Einstein-Maxwell and Einstein-Maxwell-dilaton theories.
Accretion model of a rotating gas sphere onto a Schwarzschild black hole
NASA Astrophysics Data System (ADS)
Mendoza, S.; Huerta, E. A.
2008-04-01
We construct a simple accretion model of a rotating pressureless gas sphere onto a Schwarzschild black hole. Far away from the hole, the flow is assumed to rotate as a rigid body. We show how to build analytic solutions in terms of Jacobi elliptic functions. This construction represents a general relativistic generalization of the Newtonian accretion model first proposed by Ulrich (1976). In exactly the same form as it occurs for the Newtonian case, the flow naturally predicts the existence of an equatorial rotating accretion disk about the hole. However, the radius of the disk increases monotonically without limit as the flow reaches the angular momentum corresponding to the maximum limit allowed by the model.
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.
Hidden conformal symmetry of a rotating black hole with four charges
Shao Kainan; Zhang Zhibai
2011-05-15
Kerr/CFT correspondence exhibits many remarkable connections between the near-horizon Kerr black hole and a conformal field theory (CFT). Recently, Castro, Maloney, and Strominger showed that a hidden conformal symmetry exists in the solution space of a Kerr black hole. In this paper we investigate a rotating black hole with four independent U(1) charges derived from string theory which is known as the four-dimensional Cvetic-Youm solution, and we prove that the same hidden conformal symmetry also holds. We obtain the exact black hole entropy using the temperatures derived. The entropy and absorption cross section agree with the previous results [M. Cvetic and F. Larsen, Nucl. Phys. B506, 107 (1997).] and [M. Cvetic and F. Larsen, J. High Energy Phys. 09 (2009) 088.]. In addition, we clarify a previous explanation on the temperatures of the Cvetic-Youm solution's dual CFT. This work provides more robust derivation of the hidden conformal symmetry of Kerr-like black holes and as well as Kerr/CFT correspondence.
NASA Astrophysics Data System (ADS)
Yang, Huan; Casals, Marc
2014-07-01
In this paper we study wave propagation and scattering near a black hole. In particular, we assume a coherent emission source near the black hole and investigate the wavefront distortion as seen by a distant observer. By ignoring the spin nature of the electromagnetic radiation we model it by a complex scalar field. Then, the propagating wave near the observer can be decomposed using the Laguerre-Gaussian mode basis and its wavefront distortion can be characterized by the decomposition coefficient. We find that this decomposition spectrum is symmetric with respect to the azimuthal quantum number in the case that the wave source is located near a nonrotating (Schwarzschild) black hole, whereas the spectrum is generically asymmetric if the host black hole is rotating (Kerr). The spectral asymmetry, or the net orbital angular momentum carried by the wave, is intimately related to the black-hole spin and mass, the wave frequency and the locations of the source and the observer. We present semianalytical expressions and numerical results for these parameter dependences. If the emitted radiation is temporally coherent, our results show that the secondary images (arising from the orbiting of the wavefront around the black hole) of the source can be almost as bright as its primary image. Separately, in the case of temporally incoherent radiation, we show that the nonfundamental spectrum components in the primary image could be resolved by spatially separated telescopes, although that would be degenerate with the telescope direction. Finally, our results suggest that the black-hole-induced spectral asymmetry is generally too weak to be observed in radio astronomy, even if the observer is located near an optical caustic.
Time-symmetric initial data sets in four-dimensional dilaton gravity
NASA Astrophysics Data System (ADS)
Ortín, Tomás
1995-09-01
I study the time-symmetric initial-data problem in theories with a massless scalar field (dilaton), free or coupled to a Maxwell field in the stringy way, finding different initial-data sets describing an arbitrary number of black holes with arbitrary masses, charges, and asymptotic value of the dilaton. The presence of the scalar field gives rise to a number of interesting effects. The mass and charges of a single black hole are different in its two asymptotically flat regions across the Einstein-Rosen bridge. The same happens to the value of the dilaton at infinity. This forbids the identification of these asymptotic regions in order to build (Misner) wormholes in the most naive way. Using different techniques, I find regular initial data for stringy wormholes. The price paid is the existence singularities in the dilaton field. The presence of a single-valued scalar seems to constrain strongly the allowed topologies of the initial spacelike surface. Other kinds of scalar fields (taking values on a circle or being defined up to an additive constant) are also briefly considered.
Perturbation of a Schwarzschild Black Hole Due to a Rotating Thin Disk
NASA Astrophysics Data System (ADS)
Čížek, P.; Semerák, O.
2017-09-01
Will, in 1974, treated the perturbation of a Schwarzschild black hole due to a slowly rotating, light, concentric thin ring by solving the perturbation equations in terms of a multipole expansion of the mass-and-rotation perturbation series. In the Schwarzschild background, his approach can be generalized to perturbation by a thin disk (which is more relevant astrophysically), but, due to rather bad convergence properties, the resulting expansions are not suitable for specific (numerical) computations. However, we show that Green’s functions, represented by Will’s result, can be expressed in closed form (without multipole expansion), which is more useful. In particular, they can be integrated out over the source (a thin disk in our case) to yield good converging series both for the gravitational potential and for the dragging angular velocity. The procedure is demonstrated, in the first perturbation order, on the simplest case of a constant-density disk, including the physical interpretation of the results in terms of a one-component perfect fluid or a two-component dust in a circular orbit about the central black hole. Free parameters are chosen in such a way that the resulting black hole has zero angular momentum but non-zero angular velocity, as it is just carried along by the dragging effect of the disk.
Tidal disruptions by rotating black holes: relativistic hydrodynamics with Newtonian codes
NASA Astrophysics Data System (ADS)
Tejeda, Emilio; Gafton, Emanuel; Rosswog, Stephan; Miller, John C.
2017-08-01
We propose an approximate approach for studying the relativistic regime of stellar tidal disruptions by rotating massive black holes. It combines an exact relativistic description of the hydrodynamical evolution of a test fluid in a fixed curved space-time with a Newtonian treatment of the fluid's self-gravity. Explicit expressions for the equations of motion are derived for Kerr space-time using two different coordinate systems. We implement the new methodology within an existing Newtonian smoothed particle hydrodynamics code and show that including the additional physics involves very little extra computational cost. We carefully explore the validity of the novel approach by first testing its ability to recover geodesic motion, and then by comparing the outcome of tidal disruption simulations against previous relativistic studies. We further compare simulations in Boyer-Lindquist and Kerr-Schild coordinates and conclude that our approach allows accurate simulation even of tidal disruption events where the star penetrates deeply inside the tidal radius of a rotating black hole. Finally, we use the new method to study the effect of the black hole spin on the morphology and fallback rate of the debris streams resulting from tidal disruptions, finding that while the spin has little effect on the fallback rate, it does imprint heavily on the stream morphology, and can even be a determining factor in the survival or disruption of the star itself. Our methodology is discussed in detail as a reference for future astrophysical applications.
Mirza, Behrouz; Sherkatghanad, Zeinab
2011-05-15
We study the AdS rotating black hole solution for the Bergshoeff-Hohm-Townsend massive gravity in three dimensions. The field equations of the asymptotically AdS black hole of the static metric can be expressed as the first law of thermodynamics, i.e. dE=TdS-PdV. The corrected Hawking-like temperature and entropy of the asymptotically AdS rotating black hole are calculated using the Cardy formula and the tunneling method. Comparison of these methods will help identify the unknown leading correction parameter {beta}{sub 1} in the tunneling method.
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.
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.
Slowly varying dilaton cosmologies and their field theory duals
NASA Astrophysics Data System (ADS)
Awad, Adel; Das, Sumit R.; Ghosh, Archisman; Oh, Jae-Hyuk; Trivedi, Sandip P.
2009-12-01
We consider a deformation of the AdS5×S5 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 γ. 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 γ, and find that it is smooth, horizon-free, and asymptotically AdS5×S5 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 S3 with a time dependent coupling constant which varies slowly. When Nγ≪1, we find that a quantum adiabatic approximation is applicable, and use it to argue that at late times the geometry becomes smooth AdS5×S5 again. When Nγ≫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 AdS5 space with the possible presence of a small black hole.
NASA Astrophysics Data System (ADS)
Blázquez-Salcedo, Jose Luis; Kunz, Jutta; Navarro-Lérida, Francisco; Radu, Eugen
2017-03-01
We consider rotating black hole solutions in five-dimensional Einstein-Maxwell-Chern-Simons theory with a negative cosmological constant and a generic value of the Chern-Simons coupling constant λ . Using both analytical and numerical techniques, we focus on cohomogeneity-1 configurations, with two equal-magnitude angular momenta, which approach at infinity a globally anti-de Sitter background. We find that the generic solutions share a number of basic properties with the known Cvetič, Lü, and Pope black holes which have λ =1 . New features occur as well; for example, when the Chern-Simons coupling constant exceeds a critical value, the solutions are no longer uniquely determined by their global charges. Moreover, the black holes possess radial excitations which can be labelled by the node number of the magnetic gauge potential function. Solutions with small values of λ possess other distinct features. For instance, the extremal black holes there form two disconnected branches, while not all near-horizon solutions are associated with global solutions.
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.
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)
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.
Holographic stress-energy tensor near the Cauchy horizon inside a rotating black hole
NASA Astrophysics Data System (ADS)
Ishibashi, Akihiro; Maeda, Kengo; Mefford, Eric
2017-07-01
We investigate a stress-energy tensor for a conformal field theory (CFT) at strong coupling inside a small five-dimensional rotating Myers-Perry black hole with equal angular momenta by using the holographic method. As a gravitational dual, we perturbatively construct a black droplet solution by applying the "derivative expansion" method, generalizing the work of Haddad [Classical Quantum Gravity 29, 245001 (2012), 10.1088/0264-9381/29/24/245001] and analytically compute the holographic stress-energy tensor for our solution. We find that the stress-energy tensor is finite at both the future and past outer (event) horizons and that the energy density is negative just outside the event horizons due to the Hawking effect. Furthermore, we apply the holographic method to the question of quantum instability of the Cauchy horizon since, by construction, our black droplet solution also admits a Cauchy horizon inside. We analytically show that the null-null component of the holographic stress-energy tensor negatively diverges at the Cauchy horizon, suggesting that a singularity appears there, in favor of strong cosmic censorship.
NASA Astrophysics Data System (ADS)
Zaslavskii, Oleg B.
2012-10-01
We study the effect of collisions of ultrahigh energy particles near the black hole horizon (BSW effect) for two scenarios: when one of the particles either (i) moves on a circular orbit or (ii) plunges from it toward the horizon. It is shown that such circular near-horizon orbits can exist for near-extremal black holes only. This includes the innermost stable orbit (ISCO), marginally bound orbit (MBO) and photon one (PhO). We consider generic ‘dirty’ rotating black holes not specifying the metric and show that the energy in the center-of-mass frame has the universal scaling dependence on the surface gravity κ. Namely, Ec.m. ˜ κ-n where for the ISCO, n=\\frac{1}{3} in case (i) or n=\\frac{1}{2} in case (ii). For the MBO and PhCO, n=\\frac{1}{2} in both scenarios that agrees with recent calculations of Harada and Kimura for the Kerr metric. We also generalize the Grib and Pavlov observations made for the Kerr metric. The magnitude of the BSW effect on the location of collision has a somewhat paradoxical character: it decreases when approaching the horizon.
Exact solution for a binary system of unequal counter-rotating black holes
NASA Astrophysics Data System (ADS)
Cabrera-Munguia, I.; Lämmerzahl, Claus; Macías, Alfredo
2013-09-01
A complete solution describing a binary system constituted by two unequal counter-rotating black holes with a massless strut in between is presented. It is expressed in terms of four arbitrary parameters: the half length of the two rods representing the black hole horizons σ1 and σ2, the total mass M and the relative distance R between the centers of the horizons. The explicit parametrization of this solution in terms of physical parameters, i.e., the Komar masses M1 and M2, the Komar angular momenta J1 and J2 (having J1 and J2 opposite signs) and the coordinate distance R, led us to a four-parameter subclass in which the five physical parameters satisfy a simple algebraic relation, which generalizes the two statements made by Bonnor, in order to remove the additional contributions from the massless spinning rods outside the black holes. Moreover, the interaction force turns out to be of the same form as in the double-Schwarzschild static case.
NASA Astrophysics Data System (ADS)
Panotopoulos, Grigoris; Rincón, Ángel
2017-07-01
We analyze in detail the propagation of a minimally coupled massless scalar field in the gravitational background of a four-dimensional Einstein-Born-Infeld dilaton charged black hole. We obtain analytical expressions for the absorption cross section as well as the decay rate for the scalar field in the aforementioned spacetime, and we graphically show its behavior for different values of the free parameters of the theory.
Harrison transformation and charged black objects in Kaluza-Klein theory
NASA Astrophysics Data System (ADS)
Kleihaus, Burkhard; Kunz, Jutta; Radu, Eugen; Stelea, Cristian
2009-09-01
We generate charged black brane solutions in D-dimensions in a theory of gravity coupled to a dilaton and an antisymmetric form, by using a Harrison-type transformation. The seed vacuum solutions that we use correspond to uplifted Kaluza-Klein black strings and black holes in (D-p)-dimensions. A generalization of the Marolf-Mann quasilocal formalism to the Kaluza-Klein theory is also presented, the global charges of the black objects being computed in this way. We argue that the thermodynamics of the charged solutions can be derived from that of the vacuum configurations. Our results show that all charged Kaluza-Klein solutions constructed by means of Harrison transformations are thermodynamically unstable in a grand canonical ensemble. The general formalism is applied to the case of nonuniform black strings and caged black hole solutions in D = 5,6 Einstein-Maxwell-dilaton gravity, whose geometrical properties and thermodynamics are discussed. We argue that the topology changing transition scenario, which was previously proposed in the vacuum case, also holds in this case. Spinning generalizations of the charged black strings are constructed in six dimensions in the slowly rotating limit. We find that the gyromagnetic ratio of these solutions possesses a nontrivial dependence on the nonuniformity parameter.
Light dilaton in walking gauge theories
Appelquist, Thomas; Bai Yang
2010-10-01
We analyze the existence of a dilaton in gauge theories with approximate infrared conformal symmetry. To the extent that these theories are governed in the infrared by an approximate fixed point (walking), the explicit breaking of the conformal symmetry at these scales is vanishingly small. If confinement and spontaneous chiral-symmetry breaking set in at some infrared scale, the resultant breaking of the approximate conformal symmetry can lead to the existence of a dilaton with mass parametrically small compared to the confinement scale, and potentially observable at the LHC.
NASA Astrophysics Data System (ADS)
Rasskazov, Alexander; Merritt, David
2017-01-01
The subject of our study is a binary supermassive black hole (BSBH) in the center of a galactic nucleus. We model the evolution of its orbit due to interactions with the stars of the galaxy by means of 3-body scattering experiments. Our model includes a new degree of freedom - the orientation of the BSBH’s orbital plane - which is allowed to change due to interaction with the stars in a rotating nucleus. The binary’s eccentricity also evolves in an orientation-dependent manner. We find that the dynamics are qualitatively different compared with non-rotating nuclei: 1) The BSBH's orbital plane evolves toward alignment with the plane of rotation of the nucleus; 2) The BSBH’s eccentricity decreases for aligned BSBHs and increases for counter-aligned ones.We then apply our model to calculate the effects of stellar environment on the gravitational wave background spectrum produced by BSBHs. Using the results of recent N-body/Monte-Carlo simulations we account for different rates of stellar interaction in spherical, axisymmetric and triaxial galaxies. We also consider the possibility that SBH masses are systematically lower than usually assumed. The net result of the new physical mechanisms included here is a spectrum for the stochastic gravitational wave background that has a significantly lower amplitude than in previous treatments, which could explain the discrepancy that currently exists between the models and the upper limits set by pulsar timing array observations.
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 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 $\
Thin-shell wormholes in dilaton gravity
Eiroa, Ernesto F.; Simeone, Claudio
2005-06-15
In this work we construct charged thin-shell Lorentzian wormholes in dilaton gravity. The exotic matter required for the construction is localized in the shell and the energy conditions are satisfied outside the shell. The total amount of exotic matter is calculated and its dependence with the parameters of the model is analyzed.
Compact static stars in minimal dilatonic gravity
NASA Astrophysics Data System (ADS)
Fiziev, Plamen P.
2017-09-01
In the version1 of this paper we presented for the first time the basic equations and relations for relativistic static spherically symmetric stars (SSSS) in the model of minimal dilatonic gravity (MDG). This model is locally equivalent to the f(R) theory of gravity and gives an alternative description of the effects of dark matter and dark energy using the Brans-Dicke dilaton Φ. To outline the basic properties of the MDG model of SSSS and to compare them with general relativistic results, in this paper we use the relativistic equation of state (EOS) of neutron matter as an ideal Fermi neutron gas at zero temperature. We overcome the well-known difficulties of the physics of SSSS in the f(R) theories of gravity2,3 applying novel highly nontrivial nonlinear boundary conditions, which depend on the global properties of the solution and on the EOS. We also introduce two pairs of new notions: cosmological-energy-pressure densities and dilaton-energy-pressure densities, as well as two new EOSs for them: cosmological EOS (CEOS) and dilaton EOS (DEOS). Special attention is paid to the dilatonic sphere (in brief — disphere) of SSSS, introduced in this paper for the first time. Using several realistic EOS for neutron star (NS): SLy, BSk19, BSk20 and BSk21, and current observational two-solar-masses-limit, we derive an estimate for scalar-field-mass mΦ ˜ 10‑13eV/c2 ÷ 4 × 10‑11eV/c2. Thus, the present version of the paper reflects some of the recent developments of the topic.
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.
Extremal rotating black holes in the near-horizon limit: Phase space and symmetry algebra
NASA Astrophysics Data System (ADS)
Compère, G.; Hajian, K.; Seraj, A.; Sheikh-Jabbari, M. M.
2015-10-01
We construct the NHEG phase space, the classical phase space of Near-Horizon Extremal Geometries with fixed angular momenta and entropy, and with the largest symmetry algebra. We focus on vacuum solutions to d dimensional Einstein gravity. Each element in the phase space is a geometry with SL (2 , R) × U(1) d - 3 isometries which has vanishing SL (2 , R) and constant U (1) charges. We construct an on-shell vanishing symplectic structure, which leads to an infinite set of symplectic symmetries. In four spacetime dimensions, the phase space is unique and the symmetry algebra consists of the familiar Virasoro algebra, while in d > 4 dimensions the symmetry algebra, the NHEG algebra, contains infinitely many Virasoro subalgebras. The nontrivial central term of the algebra is proportional to the black hole entropy. The conserved charges are given by the Fourier decomposition of a Liouville-type stress-tensor which depends upon a single periodic function of d - 3 angular variables associated with the U (1) isometries. This phase space and in particular its symmetries can serve as a basis for a semiclassical description of extremal rotating black hole microstates.
On extreme transient events from rotating black holes and their gravitational wave emission
NASA Astrophysics Data System (ADS)
van Putten, Maurice H. P. M.; Della Valle, Massimo
2017-01-01
The super-luminous object ASASSN-15lh (SN2015L) is an extreme event with a total energy Erad ≃ 1.1 × 1052 erg in blackbody radiation on par with its kinetic energy Ek in ejecta and a late time plateau in the UV, which defies a nuclear origin. It likely presents a new explosion mechanism for hydrogen-deprived supernovae. With no radio emission and no H-rich environment, we propose to identify Erad with dissipation of a baryon-poor outflow in the optically thick remnant stellar envelope produced by a central engine. By negligible time-scales of light crossing and radiative cooling of the envelope, SN2015L's light curve closely tracks the evolution of this engine. We here model its light curve by the evolution of black hole spin during angular momentum loss in Alvén waves to matter at the Inner Most Stable Circular Orbit (ISCO). The duration is determined by σ = MT/M of the torus mass MT around the black hole of mass M: σ ˜ 10-7 and σ ˜ 10-2 for SN2015L and, respectively, a long GRB. The observed electromagnetic radiation herein represents a minor output of the rotational energy Erot of the black hole, while most is radiated unseen in gravitational radiation. This model explains the high-mass slow-spin binary progenitor of GWB150914, as the remnant of two CC-SNe in an intra-day binary of two massive stars. This model rigorously predicts a change in magnitude Δm ≃ 1.15 in the light curve post-peak, in agreement with the light curve of SN2015L with no fine-tuning.
NASA Astrophysics Data System (ADS)
Zhu, Xiao-Dan; Wu, Di; Wu, Shuang-Qing; Yang, Shu-Zheng
2016-12-01
We initiated the program to look for new and simple forms for the five-dimensional rotating squashed black holes by solving directly the equation of motion. In a recent paper, the metric ansatz of dimensional reduction along the fifth spatial dimension was used to obtain a new but rather simple form for the five-dimensional rotating uncharged black hole solution with squashed horizons via solving the vacuum Einstein field equations. In this work, we continue to seek for another new but relatively simple form for the neutral rotating squashed black hole solution by using a different metric ansatz of time-like dimensional reduction. We then find its relation to our previous solution and investigate its thermodynamics by means of the counterterm method. Compared with the previous results given by the other author, both of our new metric forms and their associated thermodynamic expressions are very concise and elegant. Both of two new forms for the neutral rotating squashed black hole solution presented in this paper can be used as the seed to generate its charged generalization in D=5 minimal supergravity.
Lifshitz hydrodynamics from Lifshitz black branes with linear momentum
NASA Astrophysics Data System (ADS)
Hartong, Jelle; Obers, Niels A.; Sanchioni, Marco
2016-10-01
We construct a new class of 4-dimensional z = 2 Lifshitz black branes that have a non-zero linear momentum. These are solutions of an Einstein-Proca-dilaton model that can be obtained by Scherk-Schwarz circle reduction of AdS5 gravity coupled to a free real scalar field. The boundary of a bulk Lifshitz space-time is a Newton-Cartan geometry. We show that the fluid dual to the moving Lifshitz black brane leads to a novel form of Lifshitz hydrodynamics on a Newton-Cartan space-time. Since the linear momentum of the black brane cannot be obtained by a boost transformation the velocity of the fluid or rather, by boundary rotational invariance, its magnitude plays the role of a chemical potential. The conjugate dual variable is mass density. The Lifshitz perfect fluid can be thought of as arising from a Schrödinger perfect fluid with broken particle number symmetry.
Manko, V. S.; Sanchez-Mondragon, J.; Ruiz, E.
2009-04-15
In this paper we consider a magnetic analog of the double-Reissner-Nordstroem solution and construct the corresponding magnetic potential A{sub {phi}} in the explicit form. The behavior of the resulting solution under the Harrison transformation then naturally singles out the asymmetric black diholes--configurations composed of two nonextreme black holes possessing unequal masses, and charges equal in magnitude but opposite in sign - as its most general subclass for which equilibrium of the black-hole constituents can be achieved with the aid of the external magnetic (or electric) field. We also generalize the double-Reissner-Nordstroem solution to dilaton gravity with arbitrary dilaton coupling, yielding the four-dimensional double-Gibbons-Maeda spacetime. The study of some physical properties of the solutions obtained leads, in particular, to very simple formulas for the areas of the horizons and surface gravities.
NASA Astrophysics Data System (ADS)
Lemos, José P. S.; Minamitsuji, Masato; Zaslavskii, Oleg B.
2017-02-01
In a (2 +1 )-dimensional spacetime with a negative cosmological constant, the thermodynamics and the entropy of an extremal rotating thin shell, i.e., an extremal rotating ring, are investigated. The outer and inner regions with respect to the shell are taken to be the Bañados-Teitelbom-Zanelli (BTZ) spacetime and the vacuum ground state anti-de Sitter spacetime, respectively. By applying the first law of thermodynamics to the extremal thin shell, one shows that the entropy of the shell is an arbitrary well-behaved function of the gravitational area A+ alone, S =S (A+). When the thin shell approaches its own gravitational radius r+ and turns into an extremal rotating BTZ black hole, it is found that the entropy of the spacetime remains such a function of A+, both when the local temperature of the shell at the gravitational radius is zero and nonzero. It is thus vindicated by this analysis that extremal black holes, here extremal BTZ black holes, have different properties from the corresponding nonextremal black holes, which have a definite entropy, the Bekenstein-Hawking entropy S (A+)=A/+4G , where G is the gravitational constant. It is argued that for extremal black holes, in particular for extremal BTZ black holes, one should set 0 ≤S (A+)≤A/+4G;i.e., the extremal black hole entropy has values in between zero and the maximum Bekenstein-Hawking entropy A/+4 G . Thus, rather than having just two entropies for extremal black holes, as previous results have debated, namely, 0 and A/+4 G , it is shown here that extremal black holes, in particular extremal BTZ black holes, may have a continuous range of entropies, limited by precisely those two entropies. Surely, the entropy that a particular extremal black hole picks must depend on past processes, notably on how it was formed. A remarkable relation between the third law of thermodynamics and the impossibility for a massive body to reach the velocity of light is also found. In addition, in the procedure, it
Nonmetricity and torsion induced by dilaton gravity in two dimension
NASA Astrophysics Data System (ADS)
Adak, M.
2006-05-01
We develop a theory in which there are couplings amongst Dirac spinor, dilaton and non-Riemannian gravity and explore the nature of connection-induced dilaton couplings to gravity and Dirac spinor when the theory is reformulated in terms of the Levi-Civita connection. After presenting some exact solutions without spinors, we investigate the minimal spinor couplings to the model and in conclusion we cannot find any nontrivial dilaton couplings to spinor.
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.
Gravitational field of a Schwarzschild black hole and a rotating mass ring
NASA Astrophysics Data System (ADS)
Sano, Yasumichi; Tagoshi, Hideyuki
2014-08-01
The linear perturbation of the Kerr black hole has been discussed by using the Newman-Penrose formalism, and the perturbed Weyl scalars, ψ0 and ψ4 can be obtained from the Teukolsky equation. In order to obtain the other Weyl scalars and the perturbed metric, a formalism was proposed by Chrzanowski and by Cohen and Kegeles to construct these quantities in a radiation gauge via the Hertz potential. As a simple example of the construction of the perturbed gravitational field with this formalism, we consider the gravitational field produced by a rotating circular ring around a Schwarzschild black hole. In the method by Chrzanowski, Cohen, and Kegeles, the metric is constructed in a radiation gauge via the Hertz potential, which is obtained from the solution of the Teukolsky equation. Since the solutions ψ0 and ψ4 of the Teukolsky equations are spin-2 quantities, the Hertz potential is determined up to its monopole and dipole modes. Without these lower modes, the constructed metric and Newman-Penrose Weyl scalars have unphysical jumps on the spherical surface at the radius of the ring. We find that the jumps of the imaginary parts of the Weyl scalars are cancelled when we add the angular momentum perturbation to the Hertz potential. Finally, by adding the mass perturbation and choosing the parameters which are related to the gauge freedom, we obtain the perturbed gravitational field which is smooth except on the equatorial plane outside the ring. We discuss the implication of these results to the problem of the computation of the gravitational self-force to the point particles in a radiation gauge.
Dilaton stabilization by massive fermion matter
NASA Astrophysics Data System (ADS)
Cabo, Alejandro; Roos, Matts; Erfani, Encieh
2012-08-01
The study started by Cabo and Brandenberger (J. Cosmol. Astropart. Phys. 2:15, 2009) about the Dilaton mean field stabilization thanks to the effective potential generated by the existence of massive fermions, is here extended. Three loop corrections are evaluated in addition to the previously calculated two loop terms. The results indicate that the Dilaton vacuum field tends to be fixed at a high value close to the Planck scale, in accordance with the need for predicting Einstein gravity from string theory. The mass of the Dilaton is evaluated to be also a high value close to the Planck mass, which implies the absence of Dilaton scalar signals in modern cosmological observations. These properties arise when the fermion mass is chosen to be either at a lower bound corresponding to the top quark mass, or alternatively, at a very much higher value assumed to be in the grand unification energy range. One of the three 3-loop terms is exactly evaluated in terms of Master integrals. The other two graphs are however evaluated in their leading logarithm correction in the perturbative expansion. The calculation of the non leading logarithmic contribution and the inclusion of higher loops terms could made more precise the numerical estimates of the vacuum field value and masses, but seemingly are expected not to change the qualitative behavior obtained. The validity of the here employed Yukawa model approximation is argued for small value of the fermion masses with respect to the Planck one. A correction to the two loop calculation done in the previous work is here underlined.
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)
Fiacconi, Davide; Rossi, Elena M.
2017-01-01
Supermassive black holes are a key ingredient of galaxy evolution. However, their origin is still highly debated. In one of the leading formation scenarios, a black hole of ˜100 M⊙ results from the collapse of the inner core of a supermassive star (≳104-5 M⊙), created by the rapid accumulation (≳0.1 M⊙ yr-1) of pristine gas at the centre of newly formed galaxies at z ˜ 15. The subsequent evolution is still speculative: the remaining gas in the supermassive star can either directly plunge into the nascent black hole or part of it can form a central accretion disc, whose luminosity sustains a surrounding, massive, and nearly hydrostatic envelope (a system called a `quasi-star'). To address this point, we consider the effect of rotation on a quasi-star, as angular momentum is inevitably transported towards the galactic nucleus by the accumulating gas. Using a model for the internal redistribution of angular momentum that qualitatively matches results from simulations of rotating convective stellar envelopes, we show that quasi-stars with an envelope mass greater than a few 105 M_{⊙} × (black hole mass/100 M_{⊙})^{0.82} have highly sub-Keplerian gas motion in their core, preventing gas circularization outside the black hole's horizon. Less massive quasi-stars could form but last for only ≲104 yr before the accretion luminosity unbinds the envelope, suppressing the black hole growth. We speculate that this might eventually lead to a dual black hole seed population: (i) massive (>104 M⊙) seeds formed in the most massive (>108 M⊙) and rare haloes; (ii) lighter (˜102 M⊙) seeds to be found in less massive and therefore more common haloes.
NASA Astrophysics Data System (ADS)
Rasskazov, Alexander; Merritt, David
2017-04-01
We compute the isotropic gravitational wave (GW) background produced by binary supermassive black holes (SBHs) in galactic nuclei. In our model, massive binaries evolve at early times via gravitational-slingshot interaction with nearby stars, and at later times by the emission of GWs. Our expressions for the rate of binary hardening in the "stellar" regime are taken from the recent work of Vasiliev et al., who show that in the nonaxisymmetric galaxies expected to form via mergers, stars are supplied to the center at high enough rates to ensure binary coalescence on Gyr timescales. We also include, for the first time, the extra degrees of freedom associated with evolution of the binary's orbital plane; in rotating nuclei, interaction with stars causes the orientation and the eccentricity of a massive binary to change in tandem, leading in some cases to very high eccentricities (e >0.9 ) before the binary enters the GW-dominated regime. We argue that previous studies have over-estimated the mean ratio of SBH mass to galaxy bulge mass by factors of 2-3. In the frequency regime currently accessible to pulsar timing arrays (PTAs), our assumptions imply a factor 2-3 reduction in the characteristic strain compared with the values computed in most recent studies, removing the tension that currently exists between model predictions and the nondetection of GWs.
NASA Astrophysics Data System (ADS)
Li, Ran; Zhao, Jun-Kun
2016-04-01
We investigate the massive vector particles' Hawking radiation from the neutral rotating Anti-de Sitter (AdS) black holes in conformal gravity by using the tunneling method. It is well known that the dynamics of massive vector particles are governed by the Proca field equation. Applying WKB approximation to the Proca equation, the tunneling probabilities and radiation spectrums of the emitted particles are derived. Hawking temperature of the neutral rotating AdS black holes in conformal gravity is recovered, which is consistent with the previous result in the literature. Supported by the National Natural Science Foundation of China under Grant No. 11205048, and the Foundation for Young Key Teacher of Henan Normal University
D instanton on the linear-dilaton background
Gal'tsov, D. V. Orlov, D. G. Klevtsov, S. E.
2007-09-15
It is shown that, in addition to a standard asymptotically flat D instanton, IIB superstring theory contains an instanton-type excitation on the linear-dilaton background. The new solution is asymptotically flat, but the dilaton grows linearly at infinity. The total action of this configuration diverges, but the instanton action proper becomes finite upon subtracting an infinite background contribution.
Varying dilaton as a tracer of classical string interactions
NASA Astrophysics Data System (ADS)
Dodelson, Matthew; Silverstein, Eva; Torroba, Gonzalo
2017-09-01
We analyze tree-level string amplitudes in a linear dilaton background, motivated by its use as a gauge-invariant tracer of string interactions in scattering experiments and its genericity among simple perturbative string theory limits. A simple case is given by a lightlike dependence for the dilaton. The zero mode of the embedding coordinate in the direction of dilaton variation requires special care. Employing Gaussian wave packets and a well-defined modification of the dilaton profile far from the dominant interaction region, we obtain finite results which explicitly reproduce the interaction time scales expected from joining and splitting interactions involving oscillating strings in simple string scattering processes. There is an interesting interplay between the effects of the linear dilaton and the i ɛ prescription. In more general circumstances this provides a method for tracing the degree of nonlocality in string interactions, and it gives a basis for further studies of perturbative supercritical string theory at higher loop order.
John R. Jones; Wayne D. Shepperd
1985-01-01
The rotation, in forestry, is the planned number of years between formation of a crop or stand and its final harvest at a specified stage of maturity (Ford-Robertson 1971). The rotation used for many species is the age of culmination of mean usable volume growth [net mean annual increment (MAI)]. At that age, usable volume divided by age reaches its highest level. That...
Cosmological constraints on Higgs-dilaton inflation
NASA Astrophysics Data System (ADS)
Trashorras, Manuel; Nesseris, Savvas; García-Bellido, Juan
2016-09-01
We test the viability of the Higgs-dilaton model (HDM) compared to the evolving dark energy (w0waCDM ) model, in which the cosmological constant model Λ CDM is also nested, by using the latest cosmological data that include the cosmic microwave background temperature, polarization and lensing data from the Planck satellite (2015 data release), the BICEP and Keck Array experiments, the Type Ia supernovae from the JLA catalog, the baryon acoustic oscillations from CMASS, LOWZ and 6dF, the weak lensing data from the CFHTLenS survey, and the matter power spectrum measurements from the SDSS (data release 7). We find that the values of all cosmological parameters allowed by the Higgs-dilaton model inflation are well within the Planck satellite (2015 data release) constraints. In particular, we have that w0=-1.000 1-0.0074+0.0072 , wa=0.0 0-0.16+0.15, ns=0.969 3-0.0082+0.0083, αs=-0.00 1-0.014+0.013 and r0.05=0.002 5-0.0016+0.0017 (95.5% C.L.). We also place new stringent constraints on the couplings of the Higgs-dilaton model and we find that ξχ<0.00328 and ξh/√{λ }=5920 0-20000+30000 (95.5% C.L.). Furthermore, we report that the HDM is on slightly better footing than the w0waCDM model, as they both have practically the same chi-square, i.e. Δ χ2=χw0waCDM 2-χHDM2=0.18 , with the HDM model having two fewer parameters. Finally, Bayesian evidence favors equally the two models, with the HDM being preferred by the AIC and DIC information criteria.
Scaling solutions for dilaton quantum gravity
NASA Astrophysics Data System (ADS)
Henz, T.; Pawlowski, J. M.; Wetterich, C.
2017-06-01
Scaling solutions for the effective action in dilaton quantum gravity are investigated within the functional renormalization group approach. We find numerical solutions that connect ultraviolet and infrared fixed points as the ratio between scalar field and renormalization scale k is varied. In the Einstein frame the quantum effective action corresponding to the scaling solutions becomes independent of k. The field equations derived from this effective action can be used directly for cosmology. Scale symmetry is spontaneously broken by a non-vanishing cosmological value of the scalar field. For the cosmology corresponding to our scaling solutions, inflation arises naturally. The effective cosmological constant becomes dynamical and vanishes asymptotically as time goes to infinity.
Techni-Dilaton Signatures at LHC
NASA Astrophysics Data System (ADS)
Matsuzaki, Shinya; Yamawaki, Koichi
2013-03-01
We explore LHC discovery signatures of techni-dilaton (TD) arising as a composite pseudo Nambu-Goldstone boson (pNGB), associated with the spontaneous breaking of the approximate scale symmetry in the walking technicolor (WTC). We explicitly evaluate the TD 7 TeV LHC production cross sections times the branching ratios in terms of the TD mass MTD as an input parameter for the region 200 GeV < MTD < 1000 GeV in the typical WTC models. It turns out that the TD signatures are quite different from those of the standard model (SM) Higgs.
On Massive Particle's Tunneling in the Garfinkle-Horne Dilaton Gravity
NASA Astrophysics Data System (ADS)
Fu, Jing; Pu, Jin
2017-07-01
In this paper, we start from the Lagrangian analysis on the action to naturally produce the geodesic equation of the massive particle via tunneling. Then, basing on the new definition for the geodesic equation, we revisit the Hawking radiation of the massive particle via tunneling from the Garfinkle-Horne Dilaton black hole. In our treatment, the geodesic equation of the massive particle is defined uniformly with that of the massless particle, which overcomes the shortcomings of its previous definition, and is more suitable for the tunneling mechanism. It is noteworthy that, the highlight of our work is a new and important development of the Parikh-Wilczek's tunneling method.
Transgressing the horizons: Time operator in two-dimensional dilaton gravity
Kunstatter, Gabor; Louko, Jorma
2007-01-15
We present a Dirac quantization of generic single-horizon black holes in two-dimensional dilaton gravity. The classical theory is first partially reduced by a spatial gauge choice under which the spatial surfaces extend from a black or white hole singularity to a spacelike infinity. The theory is then quantized in a metric representation, solving the quantum Hamiltonian constraint in terms of (generalized) eigenstates of the ADM mass operator and specifying the physical inner product by self-adjointness of a time operator that is affinely conjugate to the ADM mass. Regularity of the time operator across the horizon requires the operator to contain a quantum correction that distinguishes the future and past horizons and gives rise to a quantum correction in the hole's surface gravity. We expect a similar quantum correction to be present in systems whose dynamics admits black hole formation by gravitational collapse.
Stettler, R.F.; Hinckley, T.M.; Heilman, P.E.; Bradshaw, H.D. Jr.
1993-04-30
This project was initiated in 1978 to serve three objectives: (1) develop genetically improved poplar cultivars offering increased productivity under short-rotation culture; (2) identify the major components of productivity in poplar and determine ways in which they can be manipulated, genetically and culturally; and (3) engage in technology transfer to regional industry and agencies so as to make poplar culture in the Pacific Northwest economically feasible. The project is aimed at capturing natural variation in the native black cottonwood. Populus trichocarpa T & G, and enhancing it through selective breeding. Major emphasis has been placed on hybridization of black cottonwood with P deltoides and P maximowiczii, more recently with p nigra. First-generation (F{sub 1}) hybrids have consistently outperformed black cottonwood by a factor of 1.5.-2. The high yields of woody biomass obtained from these clonally propagated hybrids, in rotations of 4-7 years, have fostered the establishment of large-scale plantations by the pulp and paper industry in the region. Physiological studies have helped to elucidate hybrid superiority and several of the underlying mechanisms.
NASA Astrophysics Data System (ADS)
Veste, M.; Böhm, C.; Quinckenstein, A.; Freese, D.
2012-04-01
The importance of short rotation forests and agroforestry systems for woody biomass production for bioenergy will increase in Central Europe within the next decades. In this context, black locust (Robinia pseudoacacia) has a high growth potential especially at marginal, drought-susceptible sites such as occur in Brandenburg State (Eastern Germany). As a pioneer tree species black locust grows under a wide range of site conditions. The native range of black locust in Northern America is classified by a humid to sub-humid climate with a mean annual precipitation of 1020 to 1830 mm. In Central and Eastern Europe, this species is cultivated in a more continental climate with an annual precipitation often below 600 mm. Therefore, black locust is known to be relatively drought tolerant compared to other temperate, deciduous tree species. Because of its N2-fixation ability black locust plays generally an important role for the improvement of soil fertility. This effect is of particular interest at marginal sites in the post-mining landscapes. In order to estimate the N2-fixation potential of black locust at marginal sites leaf samples were taken from black locust trees in short rotation plantations planted between 1995 and 2007 in post-mining sites south of Cottbus (Brandenburg, NE Germany). The variation of the natural 15N abundance was measured to evaluate the biological nitrogen fixation. The nitrogen derived from the atmosphere can be calculated using a two-pool model from the quotient of the natural 15N abundances of the N2-fixing plant and the plant available soil N. Because representatively determining the plant available soil N is difficult, a non-N2-fixing reference plant growing at the same site with a similar root system and temporal N uptake pattern to the N2-fixing plant is often used. In our case we used red oak (Quercus rubra) as a reference. The average nitrogen content in the leaves of black locust ranged from 3.1% (C/N 14.8) in 15 years old trees to 3
Dilaton stabilization in three-generation heterotic string model
NASA Astrophysics Data System (ADS)
Beye, Florian; Kobayashi, Tatsuo; Kuwakino, Shogo
2016-09-01
We study dilaton stabilization in heterotic string models. By utilizing the asymmetric orbifold construction, we construct an explicit three-generation model whose matter content in the visible sector is the supersymmetric standard model with additional vectorlike matter. This model does not contain any geometric moduli fields except the dilaton field. Model building at a symmetry enhancement point in moduli space enlarges the rank of the hidden gauge group. By analyzing multiple hidden gauge sectors, the dilaton field is stabilized by the racetrack mechanism. We also discuss a supersymmetry breaking scenario and F-term uplifting.
Light dilaton in the large N tricritical O (N ) model
NASA Astrophysics Data System (ADS)
Omid, Hamid; Semenoff, Gordon W.; Wijewardhana, L. C. R.
2016-12-01
The leading order of the large N limit of the O (N ) symmetric phi-six theory in three dimensions has a phase which exhibits spontaneous breaking of scale symmetry accompanied by a massless dilaton which is a Goldstone boson. At the next-to-leading order in large N , the phi-six coupling has a beta function of order 1 /N and it is expected that the dilaton acquires a small mass, proportional to the beta function and the condensate. In this article, we show that this "light dilaton" is actually a tachyon. This indicates an instability of the phase of the theory with spontaneously broken approximate scale invariance.
Strong-field tidal distortions of rotating black holes. III. Embeddings in hyperbolic three-space
NASA Astrophysics Data System (ADS)
Penna, Robert F.; Hughes, Scott A.; O'Sullivan, Stephen
2017-09-01
In previous work, we developed tools for quantifying the tidal distortion of a black hole's event horizon due to an orbiting companion. These tools use techniques which require large mass ratios (companion mass μ much smaller than black hole mass M ), but can be used for arbitrary bound orbits and for any black hole spin. We also showed how to visualize these distorted black holes by embedding their horizons in a global Euclidean three-space, E3. Such visualizations illustrate interesting and important information about horizon dynamics. Unfortunately, we could not visualize black holes with spin parameter a*>√{3 }/2 ≈0.866 : such holes cannot be globally embedded into E3. In this paper, we overcome this difficulty by showing how to embed the horizons of tidally distorted Kerr black holes in a hyperbolic three-space, H3. We use black hole perturbation theory to compute the Gaussian curvatures of tidally distorted event horizons, from which we build a two-dimensional metric of their distorted horizons. We develop a numerical method for embedding the tidally distorted horizons in H3. As an application, we give a sequence of embeddings into H3 of a tidally interacting black hole with spin a*=0.9999 . A small-amplitude, high-frequency oscillation seen in previous work shows up particularly clearly in these embeddings.
Pu, Hung-Yi; Nakamura, Masanori; Hirotani, Kouichi; Asada, Keiichi; Wu, Kinwah
2015-03-01
General relativistic magnetohydrodynamic (GRMHD) flows along magnetic fields threading a black hole can be divided into inflow and outflow parts, according to the result of the competition between the black hole gravity and magneto-centrifugal forces along the field line. Here we present the first self-consistent, semi-analytical solution for a cold, Poynting flux–dominated (PFD) GRMHD flow, which passes all four critical (inner and outer, Alfvén, and fast magnetosonic) points along a parabolic streamline. By assuming that the dominating (electromagnetic) component of the energy flux per flux tube is conserved at the surface where the inflow and outflow are separated, the outflow part of the solution can be constrained by the inflow part. The semi-analytical method can provide fiducial and complementary solutions for GRMHD simulations around the rotating black hole, given that the black hole spin, global streamline, and magnetizaion (i.e., a mass loading at the inflow/outflow separation) are prescribed. For reference, we demonstrate a self-consistent result with the work by McKinney in a quantitative level.
Giribet, Gaston; Oliva, Julio; Tempo, David; Troncoso, Ricardo
2009-12-15
Asymptotically anti-de Sitter rotating black holes for the Bergshoeff-Hohm-Townsend massive gravity theory in three dimensions are considered. In the special case when the theory admits a unique maximally symmetric solution, apart from the mass and the angular momentum, the black hole is described by an independent 'gravitational hair' parameter, which provides a negative lower bound for the mass. This bound is saturated at the extremal case, and since the temperature and the semiclassical entropy vanish, it is naturally regarded as the ground state. The absence of a global charge associated with the gravitational hair parameter reflects itself through the first law of thermodynamics in the fact that the variation of this parameter can be consistently reabsorbed by a shift of the global charges, giving further support to consider the extremal case as the ground state. The rotating black hole fits within relaxed asymptotic conditions as compared with the ones of Brown and Henneaux, such that they are invariant under the standard asymptotic symmetries spanned by two copies of the Virasoro generators, and the algebra of the conserved charges acquires a central extension. Then it is shown that Strominger's holographic computation for general relativity can also be extended to the Bergshoeff-Hohm-Townsend theory; i.e., assuming that the quantum theory could be consistently described by a dual conformal field theory at the boundary, the black hole entropy can be microscopically computed from the asymptotic growth of the number of states according to Cardy's formula, in exact agreement with the semiclassical result.
Proposal for a geophysical search for dilatonic waves
Shiomi, Sachie
2008-08-15
We propose a new method of searching for the composition-dependent dilatonic waves, predicted by unified theories of strings. In this method, Earth's surface-gravity changes due to translational motions of its inner core, excited by dilatonic waves, are searched for by using superconducting gravimeters. This method has its best sensitivity at the frequency of {approx}7x10{sup -5} Hz, which is lower than the sensitive frequencies of previous proposals using gravitational wave detectors: {approx}10 to 1000 Hz. Using available results of surface-gravity measurements with superconducting gravimeters and assuming a simple Earth model, we present preliminary upper limits on the energy density of a stochastic background of massless dilatons at the low frequency. Though the results are currently limited by the uncertainty in the Earth model, this method has a potential of detecting dilatonic waves in a new window.
Dilatonic non-linear sigma models and Ricci flow extensions
NASA Astrophysics Data System (ADS)
Carfora, M.; Marzuoli, A.
2016-09-01
We review our recent work describing, in terms of the Wasserstein geometry over the space of probability measures, the embedding of the Ricci flow in the renormalization group flow for dilatonic non-linear sigma models.
Boson star in a gravitation theory with dilaton.
NASA Astrophysics Data System (ADS)
Zhijian, Tao; Xue, Xun
1992-03-01
The authors study the possible static spherically symmetric configuration of stellar objects comprised of bosons in a gravitation theory differing from Einstein's theory in the sense that the dilaton field appears in the theory as a nonlinear realization of dilatation invariance. Different scales of the dilaton interacting with a complex scalar field and different scales of the mass of the complex scalar field are considered.
Newtonian perturbations and the Einstein Yang Mills-dilaton equations
NASA Astrophysics Data System (ADS)
Oliynyk, Todd A.
2005-06-01
In this paper, we show that the problem of proving the existence of a countable number of solutions to the static spherically symmetric SU(2) Einstein Yang Mills-dilaton (EYMd) equations can be reduced to proving the non-existence of solutions to the linearized Yang Mills-dilaton equations (lYMd) satisfying certain asymptotic conditions. The reduction from a nonlinear to a linear problem is achieved using a Newtonian perturbation-type argument.
Boson star in a gravitation theory with dilaton
Tao, Z. , Beijing Institute of Theoretical Physics, Academia Sinica, Beijing ); Xun Xue , Beijing Department of Physics, Zhongshan University, Guangzhou )
1992-03-15
We study the possible static spherically symmetric configuration of stellar objects comprised of bosons in a gravitation theory differing from Einstein's theory in the sense that the dilaton field appears in the theory as a nonlinear realization of dilatation invariance. Different scales of the dilaton interacting with a complex scalar field and different scales of the mass of the complex scalar field are considered. We also investigate the behavior of the solution via the self-coupling {lambda} of the complex field.
Class of Einstein-Maxwell-dilaton-axion space-times
Matos, Tonatiuh; Miranda, Galaxia; Sanchez-Sanchez, Ruben; Wiederhold, Petra
2009-06-15
We use the harmonic maps ansatz to find exact solutions of the Einstein-Maxwell-dilaton-axion (EMDA) equations. The solutions are harmonic maps invariant to the symplectic real group in four dimensions Sp(4,R){approx}O(5). We find solutions of the EMDA field equations for the one- and two-dimensional subspaces of the symplectic group. Specially, for illustration of the method, we find space-times that generalize the Schwarzschild solution with dilaton, axion, and electromagnetic fields.
One-loop correction and the dilaton runaway problem
NASA Astrophysics Data System (ADS)
Xiu, Rulin
1997-04-01
We examine the one-loop vacuum structure of an effective theory of gaugino condensation coupled to the dilaton for string models in which the gauge coupling constant does not receive string threshold corrections. The new ingredients in our treatment are that we take into account the one-loop correction to the dilaton Kähler potential and we use a formulation which includes a chiral field H corresponding to the gaugino bilinear. We find through explicit calculation that supersymmetry in the Yang-Mills sector is broken by gaugino condensation. The dilaton and H field have masses on the order of the gaugino condensation scale independently of the dilaton VEV. Although the calculation performed here is at best a model of the full gaugino condensation dynamics, the result shows that the one-loop correction to the dilaton Kähler potential as well as the detailed dynamics at the gaugino condensation scale may play an important role in solving the dilaton runaway problem.
NASA Astrophysics Data System (ADS)
Pani, Paolo; Berti, Emanuele; Gualtieri, Leonardo
2013-09-01
In Einstein-Maxwell theory, according to classic uniqueness theorems, the most general stationary black-hole solution is the axisymmetric Kerr-Newman metric, which is defined by three parameters: mass, spin and electric charge. The radial and angular dependence of gravitational and electromagnetic perturbations in the Kerr-Newman geometry do not seem to be separable. In this paper we circumvent this problem by studying scalar, electromagnetic and gravitational perturbations of Kerr-Newman black holes in the slow-rotation limit. We extend (and provide details of) the analysis presented in a recent Letter [P. Pani, E. Berti, and L. Gualtieri, Phys. Rev. Lett. 110, 241103 (2013)]. Working at linear order in the spin, we present the first detailed derivation of the axial and polar perturbation equations in the gravito-electromagnetic case, and we compute the corresponding quasinormal modes for any value of the electric charge. Our study is the first self-consistent stability analysis of the Kerr-Newman metric, and in principle it can be extended to any order in the small rotation parameter. We find numerical evidence that the axial and polar sectors are isospectral at first order in the spin and speculate on the possible implications of this result.
NASA Astrophysics Data System (ADS)
Takeuchi, Shingo
2017-08-01
We carry out the Kerr/CFT correspondence in a four-dimensional extremal rotating regular black hole with a non-linear magnetic monopole (NLMM). One problem in this study would be whether our geometry can be a solution or not. We search for the way making our rotating geometry into a solution based on the fact that the Schwarzschild regular geometry can be a solution. However, in the attempt to extend the Schwarzschild case that we can naturally consider, it turns out that it is impossible to construct a model in which our geometry can be a exact solution. We manage this problem by making use of the fact that our geometry can be a solution approximately in the whole space-time except for the black hole's core region. As a next problem, it turns out that the equation to obtain the horizon radii is given by a fifth-order equation due to the regularization effect. We overcome this problem by treating the regularization effect perturbatively. As a result, we can obtain the near-horizon extremal Kerr (NHEK) geometry with the correction of the regularization effect. Once obtaining the NHEK geometry, we can obtain the central charge and the Frolov-Thorne temperature in the dual CFT. Using these, we compute its entropy through the Cardy formula, which agrees with the one computed from the Bekenstein-Hawking entropy.
Quantum corrections and extremal black holes
NASA Astrophysics Data System (ADS)
Alejandro, G.; Mazzitelli, F. D.; Núñez, C.
1995-02-01
We consider static solutions of two dimensional dilaton gravity models as toy laboratories to address the question of the final fate of black holes. A nonperturbative correction to the CGHS potential term is shown to lead classically to an extremal black hole geometry, thus providing a plausible solution to the Hawking evaporation paradox. However, the full quantum theory does not admit an extremal solution.
Gravitational wave production by Hawking radiation from rotating primordial black holes
NASA Astrophysics Data System (ADS)
Dong, Ruifeng; Kinney, William H.; Stojkovic, Dejan
2016-10-01
In this paper we analyze in detail a rarely discussed question of gravity wave production from evaporating primordial black holes. These black holes emit gravitons which are, at classical level, registered as gravity waves. We use the latest constraints on their abundance, and calculate the power emitted in gravitons at the time of their evaporation. We then solve the coupled system of equations that gives us the evolution of the frequency and amplitude of gravity waves during the expansion of the universe. The spectrum of gravitational waves that can be detected today depends on multiple factors: fraction of the total energy density which was occupied by primordial black holes, the epoch in which they were formed, and quantities like their mass and angular momentum. We conclude that very small primordial black holes which evaporate before the big-bang nucleosynthesis emit gravitons whose spectral energy fraction today can be as large as 10-7.5. On the other hand, those which are massive enough so that they still exist now can yield a signal as high as 10-6.5. However, typical frequencies of the gravity waves from primordial black holes are still too high to be observed with the current and near future gravity wave observations.
General relativistic radiative transfer code in rotating black hole space-time: ARTIST
NASA Astrophysics Data System (ADS)
Takahashi, Rohta; Umemura, Masayuki
2017-02-01
We present a general relativistic radiative transfer code, ARTIST (Authentic Radiative Transfer In Space-Time), that is a perfectly causal scheme to pursue the propagation of radiation with absorption and scattering around a Kerr black hole. The code explicitly solves the invariant radiation intensity along null geodesics in the Kerr-Schild coordinates, and therefore properly includes light bending, Doppler boosting, frame dragging, and gravitational redshifts. The notable aspect of ARTIST is that it conserves the radiative energy with high accuracy, and is not subject to the numerical diffusion, since the transfer is solved on long characteristics along null geodesics. We first solve the wavefront propagation around a Kerr black hole that was originally explored by Hanni. This demonstrates repeated wavefront collisions, light bending, and causal propagation of radiation with the speed of light. We show that the decay rate of the total energy of wavefronts near a black hole is determined solely by the black hole spin in late phases, in agreement with analytic expectations. As a result, the ARTIST turns out to correctly solve the general relativistic radiation fields until late phases as t ˜ 90 M. We also explore the effects of absorption and scattering, and apply this code for a photon wall problem and an orbiting hotspot problem. All the simulations in this study are performed in the equatorial plane around a Kerr black hole. The ARTIST is the first step to realize the general relativistic radiation hydrodynamics.
Initial data for black hole-neutron star binaries, with rotating stars
NASA Astrophysics Data System (ADS)
Tacik, Nick; Foucart, Francois; Pfeiffer, Harald P.; Muhlberger, Curran; Kidder, Lawrence E.; Scheel, Mark A.; Szilágyi, Béla
2016-11-01
The coalescence of a neutron star with a black hole is a primary science target of ground-based gravitational wave detectors. Constraining or measuring the neutron star spin directly from gravitational wave observations requires knowledge of the dependence of the emission properties of these systems on the neutron star spin. This paper lays foundations for this task, by developing a numerical method to construct initial data for black hole-neutron star binaries with arbitrary spin on the neutron star. We demonstrate the robustness of the code by constructing initial-data sets in large regions of the parameter space. In addition to varying the neutron star spin-magnitude and spin-direction, we also explore neutron star compactness, mass-ratio, black hole spin, and black hole spin-direction. Specifically, we are able to construct initial data sets with neutron stars spinning near centrifugal break-up, and with black hole spins as large as {S}{BH}/{M}{BH}2=0.99.
Quantum entropies in extreme dilaton black hole backgrounds
NASA Astrophysics Data System (ADS)
Wei, Yi-Huan; Wang, Yongcheng; Zhao, Zheng
2002-06-01
For spinor fields, the entropies from the spin-1/2- and spin-1/2+ components, Sq-ext and Sq+ext, are quite different, though the former is 7/8 times the scalar entropy and the latter contains an extra term. The brick wall model is applicable to both NEBH and EBH. For the EDBH with 0≺a2≺1, using the brick wall model with the cutoff ɛ being given by ɛ(1- a2)/(1+a2)=(1+a2)κm2/ (1+a2) and κ the surface gravity on the event horizon, at the Hawking temperature TH=κ/2π, the scalar and spinor entropies are Sqext=S0/(1- a2)(1+a2)2 with S0=1/135 and SqFext=7/2Sqext+[1/6(1- a2)], respectively. For the EGHSDBH, the spin-1/2- and spin-1/2+ fields contribute the entropies Sq- ext=7/8Sqext, Sq+ext=7/8Sqext+(πm/6β) ln(L/ɛ), respectively; at the Hawking temperature, the spinor entropy is SqFext=(7/2+30)Sqext with Sqext=1/360 ln(L/ɛ).
NASA Astrophysics Data System (ADS)
Yo, Hwei-Jang; Cao, Zhoujian; Lin, Chun-Yu; Pan, Hsing-Po
2015-07-01
Different formulations of Einstein's equations used in numerical relativity can affect not only the stability but also the accuracy of numerical simulations. In the original Baumgarte-Shapiro-Shibata-Nakamura (BSSN) formulation, the loss of the angular momentum, J , is non-negligible in highly spinning single black hole evolutions. This loss also appears, usually right after the merger, in highly spinning binary black hole simulations, The loss of J may be attributed to some unclear numerical dissipation. Reducing unphysical dissipation is expected to result in more stable and accurate evolutions. In the previous work [H.-J. Yo et al., Phys. Rev. D 86, 064027 (2012).] we proposed several modifications which are able to prevent black hole evolutions from the unphysical dissipation, and the resulting simulations are more stable than in the traditional BSSN formulation. Specifically, these three modifications (M1, M2, and M3) enhance the effects of stability, hyperbolicity, and dissipation of the formulation. We experiment further in this work with these modifications, and demonstrate that these modifications improve the accuracy and also effectively suppress the loss of J , particularly in the black hole simulations with an initially large ratio of J and a square of the ADM mass.
On the near horizon rotating black hole geometries with NUT charges
NASA Astrophysics Data System (ADS)
Galajinsky, Anton; Orekhov, Kirill
2016-09-01
The near horizon geometries are usually constructed by implementing a specific limit to a given extreme black hole configuration. Their salient feature is that the isometry group includes the conformal subgroup SO(2, 1). In this work, we turn the logic around and use the conformal invariants for constructing Ricci-flat metrics in d=4 and d=5 where the vacuum Einstein equations reduce to a coupled set of ordinary differential equations. In four dimensions the analysis can be carried out in full generality and the resulting metric describes the d=4 near horizon Kerr-NUT black hole. In five dimensions we choose a specific ansatz whose structure is similar to the d=5 near horizon Myers-Perry black hole. A Ricci-flat metric involving five arbitrary parameters is constructed. A particular member of this family, which is characterized by three parameters, seems to be a natural candidate to describe the d=5 near horizon Myers-Perry black hole with a NUT charge.
Integrability of five-dimensional minimal supergravity and charged rotating black holes
NASA Astrophysics Data System (ADS)
Figueras, Pau; Jamsin, Ella; Rocha, Jorge V.; Virmani, Amitabh
2010-07-01
We explore the integrability of five-dimensional minimal supergravity in the presence of three commuting Killing vectors. We argue that to see the integrability structure of the theory one necessarily has to perform an Ehlers reduction to two dimensions. A direct dimensional reduction to two dimensions does not allow us to see the integrability of the theory in an easy way. This situation is in contrast with vacuum five-dimensional gravity. We derive the Belinski-Zakharov (BZ) Lax pair for minimal supergravity based on a symmetric 7 × 7 coset representative matrix for the coset G_{2(2)}/(SL(2, {\\mathbb {R}})\\times SL(2, {\\mathbb {R}})). We elucidate the relationship between our BZ Lax pair and the group theoretic Lax pair previously known in the literature. The BZ Lax pair allows us to generalize the well-known BZ dressing method to five-dimensional minimal supergravity. We show that the action of the three-dimensional hidden symmetry transformations on the BZ dressing method is simply the group action on the BZ vectors. As an illustration of our formalism, we obtain the doubly spinning five-dimensional Myers-Perry black hole by applying solitonic transformations on the Schwarzschild black hole. We also derive the Cveti\\checkc-Youm black hole by applying solitonic transformations on the Reissner-Nordström black hole.
Charged black holes and black hole binaries in Multi-messenger Astronomy
NASA Astrophysics Data System (ADS)
Liebling, Steven
2017-01-01
The possibility of observing electromagnetic signals from gravitational wave events holds great promise for gravitational wave astronomy. I discuss studies of black holes and black hole binaries in both Einstein-Maxwell and Einstein-Maxwell-Dilaton theories, and their implications for LIGO detections and electromagnetic followups, such as Fermi's report of a coincident followup of GW150914.
Generalized geodesic deviation equations and an entanglement first law for rotating BTZ black holes
NASA Astrophysics Data System (ADS)
Ghosh, Avirup; Mishra, Rohit
2016-12-01
The change in holographic entanglement entropy (HEE) for small fluctuations about pure anti-de Sitter is given by a perturbative expansion of the area functional in terms of the change in the bulk metric and the embedded extremal surface. However, it is known that changes in the embedding appear at second order or higher. In this paper we show that these changes in the embedding can be systematically calculated in the (2 +1 )-dimensional case by accounting for the deviation of the spacelike geodesics between a spacetime and perturbations over it. Here we consider rotating BTZ as a perturbation over AdS3 and study deviations of spacelike geodesics in them. We argue that these deviations arise naturally as solutions of a "generalized geodesic deviation equation." Using this we perturbatively calculate the changes in HEE up to second order for rotating BTZ. This expression matches with the small system size expansion of the change in HEE obtained by the proposal of Hubeny, Rangamani, and Takayanagi for rotating BTZ. We also write an alternative form of the entanglement first law for rotating BTZ. To do this one needs to go beyond the leading order in the perturbation series discussed above. That is precisely the reason we consider finding a systematic way to calculate it. To put our result on a firm footing we further show that it is this alternative first law that approaches the thermal first law in the large subsystem size limit.
Charged particle in higher dimensional weakly charged rotating black hole spacetime
Frolov, Valeri P.; Krtous, Pavel
2011-01-15
We study charged particle motion in weakly charged higher dimensional black holes. To describe the electromagnetic field we use a test field approximation and the higher dimensional Kerr-NUT-(A)dS metric as a background geometry. It is shown that for a special configuration of the electromagnetic field, the equations of motion of charged particles are completely integrable. The vector potential of such a field is proportional to one of the Killing vectors (called a primary Killing vector) from the 'Killing tower' of symmetry generating objects which exists in the background geometry. A free constant in the definition of the adopted electromagnetic potential is proportional to the electric charge of the higher dimensional black hole. The full set of independent conserved quantities in involution is found. We demonstrate that Hamilton-Jacobi equations are separable, as is the corresponding Klein-Gordon equation and its symmetry operators.
EXTREMAL ENERGY SHIFTS OF RADIATION FROM A RING NEAR A ROTATING BLACK HOLE
Karas, VladimIr; Sochora, Vjaceslav
2010-12-20
Radiation from a narrow circular ring shows a characteristic double-horn profile dominated by photons having energy around the maximum or minimum of the allowed range, i.e., near the extremal values of the energy shift. The energy span of a spectral line is a function of the ring radius, black hole spin, and observer's viewing angle. We describe a useful approach to calculate the extremal energy shifts in the regime of strong gravity. Then we consider an accretion disk consisting of a number of separate nested annuli in the equatorial plane of a Kerr black hole, above the innermost stable circular orbit. We suggest that the radial structure of the disk emission could be reconstructed using the extremal energy shifts of the individual rings deduced from the broad wings of a relativistic spectral line.
NASA Astrophysics Data System (ADS)
Bernar, Rafael P.; Crispino, Luís C. B.; Higuchi, Atsushi
2017-03-01
We analyze the gravitational radiation emitted from a particle in circular motion around a Schwarzschild black hole using the framework of quantum field theory in curved spacetime at tree level. The gravitational perturbations are written in a gauge-invariant formalism for spherically symmetric spacetimes. We discuss the results, comparing them to the radiation emitted by a particle when it is assumed to be orbiting a massive object due to a Newtonian force in flat spacetime.
The role of the dilaton in dense skyrmion matter
NASA Astrophysics Data System (ADS)
Park, Byung-Yoon; Rho, Mannque; Vento, Vicente
2008-07-01
In this note, we report on a remarkable and surprising interplay between the ω meson and the dilaton χ in the structure of a single skyrmion as well as in the phase structure of dense skyrmion matter which may have a potentially important consequence on the properties of compact stars. In our continuing effort to understand hadronic matter at high density, we have developed a unified field theoretic formalism for dense skyrmion matter using a single Lagrangian to describe simultaneously both matter and meson fluctuations and studied in-medium properties of hadrons. The effective theory used is the Skyrme model Lagrangian gauged with the vector mesons ρ and ω, implemented with the dilaton field that describes the spontaneously broken scale symmetry of QCD, in a form consistent with the symmetries of QCD and our expectations regarding the high density limit. We analyze the restoration of scale invariance and chiral symmetry as the density of the system increases. In order to preserve the restoration of scale symmetry and chiral symmetry, signalled in our case by the vanishing of the expectation value of the dilaton, and to be consistent with the "vector manifestation" of hidden local symmetry, a density dependent ω coupling is introduced. We uncover the crucial role played by both the dilaton and the ω meson in the phase structure of dense medium and discover how two different phase transition regimes arise as we "dial" the dilaton mass.
NASA Astrophysics Data System (ADS)
Pani, Paolo; Berti, Emanuele; Gualtieri, Leonardo
2013-06-01
The most general stationary black-hole solution of Einstein-Maxwell theory in vacuum is the Kerr-Newman metric, specified by three parameters: mass M, spin J, and charge Q. Within classical general relativity, one of the most important and challenging open problems in black-hole perturbation theory is the study of gravitational and electromagnetic fields in the Kerr-Newman geometry, because of the indissoluble coupling of the perturbation functions. Here we circumvent this long-standing problem by working in the slow-rotation limit. We compute the quasinormal modes up to linear order in J for any value of Q and provide the first, fully consistent stability analysis of the Kerr-Newman metric. For scalar perturbations the quasinormal modes can be computed exactly, and we demonstrate that the method is accurate within 3% for spins J/Jmax≲0.5, where Jmax is the maximum allowed spin for any value of Q. Quite remarkably, we find numerical evidence that the axial and polar sectors of the gravitoelectromagnetic perturbations are isospectral to linear order in the spin. The extension of our results to nonasymptotically flat space-times could be useful in the context of gauge-gravity dualities and string theory.
Pani, Paolo; Berti, Emanuele; Gualtieri, Leonardo
2013-06-14
The most general stationary black-hole solution of Einstein-Maxwell theory in vacuum is the Kerr-Newman metric, specified by three parameters: mass M, spin J, and charge Q. Within classical general relativity, one of the most important and challenging open problems in black-hole perturbation theory is the study of gravitational and electromagnetic fields in the Kerr-Newman geometry, because of the indissoluble coupling of the perturbation functions. Here we circumvent this long-standing problem by working in the slow-rotation limit. We compute the quasinormal modes up to linear order in J for any value of Q and provide the first, fully consistent stability analysis of the Kerr-Newman metric. For scalar perturbations the quasinormal modes can be computed exactly, and we demonstrate that the method is accurate within 3% for spins J/J(max) ≲ 0.5, where J(max) is the maximum allowed spin for any value of Q. Quite remarkably, we find numerical evidence that the axial and polar sectors of the gravitoelectromagnetic perturbations are isospectral to linear order in the spin. The extension of our results to nonasymptotically flat space-times could be useful in the context of gauge-gravity dualities and string theory.
Kuo, C. Y.; Asada, K.; Rao, R.; Nakamura, M.; Algaba, J. C.; Liu, H. B.; Inoue, M.; Koch, P. M.; Ho, P. T. P.; Matsushita, S.; Pu, H.-Y.; Nishioka, H.; Pradel, N.; Akiyama, K.
2014-03-10
We present the first constraint on the Faraday rotation measure (RM) at submillimeter wavelengths for the nucleus of M87. By fitting the polarization position angles (χ) observed with the Submillimeter Array at four independent frequencies around ∼230 GHz and interpreting the change in χ as a result of external Faraday rotation associated with accretion flow, we determine the RM of the M87 core to be between –7.5 × 10{sup 5} and 3.4 × 10{sup 5} rad m{sup –2}. Assuming a density profile of the accretion flow that follows a power-law distribution and a magnetic field that is ordered, radial, and has equipartition strength, the limit on the RM constrains the mass accretion rate M-dot to be below 9.2 × 10{sup –4} M {sub ☉} yr{sup –1} at a distance of 21 Schwarzschild radii from the central black hole. This value is at least two orders of magnitude smaller than the Bondi accretion rate, suggesting significant suppression of the accretion rate in the inner region of the accretion flow. Consequently, our result disfavors the classical advection-dominated accretion flow and prefers the adiabatic inflow-outflow solution or convection-dominated accretion flow for the hot accretion flow in M87.
Bianchi type I cosmologies in arbitrary dimensional dilaton gravities
NASA Astrophysics Data System (ADS)
Chen, Chiang-Mei; Harko, T.; Mak, M. K.
2000-12-01
We study the low energy string effective action with an exponential type dilaton potential and vanishing torsion in a Bianchi type I space-time geometry. In the Einstein and string frames the general solution of the gravitational field equations can be expressed in an exact parametric form. Depending on the values of the dilaton coupling constant and of the coefficient in the exponential, the obtained cosmological models can be generically divided into three classes, leading to both singular and non-singular behaviors. The effect of the potential on the time evolution of the mean anisotropy parameter is also considered in detail, and it is shown that a Bianchi type I universe isotropizes only in the presence of a dilaton field potential or a central deficit charge.
Canonical reduction for dilatonic gravity in 3 +1 dimensions
NASA Astrophysics Data System (ADS)
Scott, T. C.; Zhang, Xiangdong; Mann, R. B.; Fee, G. J.
2016-04-01
We generalize the 1 +1 -dimensional gravity formalism of Ohta and Mann to 3 +1 dimensions by developing the canonical reduction of a proposed formalism applied to a system coupled with a set of point particles. This is done via the Arnowitt-Deser-Misner method and by eliminating the resulting constraints and imposing coordinate conditions. The reduced Hamiltonian is completely determined in terms of the particles' canonical variables (coordinates, dilaton field and momenta). It is found that the equation governing the dilaton field under suitable gauge and coordinate conditions, including the absence of transverse-traceless metric components, is a logarithmic Schrödinger equation. Thus, although different, the 3 +1 formalism retains some essential features of the earlier 1 +1 formalism, in particular the means of obtaining a quantum theory for dilatonic gravity.
Randall-Sundrum scenario with bulk dilaton and torsion
Mukhopadhyaya, Biswarup; Sen, Somasri; SenGupta, Soumitra
2009-06-15
We consider a string-inspired torsion-dilaton-gravity action in a Randall-Sundrum braneworld scenario and show that, in an effective four-dimensional theory on the visible brane, the rank-2 antisymmetric Kalb-Ramond field (source of torsion) is exponentially suppressed. The result is similar to our earlier result in [B. Mukhopadhyaya, S. Sen, and S. SenGupta, Phys. Rev. Lett. 89, 121101 (2002); Phys. Rev. Lett. 89, 259902(E) (2002)], where no dilaton was present in the bulk. This offers an explanation of the apparent invisibility of torsion in our space-time. However, in this case the trilinear couplings {approx}TeV{sup -1} between the dilaton and torsion may lead to new signals in TeV-scale experiments, bearing the stamp of extra warped dimensions.
On light dilaton extensions of the Standard Model
NASA Astrophysics Data System (ADS)
Megías, Eugenio; Pujolàs, Oriol; Quirós, Mariano
2016-11-01
We discuss the presence of a light dilaton in Conformal Field Theories deformed by a single scalar operator, in the holographic realization consisting of confining Renormalization Group flows. Then, we apply this formalism to study the extension of the Standard Model with a light dilaton in a 5D warped model. We study the spectrum of scalar and vector perturbations, compare the model predictions with Electroweak Precision Tests and find the corresponding bounds for the lightest modes. Finally, we analyze the possibility that the Higgs resonance found at the LHC be a dilaton. Presented by E. Megías at the 4th International Conference on New Frontiers in Physics (ICNFP 2015), 23-30 August 2015, Kolymbari, Crete, Greece.
Anti-de Sitter-space/conformal-field-theory Casimir energy for rotating black holes.
Gibbons, G W; Perry, M J; Pope, C N
2005-12-02
We show that, if one chooses the Einstein static universe as the metric on the conformal boundary of Kerr-anti-de Sitter spacetime, then the Casimir energy of the boundary conformal field theory can easily be determined. The result is independent of the rotation parameters, and the total boundary energy then straightforwardly obeys the first law of thermodynamics. Other choices for the metric on the conformal boundary will give different, more complicated, results. As an application, we calculate the Casimir energy for free self-dual tensor multiplets in six dimensions and compare it with that of the seven-dimensional supergravity dual. They differ by a factor of 5/4.
[ital N]=2 supersymmetry in two-dimensional dilaton gravity
Nelson, W.M.; Park, Y. )
1993-11-15
Actions for [ital D]=2, [ital N]=2 supergravity coupled to a scalar field are calculated, and it is shown that the most general power-counting renormalizable dilaton gravity action has an [ital N]=2 locally supersymmetric extension. The presence of chiral terms in the action leads one to hope that nonrenormalization theorems similar to those in global SUSY will apply; this would eliminate some of the renormalization ambiguities which plague ordinary bosonic (and [ital N]=1) dilaton gravity. To investigate this, the model is studied in the superconformal gauge, where it is found that one chiral term becomes nonchiral, so that only one term is safe from renormalization.
N=2 supersymmetry in two-dimensional dilaton gravity
NASA Astrophysics Data System (ADS)
Nelson, William M.; Park, Youngchul
1993-11-01
Actions for D=2, N=2 supergravity coupled to a scalar field are calculated, and it is shown that the most general power-counting renormalizable dilaton gravity action has an N=2 locally supersymmetric extension. The presence of chiral terms in the action leads one to hope that nonrenormalization theorems similar to those in global SUSY will apply; this would eliminate some of the renormalization ambiguities which plague ordinary bosonic (and N=1) dilaton gravity. To investigate this, the model is studied in the superconformal gauge, where it is found that one chiral term becomes nonchiral, so that only one term is safe from renormalization.
Nonlinear structure formation with the environmentally dependent dilaton
Brax, Philippe; Davis, Anne-Christine; Shaw, Douglas J.; Li, Baojiu
2011-05-15
We have studied the nonlinear structure formation of the environmentally dependent dilaton model using N-body simulations. We find that the mechanism of suppressing the scalar fifth force in high-density regions works very well. Within the parameter space allowed by the solar-system tests, the dilaton model predicts small deviations of the matter power spectrum and the mass function from their {Lambda}CDM counterparts. The importance of taking full account of the nonlinearity of the model is also emphasized.
NASA Technical Reports Server (NTRS)
Adams, Fred C.; Graff, David S.; Mbonye, Manasse; Richstone, Douglas O.
2003-01-01
Motivated by the observed correlation between black hole masses M(sub BH) and the velocity dispersion sigma of host galaxies, we develop a theoretical model of black hole formation in galactic bulges (this paper generalizes an earlier ApJ Letter). The model assumes an initial state specified by a uniform rotation rate OMEGA and a density distribution of the form rho = a(sup 2)(sub eff)per2piGR(sup 2)(so that a(sub eff)is an effective transport speed). The black hole mass is determined when the centrifugal radius of the collapse flow exceeds the capture radius of the central black hole (for Schwarzschild geometry). This model reproduces the observed correlation between the estimated black hole masses and the velocity dispersions of galactic bulges, i.e., M(sub BH) approximately equal to 10(sup 8) solar mass(sigma per 200 kilometers per second)(sup 4) where sigma = the square root of 2a(sub eff). To obtain this normalization, the rotation rate OMEGA approximately equal to 2 x 10(exp -15) rad per second. The model also defines a bulge mass scale M(sub B). If we identify the scale M(sub B) with the bulge mass, the model determines the ratio mu(sub B) of black hole mass to the host mass: mu(sub B) approximately equal to 0.0024(sigma per 200 kilometer per second), again in reasonable agreement with observed values. In this scenario, supermassive black holes form quickly (in approximately 10(exp 5) yr) and are born rapidly rotating (with a per M approximately 0.9). This paper also shown how these results depend on the assumed initial conditions; the most important quantity is the initial distribution of specific angular momentum in the precollapse state.
Two-dimensional quantum dilaton gravity and the positivity of energy
de Alwis, S.P. )
1994-01-15
Using an argument due to Regge and Teitelboim, an expression for the ADM mass of two-dimensional quantum dilaton gravity is obtained. By evaluating this expression we establish that the quantum theories that can be written as a Liouville-like theory have a lower bound to energy, provided there is no critical boundary. This fact is then reconciled with the observation made earlier that the Hawking radiation does not appear to stop. The physical picture that emerges is that of a black hole in a bath of quantum radiation. We also evaluate the ADM mass for the models with RST boundary conditions and find that negative values are allowed. The Bondi mass of these models goes to zero for large retarded times, but becomes negative at intermediate times in a manner that is consistent with the thunderpop of RST.
Power law of shear viscosity in Einstein-Maxwell-Dilaton-Axion model
NASA Astrophysics Data System (ADS)
Ling, Yi; Xian, Zhuoyu; Zhou, Zhenhua
2017-02-01
We construct charged black hole solutions with hyperscaling violation in the infrared (IR) region in Einstein-Maxwell-Dilaton-Axion theory and investigate the temperature behavior of the ratio of holographic shear viscosity to the entropy density. When translational symmetry breaking is relevant in the IR, the power law of the ratio is verified numerically at low temperature T, namely, η/s ˜ T κ , where the values of exponent κ coincide with the analytical results. We also find that the exponent κ is not affected by irrelevant current, but is reduced by the relevant current. Supported by National Natural Science Foundation of China (11275208, 11575195), Opening Project of Shanghai Key Laboratory of High Temperature Superconductors (14DZ2260700) and Jiangxi Young Scientists (JingGang Star) Program and 555 Talent Project of Jiangxi Province
Inflationary Dilatonic de Sitter Universe from { N} = 4 Super-Yang Mills Theory Perturbed by Scalars
NASA Astrophysics Data System (ADS)
Hurtado, John Quiroga
In this paper a quantum { N} = 4 super-Yang Mills theory perturbed by dilaton-coupled scalars, is considered. The induced effective action for such a theory is calculated on a dilaton-gravitational background using the conformal anomaly found via AdS/CFT correspondence. Considering such an effective action (using the large N method) as a quantum correction to the classical gravity action with cosmological constant we study the effect from dilaton to the scale factor (which corresponds to the inflationary universe without dilaton). It is shown that, depending on the initial conditions for the dilaton, the dilaton may slow down, or accelerate, the inflation process. At late times, the dilaton is decaying exponentially. At the end of this work, we consider the question how the perturbation of the solution for the scale factor affects the stability of the solution for the equations of motion and therefore the stability of the Inflationary Universe, which could be eternal.
Charged scalar quasi-normal modes for linearly charged dilaton-Lifshitz solutions
NASA Astrophysics Data System (ADS)
Kord Zangeneh, M.; Wang, B.; Sheykhi, A.; Tang, Z. Y.
2017-08-01
Most available studies of quasi-normal modes for Lifshitz black solutions are limited to the neutral scalar perturbations. In this letter, we investigate the wave dynamics of massive charged scalar perturbation in the background of (3 + 1)-dimensional charged dilaton Lifshitz black branes/holes. We disclose the dependence of the quasi-normal modes on the model parameters, such as the Lifshitz exponent z, the mass and charge of the scalar perturbation field and the charge of the Lifshitz configuration. In contrast with neutral perturbations, we observe the possibility to destroy the original Lifshitz background near the extreme value of charge where the temperature is low. We find out that when the Lifshitz exponent deviates more from unity, it is more difficult to break the stability of the configuration. We also study the behavior of the real part of the quasi-normal frequencies. Unlike the neutral scalar perturbation around uncharged black branes where an overdamping was observed to start at z = 2 and independent of the value of scalar mass, our observation discloses that the overdamping starting point is no longer at z = 2 and depends on the mass of scalar field for charged Lifshitz black branes. For charged scalar perturbations, fixing ms, the asymptotic value of ωR for high z is more away from zero when the charge of scalar perturbation qs increases. There does not appear the overdamping.
Analytic rotating black-hole solutions in N-dimensional f( T) gravity
NASA Astrophysics Data System (ADS)
Nashed, G. G. L.; El Hanafy, W.
2017-02-01
A non-diagonal vielbein ansatz is applied to the N-dimension field equations of f( T) gravity. An analytical vacuum solution is derived for the quadratic polynomial f(T)=T+ɛ T^2 and an inverse relation between the coupling constant ɛ and the cosmological constant Λ . Since the induced metric has off-diagonal components, it cannot be removed by a mere coordinate transformation, the solution has a rotating parameter. The curvature and torsion scalars invariants are calculated to study the singularities and horizons of the solution. In contrast to general relativity, the Cauchy horizon differs from the horizon which shows the effect of the higher order torsion. The general expression of the energy-momentum vector of f( T) gravity is used to calculate the energy of the system. Finally, we have shown that this kind of solution satisfies the first law of thermodynamics in the framework of f( T) gravitational theories.
NASA Astrophysics Data System (ADS)
Donmez, Orhan
The shocked wave created on the accretion disk after different physical phenomena (accretion flows with pressure gradients, star-disk interaction etc.) may be responsible observed Quasi Periodic Oscillations (QPOs) in X-ray binaries. We present the set of characteristics frequencies associated with accretion disk around the rotating and non-rotating black holes for one particle case. These persistent frequencies are results of the rotating pattern in an accretion disk. We compare the frequency's from two different numerical results for fluid flow around the non-rotating black hole with one particle case. The numerical results are taken from Refs. 1 and 2 using fully general relativistic hydrodynamical code with non-selfgravitating disk. While the first numerical result has a relativistic tori around the black hole, the second one includes one-armed spiral shock wave produced from star-disk interaction. Some physical modes presented in the QPOs can be excited in numerical simulation of relativistic tori and spiral waves on the accretion disk. The results of these different dynamical structures on the accretion disk responsible for QPOs are discussed in detail.
Igata, Takahisa; Ishihara, Hideki; Koike, Tatsuhiko
2011-03-15
We discuss constants of motion of a particle under an external field in a curved spacetime, taking into account the Hamiltonian constraint, which arises from the reparametrization invariance of the particle orbit. As the necessary and sufficient condition for the existence of a constant of motion, we obtain a set of equations with a hierarchical structure, which is understood as a generalization of the Killing tensor equation. It is also a generalization of the conventional argument in that it includes the case when the conservation condition holds only on the constraint surface in the phase space. In that case, it is shown that the constant of motion is associated with a conformal Killing tensor. We apply the hierarchical equations and find constants of motion in the case of a charged particle in an electromagnetic field in black hole spacetimes. We also demonstrate that gravitational and electromagnetic fields exist in which a charged particle has a constant of motion associated with a conformal Killing tensor.
Numerical simulations of optically thick accretion onto a black hole. II. Rotating flow
Fragile, P. Chris; Olejar, Ally; Anninos, Peter
2014-11-20
In this paper, we report on recent upgrades to our general relativistic radiation magnetohydrodynamics code, Cosmos++, including the development of a new primitive inversion scheme and a hybrid implicit-explicit solver with a more general M {sub 1} closure relation for the radiation equations. The new hybrid solver helps stabilize the treatment of the radiation source terms, while the new closure allows for a much broader range of optical depths to be considered. These changes allow us to expand by orders of magnitude the range of temperatures, opacities, and mass accretion rates, and move a step closer toward our goal of performing global simulations of radiation-pressure-dominated black hole accretion disks. In this work, we test and validate the new method against an array of problems. We also demonstrate its ability to handle super-Eddington, quasi-spherical accretion. Even with just a single proof-of-principle simulation, we already see tantalizing hints of the interesting phenomenology associated with the coupling of radiation and gas in super-Eddington accretion flows.
Well-behaved harmonic time slices of a charged, rotating, boosted black hole
NASA Astrophysics Data System (ADS)
Cook, Gregory B.; Scheel, Mark A.
1997-10-01
Harmonic time slicings are used in some hyperbolic formulations of Einstein's equations and are therefore of considerable interest to the field of numerical relativity. We construct an analytic coordinate representation of the Kerr-Newman geometry that is harmonic in both its spatial and temporal coordinates. The metric is independent of time and the spacelike, t= const slices extend from spatial infinity smoothly through the event horizon at r=r+ and end at the Cauchy horizon at r=r-. When the spatial harmonic coordinate condition is imposed, there is also a spatial coordinate singularity at r=M, but this fully harmonic metric can be trivially boosted to yield an analytic solution for a harmonically sliced translating, spinning black hole. We also examine the behavior of evolutions which obey the harmonic slicing condition but start from initial data that is not in the time-independent harmonic slicing foliation. We find that with a suitable choice of the spatial gauge, the evolving three-geometry is ``attracted'' to the time-independent three-geometry we present in this paper.
The Formation of Rapidly Rotating Black Holes in High-mass X-Ray Binaries
NASA Astrophysics Data System (ADS)
Batta, Aldo; Ramirez-Ruiz, Enrico; Fryer, Chris
2017-09-01
High-mass X-ray binaries (HMXRBs), such as Cygnus X-1, host some of the most rapidly spinning black holes (BHs) known to date, reaching spin parameters a≳ 0.84. However, there are several effects that can severely limit the maximum BH spin parameter that could be obtained from direct collapse, such as tidal synchronization, magnetic core-envelope coupling, and mass loss. Here, we propose an alternative scenario where the BH is produced by a failed supernova (SN) explosion that is unable to unbind the stellar progenitor. A large amount of fallback material ensues, whose interaction with the secondary naturally increases its overall angular momentum content, and therefore the spin of the BH when accreted. Through SPH hydrodynamic simulations, we studied the unsuccessful explosion of an 8 {M}ȯ pre-SN star in a close binary with a 12 {M}ȯ companion with an orbital period of ≈1.2 days, finding that it is possible to obtain a BH with a high spin parameter a≳ 0.8 even when the expected spin parameter from direct collapse is a≲ 0.3. This scenario also naturally explains the atmospheric metal pollution observed in HMXRB stellar companions.
The Iron Kα-LINE as a Tool for a Rotating Black Hole Geometry Analysis
NASA Astrophysics Data System (ADS)
Zakharov, A. F.; Repin, S. V.
2003-02-01
Observations of Seyfert galaxies in X-ray region reveal the broad emission lines in their spectra, which can arise in inner parts of accretion disks, where the effects of General Relativity in the strong field limit must be taken into account. A spectrum of a solitary emission line (the Kα-line of iron, for example) of a hot spot in Kerr accretion disk is simulated, depending on the radial coordinate r and the angular momentum a = J/M of a black hole, under the assumption of an equatorial circular motion of a hot spot. Using results of numerical simulations it is shown that the characteristic two-peak line profile with the sharp edges arises at a large distance, if radii of emitting rings r ~ (3 - 10)rg. The inner regions emit the line, which is observed with one maximum and extremely broad red wing. We analyzed the different parameters of problems on the observable shape of this line and discussed some possible kinds of these shapes.
Wormholes in dilatonic Einstein-Gauss-Bonnet theory.
Kanti, Panagiota; Kleihaus, Burkhard; Kunz, Jutta
2011-12-30
We construct traversable wormholes in dilatonic Einstein-Gauss-Bonnet theory in four spacetime dimensions, without needing any form of exotic matter. We determine their domain of existence, and show that these wormholes satisfy a generalized Smarr relation. We demonstrate linear stability with respect to radial perturbations for a subset of these wormholes.
Collapse of charged scalar field in dilaton gravity
Borkowska, Anna; Rogatko, Marek; Moderski, Rafal
2011-04-15
We elaborated the gravitational collapse of a self-gravitating complex charged scalar field in the context of the low-energy limit of the string theory, the so-called dilaton gravity. We begin with the regular spacetime and follow the evolution through the formation of an apparent horizon and the final central singularity.
Primordial perturbations from dilaton-induced gauge fields
Choi, Kiwoon; Choi, Ki-Young; Kim, Hyungjin; Shin, Chang Sub E-mail: kiyoungchoi@kasi.re.kr E-mail: changsub@physics.rutgers.edu
2015-10-01
We study the primordial scalar and tensor perturbations in inflation scenario involving a spectator dilaton field. In our setup, the rolling spectator dilaton causes a tachyonic instability of gauge fields, leading to a copious production of gauge fields in the superhorizon regime, which generates additional scalar and tensor perturbations through gravitational interactions. Our prime concern is the possibility to enhance the tensor-to-scalar ratio r relative to the standard result, while satisfying the observational constraints. To this end, we allow the dilaton field to be stabilized before the end of inflation, but after the CMB scales exit the horizon. We show that for the inflaton slow roll parameter ε ∼> 10{sup −3}, the tensor-to-scalar ratio in our setup can be enhanced only by a factor of O(1) compared to the standard result. On the other hand, for smaller ε corresponding to a lower inflation energy scale, a much bigger enhancement can be achieved, so that our setup can give rise to an observably large r∼> 10{sup −2} even when ε|| 10{sup −3}. The tensor perturbation sourced by the spectator dilaton can have a strong scale dependence, and is generically red-tilted. We also discuss a specific model to realize our scenario, and identify the parameter region giving an observably large r for relatively low inflation energy scales.
Cosmological consequences of dilatons in the electroweak model
NASA Astrophysics Data System (ADS)
McDonald, J.
1992-01-01
We consider the cosmological evolution of an electroweak model with a Jordan-Brans-Dicke dilaton, as would result from spontaneously breaking scale-invariance in a complete theory. For the case where the Friedman-Robertson-Walker (FRW) metric is introduced in the Einstein frame, it is shown that the phase transition is first-order, in agreement with previous treatments of this question. It is however argued that the treatment given here is more physically correct than previous treatments. It is also shown that at the electroweak phase transition, which occurs at the temperature of chiral symmetry breaking, most of the vacuum energy goes into oscillations of the dilaton field, with essentially no reheating or increase in entropy. As a result, the universe becomes effectively matter dominated before nucleosynthesis, ruling out the model. The only way to avoid this problem is to have scale-invariance broken at less than O(107) GeV. For the case where the FRW metric is introduced in the Jordan frame, the electroweak phase transition is of second-order as for the minimal standard model. The question of the energy density in dilatons is dependent upon the assumed form of the dilaton potential.
Conductivity bound from dirty black holes
NASA Astrophysics Data System (ADS)
Bitaghsir Fadafan, Kazem
2016-11-01
We propose a lower bound of the dc electrical conductivity in strongly disordered, strongly interacting quantum field theories using holography. We study linear response of black holes with broken translational symmetry in Einstein-Maxwell-dilaton theories of gravity. Using the generalized Stokes equations at the horizon, we derive the lower bound of the electrical conductivity for the dual two dimensional disordered field theory.
Holography for Einstein-Maxwell-dilaton theories from generalized dimensional reduction
NASA Astrophysics Data System (ADS)
Goutéraux, Blaise; Smolic, Jelena; Smolic, Milena; Skenderis, Kostas; Taylor, Marika
2012-01-01
We show that a class of Einstein-Maxwell-Dilaton (EMD) theories are re- lated to higher dimensional AdS-Maxwell gravity via a dimensional reduction over com- pact Einstein spaces combined with continuation in the dimension of the compact space to non-integral values (`generalized dimensional reduction'). This relates (fairly complicated) black hole solutions of EMD theories to simple black hole/brane solutions of AdS-Maxwell gravity and explains their properties. The generalized dimensional reduction is used to infer the holographic dictionary and the hydrodynamic behavior for this class of theories from those of AdS. As a specific example, we analyze the case of a black brane carrying a wave whose universal sector is described by gravity coupled to a Maxwell field and two neutral scalars. At thermal equilibrium and finite chemical potential the two operators dual to the bulk scalar fields acquire expectation values characterizing the breaking of con- formal and generalized conformal invariance. We compute holographically the first order transport coefficients (conductivity, shear and bulk viscosity) for this system.
Techni-Dilaton Signatures at LHC
NASA Astrophysics Data System (ADS)
Matsuzaki, S.; Yamawaki, K.
2012-02-01
We explore discovery signatures of techni-dilaton (TD) at LHC. The TD was predicted long ago as a composite pseudo Nambu-Goldstone boson (pNGB) associated with the spontaneous breaking of the approximate scale symmetry in the walking technicolor (WTC) (initially dubbed ``scale-invariant technicolor''). Being pNGB, whose mass arises from the explicit scale-symmetry breaking due to the spontaneous breaking itself (dynamical mass generation), the TD as a composite scalar should have a mass M_{TD} lighter than other techni-hadrons, say M_{TD} ≃ 600 GeV for the typical WTC model, which is well in the discovery range of the ongoing LHC experiment. We develop a spurion method of nonlinear realization to calculate the TD couplings to the standard model (SM) particles and explicitly evaluate the TD LHC production cross sections at √{s} = 7 TeV times the branching ratios in terms of M_{TD} as an input parameter for the region 200 GeV < M_{TD} < 1000 GeV in the typical WTC models. It turns out that the TD signatures are quite different from those of the SM Higgs: In the one-doublet model (1DM) all the cross sections including the WW/ZZ mode are suppressed compared to those of the SM Higgs due to the suppressed TD couplings, while in the one-family model (1FM) all those cross sections get highly enhanced because of the presence of extra colored fermion (techni-quark) contributions. We compare the {TD} → WW/ZZ signature with the recent ATLAS and CMS bounds and find that in the case of 1DM the signature is consistent over the whole mass range 200 GeV < M_{TD} < 1000 GeV due to the large suppression of TD couplings, and by the same token the signal is too tiny for the TD to be visible through this channel at LHC. As for the 1FMs, on the other hand, a severe constraint is given on the TD mass to exclude the TD with mass ≲ 600 GeV, which, however, would imply an emergence of somewhat dramatic excess as the TD signature at 600 GeV ≲ M_{TD} < 1000 GeV in the near future. We
Structures of general relativity in dilaton-Maxwell electrodynamics
NASA Astrophysics Data System (ADS)
Kechkin, O. V.; Mosharev, P. A.
2016-08-01
It is shown that electro (magneto) static sector of Maxwell’s electrodynamics coupled to the dilaton field in a string theory form possesses the symmetry group of the stationary General Relativity in vacuum. Performing the Ernst formalism, we develope a technique for generation of exact solutions in this modified electrodynamics on the base of the normalized Ehlers symmetry transformation. In the electrostatic case, we construct and study a general class of spherically symmetric solutions that describes a pointlike source of the Coulomb type. It is demonstrated that this source is characterized by finite and singularity-free interaction at short distances. Also it is established that the total electrostatic energy of this source is finite and inversely proportional to the dilaton-Maxwell coupling constant.
Cohomogeneity-one solutions in Einstein-Maxwell-dilaton gravity
NASA Astrophysics Data System (ADS)
Lim, Yen-Kheng
2017-05-01
The field equations for Einstein-Maxwell-dilaton gravity in D dimensions are reduced to an effective one-dimensional system under the influence of exponential potentials. Various cases where exact solutions can be found are explored. With this procedure, we present interesting solutions such as a one-parameter generalization of the dilaton-Melvin spacetime and a three-parameter solution that interpolates between the Reissner-Nordström and Bertotti-Robinson solutions. This procedure also allows simple, alternative derivations of known solutions such as the Lifshitz spacetime and the planar anti-de Sitter naked singularity. In the latter case, the metric is cast in a simpler form which reveals the presence of an additional curvature singularity.
Frozen up dilaton and the GUT/Planck mass ratio
NASA Astrophysics Data System (ADS)
Davidson, Aharon; Ygael, Tomer
2017-09-01
By treating modulus and phase on equal footing, as prescribed by Dirac, local scale invariance can consistently accompany any Brans-Dicke ω-theory. We show that in the presence of a soft scale symmetry breaking term, the classical solution, if it exists, cannot be anything else but general relativistic. The dilaton modulus gets frozen up by the Weyl-Proca vector field, thereby constituting a gravitational quasi-Higgs mechanism. Assigning all grand unified scalars as dilatons, they enjoy Weyl universality, and upon symmetry breaking, the Planck (mass)2 becomes the sum of all their individual (VEV)2s. The emerging GUT/Planck (mass)2 ratio is thus ∼ ωgGUT2 / 4 π.
Chiral-scale effective theory including a dilatonic meson
NASA Astrophysics Data System (ADS)
Li, Yan-Ling; Ma, Yong-Liang; Rho, Mannque
2017-06-01
A scale-invariant chiral effective Lagrangian is constructed for octet pions and a dilaton figuring, as Nambu-Goldstone bosons, with vector mesons incorporated as hidden gauge fields. The Lagrangian is built to the next-to-leading order in chiral-scale counting without baryon fields and then to leading order including baryons. The resulting theory is hidden scale symmetric and local symmetric. We also discuss some possible applications of the present Lagrangian.
Chiral primordial gravitational waves from dilaton induced delayed chromonatural inflation
NASA Astrophysics Data System (ADS)
Obata, Ippei; Soda, Jiro; CLEO Collaboration
2016-06-01
We study inflation driven by a dilaton and an axion, both of which are coupled to a SU(2) gauge field. We find that the inflation driven by the dilaton occurs in the early stage of inflation during which the gauge field grows due to the gauge-kinetic function. When the energy density of magnetic fields catches up with that of electric fields, chromonatural inflation takes over in the late stage of inflation, which we call delayed chromonatural inflation. Thus, the delayed chromonatural inflation driven by the axion and the gauge field is induced by the dilaton. The interesting outcome of the model is the generation of chiral primordial gravitational waves on small scales. Since the gauge field is inert in the early stage of inflation, it is viable in contrast to the conventional chromonatural inflation. We find the parameter region where chiral gravitational waves are generated in a frequency range higher than nHz, which are potentially detectable in future gravitational wave interferometers and pulsar-timing arrays such as DECi-hertz Interferometer Gravitational wave Observatory (DECIGO), evolved Laser Interferometer Space Antenna (eLISA), and Square Kilometer Array (SKA).
All extremal instantons in Einstein-Maxwell-dilaton-axion theory
NASA Astrophysics Data System (ADS)
Azreg-Aïnou, Mustapha; Clément, Gérard; Gal'Tsov, Dmitri V.
2011-11-01
We construct explicitly all extremal instanton solutions to N=4, D=4 supergravity truncated to one vector field (Einstein-Maxwell-dilaton-axion theory). These correspond to null geodesics of the target space of the sigma-model G/H=Sp(4,R)/GL(2,R) obtained by compactification of four-dimensional Euclidean Einstein-Maxwell-dilaton-axion on a circle. They satisfy a no-force condition in terms of the asymptotic charges and part of them (corresponding to nilpotent orbits of the Sp(4,R) U-duality) are presumably supersymmetric. The space of finite action solutions is found to be unexpectedly large and includes, besides the Euclidean versions of known Lorentzian solutions, a number of new asymptotically locally flat instantons endowed with electric, magnetic, dilaton and axion charges. We also describe new classes of charged asymptotically locally Euclidean instantons as well as some exceptional solutions. Our classification scheme is based on the algebraic classification of matrix generators according to their rank, according to the nature of the charge vectors, and according to the number of independent harmonic functions with unequal charges. Besides the nilpotent orbits of G, we find solutions which satisfy the asymptotic no-force condition, but are not supersymmetric. The renormalized on-shell action for instantons is calculated using the method of matched background subtraction.
Conformal invariance beyond the leading order in the supersymmetric nonlinear σ model with dilaton
NASA Astrophysics Data System (ADS)
Diamandis, G. A.; Georgalas, B. C.; Lahanas, A. B.
1990-12-01
We calculate the O(α'3) contributions to the renormalization-group β functions in the N=1 supersymmetric σ model with a dilaton. At this order both metric and dilaton β functions are found to depend nontrivially on the dilaton field and vanish if the dilaton satisfies ∇μ∇νφ=0. By employing the Curci-Paffuti relation it is shown that such dilaton backgrounds in Ricci-flat spaces Rμν=0 satisfy the conformal invariance conditions up to this order. The particular class of Ricci-flat, compact, and orientable manifolds naturally emerge as appropriate internal-space configurations consistent with local scale invariance. We further explore the cosmological consequences of these dilaton configurations. In a Robertson-Walker four-dimensional background we find all dilatons satisfying ∇μ∇νφ=0. Except for the constant and the time-dependent dilaton φ(t)=-2 lnt+λ whose cosmological implications have been already discussed in the literature, additional solutions are found. These may be of relevance beyond leading order and for nonvanishing background values for the antisymmetric tensor Bμν. For these solutions, also the cosmic scale factor is at most linear in time therefore giving rise to either a static or a linearly expanding (contracting) universe.
Diamandis, G.A.; Georgalas, B.C.; Lahanas, A.B. )
1990-12-15
We calculate the {ital O}({alpha}{prime}{sup 3}) contributions to the renormalization-group {beta} functions in the {ital N}=1 supersymmetric {sigma} model with a dilaton. At this order both metric and dilaton {beta} functions are found to depend nontrivially on the dilaton field and vanish if the dilaton satisfies {del}{sub {mu}}{del}{sub {nu}}{phi}=0. By employing the Curci-Paffuti relation it is shown that such dilaton backgrounds in Ricci-flat spaces {ital R}{sub {mu}{nu}}=0 satisfy the conformal invariance conditions up to this order. The particular class of Ricci-flat, compact, and orientable manifolds naturally emerge as appropriate internal-space configurations consistent with local scale invariance. We further explore the cosmological consequences of these dilaton configurations. In a Robertson-Walker four-dimensional background we find all dilatons satisfying {del}{sub {mu}}{del}{sub {nu}}{phi}=0. Except for the constant and the time-dependent dilaton {phi}({ital t})={minus}2 ln{ital t}+{lambda} whose cosmological implications have been already discussed in the literature, additional solutions are found. These may be of relevance beyond leading order and for nonvanishing background values for the antisymmetric tensor {ital B}{sub {mu}{nu}}. For these solutions, also the cosmic scale factor is at most linear in time therefore giving rise to either a static or a linearly expanding (contracting) universe.
NASA Astrophysics Data System (ADS)
Novikov, Igor
Astrophysics of Black Holes Introduction The Origin of Stellar Black Holes A Nonrotating Black Hole Introduction Schwarzschild Gravitational Field Motion of Photons Along the Radial Direction Radial Motion of Nonrelativistic Particles The Puzzle of the Gravitational Radius R and T Regions Two Types of T-Regions Gravitational Collapse and White Holes Eternal Black Hole? Black Hole Celestial Mechanics Circular Motion Around a Black Hole Gravitational Capture of Particles by a Black Hole Corrections for Gravitational Radiation A Rotating Black Hole Introduction Gravitational Field of a Rotating Black Hole Specific Reference Frames General Properties of the Spacetime of a Rotating Black Hole; - Spacetime Inside the Horizon Celestial Mechanics of a Rotating Black Hole Motion of Particle in the Equatorial Plane Motion of Particles off the Equatorial Plane Peculiarities of the Gravitational Capture of Bodies by a Rotating - Black Hole Electromagnetic Fields Near a Black Hole Introduction Maxwell's Equations in the Neighborhood of a Rotating Black Hole Stationary Electrodynamics Boundary Conditions at the Event Horizon Electromagnetic Fields in Vacuum Magnetosphere of a Black Hole Some Aspects of Physics of Black Holes, Wormholes, and Time Machines Observational Appearence of the Black Holes in the Universe Black Holes in the Interstellar Medium Disk Accretion Black Holes in Stellar Binary Systems Black Holes in Galactic Centers Dynamical Evidence for Black Holes in Galaxy Nuclei Primordial Black Holes Acknowledgements References
Semiclassical geometry of charged black holes
Frolov, Andrei V.; Kristjansson, Kristjan R.; Thorlacius, Larus
2005-07-15
At the classical level, two-dimensional dilaton gravity coupled to an abelian gauge field has charged black hole solutions, which have much in common with four-dimensional Reissner-Nordstroem black holes, including multiple asymptotic regions, timelike curvature singularities, and Cauchy horizons. The black hole spacetime is, however, significantly modified by quantum effects, which can be systematically studied in this two-dimensional context. In particular, the back-reaction on the geometry due to pair-creation of charged fermions destabilizes the inner horizon and replaces it with a spacelike curvature singularity. The semiclassical geometry has the same global topology as an electrically neutral black hole.
Constraining the Runaway Dilaton and Quintessential Dark Energy
NASA Astrophysics Data System (ADS)
Neupane, Ishwaree P.; Trowland, Holly
Dark energy is some of the weirdest and most mysterious stuff in the universe that tends to increase the rate of expansion of the universe. Two commonly known forms of dark energy are the cosmological constant, a constant energy density filling space homogeneously, and scalar fields such as quintessence or moduli whose energy density can vary with time. We explore one particular model for dynamic dark energy: quintessence driven by a scalar dilaton field. We propose an ansatz for the form of the dilaton field, |ϕ(a)|mP ≡ α1 ln t + α2tn = α ln a + βa2ζ, where a is the scale factor and α and ζ are parameters of the model. This phenomenological ansatz for ϕ can be motivated by generic solutions of a scalar dilaton field in many effective string theory and string-inspired gravity models in four dimensions. Most of the earlier discussions in the literature correspond to the choice that ζ = 0 so that ϕ(t) ∝ ln t or ϕ(t) ∝ ln a(t). Using a compilation of current data including type Ia supernovae, we impose observational constraints on the slope parameters like α and ζ and then discuss the relation of our results to analytical constraints on various cosmological parameters, including the dark energy equation of state. Some useful constraints are imposed on model parameters like α and ζ as well as on the dark energy/dark matter couplings using results from structure formation. The constraints of this model are shown to encompass the cosmological constant limit within 1σ error bars.
Calculable mass hierarchies and a light dilaton from gravity duals
NASA Astrophysics Data System (ADS)
Elander, Daniel; Piai, Maurizio
2017-09-01
In the context of gauge/gravity dualities, we calculate the scalar and tensor mass spectrum of the boundary theory defined by a special 8-scalar sigma-model in five dimensions, the background solutions of which include the 1-parameter family dual to the baryonic branch of the Klebanov-Strassler field theory. This provides an example of a strongly-coupled, multi-scale system that yields a parametrically light mass for one of the composite scalar particles: the dilaton. We briefly discuss the implications of these findings towards identifying a satisfactory solution to both the big and little hierarchy problems of the electro-weak theory.
Light wave propagation through a dilaton-Maxwell domain wall
NASA Astrophysics Data System (ADS)
Morris, J. R.; Schulze-Halberg, A.
2015-10-01
We consider the propagation of electromagnetic waves through a dilaton-Maxwell domain wall of the type introduced by Gibbons and Wells [G. W. Gibbons and C. G. Wells, Classical and Quantum Gravity 11, 2499 (1994)]. It is found that if such a wall exists within our observable Universe, it would be absurdly thick, or else have a magnetic field in its core which is much stronger than observed intergalactic fields. We conclude that it is highly improbable that any such wall is physically realized.
Baryon asymmetry from hypermagnetic helicity in dilaton hypercharge electromagnetism
Bamba, Kazuharu
2006-12-15
The generation of the baryon asymmetry of the Universe from the hypermagnetic helicity, the physical interpretation of which is given in terms of hypermagnetic knots, is studied in inflationary cosmology, taking into account the breaking of the conformal invariance of hypercharge electromagnetic fields through both a coupling with the dilaton and with a pseudoscalar field. It is shown that, if the electroweak phase transition is strongly first order and the present amplitude of the generated magnetic fields on the horizon scale is sufficiently large, a baryon asymmetry with a sufficient magnitude to account for the observed baryon-to-entropy ratio can be generated.
Quantization of a theory of 2D dilaton gravity
NASA Astrophysics Data System (ADS)
de Alwis, S. P.
1992-09-01
We discuss the quantization of the 2D gravity theory of Callan, Giddings, Harvey, and Strominger (CGHS), following the procedure of David, and of Distler and Kawai. We find that the physics depends crucially on whether the number of matter fields is greater than or less than 24. In the latter case the singularity pointed out by several authors is absent but the physical interpretation is unclear. In the former case (the one studied by CGHS) the quantum theory which gives CGHS in the linear dilaton semi-classical limit, is different from that which gives CGHS in the extreme Liouville regime.
Charged black holes on a Kaluza-Klein bubble
Kunz, Jutta; Yazadjiev, Stoytcho
2009-01-15
We construct a solution of two black holes on a Kaluza-Klein bubble in Einstein-Maxwell-dilaton theory. We explore the consequences of the presence of charge for the properties of this solution, and obtain a generalized Smarr relation and first law.
Near-horizon conformal symmetry and black hole entropy.
Carlip, S
2002-06-17
Near an event horizon, the action of general relativity acquires a new asymptotic conformal symmetry. For two-dimensional dilaton gravity, this symmetry results in a chiral Virasoro algebra, and Cardy's formula for the density of states reproduces the Bekenstein-Hawking entropy. This lends support to the notion that black hole entropy is controlled universally by conformal symmetry near the horizon.
E-ELT constraints on runaway dilaton scenarios
Martinelli, M.; Calabrese, E.; Martins, C.J.A.P. E-mail: erminia.calabrese@physics.ox.ac.uk
2015-11-01
We use a combination of simulated cosmological probes and astrophysical tests of the stability of the fine-structure constant α, as expected from the forthcoming European Extremely Large Telescope (E-ELT), to constrain the class of string-inspired runaway dilaton models of Damour, Piazza and Veneziano. We consider three different scenarios for the dark sector couplings in the model and discuss the observational differences between them. We improve previously existing analyses investigating in detail the degeneracies between the parameters ruling the coupling of the dilaton field to the other components of the universe, and studying how the constraints on these parameters change for different fiducial cosmologies. We find that if the couplings are small (e.g., α{sub b} = α{sub V} ∼ 0) these degeneracies strongly affect the constraining power of future data, while if they are sufficiently large (e.g., α{sub b} ∼> 10{sup −5}−α{sub V} ∼> 0.05, as in agreement with current constraints) the degeneracies can be partially broken. We show that E-ELT will be able to probe some of this additional parameter space.
AdS vacua from dilaton tadpoles and form fluxes
NASA Astrophysics Data System (ADS)
Mourad, J.; Sagnotti, A.
2017-05-01
We describe how unbounded three-form fluxes can lead to families of AdS3 ×S7 vacua, with constant dilaton profiles, in the USp (32) model with ;brane supersymmetry breaking; and in the U (32) 0'B model, if their (projective-)disk dilaton tadpoles are taken into account. We also describe how, in the SO (16) × SO (16) heterotic model, if the torus vacuum energy Λ is taken into account, unbounded seven-form fluxes can support similar AdS7 ×S3 vacua, while unbounded three-form fluxes, when combined with internal gauge fields, can support AdS3 ×S7 vacua, which continue to be available even if Λ is neglected. In addition, special gauge field fluxes can support, in the SO (16) × SO (16) heterotic model, a set of AdSn ×S10-n vacua, for all n = 2 , . . , 8. String loop and α‧ corrections appear under control when large form fluxes are allowed.
Energy Associated with the Gibbons-Maeda Dilaton Spacetime
NASA Astrophysics Data System (ADS)
Aydogdu, Oktay; Salti, Mustafa; Korunur, Murat; Acikgoz, Irfan
2006-12-01
In order to obtain energy and momentum (due to matter and fields including gravitation) distributions of the Gibbons-Maeda dilaton spacetime, we use the Møller energy-momentum prescription both in Einstein's theory of general relativity and teleparallel gravity. We find the same energy distribution for a given metric in both of these different gravitation theories. Under two limits, we also calculate energy associated with two other models such as the Garfinkle-Horowitz-Strominger dilaton spacetime and the Reissner-Nordstrom spacetime. The energy obtained is also independent of the teleparallel dimensionless coupling constant, which means that it is valid in any teleparallel model. Our result also sustains (a) the importance of the energy-momentum definitions in the evaluation of the energy distribution for a given spacetime and (b) the viewpoint of Lessner that the Møller energy-momentum complex is a powerful concept of energy and momentum (c) the hypothesis of Vagenas that there is a connection between the coefficients of the energy-momentum expression of Einstein and those of Møller.
NASA Astrophysics Data System (ADS)
Gnerucci, A.; Marconi, A.; Capetti, A.; Axon, D. J.; Robinson, A.; Neumayer, N.
2011-12-01
We measure the black hole mass in the nearby active galaxy Centaurus A (NGC 5128) using a new method based on spectroastrometry of a rotating gas disk. The spectroastrometric approach consists in measuring the photocenter position of emission lines for different velocity channels. In a previous paper we focused on the basic methodology and the advantages of the spectroastrometric approach with a detailed set of simulations demonstrating the possibilities for black hole mass measurements going below the conventional spatial resolution. In this paper we apply the spectroastrometric method to multiple longslit and integral field near infrared spectroscopic observations of Centaurus A. We find that the application of the spectroastrometric method provides results perfectly consistent with the more complex classical method based on rotation curves: the measured BH mass is nearly independent of the observational setup and spatial resolution and the spectroastrometric method allows the gas dynamics to be probed down to spatial scales of ~0.02″, i.e. 1/10 of the spatial resolution and ~1/50 of BH sphere of influence radius. The best estimate for the BH mass based on kinematics of the ionised gas is then log (MBH sin i2/M⊙) ≃ 7.5 ± 0.1 which corresponds to MBH= 9.6-1.8+2.5 × 107 M⊙ for an assumed disk inclination of i = 35°. The complementarity of this method with the classic rotation curve method will allow us to put constraints on the disk inclination which cannot be otherwise derived from spectroastrometry. With the application to Centaurus A, we have shown that spectroastrometry opens up the possibility of probing spatial scales smaller than the spatial resolution, extending the measured MBH range to new domains which are currently not accessible: smaller BHs in the local universe and similar BHs in more distant galaxies.
Could fermion masses play a role in the stabilization of the dilaton in cosmology?
NASA Astrophysics Data System (ADS)
Cabo, Alejandro; Brandenberger, Robert
2009-02-01
We study the possibility that the Dilaton is stabilized by the contribution of fermion masses to its effective potential. We consider the Dilaton gravity action in four dimensions to which we add a mass term for a Dirac fermion. Such an action describes the interaction of the Dilaton with the fermions in the Yang-Mills sector of the coupled supergravity/super-Yang-Mills action which emerges as the low energy effective action of superstring theory after the extra spatial dimensions have been fixed. The Dilaton couples to the Fermion mass term via the usual exponential factor of this field which multiplies the non-kinetic terms of the matter Lagrangian, if we work in the Einstein frame. In the kinetic part of the Fermion action in the Einstein frame the Dilaton does not enter. Such masses can be generated in several ways: they can arise as a consequence of flux about internal spatial dimensions, they may arise as thermal fermion masses in a quasi-static phase in the early universe, and they will arise after the breaking of supersymmetry at late times. The vacuum contribution to the potential for the Dilaton is evaluated up to two loops. The result shows a minimum which could stabilize the Dilaton for reasonable ranges of parameter values.
Could fermion masses play a role in the stabilization of the dilaton in cosmology?
Cabo, Alejandro; Brandenberger, Robert E-mail: rhb@hep.physics.mcgill.ca
2009-02-15
We study the possibility that the Dilaton is stabilized by the contribution of fermion masses to its effective potential. We consider the Dilaton gravity action in four dimensions to which we add a mass term for a Dirac fermion. Such an action describes the interaction of the Dilaton with the fermions in the Yang-Mills sector of the coupled supergravity/super-Yang-Mills action which emerges as the low energy effective action of superstring theory after the extra spatial dimensions have been fixed. The Dilaton couples to the Fermion mass term via the usual exponential factor of this field which multiplies the non-kinetic terms of the matter Lagrangian, if we work in the Einstein frame. In the kinetic part of the Fermion action in the Einstein frame the Dilaton does not enter. Such masses can be generated in several ways: they can arise as a consequence of flux about internal spatial dimensions, they may arise as thermal fermion masses in a quasi-static phase in the early universe, and they will arise after the breaking of supersymmetry at late times. The vacuum contribution to the potential for the Dilaton is evaluated up to two loops. The result shows a minimum which could stabilize the Dilaton for reasonable ranges of parameter values.
All or nothing: On the small fluctuations of two-dimensional string theoretic black holes
Gilbert, Gerald; Raiten, Eric
1992-10-01
A comprehensive analysis of small fluctuations about two-dimensional string-theoretic and string-inspired black holes is presented. It is shown with specific examples that two-dimensional black holes behave in a radically different way from all known black holes in four dimensions. For both the SL(2,R)/U(1) black hole and the two-dimensional black hole coupled to a massive dilaton with constant field strength, it is shown that there are a {\\it continuous infinity} of solutions to the linearized equations of motion, which are such that it is impossible to ascertain the classical linear response. It is further shown that the two-dimensional black hole coupled to a massive, linear dilaton admits {\\it no small fluctuations at all}. We discuss possible implications of our results for the Callan-Giddings-Harvey-Strominger black hole.
Extremal dyonic black holes in D=4 Gauss-Bonnet gravity
NASA Astrophysics Data System (ADS)
Chen, Chiang-Mei; Gal'Tsov, Dmitri V.; Orlov, Dmitry G.
2008-11-01
We investigate extremal dyon black holes in the Einstein-Maxwell-dilaton theory with higher curvature corrections in the form of the Gauss-Bonnet density coupled to the dilaton. In the same theory without the Gauss-Bonnet term the extremal dyon solutions exist only for discrete values of the dilaton coupling constant a. We show that the Gauss-Bonnet term acts as a dyon hair tonic enlarging the allowed values of a to continuous domains in the plane (a,qm) where qm is the magnetic charge. In the limit of the vanishing curvature coupling (a large magnetic charge) the dyon solutions obtained tend to the Reissner-Nordström solution but not to the extremal dyons of the Einstein-Maxwell-dilaton theory. Both solutions have the same dependence of the horizon radius in terms of charges. The entropy of new dyonic black holes interpolates between the Bekenstein-Hawking value in the limit of the large magnetic charge (equivalent to the vanishing Gauss-Bonnet coupling) and twice this value for the vanishing magnetic charge. Although an expression for the entropy can be obtained analytically using purely local near-horizon solutions, its interpretation as the black hole entropy is legitimate only once the global black hole solution is known to exist, and we obtain numerically the corresponding conditions on the parameters. Thus, a purely local analysis is insufficient to fully understand the entropy of the curvature-corrected black holes. We also find dyon solutions which are not asymptotically flat, but approach the linear dilaton background at infinity. They describe magnetic black holes on the electric linear dilaton background.
Black hole mining in the RST model
NASA Astrophysics Data System (ADS)
Basavaraju, Rohitvarma; Lowe, David A.
2017-06-01
We consider the possibility of mining black holes in the 1 + 1-dimensional dilaton gravity model of Russo, Susskind and Thorlacius. The model correctly incorporates Hawking radiation and back-reaction in a semiclassical expansion in 1/N, where N is the number of matter species. It is shown that the lifetime of a perturbed black hole is independent of the addition of any extra apparatus when realized by an arbitrary positive energy matter source. We conclude that mining does not occur in the RST model and comment on the implications of this for the black hole information paradox.
Astrophysical black holes in screened modified gravity
Davis, Anne-Christine; Jha, Rahul; Muir, Jessica; Gregory, Ruth E-mail: r.a.w.gregory@durham.ac.uk E-mail: jlmuir@umich.edu
2014-08-01
Chameleon, environmentally dependent dilaton, and symmetron gravity are three models of modified gravity in which the effects of the additional scalar degree of freedom are screened in dense environments. They have been extensively studied in laboratory, cosmological, and astrophysical contexts. In this paper, we present a preliminary investigation into whether additional constraints can be provided by studying these scalar fields around black holes. By looking at the properties of a static, spherically symmetric black hole, we find that the presence of a non-uniform matter distribution induces a non-constant scalar profile in chameleon and dilaton, but not necessarily symmetron gravity. An order of magnitude estimate shows that the effects of these profiles on in-falling test particles will be sub-leading compared to gravitational waves and hence observationally challenging to detect.
AdS2 holography is (non-)trivial for (non-)constant dilaton
NASA Astrophysics Data System (ADS)
Grumiller, Daniel; Salzer, Jakob; Vassilevich, Dmitri
2015-12-01
We study generic two-dimensional dilaton gravity with a Maxwell field and prove its triviality for constant dilaton boundary conditions, despite of the appearance of a Virasoro algebra with non-zero central charge. We do this by calculating the canonical boundary charges, which turn out to be trivial, and by calculating the quantum gravity partition function, which turns out to be unity. We show that none of the following modifications changes our conclusions: looser boundary conditions, non-linear interactions of the Maxwell field with the dilaton, inclusion of higher spin fields, inclusion of generic gauge fields. Finally, we consider specifically the charged Jackiw-Teitelboim model, whose holographic study was pioneered by Hartman and Strominger, and show that it is non-trivial for certain linear dilaton boundary conditions. We calculate the entropy from the Euclidean path integral, using Wald's method and exploiting the chiral Cardy formula. The macroscopic and microscopic results for entropy agree with each other.
More on critical collapse of axion-dilaton system in dimension four
Álvarez-Gaumé, Luis; Hatefi, Ehsan E-mail: ehsan.hatefi@cern.ch
2013-10-01
We complete our previous study of critical gravitational collapse in the axion-dilaton system by analysing the hyperbolic and parabolic ansaetze. As could be expected, the corresponding Choptuik exponents in four-dimensions differ from the elliptic case.
Saddle-point solutions in Yang-Mills-dilaton theory
NASA Astrophysics Data System (ADS)
Bizon, Piotr
1993-02-01
The coupling of a dilaton to the SU(2)-Yang-Mills field leads to interesting nonperturbative static spherically symmetric solutions which are studied by mixed analytical and numerical methods. In the Abelian sector of the theory there are finite-energy magnetic and electric monopole solutions which saturate the Bogomol'nyi bound. In the non-Abelian sector there exists a countable family of globally regular solutions which are purely magnetic but have a zero Yang-Mills magnetic charge. Their discrete spectrum of energies is bounded from above by the energy of the Abelian magnetic monopole with unit magnetic charge. The stability analysis demonstrates that the solutions are saddle points of the energy functional with an increasing number of unstable modes. The existence and instability of these solutions are ``explained'' by the Morse-theory argument recently proposed by Sudarsky and Wald.
Saddle-point solutions in Yang-Mills--dilaton theory
Bizon, P. )
1993-02-15
The coupling of a dilaton to the SU(2)-Yang-Mills field leads to interesting nonperturbative static spherically symmetric solutions which are studied by mixed analytical and numerical methods. In the Abelian sector of the theory there are finite-energy magnetic and electric monopole solutions which saturate the Bogomol'nyi bound. In the non-Abelian sector there exists a countable family of globally regular solutions which are purely magnetic but have a zero Yang-Mills magnetic charge. Their discrete spectrum of energies is bounded from above by the energy of the Abelian magnetic monopole with unit magnetic charge. The stability analysis demonstrates that the solutions are saddle points of the energy functional with an increasing number of unstable modes. The existence and instability of these solutions are explained'' by the Morse-theory argument recently proposed by Sudarsky and Wald.
Ultra-weak sector, Higgs boson mass, and the dilaton
Allison, Kyle; Hill, Christopher T.; Ross, Graham G.
2014-09-26
The Higgs boson mass may arise from a portal coupling to a singlet fieldmore » $$\\sigma$$ which has a very large VEV $$f \\gg m_\\text{Higgs}$$. This requires a sector of "ultra-weak" couplings $$\\zeta_i$$, where $$\\zeta_i \\lesssim m_\\text{Higgs}^2 / f^2$$. Ultra-weak couplings are technically naturally small due to a custodial shift symmetry of $$\\sigma$$ in the $$\\zeta_i \\rightarrow 0$$ limit. The singlet field $$\\sigma$$ has properties similar to a pseudo-dilaton. We engineer explicit breaking of scale invariance in the ultra-weak sector via a Coleman-Weinberg potential, which requires hierarchies amongst the ultra-weak couplings.« less
Ultra-weak sector, Higgs boson mass, and the dilaton
Allison, Kyle; Hill, Christopher T.; Ross, Graham G.
2014-09-26
The Higgs boson mass may arise from a portal coupling to a singlet field $\\sigma$ which has a very large VEV $f \\gg m_\\text{Higgs}$. This requires a sector of "ultra-weak" couplings $\\zeta_i$, where $\\zeta_i \\lesssim m_\\text{Higgs}^2 / f^2$. Ultra-weak couplings are technically naturally small due to a custodial shift symmetry of $\\sigma$ in the $\\zeta_i \\rightarrow 0$ limit. The singlet field $\\sigma$ has properties similar to a pseudo-dilaton. We engineer explicit breaking of scale invariance in the ultra-weak sector via a Coleman-Weinberg potential, which requires hierarchies amongst the ultra-weak couplings.
Holm, D.K. . Dept. of Geology); Geissman, J.W. . Dept. of Geology and Planetary Sciences); Wernicke, B. . Dept. of Geology and Planetary Sciences)
1993-04-01
Paleomagnetic data have been obtained from Miocene intrusions, Proterozoic Paleomagnetic data have been obtained from Miocene intrusions, Proterozoic crystalline rocks and cross-cutting mafic to felsic dikes to evaluate footwall deformation during extension and unroofing of the crystalline core of the Black Mountains, Death Valley, California. Synrift intrusions contain a well-defined and, at the site level, well-grouped magnetization, interpreted to be of dual polarity, whose in situ direction is discordant in declination and inclination with an expected late Cenozoic reference direction. In situ site mean directions of this magnetization are directed towards the west and west-northwest with moderate to shallow positive and negative inclinations. The variation in magnetization direction, particularly inclination, with site locality around the turtleback structures along the western flank of the Black Mountains suggests folding of the intrusion after remanence acquisition. Two populations of in situ site means are identified: one with southwest declination and negative inclination, the other with northward declination and positive inclination. A preferred interpretation for footwall deformation involves, from oldest to youngest: (1) northeast-side up tilting of 20--40[degree] and local folding of the crystalline rocks associated with early structures (the Death Valley turtlebacks) between 11.6 and 8.7 Ma, (2) progressive east to west footwall unroofing between 8.7 and [approximately]6.5 Ma, and (3) large-scale clockwise rotation (50--80[degree]) after the core detached from stable terrane to the west. The authors interpret late rotation as oroflexure related to right-lateral shear along the Death Valley fault zone.
Black hole entropy from conformal symmetry on the horizon
NASA Astrophysics Data System (ADS)
Carlip, Steven
2017-01-01
The idea that black hole entropy might be governed by a conformal symmetry is an old one, but until now most efforts have focused on either asymptotic symmetries or symmetries on a ``stretched horizon. For two-dimensional dilaton gravity, I show the existence of a well-behaved conformal symmetry that is on the horizon, with a central charge that correctly determines the black hole entropy. Supported by Department of Energy grant DE-FG02-91ER40674.
Shear viscosity from Gauss-Bonnet gravity with a dilaton coupling
Cai Ronggen; Nie Zhangyu; Sun Yawen; Ohta, Nobuyoshi
2009-03-15
We calculate the shear viscosity of field theories with gravity duals of Gauss-Bonnet gravity with a nontrivial dilaton using anti-de Sitter/conformal field theory. We find that the dilaton field has a nontrivial contribution to the ratio of shear viscosity over entropy density, and, after imposing a causal constraint for the boundary field theory, the new lower bound 4/25{pi}, obtained from pure Gauss-Bonnet gravity, may have a small violation.
Koide, Shinji; Kudoh, Takahiro; Shibata, Kazunari
2006-08-15
We report two-dimensional numerical results of jet formation driven by a magnetic field due to a current loop near a rapidly rotating black hole. We initially set the current loop along the intersection of the equatorial plane and the surface of the ergosphere around the black hole. In such magnetic configurations, there are magnetic flux tubes which bridge the region between the ergosphere and the corotating disk. The magnetic flux tube, which we call a 'magnetic bridge', is twisted rapidly by the plasma in the ergosphere due to the frame-dragging effect. The magnetic pressure of the magnetic flux tube increases and the strong magnetic pressure blows off the plasma near the ergosphere to form outflow. The outflow is pinched by the magnetic tension of the magnetic flux tube. Then, eventually, the jet is formed. That is, the magnetic bridges cannot be stationary, and they expand explosively to form a jet. The parameter survey of the background pressure shows that the radius of the collimated jet depends on the gas pressure of the corona. However, this does not mean the gas pressure collimates the jet. The gas pressure decelerates the jet and the pinch effect by the magnetic field becomes significant.
Quinkenstein, A; Jochheim, H
2016-03-01
In the temperate zone short rotation coppice systems for the production of woody biomass (SRC) have gained great interest as they offer a pathway to both sustainable bioenergy production and the potential sequestration of CO2 within the biomass and the soil. This study used the carbon model SHORTCAR to assess the carbon cycle of a poplar (Populus suaveolens Fisch. x Populus trichocarpa Torr. et Gray cv. Androscoggin) and a black locust (Robinia pseudoacacia L.) SRC. The model was calibrated using data from established SRC plantations on reclaimed mine sites in northeast Germany and validated through the determination of uncertainty ranges of selected model parameters and a sensitivity analysis. In addition to a 'reference scenario', representing the actual site conditions, 7 hypothetical scenarios, which varied in climate conditions, rotation intervals, runtimes, and initial soil organic carbon (SOC) stocks, were defined for each species. Estimates of carbon accumulation within the biomass, the litter layer, and the soil were compared to field data and previously published results. The model was sensitive to annual stem growth and initial soil organic carbon stocks. In the reference scenario net biome production for SRC on reclaimed sites in Lusatia, Germany amounted to 64.5 Mg C ha(-1) for R. pseudoacacia and 8.9 Mg C ha(-1) for poplar, over a period of 36 years. These results suggest a considerable potential of SRC for carbon sequestration at least on marginal sites. Copyright © 2015 Elsevier Ltd. All rights reserved.
NASA Astrophysics Data System (ADS)
Trova, A.; Karas, V.; Slaný, P.; Kovář, J.
2016-09-01
We present an analytical approach for the equilibrium of a self-gravitating charged fluid embedded in a spherical gravitational and dipolar magnetic fields produced by a central mass. Our scheme is proposed, as a toy model, in the context of gaseous/dusty tori surrounding supermassive black holes in galactic nuclei. While the central black hole dominates the gravitational field and remains electrically neutral, the surrounding material has a non-negligible self-gravitational effect on the torus structure. By charging mechanisms it also acquires non-zero electric charge density, so the two influences need to be taken into account to achieve a self-consistent picture. Using our approach we discuss the impact of self-gravity, represented by the term {d}{{t}} (ratio of the torus total mass to the mass of the central body), on the conditions for existence of the equilibrium and the morphology and typology of the tori. By comparison with a previous work without self-gravity, we show that the conditions can be different. Although the main aim of the present paper is to discuss a framework for the classification of electrically charged, magnetized, self-gravitating tori, we also mention potential astrophysical applications to vertically stratified fluid configurations.
Black rings and the physical process version of the first law of thermodynamics
Rogatko, Marek
2005-10-01
We consider the problem of the physical process version of the first law of black ring thermodynamics in n-dimensional Einstein gravity with additional (p+1)-form field strength and dilaton fields. The first order variations of mass, angular momentum and local charge for black ring are derived. From them we prove the physical process version of the first law of thermodynamic for stationary black rings.
NASA Astrophysics Data System (ADS)
Gnerucci, A.; Marconi, A.; Capetti, A.; Axon, D. J.; Robinson, A.
2013-01-01
We present new CRIRES spectroscopic observations of the Brγ emission line in the nuclear region of the Circinus galaxy, obtained with the aim of measuring the black hole (BH) mass with the spectroastrometric technique. The Circinus galaxy is an ideal benchmark for the spectroastrometric technique given its proximity and secure BH measurement obtained with the observation of its nuclear H2O maser disk. The kinematical data have been analyzed both with the classical method based on the analysis of the rotation curves and with the new method developed by us that is based on spectroastrometry. The classical method indicates that the gas disk rotates in a gravitational potential resulting from an extended stellar mass distribution and a spatially unresolved dynamical mass of (1.7 ± 0.2) × 107 M⊙, concentrated within r < 7 pc, corresponding to the seeing-limited resolution of the observations. The new method is capable of probing the gas rotation at scales that are a factor ~3.5 smaller than those probed by the rotation curve analysis, highlighting the potential of spectroastrometry. The dynamical mass, which is spatially unresolved with the spectroastrometric method, is a factor ~2 smaller, 7.9+1.4-1.1 × 106M⊙, indicating that spectroastrometry has been able to spatially resolve the nuclear mass distribution down to 2 pc scales. This unresolved mass is still a factor ~4.5 larger than the BH mass measurement obtained with the H2O maser emission, indicating that even with spectroastrometry, it has not been possible to resolve the sphere of influence of the BH. Based on literature data, this spatially unresolved dynamical mass distribution is likely dominated by warm molecular gas and has been tentatively identified with the circum-nuclear torus that prevents a direct view of the central BH in Circinus. This mass distribution, with a size of ~2 pc, is similar in shape to that of the star cluster of the Milky Way, suggesting that a molecular torus, forming stars at
Improved soft-wall model with a negative dilaton
Zuo Fen
2010-10-15
I propose to change the sign of the dilaton in the infrared (IR) soft-wall anti-de Sitter/QCD model, in order to implement confinement. The deformed model exhibits interesting properties, especially in describing chiral symmetry breaking. The expectation value of the scalar field X, which determines the quark mass and condensate, approaches a constant in the IR limit, rather than blows up in the original model. In contrast to the estimate in [M. Shifman and A. Vainshtein, Phys. Rev. D 77, 034002 (2008).], this kind of solution will not lead to chiral symmetry restoration for highly-excited states due to the property of the harmonic-oscillator equation. Instead, it will guarantee the Regge behavior of the axial meson spectrum and also the pseudoscalar mesons. The value of the condensate can be fixed by requiring that the pion be massless in the chiral limit, but only under some approximation in the present model. We also find that, by relaxing the IR boundary conditions, the unphysical massless state in the vector channel can be eliminated.
The Soliton-Soliton Interaction in the Chiral Dilaton Model
NASA Astrophysics Data System (ADS)
Mantovani-Sarti, Valentina; Park, Byung-Yoon; Vento, Vicente
2013-10-01
We study the interaction between two B = 1 states in the Chiral Dilaton Model where baryons are described as nontopological solitons arising from the interaction of chiral mesons and quarks. By using the hedgehog solution for B = 1 states we construct, via a product ansatz, three possible B = 2 configurations to analyse the role of the relative orientation of the hedgehog quills in the dynamics of the soliton-soliton interaction and investigate the behavior of these solutions in the range of long/intermediate distance. One of the solutions is quite binding due to the dynamics of the π and σ fields at intermediate distance and should be used for nuclear matter studies. Since the product ansatz break down as the two solitons get close, we explore the short range distance regime with a model that describes the interaction via a six-quark bag ansatz. We calculate the interaction energy as a function of the inter-soliton distance and show that for small separations the six quarks bag, assuming a hedgehog structure, provides a stable bound state that at large separations connects with a special configuration coming from the product ansatz.
Weyl gauge-vector and complex dilaton scalar for conformal symmetry and its breaking
NASA Astrophysics Data System (ADS)
Ohanian, Hans C.
2016-03-01
Instead of the scalar "dilaton" field that is usually adopted to construct conformally invariant Lagrangians for gravitation, we here propose a hybrid construction, involving both a complex dilaton scalar and a Weyl gauge-vector, in accord with Weyl's original concept of a non-Riemannian conformal geometry with a transport law for length and time intervals, for which this gauge vector is required. Such a hybrid construction permits us to avoid the wrong sign of the dilaton kinetic term (the ghost problem) that afflicts the usual construction. The introduction of a Weyl gauge-vector and its interaction with the dilaton also has the collateral benefit of providing an explicit mechanism for spontaneous breaking of the conformal symmetry, whereby the dilaton and the Weyl gauge-vector acquire masses somewhat smaller than {m}_{P} by the Coleman-Weinberg mechanism. Conformal symmetry breaking is assumed to precede inflation, which occurs later by a separate GUT or electroweak symmetry breaking, as in inflationary models based on the Higgs boson.
Spin distribution of primordial black holes
NASA Astrophysics Data System (ADS)
Chiba, Takeshi; Yokoyama, Shuichiro
2017-08-01
We estimate the spin distribution of primordial black holes based on the recent study of the critical phenomena in the gravitational collapse of a rotating radiation fluid. We find that primordial black holes are mostly slowly rotating.
New class of exact solutions in Einstein-Maxwell-dilaton theory
NASA Astrophysics Data System (ADS)
Ghezelbash, A. M.
2017-03-01
We find new solutions to the five-dimensional Einstein-Maxwell-dilaton theory with cosmological constant where the dilaton field couples to the electromagnetic field as well as to the cosmological term with two different coupling constants. The five-dimensional spacetime is nonstationary and is a conformally regular spacetime, everywhere. Both the dilaton field and the electromagnetic field depend on time and two spatial directions. The cosmological constant takes a positive, negative, or zero value, depending on the value of the coupling constant. We study the physical properties of the spacetime, and we show that the solutions are unique in five dimensions and that they cannot be uplifted to higher-dimensional Einstein-Maxwell theory or Einstein gravity in the presence of the cosmological constant. Moreover, we construct new solutions to the theory in which both coupling constants are equal.
RG flows in d dimensions, the dilaton effective action, and the a-theorem
NASA Astrophysics Data System (ADS)
Elvang, Henriette; Olson, Timothy M.
2013-03-01
Motivated by the recent dilaton-based proof of the 4d a-theorem, we study the dilaton effective action for RG flows in d dimensions. When d is even, the action consists of a Wess-Zumino (WZ) term, whose Weyl-variation encodes the trace-anomaly, plus all Weyl-invariants. For d odd, the action consists of Weyl-invariants only. We present explicit results for the flat-space limit of the dilaton effective action in d-dimensions up to and including 8-derivative terms. GJMS-operators from conformal geometry motivate a form of the action that unifies the Weyl-invariants and anomaly-terms into a compact general- d structure. A new feature in 8d is the presence of an 8-derivative Weyl-invariant that pollutes the O( p 8)-contribution from the WZ action to the dilaton scattering amplitudes; this may challenge a dilaton-based proof of an a-theorem in 8d. We use the example of a free massive scalar for two purposes: 1) it allows us to confirm the structure of the d-dimensional dilaton effective action explicitly; we carry out this check for d = 3, 4, 5, . . . , 10; and 2) in 8d we demonstrate how the flow Δ a = a UV - a IR can be extracted systematically from the O( p 8)-amplitudes despite the contamination from the 8-derivative Weyl-invariant. This computation gives a value for the a-anomaly of the 8d free conformal scalar that is shown to match the value obtained from zeta-function regularization of the log-term in the free energy.
Bulk antisymmetric tensor fields coupled to a dilaton in a Randall-Sundrum model
Alencar, G.; Tahim, M. O.; Landim, R. R.; Muniz, C. R.
2010-11-15
A string-inspired three-form-dilaton-gravity model is studied in a Randall-Sundrum brane world scenario. As expected, the rank-3 antisymmetric field is exponentially suppressed. For each mass level, the mass spectrum is bigger than the one for the Kalb-Ramond field. The coupling between the dilaton and the massless Kaluza-Klein mode of the three-form is calculated, and the coupling constant of the cubic interactions is obtained numerically. This coupling are of the order of Tev{sup -1}; therefore, there exists a possibility to find some signal of it at Tev scale.
Signature change in loop quantum gravity: Two-dimensional midisuperspace models and dilaton gravity
NASA Astrophysics Data System (ADS)
Bojowald, Martin; Brahma, Suddhasattwa
2017-06-01
Models of loop quantum gravity based on real connections have a deformed notion of general covariance, which leads to the phenomenon of signature change. This result is confirmed here in a general analysis of all midisuperspace models without local degrees of freedom. As a subclass of models, two-dimensional theories of dilaton gravity appear, but a larger set of examples is possible based only on the condition of anomaly freedom. While the classical dilaton gravity models are the only such systems without deformed covariance, they do give rise to signature change when holonomy modifications are included.
1999-11-30
This three-dimensional illustration shows how the rotating space around a black hole twists up the magnetic field in the plasma falling toward the black hole. The black sphere at the center of the figure is the black hole itself. http://photojournal.jpl.nasa.gov/catalog/PIA04207
NASA Astrophysics Data System (ADS)
Liu, Wen-Juan; Qian, Lei; Dong, Xiao-Bo; Jiang, Ning; Lira, Paulina; Cai, Zheng; Wang, Feige; Yang, Jinyi; Xiao, Ting; Kim, Minjin
2017-03-01
We report the discovery of a 20 kpc sized {{H}}α emission in SDSS J083803.68+540642.0, a ringed dwarf galaxy ({M}V=-17.89 mag) hosting an accreting intermediate-mass black hole at z = 0.02957. Analysis of the Hubble Space Telescope images indicates that it is an early-type galaxy with a featureless low-surface brightness disk ({μ }0=20.39 mag arcsec‑2 in the V band) and a prominent, relatively red bulge (V ‑ I = 2.03, {R}{{e}}=0.28 {kpc} or 0.″48) that accounts for ≈81% of the total light in the I band. A circumgalactic ring of a diameter 16 kpc is also detected, with a disperse shape on its south side. The optical emission lines reveal the nucleus to be a broad-line LINER. Our MMT longslit observation indicates that the kinematics of the extended {{H}}α emission is consistent with a rotational gaseous disk, with a mean blueshifted velocity of 162 {km} {{{s}}}-1 and mean redshifted velocity of 86 {km} {{{s}}}-1. According to our photoionization calculations, the large-scale {{H}}α emission is unlikely to be powered by the central nucleus or by hot evolved (post-AGB) stars interspersed in the old stellar populations, but by in situ star formation; this is vindicated by the line-ratio diagnostic of the extended emission. We propose that both the ring and large-scale {{H}}α -emitting gas are created by the tidal accretion in a collision—and then merger—with a gas-rich galaxy of a comparable mass.
Dynamical black holes in low-energy string theory
NASA Astrophysics Data System (ADS)
Aniceto, Pedro; Rocha, Jorge V.
2017-05-01
We investigate time-dependent spherically symmetric solutions of the four-dimensional Einstein-Maxwell-axion-dilaton system, with the dilaton coupling that occurs in low-energy effective heterotic string theory. A class of dilaton-electrovacuum radiating solutions with a trivial axion, previously found by Güven and Yörük, is re-derived in a simpler manner and its causal structure is clarified. It is shown that such dynamical spacetimes featuring apparent horizons do not possess a regular light-like past null infinity or future null infinity, depending on whether they are radiating or accreting. These solutions are then extended in two ways. First we consider a Vaidya-like generalisation, which introduces a null dust source. Such spacetimes are used to test the status of cosmic censorship in the context of low-energy string theory. We prove that — within this family of solutions — regular black holes cannot evolve into naked singularities by accreting null dust, unless standard energy conditions are violated. Secondly, we employ S-duality to derive new time-dependent dyon solutions with a nontrivial axion turned on. Although they share the same causal structure as their Einstein-Maxwell-dilaton counterparts, these solutions possess both electric and magnetic charges.
NASA Astrophysics Data System (ADS)
Tanabe, Kentaro
2016-02-01
We study the effective theory of slowly rotating black holes at the infinite limit of the spacetime dimension D. This large D effective theory is obtained by integrating the Einstein equation with respect to the radial direction. The effective theory gives equations for non-linear dynamical deformations of a slowly rotating black hole by effective equations. The effective equations contain the slowly rotating Myers-Perry black hole, slowly boosted black string, non-uniform black string and black ring as stationary solutions. We obtain the analytic solution of the black ring by solving effective equations. Furthermore, by perturbation analysis of effective equations, we find a quasinormal mode condition of the black ring in analytic way. As a result we confirm that thin black ring is unstable against non-axisymmetric perturbations. We also include 1 /D corrections to the effective equations and discuss the effects by 1 /D corrections.
Dilaton dominance in the early universe dilutes dark matter relic abundances
Lahanas, A. B.
2011-05-15
The role of the dilaton field and its coupling to matter may result in a dilution of dark matter (DM) relic densities. This is to be contrasted with quintessence scenarios in which relic densities are augmented, due to modification of the expansion rate, since the Universe is not radiation dominated at DM decoupling. The dilaton field, besides this, affects relic densities through its coupling to dust which tends to decrease relic abundances. Thus two separate mechanisms compete with each other resulting, in general, in a decrease of the relic density. This feature may be welcomed and can help the situation if direct dark matter experiments point towards small neutralino-nucleon cross sections, implying small neutralino annihilation rates and hence large relic densities, at least in the popular supersymmetric scenarios. In the presence of a diluting mechanism, both experimental constraints can be met. The role of the dilaton for this mechanism has been studied in the context of the noncritical string theory but in this work we follow a rather general approach assuming that the dilaton dominates only at early eras long before big bang nucleosynthesis.
Light-cone gauge superstring field theory in a linear dilaton background
NASA Astrophysics Data System (ADS)
Ishibashi, Nobuyuki
2017-03-01
The Feynman amplitudes of light-cone gauge superstring field theory suffer from various divergences. In order to regularize them, we study the theory in a linear dilaton background Φ =-i Q X1 with the number of spacetime dimensions fixed. We show that the theory with the Feynman i ɛ (ɛ >0 ) and Q2>10 yields finite results.
EFT for vortices with dilaton-dependent localized flux
NASA Astrophysics Data System (ADS)
Burgess, C. P.; Diener, Ross; Williams, M.
2015-11-01
We study how codimension-two objects like vortices back-react gravitationally with their environment in theories (such as 4D or higher-dimensional supergravity) where the bulk is described by a dilaton-Maxwell-Einstein system. We do so both in the full theory, for which the vortex is an explicit classical `fat brane' solution, and in the effective theory of `point branes' appropriate when the vortices are much smaller than the scales of interest for their back-reaction (such as the transverse Kaluza-Klein scale). We extend the standard Nambu-Goto description to include the physics of flux-localization wherein the ambient flux of the external Maxwell field becomes partially localized to the vortex, generalizing the results of a companion paper [4] from N=2 supergravity as the end-point of a hierarchical limit in which the Planck mass first and then the supersymmetry breaking scale are sent to infinity. We define, in the parent supergravity model, a new symplectic frame in which, in the rigid limit, manifest symplectic invariance is preserved and the electric and magnetic Fayet-Iliopoulos terms are fully originated from the dyonic components of the embedding tensor. The supergravity origin of several features of the resulting rigid supersymmetric theory are then elucidated, such as the presence of a traceless SU(2)- Lie algebra term in the Ward identity and the existence of a central charge in the supersymmetry algebra which manifests itself as a harmless gauge transformation on the gauge vectors of the rigid theory; we show that this effect can be interpreted as a kind of "superspace non-locality" which does not affect the rigid theory on space-time. To set the stage of our analysis we take the opportunity in this paper to provide and prove the relevant identities of the most general dyonic gauging of Special-Kaehler and Quaternionic-Kaehler isometries in a generic N=2 model, which include the supersymmetry Ward identity, in a fully symplectic-covariant formalism.
Global solutions for higher-dimensional stretched small black holes
Chen, C.-M.; Gal'tsov, Dmitri V.; Ohta, Nobuyoshi; Orlov, Dmitry G.
2010-01-15
Small black holes in heterotic string theory have a vanishing horizon area at the supergravity level, but the horizon is stretched to the finite radius AdS{sub 2}xS{sup D-2} geometry once higher curvature corrections are turned on. This has been demonstrated to give good agreement with microscopic entropy counting. Previous considerations, however, were based on the classical local solutions valid only in the vicinity of the event horizon. Here we address the question of global existence of extremal black holes in the D-dimensional Einstein-Maxwell-Dilaton theory with the Gauss-Bonnet term introducing a variable dilaton coupling a as a parameter. We show that asymptotically flat black holes exist only in a bounded region of the dilaton couplings 0=}5 (but not for D=4) the allowed range of a includes the heterotic string values. For a>a{sub cr} numerical solutions meet weak naked singularities at finite radii r=r{sub cusp} (spherical cusps), where the scalar curvature diverges as |r-r{sub cusp}|{sup -1/2}. For D{>=}7 cusps are met in pairs, so that solutions can be formally extended to asymptotically flat infinity choosing a suitable integration variable. We show, however, that radial geodesics cannot be continued through the cusp singularities, so such a continuation is unphysical.
Global geometry of two-dimensional charged black holes
Frolov, Andrei V.; Kristjansson, Kristjan R.; Thorlacius, Larus
2006-06-15
The semiclassical geometry of charged black holes is studied in the context of a two-dimensional dilaton gravity model where effects due to pair-creation of charged particles can be included in a systematic way. The classical mass-inflation instability of the Cauchy horizon is amplified and we find that gravitational collapse of charged matter results in a spacelike singularity that precludes any extension of the spacetime geometry. At the classical level, a static solution describing an eternal black hole has timelike singularities and multiple asymptotic regions. The corresponding semiclassical solution, on the other hand, has a spacelike singularity and a Penrose diagram like that of an electrically neutral black hole. Extremal black holes are destabilized by pair-creation of charged particles. There is a maximally charged solution for a given black hole mass but the corresponding geometry is not extremal. Our numerical data exhibits critical behavior at the threshold for black hole formation.
Black Saturn with a dipole ring
Yazadjiev, Stoytcho S.
2007-09-15
We present a new stationary, asymptotically flat solution of 5D Einstein-Maxwell gravity describing a Saturn-like black object: a rotating black hole surrounded by a rotating dipole black ring. The solution is generated by combining the vacuum black Saturn solution and the vacuum black ring solution with appropriately chosen parameters. Some basic properties of the solution are analyzed and the basic quantities are calculated.
Iguchi, Hideo; Mishima, Takashi
2010-10-15
Previously the five dimensional S{sup 1}-rotating black rings have been superposed in a concentric way by some solitonic methods, and regular systems of two S{sup 1}-rotating black rings were constructed by the authors and then Evslin and Krishnan (we called these solutions 'black di-rings'). In this place we show some characteristics of the solutions of five dimensional black di-rings, especially in thermodynamic equilibrium. After the summary of the di-ring expressions and their physical quantities, first we comment on the equivalence of the two different solution sets of the black di-rings. Then the existence of thermodynamic black di-rings is shown, in which both isothermality and isorotation between the inner black ring and the outer black ring are realized. We also give detailed analysis of peculiar properties of the thermodynamic black di-ring including discussion about a certain kind of thermodynamic stability (instability) of the system.
Black holes: Supersymmetry and the information paradox
NASA Astrophysics Data System (ADS)
Peet, Amanda Wensley
1994-01-01
U(1) times U(1) asymptotically flat dilaton black holes are investigated in the context of N = 4, d = 4 supergravity, or dimensionally reduced superstring theory. It is found that extremal (multi-) black holes are supersymmetric, and that the supersymmetric positivity bounds on the black hole mass coincide with the bounds coming from cosmic censorship. Temperature, entropy and horizon properties are discussed in connection with the extremal limit. The on-shell action is given and for extremal black holes is argued to be unaltered by higher-order quantum corrections in the supersymmetric theory. The entropy is related to the Euclidean action via the Gibbons-Hawking method, is found to be one-quarter of the horizon area, and vanishes for maximally supersymmetric black holes. Lastly, the near-horizon behavior of extremal black holes is investigated. N = 1 supersymmetric black holes are found to tend to a Robinson-Bertotti-type geometry with doubling of supersymmetries; no such doubling is found for the N = 2 case. Topics relevant to the Information Paradox of black hole physics are investigated. First, prime-t Hooft's S-matrix approach to the puzzles of black hole evaporation is clarified by considering d = 1 + 1 electrodynamic in a linear dilaton background; analogues of black holes, Hawking evaporation, and an information paradox exist in this system. The paradox is resolved in the full quantum theory where the exact S-matrix is calculated. Secondly, a study of tachyon hair on black holes in two-dimensional string theory is presented. Such black holes if static can have tachyon hair; configurations nonsingular at the horizon have nonvanishing asymptotic energy density. There also exist static solutions with finite total energy and singular horizon. Dynamical arguments suggest that neither type of tachyon hair will be present on a black hole formed in gravitational collapse. Lastly, thermalization of a (fundamental) string falling toward the horizon of a four
History of cosmic evolution with modified Gauss-Bonnet-dilatonic coupled term
NASA Astrophysics Data System (ADS)
Debnath, Subhra; Ruz, Soumendra Nath; Mandal, Ranajit; Sanyal, Abhik Kumar
2017-05-01
Gauss-Bonnet-dilatonic coupling in four dimensions plays an important role to explain late-time cosmic evolution. However, this term is an outcome of the low energy string effective action and thus ought to be important in the early universe too. Unfortunately, a phase-space formulation of such a theory does not exist in the literature due to branching. We therefore consider a modified theory of gravity, which contains a nonminimally coupled scalar-tensor sector in addition to a higher-order scalar curvature invariant term with Gauss-Bonnet-dilatonic coupling. Such an action unifies early inflation with late-time cosmic acceleration. The quantum version of the theory is also well behaved.
Double-soft behavior of the dilaton of spontaneously broken conformal invariance
NASA Astrophysics Data System (ADS)
Di Vecchia, Paolo; Marotta, Raffaele; Mojaza, Matin
2017-09-01
The Ward identities involving the currents associated to the spontaneously broken scale and special conformal transformations are derived and used to determine, through linear order in the two soft-dilaton momenta, the double-soft behavior of scattering amplitudes involving two soft dilatons and any number of other particles. It turns out that the double-soft behavior is equivalent to performing two single-soft limits one after the other. We confirm the new double-soft theorem perturbatively at tree-level in a D-dimensional conformal field theory model, as well as nonperturbatively by using the "gravity dual" of N=4 super Yang-Mills on the Coulomb branch; i.e. the Dirac-Born-Infeld action on AdS5 × S 5.
Differentiating the Higgs boson from the dilaton and radion at Hadron colliders.
Barger, Vernon; Ishida, Muneyuki; Keung, Wai-Yee
2012-03-09
A number of candidate theories beyond the standard model (SM) predict new scalar bosons below the TeV region. Among these, the radion, which is predicted in the Randall-Sundrum model, and the dilaton, which is predicted by the walking technicolor theory, have very similar couplings to those of the SM Higgs boson, and it is very difficult to differentiate these three spin-0 particles in the expected signals of the Higgs boson at the LHC and Tevatron. We demonstrate that the observation of the ratio σ(γγ)/σ(WW) gives a simple and decisive way to differentiate these, independent of the values of model parameters, the vacuum expectation values of the radion, and dilaton fields.
NASA Astrophysics Data System (ADS)
Rador, Tonguç
2005-06-01
We show that, in the context of dilaton gravity, a recently proposed democratic principle for intersection possibilities of branes winding around extra dimensions yield stabilization, even with the inclusion of momentum modes of the wrapped branes on top of the winding modes. The constraints for stabilization massaged by string theory inputs forces the number of observed dimensions to be three. We also discuss consequences of adding ordinary matter living in the observed dimensions.
Bogomol'nyi equations and solutions for Einstein-Yang-Mills-dilaton-σ models
NASA Astrophysics Data System (ADS)
Braden, H. W.; Varela, V.
1998-12-01
We derive Bogomol'nyi equations for an Einstein-Yang-Mills-dilaton-σ model on a static spacetime, showing that the Einstein equations are satisfied if and only if the associated (conformally scaled) three-metric is flat. These are precisely the static metrics for which super-covariantly constant spinors exist. We study some general properties of these equations and then consider the problem of obtaining axially symmetric solutions for the gauge group SU(2).
Matsuzaki, Shinya; Yamawaki, Koichi
2014-08-22
We propose a scale-invariant chiral perturbation theory of the pseudo-Nambu-Goldstone bosons of chiral symmetry (pion π) as well as the scale symmetry (dilaton ϕ) for large N(f) QCD. The resultant dilaton mass M(ϕ) reads M(ϕ)(2) = m(ϕ)(2)+1/4(3-γ(m))(1+γ(m))(2N(f)F(π)(2)/F(ϕ)(2))m(π)(2)+(chiral log corrections), where m(ϕ), m(π), γ(m), F(π), and F(ϕ) are the dilaton mass in the chiral limit, the pion mass, the mass anomalous dimension, and the decay constants of π and ϕ, respectively. The chiral extrapolation of the lattice data, when plotted as M(ϕ)(2) versus m(π)(2), then simultaneously determines (m(ϕ), F(ϕ)) of the technidilaton in walking technicolor with γ(m) ≃ 1. The chiral logarithmic corrections are explicitly given.
Electric hyperscaling violating solutions in Einstein-Maxwell-dilaton gravity with R2 corrections
NASA Astrophysics Data System (ADS)
O'Keeffe, Daniel K.; Peet, Amanda W.
2014-07-01
In the context of holography applied to condensed matter physics, we study Einstein-Maxwell-dilaton theory with curvature squared corrections. This theory has three couplings ηi for the three R2 invariants and two theory functions: a dilaton potential V(ϕ) and a dilaton-dependent gauge coupling f(ϕ). We find hyperscaling violating (HSV) solutions of this theory, parametrized by dynamical critical exponent z and HSV parameter θ. We obtain restrictions on the form of the theory functions required to support HSV-type solutions using three physical inputs: the null energy condition, causality z≥1, and deff≡d-θ lying in the range 0
Wu Shuangqing
2009-10-15
We continue to investigate the separability of massive field equations for spin-0 and spin-1/2 charged particles in the general, nonextremal, rotating, charged, Chong-Cvetic-Lue-Pope black holes with two independent angular momenta and a nonzero cosmological constant in minimal D=5 gauged supergravity theory. We show that the complex Klein-Gordon equation and the modified Dirac equation with the inclusion of an extra counterterm can be separated by variables into purely radial and purely angular parts in this general Einstein-Maxwell-Chern-Simons background spacetime. A second-order symmetry operator that commutes with the complex Laplacian operator is constructed from the separated solutions and expressed compactly in terms of a rank-2 Staeckel-Killing tensor which admits a simple diagonal form in the chosen pentad one-forms so that it can be understood as the square of a rank-3 totally antisymmetric tensor. A first-order symmetry operator that commutes with the modified Dirac operator is expressed in terms of a rank-3 generalized Killing-Yano tensor and its covariant derivative. The Hodge dual of this generalized Killing-Yano tensor is a generalized principal conformal Killing-Yano tensor of rank-2, which can generate a 'tower' of generalized (conformal) Killing-Yano and Staeckel-Killing tensors that are responsible for the whole hidden symmetries of this general, rotating, charged, Kerr-anti-de Sitter black hole geometry. In addition, the first laws of black hole thermodynamics have been generalized to the case that the cosmological constant can be viewed as a thermodynamical variable.
Einstein-Maxwell-dilaton theories with a Liouville potential
Charmousis, Christos; Gouteraux, Blaise; Soda, Jiro
2009-07-15
We find and analyze solutions of Einstein's equations in arbitrary dimensions and in the presence of a scalar field with a Liouville potential coupled to a Maxwell field. We consider spacetimes of cylindrical symmetry or again subspaces of dimension d-2 with constant curvature and analyze in detail the field equations and manifest their symmetries. The field equations of the full system are shown to reduce to a single or couple of ordinary differential equations, which can be used to solve analytically or numerically the theory for the symmetry at hand. Further solutions can also be generated by a solution-generating technique akin to the electromagnetic duality in the absence of a cosmological constant. We then find and analyze explicit solutions including black holes and gravitating solitons for the case of four-dimensional relativity and the higher-dimensional oxidized five-dimensional spacetime. The general solution is obtained for a certain relation between couplings in the case of cylindrical symmetry.
NASA Astrophysics Data System (ADS)
Costa, Miguel S.; Greenspan, Lauren; Penedones, João; Santos, Jorge E.
2017-06-01
We numerically construct asymptotically AdS 4 solutions to Einstein-Maxwell-dilaton theory. These have a dipolar electrostatic potential turned on at the conformal boundary {S}^2× {\\mathbb{R}}_t . We find two classes of geometries: AdS soliton solutions that encode the full backreaction of the electric field on the AdS geometry without a horizon, and neutral black holes that are "polarised" by the dipolar potential. For a certain range of the electric field \\mathcal{E} , we find two distinct branches of the AdS soliton that exist for the same value of \\mathcal{E} . For the black hole, we find either two or four branches depending on the value of the electric field and horizon temperature. These branches meet at critical values of the electric field and impose a maximum value of \\mathcal{E} that should be reflected in the dual field theory. For both the soliton and black hole geometries, we study boundary data such as the stress tensor. For the black hole, we also consider horizon observables such as the entropy. At finite temperature, we consider the Gibbs free energy for both phases and determine the phase transition between them. We find that the AdS soliton dominates at low temperature for an electric field up to the maximum value. Using the gauge/gravity duality, we propose that these solutions are dual to deformed ABJM theory and compute the corresponding weak coupling phase diagram.
Corrected Entropy of BTZ Black Holes
NASA Astrophysics Data System (ADS)
Farahani, Hoda; Sadeghi, Jafar; Saadat, Hassan
2012-12-01
In this paper, corrected entropy of a class of BTZ black holes, include charge and rotation, studied. We obtain corrected Bekenstein-Hawking entropy and find that effect of charge viewed at order A -2, and effect of rotation viewed at order A -6, therefore Q and J don't have contribution in corrected entropy lower than the second order. We also write the first law of black hole thermodynamics for the case of charged rotating BTZ black hole.
Butterflies with rotation and charge
NASA Astrophysics Data System (ADS)
Reynolds, Alan P.; Ross, Simon F.
2016-11-01
We explore the butterfly effect for black holes with rotation or charge. We perturb rotating BTZ and charged black holes in 2 + 1 dimensions by adding a small perturbation on one asymptotic region, described by a shock wave in the spacetime, and explore the effect of this shock wave on the length of geodesics through the wormhole and hence on correlation functions. We find the effect of the perturbation grows exponentially at a rate controlled by the temperature; dependence on the angular momentum or charge does not appear explicitly. We comment on issues affecting the extension to higher-dimensional charged black holes.
Uniformly accelerated black holes
NASA Astrophysics Data System (ADS)
Letelier, Patricio S.; Oliveira, Samuel R.
2001-09-01
The static and stationary C metric are examined in a generic framework and their interpretations studied in some detail, especially those with two event horizons, one for the black hole and another for the acceleration. We find that (i) the spacetime of an accelerated static black hole is plagued by either conical singularities or a lack of smoothness and compactness of the black hole horizon, (ii) by using standard black hole thermodynamics we show that accelerated black holes have a higher Hawking temperature than Unruh temperature of the accelerated frame, and (iii) the usual upper bound on the product of the mass and acceleration parameters (<1/27) is just a coordinate artifact. The main results are extended to accelerated rotating black holes with no significant changes.
NASA Astrophysics Data System (ADS)
Boyce, H.; Lützgendorf, N.; van der Marel, R. P.; Baumgardt, H.; Kissler-Patig, M.; Neumayer, N.; de Zeeuw, P. T.
2017-09-01
We constrain the possible presence of a central black hole (BH) in the center of the Large Magellanic Cloud. This requires spectroscopic measurements over an area of the order of a square degree, due to the poorly known position of the kinematic center. Such measurements are now possible with the impressive field of view of the Multi Unit Spectroscopic Explorer (MUSE) on the ESO Very Large Telescope. We used the Calcium Triplet (∼850 nm) spectral lines in many short-exposure MUSE pointings to create a two-dimensional integrated-light line-of-sight velocity map from the ∼ {10}8 individual spectra, taking care to identify and remove Galactic foreground populations. The data reveal a clear velocity gradient at an unprecedented spatial resolution of 1 arcmin2. We fit kinematic models to arrive at a 3σ upper-mass limit of {10}7.1 {M}ȯ for any central BH—consistent with the known scaling relations for supermassive black holes and their host systems. This adds to the growing body of knowledge on the presence of BHs in low-mass and dwarf galaxies, and their scaling relations with host-galaxy properties, which can shed light on theories of BH growth and host system interaction.
Akarsu, Özgür; Dereli, Tekin E-mail: tdereli@ku.edu.tr
2013-02-01
We present cosmological solutions for (1+3+n)-dimensional steady state universe in dilaton gravity with an arbitrary dilaton coupling constant w and exponential dilaton self-interaction potentials in the string frame. We focus particularly on the class in which the 3-space expands with a time varying deceleration parameter. We discuss the number of the internal dimensions and the value of the dilaton coupling constant to determine the cases that are consistent with the observed universe and the primordial nucleosynthesis. The 3-space starts with a decelerated expansion rate and evolves into accelerated expansion phase subject to the values of w and n, but ends with a Big Rip in all cases. We discuss the cosmological evolution in further detail for the cases w = 1 and w = ½ that permit exact solutions. We also comment on how the universe would be conceived by an observer in four dimensions who is unaware of the internal dimensions and thinks that the conventional general relativity is valid at cosmological scales.
NASA Astrophysics Data System (ADS)
Bandyopadhyay, Priyotosh; Corianò, Claudio; Costantini, Antonio; Rose, Luigi Delle
2016-09-01
We explore the potential for the discovery of a dilaton O(200-500) GeV in a classical scale/conformal invariant extension of the Standard Model by investigating the size of the corresponding breaking scale Λ at the LHC, extending a previous analysis. In particular, we address the recent bounds on Λ derived from Higgs boson searches. We investigate if such a dilaton can be produced via gluon-gluon fusion at the LHC, presenting rates for its decay either into a pair of Higgs bosons or into two heavy gauge bosons, which can give rise to multi-leptonic final states. A detailed analysis via PYTHIA-FastJet has been carried out of the dominant Standard Model backgrounds at the LHC, at a centre of mass energy of 14 TeV. We show that early data of ˜ 20 fb-1 can certainly probe the region of parameter space where such a dilaton is allowed. A conformal scale of 5 TeV is allowed by the current data, for almost all values of the dilaton mass investigated.
Black holes on gravitational instantons
NASA Astrophysics Data System (ADS)
Chen, Yu; Teo, Edward
2011-09-01
In this paper, we classify and construct five-dimensional black holes on gravitational instantons in vacuum Einstein gravity, with R×U(1)×U(1) isometry. These black holes have spatial backgrounds which are Ricci-flat gravitational instantons with U(1)×U(1) isometry, and are completely regular space-times outside the event horizon. Most of the known exact five-dimensional vacuum black-hole solutions can be classified within this scheme. Amongst the new space-times presented are static black holes on the Euclidean Kerr and Taub-bolt instantons. We also present a rotating black hole on the Eguchi-Hanson instanton.
Hawking radiation from black rings
Miyamoto, Umpei; Murata, Keiju
2008-01-15
We calculate the quantum radiation from the 5-dimensional charged rotating black rings by demanding the radiation eliminate the possible anomalies on the horizons. It is shown that the temperature, energy flux, and angular-momentum flux exactly coincide with those of the Hawking radiation. The black rings considered in this paper contain the Myers-Perry black hole as a limit, and the quantum radiation for this black hole, obtained in the literature, is recovered in the limit. The results support the picture that the Hawking radiation can be regarded as the anomaly eliminator on horizons and suggest its general applicability to the higher-dimensional black holes discovered recently.
NASA Astrophysics Data System (ADS)
Manko, V. S.; Rabadán, R. I.; Sanabria-Gómez, J. D.
2014-03-01
In this paper, we present and analyze the simplest physically meaningful model for stationary black diholes—a binary configuration of counterrotating Kerr-Newman black holes endowed with opposite electric charges—elaborated in a physical parametrization on the basis of one of the Ernst-Manko-Ruiz equatorially antisymmetric solutions of the Einstein-Maxwell equations. The model saturates the Gabach-Clement inequality for interacting black holes with struts, and in the absence of rotation, it reduces to the Emparan-Teo electric dihole solution. The physical characteristics of each dihole constituent satisfy identically the well-known Smarr's mass formula.
String triality, black hole entropy, and Cayley's hyperdeterminant
NASA Astrophysics Data System (ADS)
Duff, M. J.
2007-07-01
The four-dimensional N=2 STU model of string compactification is invariant under an SL(2,Z)S×SL(2,Z)T×SL(2,Z)U duality acting on the dilaton/axion S, complex Kahler form T, and the complex structure fields U, and also under a string/string/string triality S↔T↔U. The model admits an extremal black hole solution with four electric and four magnetic charges whose entropy must respect these symmetries. It is given by the square root of the hyperdeterminant introduced by Cayley in 1845. This also features three-qubit quantum entanglement.
Fluctuating black hole horizons
NASA Astrophysics Data System (ADS)
Mei, Jianwei
2013-10-01
In this paper we treat the black hole horizon as a physical boundary to the spacetime and study its dynamics following from the Gibbons-Hawking-York boundary term. Using the Kerr black hole as an example we derive an effective action that describes, in the large wave number limit, a massless Klein-Gordon field living on the average location of the boundary. Complete solutions can be found in the small rotation limit of the black hole. The formulation suggests that the boundary can be treated in the same way as any other matter contributions. In particular, the angular momentum of the boundary matches exactly with that of the black hole, suggesting an interesting possibility that all charges (including the entropy) of the black hole are carried by the boundary. Using this as input, we derive predictions on the Planck scale properties of the boundary.
Information retrieval from black holes
NASA Astrophysics Data System (ADS)
Lochan, Kinjalk; Chakraborty, Sumanta; Padmanabhan, T.
2016-08-01
It is generally believed that, when matter collapses to form a black hole, the complete information about the initial state of the matter cannot be retrieved by future asymptotic observers, through local measurements. This is contrary to the expectation from a unitary evolution in quantum theory and leads to (a version of) the black hole information paradox. Classically, nothing else, apart from mass, charge, and angular momentum is expected to be revealed to such asymptotic observers after the formation of a black hole. Semiclassically, black holes evaporate after their formation through the Hawking radiation. The dominant part of the radiation is expected to be thermal and hence one cannot know anything about the initial data from the resultant radiation. However, there can be sources of distortions which make the radiation nonthermal. Although the distortions are not strong enough to make the evolution unitary, these distortions carry some part of information regarding the in-state. In this work, we show how one can decipher the information about the in-state of the field from these distortions. We show that the distortions of a particular kind—which we call nonvacuum distortions—can be used to fully reconstruct the initial data. The asymptotic observer can do this operationally by measuring certain well-defined observables of the quantum field at late times. We demonstrate that a general class of in-states encode all their information content in the correlation of late time out-going modes. Further, using a 1 +1 dimensional dilatonic black hole model to accommodate backreaction self-consistently, we show that observers can also infer and track the information content about the initial data, during the course of evaporation, unambiguously. Implications of such information extraction are discussed.
NASA Astrophysics Data System (ADS)
Ray, Shannon; Miller, Warner
2017-01-01
We present the first non-trivial illustration of Wang and Yau's quasilocal energy (WYQLE) for a maximally rotating Kerr spacetime. The surfaces for which we compute quasilocal energy (QLE) are axisymmetric closed space like 2-surfaces S with constant radii in Boyer-Lindquist coordinates. There exists a critical radius r* for which these 2-surfaces are isometrically embeddable in R3 . For surfaces with r >=r* , the WYQLE trivially becomes the Brown and York QLE (BYQLE). To fully illustrate Wang and Yau's formulation, we compute the WYQLE for surfaces with r
Non-Abelian black holes in D=5 maximal gauged supergravity
Cvetic, M.; Lue, H.; Pope, C. N.
2010-02-15
We investigate static non-Abelian black hole solutions of anti-de Sitter (AdS) Einstein-Yang-Mills-dilaton gravity, which is obtained as a consistent truncation of five-dimensional maximal gauged supergravity. If the dilaton is (consistently) set to zero, the remaining equations of motion, with a spherically-symmetric ansatz, may be derived from a superpotential. The associated first-order equations admit an explicit solution supported by a non-Abelian SU(2) gauge potential, which has a logarithmically growing mass term. In an extremal limit the horizon geometry becomes AdS{sub 2}xS{sup 3}. If the dilaton is also excited, the equations of motion cannot easily be solved explicitly, but we obtain the asymptotic form of the more general non-Abelian black holes in this case. An alternative consistent truncation, in which the Yang-Mills fields are set to zero, also admits a description in terms of a superpotential. This allows us to construct explicit wormhole solutions (neutral spherically-symmetric domain walls). These solutions may be generalized to dimensions other than five.
NASA Technical Reports Server (NTRS)
2000-01-01
During its 1979 flyby, Voyager 2 observed Io only from a distance. However, the volcanic activity discovered by Voyager 1 months earlier was readily visible. This sequence of nine color images was collected using the Blue, Green and Orange filters from about 1.2 million kilometers. A 2.5 hour period is covered during which Io rotates 7 degrees.
Rotating into view over the limb of Io are the plumes of the volcanoes Amirani (top) and Maui (lower). These plumes are very distinct against the black sky because they are being illuminated from behind. Notice that as Io rotates, the proportion of Io which is sunlit decreases greatly. This changing phase angle is because Io is moving between the spacecraft and the Sun.
This time-lapse movie was produced at JPL by the Image Processing Laboratory in 1985.
Dilatonic repulsons and confinement via the AdS/CFT correspondence
Bak, Dongsu; Gutperle, Michael; Hirano, Shinji; Ohta, Nobuyoshi
2004-10-15
We study a class of dilatonic deformations of asymptotically AdS{sub 5}xS{sup 5} geometry analytically and numerically. The spacetime is nonsupersymmetric and suffers from a naked singularity. We propose that the causality bound may serve as a criterion for such a geometry with a naked singularity to still make sense in the AdS/CFT correspondence. We show that the static string, the one corresponding to a large Wilson loop in the dual gauge theory, reveals confinement in a certain range of parameters of our solutions, where the singularity exhibits the repulsion that can well cloak the singularity from the static string probe. In particular, we find the exact expression for the tension of the QCD strings. We also discuss a possible interpretation of our solution in terms of unstable branes and their tachyon matter.
Tunnelling Phenomenon near an Apparent Horizon in Two-Dimensional Dilaton Gravity*
NASA Astrophysics Data System (ADS)
Cao, Li-Ming; Jiang, Xiao-Zhu; Pen, Yu-Xuan
2017-09-01
Based on the definition of the apparent horizon in a general two-dimensional dilaton gravity theory, we analyze the tunnelling phenomenon near the apparent horizon. In this theory the definition of the horizon is very different from those in higher-dimensional gravity theories. By using the Hamilton–Jacobi method, the spectrum of the radiation is obtained and the temperature of the radiation is read out from this spectrum. The temperature is proportional to the surface gravity of the apparent horizon as usual. Besides, in stationary cases we calculate the spectrum by using Parikh and Wilczek’s null geodesic method and the result conforms to that obtained by using the Hamilton–Jacobi method. This is expected since the Hamilton–Jacobi method applies to generic spacetimes, including stationary ones.
Production of techni-dilaton associated with a top quark at the LHC
NASA Astrophysics Data System (ADS)
Yu, You; Yue, Chong-Xing; Zeng, Qing-Guo; Yang, Shuo
2014-05-01
One kind of walking technicolor (WTC) theories predict the existence of a new scalar particle called techni-dilaton (TD) which can explain the current Higgs data at the CERN Large Hadron Collider (LHC). We calculate the cross-sections for the production of the TD in association with single top quark (tϕj production) in the framework of the one-family model (1FM) at the LHC. Our numerical results show that their values are at the level of several tens fb over the mass range 100 GeV < Mϕ < 600 GeV with the center-of-mass (c.m.) energy √ {s} = 14 TeV. We further analyze the signal induced by the tϕj production and the relevant Standard Model (SM) backgrounds.
An ultra-weak sector, the strong CP problem and the pseudo-Goldstone dilaton
Allison, Kyle; Hill, Christopher T.; Ross, Graham G.
2014-12-29
In the context of a Coleman–Weinberg mechanism for the Higgs boson mass, we address the strong CP problem. We show that a DFSZ-like invisible axion model with a gauge-singlet complex scalar field S, whose couplings to the Standard Model are naturally ultra-weak, can solve the strong CP problem and simultaneously generate acceptable electroweak symmetry breaking. The ultra-weak couplings of the singlet S are associated with underlying approximate shift symmetries that act as custodial symmetries and maintain technical naturalness. The model also contains a very light pseudo-Goldstone dilaton that is consistent with cosmological Polonyi bounds, and the axion can be themore » dark matter of the universe. As a result, we further outline how a SUSY version of this model, which may be required in the context of Grand Unification, can avoid introducing a hierarchy problem.« less
Crawford, R J; Kearns, M P
2003-10-01
Rotational moulding promises designers attractive economics and a low-pressure process. The benefits of rotational moulding are compared here with other manufacturing methods such as injection and blow moulding.
Astronomers combined 146 exposures taken by NASA's Hubble SpaceTelescope to make this 73-frame movie of the asteroid Vesta's rotation.Vesta completes a rotation every 5.34 hours.âº Asteroid and...
NASA Astrophysics Data System (ADS)
Ovgun, A.
2016-11-01
We construct a rotating thin-shell wormhole using a Myers-Perry black hole in five dimensions, using the Darmois-Israel junction conditions. The stability of the wormhole is analyzed under perturbations. We find that exotic matter is required at the throat of the wormhole to keep it stable. Our analysis shows that stability of the rotating thin-shell wormhole is possible if suitable parameter values are chosen.
NASA Astrophysics Data System (ADS)
Hirotani, Kouichi; Pu, Hung-Yi; Chun-Che Lin, Lupin; Chang, Hsiang-Kuang; Inoue, Makoto; Kong, Albert K. H.; Matsushita, Satoki; Tam, Pak-Hin T.
2016-12-01
We investigate the electrostatic acceleration of electrons and positrons in the vicinity of the event horizon, applying the pulsar outer-gap model to black hole (BH) magnetospheres. During a low accretion phase, the radiatively inefficient accretion flow (RIAF) cannot emit enough MeV photons that are needed to sustain the force-free magnetosphere via two-photon collisions. In such a charge-starved region (or a gap), an electric field arises along the magnetic field lines to accelerate electrons and positrons into ultra-relativistic energies. These relativistic leptons emit copious gamma rays via curvature and inverse-Compton (IC) processes. Some of such gamma rays collide with the submillimeter-IR photons emitted from the RIAF to materialize as pairs, which polarize to partially screen the original acceleration electric field. It is found that the gap gamma-ray luminosity increases with decreasing accretion rate. However, if the accretion rate decreases too much, the diminished RIAF soft photon field can no longer sustain a stationary pair production within the gap. As long as a stationary gap is formed, the magnetosphere becomes force-free outside the gap by the cascaded pairs, irrespective of the BH mass. If a nearby stellar-mass BH is in quiescence, or if a galactic intermediate-mass BH is in a very low accretion state, its curvature and IC emissions are found to be detectable with Fermi/LAT and imaging atmospheric Cherenkov telescopes (IACT). If a low-luminosity active galactic nucleus is located within about 30 Mpc, the IC emission from its supermassive BH is marginally detectable with IACT.
Action growth of charged black holes with a single horizon
NASA Astrophysics Data System (ADS)
Cai, Rong-Gen; Sasaki, Misao; Wang, Shao-Jiang
2017-06-01
According to the conjecture "complexity equals action," the complexity of a holographic state is equal to the action of a Wheeler-DeWitt (WDW) patch of black holes in anti-de Sitter space. In this paper we calculate the action growth of charged black holes with a single horizon, paying attention to the contribution from a spacelike singularity inside the horizon. We consider two kinds of such charged black holes: one is a charged dilaton black hole, and the other is a Born-Infeld black hole with β2Q2<1 /4 . In both cases, although an electric charge appears in the black hole solutions, the inner horizon is absent; instead a spacelike singularity appears inside the horizon. We find that the action growth of the WDW patch of the charged black hole is finite and satisfies the Lloyd bound. As a check, we also calculate the action growth of a charged black hole with a phantom Maxwell field. In this case, although the contributions from the bulk integral and the spacelike singularity are individually divergent, these two divergences just cancel each other and a finite action growth is obtained. But in this case, the Lloyd bound is violated as expected.
Black Holes at the LHC: Progress since 2002
Park, Seong Chan
2008-11-23
We review the recent noticeable progresses in black hole physics focusing on the up-coming super-collider, the LHC. We discuss the classical formation of black holes by particle collision, the greybody factors for higher dimensional rotating black holes, the deep implications of black hole physics to the 'energy-distance' relation, the security issues of the LHC associated with black hole formation and the newly developed Monte-Carlo generators for black hole events.
ERIC Educational Resources Information Center
McGowan, Jr., Martin J.
1969-01-01
"A television show by blacks for blacks--coupled with a program of training for black television technicians--was the basic concept of the Black Voices" series aired over KTCA-TV and KTCI-TV in Minneapolis and St. Paul during the 1968-1969 television season. The series was designed to provide understanding among blacks of the Twin…
NASA Astrophysics Data System (ADS)
Di Vecchia, Paolo; Marotta, Raffaele; Mojaza, Matin
2016-12-01
We consider the tree-level scattering amplitudes in the NS-NS (Neveu-Schwarz) massless sector of closed superstrings in the case where one external state becomes soft. We compute the amplitudes generically for any number of dimensions and any number and kind of the massless closed states through the subsubleading order in the soft expansion. We show that, when the soft state is a graviton or a dilaton, the full result can be expressed as a soft theorem factorizing the amplitude in a soft and a hard part. This behavior is similar to what has previously been observed in field theory and in the bosonic string. Differently from the bosonic string, the supersymmetric soft theorem for the graviton has no string corrections at subsubleading order. The dilaton soft theorem, on the other hand, is found to be universally free of string corrections in any string theory.
NASA Astrophysics Data System (ADS)
Wu, Shuang-Qing; Wang, He
2015-05-01
In a previous paper [S. Q. Wu, Phys. Rev. D 83, 121502(R) (2011)], a new kind of metric ansatz was found to fairly describe all already-known black hole solutions in the ungauged Kaluza-Klein (KK) supergravity theories. That metric ansatz somewhat resembles the famous Kerr-Schild (KS) form, but it is different from the KS one in two distinct aspects. That is, apart from a global conformal factor, the metric ansatz can be written as a vacuum background spacetime plus a "perturbation" modification term, the latter of which is associated with a timelike geodesic vector field rather than a null geodesic congruence in the usual KS ansatz. Replacing the flat vacuum background metric by the (anti-)de Sitter [(A)dS] spacetime, the general rotating charged KK-(A)dS black hole solutions in all higher dimensions have been successfully constructed and put into a unified form. In this paper, we shall study this novel metric ansatz in detail, aiming at achieving some inspiration as to the construction of rotating charged AdS black holes with multiple charges in other gauged supergravity theories. We find that the traditional perturbation expansion method often successfully used in the KS form is no longer useful in our new ansatz, since here no good parameter can be chosen as a suitable perturbation indicator. In order to investigate the metric properties of the general KK-AdS solutions, in this paper we devise a new effective method, dubbed the background metric expansion method, which can be thought of as a generalization of the perturbation expansion method, to deal with the Lagrangian and all equations of motion. In addition to two previously known conditions, namely the timelike and geodesic properties of the vector, we get three additional constraints via contracting the Maxwell and Einstein equations once or twice with this timelike geodesic vector. In particular, we find that these are a simpler set of sufficient conditions to determine the vector and the dilaton scalar
NASA Technical Reports Server (NTRS)
1999-01-01
This graphic shows the computer simulation of a black hole from start to finish. Plasma is falling slowly toward the black hole in a (at the upper left). The plasma has a magnetic field, shown by the white lines. It picks up speed as it falls toward the hole in b (at the upper right), c (lower left) and d (lower right). However, the rotating black hole twists up space itself (and the magnetic field lines) and ejects electromagnetic power along the north and south poles above the black hole. The red and white color shows the immense electromagnetic power output, which eventually will pick up particles and form squirting jets. This simulation was conducted using supercomputers at Japan's National Institute for Fusion Science.
1999-11-30
This graphic shows the computer simulation of a black hole from start to finish. Plasma is falling slowly toward the black hole in a (at the upper left). The plasma has a magnetic field, shown by the white lines. It picks up speed as it falls toward the hole in b (at the upper right), c (lower left) and d (lower right). However, the rotating black hole twists up space itself (and the magnetic field lines) and ejects electromagnetic power along the north and south poles above the black hole. The red and white color shows the immense electromagnetic power output, which eventually will pick up particles and form squirting jets. This simulation was conducted using supercomputers at Japan's National Institute for Fusion Science. http://photojournal.jpl.nasa.gov/catalog/PIA04206
Furman, J M
2016-01-01
The natural stimulus for the semicircular canals is rotation of the head, which also might stimulate the otolith organs. Vestibular stimulation usually induces eye movements via the vestibulo-ocular reflex (VOR). The orientation of the subject with respect to the axis of rotation and the orientation of the axis of rotation with respect to gravity together determine which labyrinthine receptors are stimulated for particular motion trajectories. Rotational testing usually includes the measurement of eye movements via a video system but might use a subject's perception of motion. The most common types of rotational testing are whole-body computer-controlled sinusoidal or trapezoidal stimuli during earth-vertical axis rotation (EVAR), which stimulates primarily the horizontal semicircular canals bilaterally. Recently, manual impulsive rotations, known as head impulse testing (HIT), have been developed to assess individual horizontal semicircular canals. Most types of rotational stimuli are not used routinely in the clinical setting but may be used in selected research environments. This chapter will discuss clinically relevant rotational stimuli and several types of rotational testing that are used primarily in research settings.
Chiba, Takeshi; Kobayashi, Tatsuo; Yamaguchi, Masahide; Yokoyama, Jun'ichi
2007-02-15
Recent astrophysical observations indicate that the proton-electron mass ratio and the fine structure constant have gone through nontrivial time evolution. We discuss their time variation in the context of a dilaton runaway scenario with gauge coupling unification at the string scale M{sub s}. We show that the choice of adjustable parameters allows them to fit the same order magnitude of both variations and their (opposite) signs in such a scenario.
Geometric Analyses of Rotational Faults.
ERIC Educational Resources Information Center
Schwert, Donald Peters; Peck, Wesley David
1986-01-01
Describes the use of analysis of rotational faults in undergraduate structural geology laboratories to provide students with applications of both orthographic and stereographic techniques. A demonstration problem is described, and an orthographic/stereographic solution and a reproducible black model demonstration pattern are provided. (TW)
NASA Astrophysics Data System (ADS)
Hehl, Friedrich W.
2016-08-01
We take a quick look at the different possible universally coupled scalar fields in nature. Then, we discuss how the gauging of the group of scale transformations (dilations), together with the Poincaré group, leads to a Weyl-Cartan spacetime structure. There the dilaton field finds a natural surrounding. Moreover, we describe shortly the phenomenology of the hypothetical axion field. In the second part of our essay, we consider a spacetime, the structure of which is exclusively specified by the premetric Maxwell equations and a fourth rank electromagnetic response tensor density χijkl = -χjikl = -χijlk with 36 independent components. This tensor density incorporates the permittivities, permeabilities and the magneto-electric moduli of spacetime. No metric, no connection, no further property is prescribed. If we forbid birefringence (double-refraction) in this model of spacetime, we eventually end up with the fields of an axion, a dilaton and the 10 components of a metric tensor with Lorentz signature. If the dilaton becomes a constant (the vacuum admittance) and the axion field vanishes, we recover the Riemannian spacetime of general relativity theory. Thus, the metric is encapsulated in χijkl, it can be derived from it.
Bouhmadi-Lopez, Mariam; Ferrera, Antonio E-mail: a.ferrera.pardo@gmail.com
2008-10-15
We construct a new brane-world model composed of a bulk with a dilatonic field, plus a brane with brane tension coupled to the dilaton, cold dark matter and an induced gravity term. It is possible to show that, depending on the nature of the coupling between the brane tension and the dilaton, this model can describe the late time acceleration of the brane expansion (for the normal branch) as it moves within the bulk. The acceleration is produced together with a mimicry of the crossing of the cosmological constant line (w = -1) on the brane, although this crossing of the phantom divide is obtained without invoking any phantom matter either on the brane or in the bulk. The role of dark energy is played by the brane tension, which reaches a maximum positive value along the cosmological expansion of the brane. It is precisely at that maximum that the crossing of the phantom divide takes place. We also show that these results remain valid when the induced gravity term on the brane is switched off.
Solitonic generation of the five-dimensional black ring solution
Iguchi, Hideo; Mishima, Takashi
2006-06-15
Using the solitonic solution-generating technique, we rederived the one-rotational five-dimensional black ring solution found by Emparan and Reall. The seed solution is not the Minkowski metric, which is the seed of the S{sup 2}-rotating black ring. The obtained solution has more parameters than Emparan and Reall's S{sup 1}-rotating black ring. We found the conditions of parameters to reduce the solution to the S{sup 1}-rotating black ring. In addition, we examined the relation between the expressions of the metric in the prolate-spheroidal coordinates and in the canonical coordinates.
Varying fine structure 'constant' and charged black holes
Bekenstein, Jacob D.; Schiffer, Marcelo
2009-12-15
Speculation that the fine-structure constant {alpha} varies in spacetime has a long history. We derive, in 4-D general relativity and in isotropic coordinates, the solution for a charged spherical black hole according to the framework for dynamical {alpha} J. D. Bekenstein, Phys. Rev. D 25, 1527 (1982).. This solution coincides with a previously known one-parameter extension of the dilatonic black hole family. Among the notable properties of varying-{alpha} charged black holes are adherence to a 'no hair' principle, the absence of the inner (Cauchy) horizon of the Reissner-Nordstroem black holes, the nonexistence of precisely extremal black holes, and the appearance of naked singularities in an analytic extension of the relevant metric. The exteriors of almost extremal electrically (magnetically) charged black holes have simple structures which makes their influence on applied magnetic (electric) fields transparent. We rederive the thermodynamic functions of the modified black holes; the otherwise difficult calculation of the electric potential is done by a shortcut. We confirm that variability of {alpha} in the wake of expansion of the universe does not threaten the generalized second law.
The Thermodynamic Efficiency in Static and Dynamic Black Holes
NASA Astrophysics Data System (ADS)
Jafarzade, Kh.; Sadeghi, J.
2017-08-01
We note that, in extended phase space the cosmological constant is a thermodynamic variable. In this paper, this cosmological constant lead us to consider a black hole as a heat engine. So, here we take advantage from holographic heat engine and study two kind of different black holes. We first investigate a static black hole (Dyonic BH) and consider the necessary condition to have high efficiency. Also we continue our investigation for dynamic black hole (rotating charged black hole) and study the effect of rotating parameter on the thermodynamic efficiency of holographic heat engine. We show that the rotating parameter has a more effective role than electric charge in thermodynamic efficiency.
Lyutikov, Maxim; McKinney, Jonathan C.
2011-10-15
The 'no-hair' theorem, a key result in general relativity, states that an isolated black hole is defined by only three parameters: mass, angular momentum, and electric charge; this asymptotic state is reached on a light-crossing time scale. We find that the no-hair theorem is not formally applicable for black holes formed from the collapse of a rotating neutron star. Rotating neutron stars can self-produce particles via vacuum breakdown forming a highly conducting plasma magnetosphere such that magnetic field lines are effectively ''frozen in'' the star both before and during collapse. In the limit of no resistivity, this introduces a topological constraint which prohibits the magnetic field from sliding off the newly-formed event horizon. As a result, during collapse of a neutron star into a black hole, the latter conserves the number of magnetic flux tubes N{sub B}=e{Phi}{sub {infinity}}/({pi}c({h_bar}/2{pi})), where {Phi}{sub {infinity}}{approx_equal}2{pi}{sup 2}B{sub NS}R{sub NS}{sup 3}/(P{sub NS}c) is the initial magnetic flux through the hemispheres of the progenitor and out to infinity. We test this theoretical result via 3-dimensional general relativistic plasma simulations of rotating black holes that start with a neutron star dipole magnetic field with no currents initially present outside the event horizon. The black hole's magnetosphere subsequently relaxes to the split-monopole magnetic field geometry with self-generated currents outside the event horizon. The dissipation of the resulting equatorial current sheet leads to a slow loss of the anchored flux tubes, a process that balds the black hole on long resistive time scales rather than the short light-crossing time scales expected from the vacuum no-hair theorem.
NASA Astrophysics Data System (ADS)
Lyutikov, Maxim; McKinney, Jonathan C.
2011-10-01
The “no-hair” theorem, a key result in general relativity, states that an isolated black hole is defined by only three parameters: mass, angular momentum, and electric charge; this asymptotic state is reached on a light-crossing time scale. We find that the no-hair theorem is not formally applicable for black holes formed from the collapse of a rotating neutron star. Rotating neutron stars can self-produce particles via vacuum breakdown forming a highly conducting plasma magnetosphere such that magnetic field lines are effectively “frozen in” the star both before and during collapse. In the limit of no resistivity, this introduces a topological constraint which prohibits the magnetic field from sliding off the newly-formed event horizon. As a result, during collapse of a neutron star into a black hole, the latter conserves the number of magnetic flux tubes NB=eΦ∞/(πcℏ), where Φ∞≈2π2BNSRNS3/(PNSc) is the initial magnetic flux through the hemispheres of the progenitor and out to infinity. We test this theoretical result via 3-dimensional general relativistic plasma simulations of rotating black holes that start with a neutron star dipole magnetic field with no currents initially present outside the event horizon. The black hole’s magnetosphere subsequently relaxes to the split-monopole magnetic field geometry with self-generated currents outside the event horizon. The dissipation of the resulting equatorial current sheet leads to a slow loss of the anchored flux tubes, a process that balds the black hole on long resistive time scales rather than the short light-crossing time scales expected from the vacuum no-hair theorem.
Characterizing Black Hole Mergers
NASA Technical Reports Server (NTRS)
Baker, John; Boggs, William Darian; Kelly, Bernard
2010-01-01
Binary black hole mergers are a promising source of gravitational waves for interferometric gravitational wave detectors. Recent advances in numerical relativity have revealed the predictions of General Relativity for the strong burst of radiation generated in the final moments of binary coalescence. We explore features in the merger radiation which characterize the final moments of merger and ringdown. Interpreting the waveforms in terms of an rotating implicit radiation source allows a unified phenomenological description of the system from inspiral through ringdown. Common features in the waveforms allow quantitative description of the merger signal which may provide insights for observations large-mass black hole binaries.
Characterizing Black Hole Mergers
NASA Technical Reports Server (NTRS)
Baker, John; Boggs, William Darian; Kelly, Bernard
2010-01-01
Binary black hole mergers are a promising source of gravitational waves for interferometric gravitational wave detectors. Recent advances in numerical relativity have revealed the predictions of General Relativity for the strong burst of radiation generated in the final moments of binary coalescence. We explore features in the merger radiation which characterize the final moments of merger and ringdown. Interpreting the waveforms in terms of an rotating implicit radiation source allows a unified phenomenological description of the system from inspiral through ringdown. Common features in the waveforms allow quantitative description of the merger signal which may provide insights for observations large-mass black hole binaries.
Horizon detection and higher dimensional black rings
NASA Astrophysics Data System (ADS)
Coley, A. A.; McNutt, D. D.
2017-02-01
In this paper we study the stationary horizons of the rotating black ring and the supersymmetric black ring spacetimes in five dimensions. In the case of the rotating black ring we use Weyl aligned null directions to algebraically classify the Weyl tensor, and utilize an adapted Cartan algorithm in order to produce Cartan invariants. For the supersymmetric black ring we employ the discriminant approach and repeat the adapted Cartan algorithm. For both of these metrics we are able to construct Cartan invariants that detect the horizon alone, and which are easier to compute and analyse than scalar polynomial curvature invariants.
ERIC Educational Resources Information Center
Lekner, John
2008-01-01
Any free-particle wavepacket solution of Schrodinger's equation can be converted by differentiations to wavepackets rotating about the original direction of motion. The angular momentum component along the motion associated with this rotation is an integral multiple of [h-bar]. It is an "intrinsic" angular momentum: independent of origin and…
ERIC Educational Resources Information Center
Lekner, John
2008-01-01
Any free-particle wavepacket solution of Schrodinger's equation can be converted by differentiations to wavepackets rotating about the original direction of motion. The angular momentum component along the motion associated with this rotation is an integral multiple of [h-bar]. It is an "intrinsic" angular momentum: independent of origin and…
Extremal vacuum black holes in higher dimensions
Figueras, Pau; Lucietti, James; Rangamani, Mukund; Kunduri, Hari K.
2008-08-15
We consider extremal black hole solutions to the vacuum Einstein equations in dimensions greater than five. We prove that the near-horizon geometry of any such black hole must possess an SO(2,1) symmetry in a special case where one has an enhanced rotational symmetry group. We construct examples of vacuum near-horizon geometries using the extremal Myers-Perry black holes and boosted Myers-Perry strings. The latter lead to near-horizon geometries of black ring topology, which in odd spacetime dimensions have the correct number of rotational symmetries to describe an asymptotically flat black object. We argue that a subset of these correspond to the near-horizon limit of asymptotically flat extremal black rings. Using this identification we provide a conjecture for the exact 'phase diagram' of extremal vacuum black rings with a connected horizon in odd spacetime dimensions greater than five.
Quasilocal Nonequilibrium Dynamics of ϕ-SPINNING Black Rings
NASA Astrophysics Data System (ADS)
Liu, Zhenxing; Chen, Zeqian
In this work, we study the nonequilibrium dynamics of ϕ-spinning black rings within the quasilocal formalism. We adopt the counterterm method and compute the renormalized boundary stress-energy tensor. By considering the conservation of this tensor, the condition for removing the conical singularity at spatial infinity is derived. It is subsequently shown that a ϕ-spinning black ring cannot be kept in a state of equilibrium, which is consistent with the physical interpretation that the angular momentum is on the plane orthogonal to the ring and there is no force to balance the tension and gravitational self-attraction. The results of these computations lay a foundation for studying the thermodynamics of ϕ-spinning rings in detail. Finally, we charge up the rings in Einstein-Maxwell-dilaton system and suggest feasible ways to make them balanced.
Brügmann, B.; Ghez, A. M.; Greiner, J.
2001-01-01
Recent progress in black hole research is illustrated by three examples. We discuss the observational challenges that were met to show that a supermassive black hole exists at the center of our galaxy. Stellar-size black holes have been studied in x-ray binaries and microquasars. Finally, numerical simulations have become possible for the merger of black hole binaries. PMID:11553801
ERIC Educational Resources Information Center
Brown, Angela Khristin
2013-01-01
The migration of blacks in North America through slavery became united. The population of blacks passed down a tradition of artist through art to native born citizens. The art tradition involved telling stories to each generation in black families. The black culture elevated by tradition created hope to determine their personal freedom to escape…
Brügmann, B; Ghez, A M; Greiner, J
2001-09-11
Recent progress in black hole research is illustrated by three examples. We discuss the observational challenges that were met to show that a supermassive black hole exists at the center of our galaxy. Stellar-size black holes have been studied in x-ray binaries and microquasars. Finally, numerical simulations have become possible for the merger of black hole binaries.
ERIC Educational Resources Information Center
Watts, Thomas D.; Wright, Roosevelt
1988-01-01
Examines some aspects of the problem of alcoholism among Blacks, asserting that Black alcoholism can best be considered in an ecological, environmental, sociocultural, and public health context. Notes need for further research on alcoholism among Blacks and for action to reduce the problem of Black alcoholism. (NB)
NASA Astrophysics Data System (ADS)
Vassiliev, Dmitri
2017-04-01
We consider an infinite three-dimensional elastic continuum whose material points experience no displacements, only rotations. This framework is a special case of the Cosserat theory of elasticity. Rotations of material points are described mathematically by attaching to each geometric point an orthonormal basis that gives a field of orthonormal bases called the coframe. As the dynamical variables (unknowns) of our theory, we choose the coframe and a density. We write down the general dynamic variational functional for our rotational theory of elasticity, assuming our material to be physically linear but the kinematic model geometrically nonlinear. Allowing geometric nonlinearity is natural when dealing with rotations because rotations in dimension three are inherently nonlinear (rotations about different axes do not commute) and because there is no reason to exclude from our study large rotations such as full turns. The main result of the talk is an explicit construction of a class of time-dependent solutions that we call plane wave solutions; these are travelling waves of rotations. The existence of such explicit closed-form solutions is a non-trivial fact given that our system of Euler-Lagrange equations is highly nonlinear. We also consider a special case of our rotational theory of elasticity which in the stationary setting (harmonic time dependence and arbitrary dependence on spatial coordinates) turns out to be equivalent to a pair of massless Dirac equations. The talk is based on the paper [1]. [1] C.G.Boehmer, R.J.Downes and D.Vassiliev, Rotational elasticity, Quarterly Journal of Mechanics and Applied Mathematics, 2011, vol. 64, p. 415-439. The paper is a heavily revised version of preprint https://arxiv.org/abs/1008.3833
Particle creation phenomenology, Dirac sea and the induced Weyl and Einstein-dilaton gravity
NASA Astrophysics Data System (ADS)
Berezin, V. A.; Dokuchaev, V. I.; Eroshenko, Yu. N.
2017-01-01
We constructed the conformally invariant model for scalar particle creation induced by strong gravitational fields. Starting from the "usual" hydrodynamical description of the particle motion written in the Eulerian coordinates we substituted the particle number conservation law (which enters the formalism) by "the particle creation law", proportional to the square of the Weyl tensor (following the famous result by Ya.B. Zel'dovich and A.A. Starobinsky). Then, demanding the conformal invariance of the whole dynamical system, we have got both the (Weyl)-conformal gravity and the Einstein-Hilbert gravity action integral with dilaton field. Thus, we obtained something like the induced gravity suggested first by A.D. Sakharov. It is shown that the resulting system is self-consistent. We considered also the vacuum equations. It is shown that, beside the "empty vacuum", there may exist the "dynamical vacuum", which is nothing more but the Dirac sea. The latter is described by the unexpectedly elegant equation which includes both the Bach and Einstein tensors and the cosmological terms.
Dilaton assisted two-field inflation from no-scale supergravity
NASA Astrophysics Data System (ADS)
Chakravarty, Girish Kumar; Das, Suratna; Lambiase, Gaetano; Mohanty, Subhendra
2016-07-01
We present a two-field inflation model where the inflaton field has a noncanonical kinetic term due to the presence of a dilaton field. It is a two-parameter generalization of one-parameter Brans-Dicke gravity in the Einstein frame. We show that in such an inflation model the quartic and quadratic inflaton potentials, which are otherwise ruled out by the present Planck-Keck/BICEP2 data, yield the scalar spectral index and tensor-to-scalar ratio in accordance with the present data. Such a model yields a tensor-to-scalar ratio of the order of 10-2 which is within the reach of B -mode experiments like Keck/BICEP3, CMBPol and thus can be put to the test in the near future. This model yields negligible non-Gaussianity and no isocurvature perturbations up to slow-roll approximation. Finally, we show that such a model can be realized in the realm of no-scale supergravity.
Discovering the 125 GeV techni-dilaton at the LHC
NASA Astrophysics Data System (ADS)
Matsuzaki, Shinya; Yamawaki, Koichi
2012-08-01
The techni-dilaton (TD) is predicted in walking technicolor (WTC) arising as a pseudo—Nambu-Goldstone boson associated with the approximate scale symmetry spontaneously broken by techni-fermion condensation. The TD mass is therefore smaller than those of other techni-hadrons on the order of several TeVs, small enough to be within reach of the current LHC search. We present a new method to derive the TD couplings directly from the Ward-Takahashi identities, which enables us to explicitly calculate the quantities relevant to the TD LHC signatures. To set definite benchmarks, we take one-doublet and one-family models of WTC and discuss the TD signatures at the LHC, in comparison with those of the standard model (SM) Higgs. It is shown that the TD in the one-doublet model is invisible at the LHC, while the TD signals in the one-family model can be found as a large excess relative to the SM Higgs at around 125 GeV only in the diphoton channel.
Geometric properties of static Einstein-Maxwell dilaton horizons with a Liouville potential
Abdolrahimi, Shohreh; Shoom, Andrey A.
2011-05-15
We study nondegenerate and degenerate (extremal) Killing horizons of arbitrary geometry and topology within the Einstein-Maxwell-dilaton model with a Liouville potential (the EMdL model) in d-dimensional (d{>=}4) static space-times. Using Israel's description of a static space-time, we construct the EMdL equations and the space-time curvature invariants: the Ricci scalar, the square of the Ricci tensor, and the Kretschmann scalar. Assuming that space-time metric functions and the model fields are real analytic functions in the vicinity of a space-time horizon, we study the behavior of the space-time metric and the fields near the horizon and derive relations between the space-time curvature invariants calculated on the horizon and geometric invariants of the horizon surface. The derived relations generalize similar relations known for horizons of static four- and five-dimensional vacuum and four-dimensional electrovacuum space-times. Our analysis shows that all the extremal horizon surfaces are Einstein spaces. We present the necessary conditions for the existence of static extremal horizons within the EMdL model.
Thermodynamics of charged rotating solutions in Brans-Dicke gravity with Born-Infeld field
NASA Astrophysics Data System (ADS)
Pakravan, J.; Takook, M. V.
2017-09-01
We derive new exact charged rotating solutions of (n+1)-dimensional Brans-Dicke theory in the presence of Born-Infeld field and investigated their properties. Because of the coupling between scalar field and curvature, the field equations cannot to be solved directly. Using a new conformal transformation, which transforms the Einstein-dilaton-Born-Infeld gravity Lagrangian to the Brans-Dicke-Born-Infeld gravity one, the field equations are solved. We also compute temperature, charge, mass, electric potential, and entropy; entropy, however, does not obey the area law. These quantities are invariant under conformal transformation and satisfy the first law of thermodynamics.
Thermodynamics of charged rotating solutions in Brans-Dicke gravity with Born-Infeld field
NASA Astrophysics Data System (ADS)
Pakravan, J.; Takook, M. V.
2017-07-01
We derive new exact charged rotating solutions of (n+1) -dimensional Brans-Dicke theory in the presence of Born-Infeld field and investigated their properties. Because of the coupling between scalar field and curvature, the field equations cannot to be solved directly. Using a new conformal transformation, which transforms the Einstein-dilaton-Born-Infeld gravity Lagrangian to the Brans-Dicke-Born-Infeld gravity one, the field equations are solved. We also compute temperature, charge, mass, electric potential, and entropy; entropy, however, does not obey the area law. These quantities are invariant under conformal transformation and satisfy the first law of thermodynamics.
Belgiorno, F.; Cattaneo, A.S. ); Fucito, F. ); Martellini, M. )
1993-09-15
In this paper we investigate a dilaton-gravity theory, which can be viewed as an SL(2) conformal affine Toda (CAT) theory. This new model is inspired by some previous work by Bilal, Callan, and de Alwis. The main results obtained in our approach are (i) a field redefinition of the CAT basis in terms of which it is possible to get the black hole solutions already known in the literature, and (ii) an investigation of the scattering matrix problem for the quantum black hole states. Given the validity of our assumptions, there is a range of values of the [ital N] free-falling shock matter fields forming the black hole solution, for which the end-point state of the black hole evaporation is a zero temperature regular remnant geometry. The quantum evolution to this final state seems to be nonunitary, in agreement with Hawking's scenario for black hole evaporation.
NASA Astrophysics Data System (ADS)
Schou, Jesper; Beck, John G.
2001-01-01
Simple convection models estimate the depth of supergranulation at approximately 15,000 km which suggests that supergranules should rotate at the rate of the plasma in the outer 2% of the Sun by radius. Previous measurements (Snodgrass & Ulrich, 1990; Beck & Schou, 2000) found that supergranules rotate significantly faster than this, with a size-dependent rotation rate. We expand on previous work and show that the torsional oscillation signal seen in the supergranules tracks that obtained for normal modes. We also find that the amplitudes and lifetimes of the supergranulation are size dependent.
Phantom black holes and critical phenomena
Azreg-Aïnou, Mustapha; Marques, Glauber T.
2014-07-01
We consider the two classes cosh and sinh of normal and phantom black holes of Einstein-Maxwell-dilaton theory. The thermodynamics of these holes is characterized by heat capacities that may have both signs depending on the parameters of the theory. Leaving aside the normal Reissner-Nordström black hole, it is shown that only some phantom black holes of both classes exhibit critical phenomena. The two classes share a nonextremality, but special, critical point where the transition is continuous and the heat capacity, at constant charge, changes sign with an infinite discontinuity. This point yields a classification scheme for critical points. It is concluded that the two unstable and stable phases coexist on one side of the criticality state and disappear on the other side, that is, there is no configuration where only one phase exists. The sinh class has an extremality critical point where the entropy diverges. The transition from extremality to nonextremality with the charge held constant is accompanied by a loss of mass and an increase in the temperature. A special case of this transition is when the hole is isolated (microcanonical ensemble), it will evolve by emission of energy, which results in a decrease of its mass, to the final state of minimum mass and vanishing heat capacity. The Ehrenfest scheme of classification is inaccurate in this case but the generalized one due to Hilfer leads to conclude that the transition is of order less than unity. Fluctuations near criticality are also investigated.
ERIC Educational Resources Information Center
Lockett, Keith
1988-01-01
Demonstrates several objects rolling down a slope to explain the energy transition among potential energy, translational kinetic energy, and rotational kinetic energy. Contains a problem from Galileo's rolling ball experiment. (YP)
ERIC Educational Resources Information Center
Lockett, Keith
1988-01-01
Demonstrates several objects rolling down a slope to explain the energy transition among potential energy, translational kinetic energy, and rotational kinetic energy. Contains a problem from Galileo's rolling ball experiment. (YP)
NASA Astrophysics Data System (ADS)
Dziembowski, W.
Sunspot observations made by Johannes Hevelius in 1642 - 1644 are the first ones providing significant information about the solar differential rotation. In modern astronomy the determination of the rotation rate is done in a routine way by measuring positions of various structures on the solar surface as well as by studying the Doppler shifts of spectral lines. In recent years a progress in helioseismology enabled determination of the rotation rate in the layers inaccessible for direct observations. There are still uncertainties concerning, especially, the temporal variations of the rotation rate and its behaviour in the radiative interior. We are far from understanding the observations. Theoretical works have not yet resulted in a satisfactory model for the angular momentum transport in the convective zone.
Black hole thermodynamics in MOdified Gravity (MOG)
NASA Astrophysics Data System (ADS)
Mureika, Jonas R.; Moffat, John W.; Faizal, Mir
2016-06-01
We analyze the thermodynamical properties of black holes in a modified theory of gravity, which was initially proposed to obtain correct dynamics of galaxies and galaxy clusters without dark matter. The thermodynamics of non-rotating and rotating black hole solutions resembles similar solutions in Einstein-Maxwell theory with the electric charge being replaced by a new mass dependent gravitational charge Q =√{ αGN } M. This new mass dependent charge modifies the effective Newtonian constant from GN to G =GN (1 + α), and this in turn critically affects the thermodynamics of the black holes. We also investigate the thermodynamics of regular solutions, and explore the limiting case when no horizons forms. So, it is possible that the modified gravity can lead to the absence of black hole horizons in our universe. Finally, we analyze corrections to the thermodynamics of a non-rotating black hole and obtain the usual logarithmic correction term.
Wick rotation in the tangent space
NASA Astrophysics Data System (ADS)
Samuel, Joseph
2016-01-01
Wick rotation is usually performed by rotating the time coordinate to imaginary values. In a general curved spacetime, the notion of a time coordinate is ambiguous. We note here, that within the tetrad formalism of general relativity, it is possible to perform a Wick rotation directly in the tangent space using considerably less structure: a timelike, future pointing vector field, which need not be killing or hypersurface orthogonal. This method has the advantage of yielding real Euclidean metrics, even in spacetimes which are not static. When applied to a black hole exterior, the null generators of the event horizon reduce to points in the Euclidean spacetime. Requiring that the Wick rotated holonomy of the null generators be trivial ensures the absence of a 'conical singularity' in the Euclidean space. To illustrate the basic idea, we use the tangent space Wick rotation to compute the Hawking temperature by Euclidean methods in a few spacetimes including the Kerr black hole.
Nathanail, Antonios; Contopoulos, Ioannis
2014-06-20
We investigate the structure of the steady-state force-free magnetosphere around a Kerr black hole in various astrophysical settings. The solution Ψ(r, θ) depends on the distributions of the magnetic field line angular velocity ω(Ψ) and the poloidal electric current I(Ψ). These are obtained self-consistently as eigenfunctions that allow the solution to smoothly cross the two singular surfaces of the problem, the inner light surface inside the ergosphere, and the outer light surface, which is the generalization of the pulsar light cylinder. Magnetic field configurations that cross both singular surfaces (e.g., monopole, paraboloidal) are uniquely determined. Configurations that cross only one light surface (e.g., the artificial case of a rotating black hole embedded in a vertical magnetic field) are degenerate. We show that, similar to pulsars, black hole magnetospheres naturally develop an electric current sheet that potentially plays a very important role in the dissipation of black hole rotational energy and in the emission of high-energy radiation.
NASA Astrophysics Data System (ADS)
Ge, Xian-Hui; Tian, Yu; Wu, Shang-Yu; Wu, Shao-Feng
2017-08-01
We derive new black hole solutions in Einstein-Maxwell-axion-dilaton theory with a hyperscaling violation exponent. We then examine the corresponding anomalous transport exhibited by cuprate strange metals in the normal phase of high-temperature superconductors via gauge-gravity duality. Linear-temperature-dependence resistivity and quadratic-temperature-dependence inverse Hall angle can be achieved. In the high-temperature regime, the heat conductivity and Hall Lorenz ratio are proportional to the temperature. The Nernst signal first increases as temperature goes up, but it then decreases with increasing temperature in the high-temperature regime.
Boosting jet power in black hole spacetimes.
Neilsen, David; Lehner, Luis; Palenzuela, Carlos; Hirschmann, Eric W; Liebling, Steven L; Motl, Patrick M; Garrett, Travis
2011-08-02
The extraction of rotational energy from a spinning black hole via the Blandford-Znajek mechanism has long been understood as an important component in models to explain energetic jets from compact astrophysical sources. Here we show more generally that the kinetic energy of the black hole, both rotational and translational, can be tapped, thereby producing even more luminous jets powered by the interaction of the black hole with its surrounding plasma. We study the resulting Poynting jet that arises from single boosted black holes and binary black hole systems. In the latter case, we find that increasing the orbital angular momenta of the system and/or the spins of the individual black holes results in an enhanced Poynting flux.
Boosting jet power in black hole spacetimes
Neilsen, David; Lehner, Luis; Palenzuela, Carlos; Hirschmann, Eric W.; Liebling, Steven L.; Motl, Patrick M.; Garrett, Travis
2011-01-01
The extraction of rotational energy from a spinning black hole via the Blandford–Znajek mechanism has long been understood as an important component in models to explain energetic jets from compact astrophysical sources. Here we show more generally that the kinetic energy of the black hole, both rotational and translational, can be tapped, thereby producing even more luminous jets powered by the interaction of the black hole with its surrounding plasma. We study the resulting Poynting jet that arises from single boosted black holes and binary black hole systems. In the latter case, we find that increasing the orbital angular momenta of the system and/or the spins of the individual black holes results in an enhanced Poynting flux. PMID:21768341
Tapping into the Energy of Black Holes
NASA Astrophysics Data System (ADS)
Motl, Patrick M.; Lenher, L.; Liebling, S.; Palenzuela, C.; Neilsen, D.; Hirschmann, E.
2012-01-01
The extraction of rotational energy from a spinning black hole via the Blandford-Znajek mechanism has long been understood as an important component in models to explain energetic jets from compact astrophysical sources. Here we show more generally that the kinetic energy of the black hole, both rotational and translational, can be tapped, thereby producing even more luminous jets powered by the interaction of the black hole with its surrounding plasma. We study the resulting Poynting jet that arises from single boosted black holes and binary black hole systems. In the latter case, we find that increasing the orbital angular momenta of the system and/or the spins of the individual black holes results in an enhanced Poynting flux.
Self-tuning at large (distances): 4D description of runaway dilaton capture
NASA Astrophysics Data System (ADS)
Burgess, C. P.; Diener, Ross; Williams, M.
2015-10-01
We complete here a three-part study (see also arXiv:1506.08095 and arXiv:1508.00856) of how codimension-two objects back-react gravitationally with their environment, with particular interest in situations where the transverse `bulk' is stabilized by the interplay between gravity and flux-quantization in a dilaton-Maxwell-Einstein system such as commonly appears in higher-dimensional supergravity and is used in the Supersymmetric Large Extra Dimensions (SLED) program. Such systems enjoy a classical flat direction that can be lifted by interactions with the branes, giving a mass to the would-be modulus that is smaller than the KK scale. We construct the effective low-energy 4D description appropriate below the KK scale once the transverse extra dimensions are integrated out, and show that it reproduces the predictions of the full UV theory for how the vacuum energy and modulus mass depend on the properties of the branes and stabilizing fluxes. In particular we show how this 4D theory learns the news of flux quantization through the existence of a space-filling four-form potential that descends from the higher-dimensional Maxwell field. We find a scalar potential consistent with general constraints, like the runaway dictated by Weinberg's theorem. We show how scale-breaking brane interactions can give this potential minima for which the extra-dimensional size, ℓ, is exponentially large relative to underlying physics scales, r B , with ℓ 2 = r B 2 e - φ where - φ ≫ 1 can be arranged with a small hierarchy between fundamental parameters. We identify circumstances where the potential at the minimum can (but need not) be parametrically suppressed relative to the tensions of the branes, provide a preliminary discussion of the robustness of these results to quantum corrections, and discuss the relation between what we find and earlier papers in the SLED program.
ERIC Educational Resources Information Center
Baraka, Amiri
1987-01-01
Discusses black art as not only an expression of black life but as revolutionary art. It must be collective, functional, and committing. It must also be anti-racist, anti-capitalist, and anti-imperialist. (LHW)
Effective Potential in Noncommutative BTZ Black Hole
NASA Astrophysics Data System (ADS)
Sadeghi, Jafar; Shajiee, Vahid Reza
2016-02-01
In this paper, we investigated the noncommutative rotating BTZ black hole and showed that such a space-time is not maximally symmetric. We calculated effective potential for the massive and the massless test particle by geodesic equations, also we showed effect of non-commutativity on the minimum mass of BTZ black hole.
ERIC Educational Resources Information Center
Jones, Reginald L., Ed.
The contents of the present volume, designed to bring together in a single place writings by the new black psychologists and other black social and behavioral scientists, are organized in seven parts, as follows: Part I, "Black Psychology: Perspectives," includes articles by Cedric Clark, Wade W. Nobles, Doris P. Mosby, Joseph White, and William…
ERIC Educational Resources Information Center
Edwards, Harry
The black student revolt did not start with the highly publicized activities of the black students at San Francisco State College. The roots of the revolt lie deeply imbedded within the history and structure of the overall black liberation struggle in America. The beginnings of this revolt can be found in the students of Southern Negro colleges in…
ERIC Educational Resources Information Center
Jones, Reginald L., Ed.
The contents of the present volume, designed to bring together in a single place writings by the new black psychologists and other black social and behavioral scientists, are organized in seven parts, as follows: Part I, "Black Psychology: Perspectives," includes articles by Cedric Clark, Wade W. Nobles, Doris P. Mosby, Joseph White, and William…
Magnetic fields around black holes
NASA Astrophysics Data System (ADS)
Garofalo, David A. G.
Active Galactic Nuclei are the most powerful long-lived objects in the universe. They are thought to harbor supermassive black holes that range from 1 million solar masses to 1000 times that value and possibly greater. Theory and observation are converging on a model for these objects that involves the conversion of gravitational potential energy of accreting gas to radiation as well as Poynting flux produced by the interaction of the rotating spacetime and the electromagnetic fields originating in the ionized accretion flow. The presence of black holes in astrophysics is taking center stage, with the output from AGN in various forms such as winds and jets influencing the formation and evolution of the host galaxy. This dissertation addresses some of the basic unanswered questions that plague our current understanding of how rotating black holes interact with their surrounding magnetized accretion disks to produce the enormous observed energy. Two magnetic configurations are examined. The first involves magnetic fields connecting the black hole with the inner accretion disk and the other involves large scale magnetic fields threading the disk and the hole. We study the effects of the former type by establishing the consequences that magnetic torques between the black hole and the inner accretion disk have on the energy dissipation profile. We attempt a plausible explanation to the observed "Deep Minimum" state in the Seyfert galaxy MCG-6- 30-15. For the latter type of magnetic geometry, we study the effects of the strength of the magnetic field threading the black hole within the context of the cherished Blandford & Znajek mechanism for black hole spin energy extraction. We begin by addressing the problem in the non-relativistic regime where we find that the black hole-threading magnetic field is stronger for greater disk thickness, larger magnetic Prandtl number, and for a larger accretion disk. We then study the problem in full relativity where we show that our
NASA Technical Reports Server (NTRS)
Dickey, Jean O.
1995-01-01
The study of the Earth's rotation in space (encompassing Universal Time (UT1), length of day, polar motion, and the phenomena of precession and nutation) addresses the complex nature of Earth orientation changes, the mechanisms of excitation of these changes and their geophysical implications in a broad variety of areas. In the absence of internal sources of energy or interactions with astronomical objects, the Earth would move as a rigid body with its various parts (the crust, mantle, inner and outer cores, atmosphere and oceans) rotating together at a constant fixed rate. In reality, the world is considerably more complicated, as is schematically illustrated. The rotation rate of the Earth's crust is not constant, but exhibits complicated fluctuations in speed amounting to several parts in 10(exp 8) [corresponding to a variation of several milliseconds (ms) in the Length Of the Day (LOD) and about one part in 10(exp 6) in the orientation of the rotation axis relative to the solid Earth's axis of figure (polar motion). These changes occur over a broad spectrum of time scales, ranging from hours to centuries and longer, reflecting the fact that they are produced by a wide variety of geophysical and astronomical processes. Geodetic observations of Earth rotation changes thus provide insights into the geophysical processes illustrated, which are often difficult to obtain by other means. In addition, these measurements are required for engineering purposes. Theoretical studies of Earth rotation variations are based on the application of Euler's dynamical equations to the problem of finding the response of slightly deformable solid Earth to variety of surface and internal stresses.
Dirac fermions in nontrivial topology black hole backgrounds
Gozdz, Marek; Nakonieczny, Lukasz; Rogatko, Marek
2010-05-15
We discuss the behavior of the Dirac fermions in a general spherically symmetric black hole background with a nontrivial topology of the event horizon. Both massive and massless cases are taken into account. We will conduct an analytical study of intermediate and late-time behavior of massive Dirac hair in the background of a black hole with a global monopole and dilaton black hole pierced by a cosmic string. In the case of a global monopole swallowed by a static black hole, the intermediate late-time behavior depends on the mass of the Dirac field, the multiple number of the wave mode, and the global monopole parameter. The late-time behavior is quite independent of these factors and has a decay rate proportional to t{sup -5/6}. As far as the black hole pierced by a cosmic string is concerned, the intermediate late-time behavior depends only on the hair mass and the multipole number of the wave mode, while the late-time behavior dependence is the same as in the previous case. The main modification stems from the topology of the S{sup 2} sphere pierced by a cosmic string. This factor modifies the eigenvalues of the Dirac operator acting on the transverse manifold.
NASA Astrophysics Data System (ADS)
Luminet, Jean-Pierre
1992-09-01
Foreword to the French edition; Foreword to the English edition; Acknowledgements; Part I. Gravitation and Light: 1. First fruits; 2. Relativity; 3. Curved space-time; Part II. Exquisite Corpses: 4. Chronicle of the twilight years; 5. Ashes and diamonds; 6. Supernovae; 7. Pulsars; 8. Gravitation triumphant; Part III. Light Assassinated: 9. The far horizon; 10. Illuminations; 11. A descent into the maelstrom; 12. Map games; 13. The black hole machine; 14. The quantum black hole; Part IV. Light Regained: 15. Primordial black holes; 16. The zoo of X-ray stars; 17. Giant black holes; 18. Gravitational light; 19. The black hole Universe; Appendices; Bibliography; Name index; Subject index.
Formation of black hole and emission of gravitational waves
Nakamura, Takashi
2006-01-01
Numerical simulations were performed for the formation process of rotating black holes. It is suggested that Kerr black holes are formed for wide ranges of initial parameters. The nature of gravitational waves from a test particle falling into a Kerr black hole as well as the development of 3D numerical relativity for the coalescing binary neutron stars are discussed. PMID:25792793
Formation of black hole and emission of gravitational waves.
Nakamura, Takashi
2006-12-01
Numerical simulations were performed for the formation process of rotating black holes. It is suggested that Kerr black holes are formed for wide ranges of initial parameters. The nature of gravitational waves from a test particle falling into a Kerr black hole as well as the development of 3D numerical relativity for the coalescing binary neutron stars are discussed.
Christiansen, H. R.; Cunha, M. S.; Tahim, M. O.
2010-10-15
We analytically find the exact propagation modes of the electromagnetic and the Kalb-Ramond fields together in a five-dimensional curved space-time. The existence and localization of gauge particles into our four-dimensional world (4D) is studied in detail on a brane-world scenario in which two gauge fields interact with a dilaton and a gravitational background. The coupling to the dilaton is different in each case causing the splitting between gauge spectra. The gauge-field zero-modes and an infinite tower of Kaluza-Klein massive states are analytically obtained. Relevant conditions on the dilaton coupling constant are found in order to identify with precision every finite tensor and vector eigenstate in the theory. An exact quantization condition on the whole mass spectrum, depending on the dilaton coupling constant and the bulk Planck mass, is inherited from the extra-dimension. This allows finding an exact rule to prevent tachyons in the theory and, by the same token, predicting a possible tensor zero-mode in 4D world. We also show that KK massive-modes contributions onto 4D physics are strongly suppressed.
Tear rotation in reinforced natural rubber
NASA Astrophysics Data System (ADS)
Sotta, Paul; Gabrielle, Brice; Vieyres, Arnaud; Vanel, Loic; Long, Didier; Sanseau, Olivier; Albouy, Pierre-Antoine
2012-02-01
We analyze the impact of tear rotation, that is, an abrupt instability in the direction of propagation of a notch, on the tensile strength of natural rubber elastomers reinforced with carbon black or precipitated silica, in single edge notched samples stretched at constant velocity. As a consequence of tear rotation, the energy at break increases by a factor of 6 to 8 in some cases. We show how the tensile strength of a test sample is related to the presence of tear rotations and analyze semi-quantitatively this increase in tensile strength, based on energetic arguments, without entering into a detailed description of the elastic strain field in the vicinity of the tear tip. The proposed interpretation is based on the idea that tear rotations creates a macroscopic tip radius, which relaxes the local strain (or stress) at the tear tip. Materials reinforced with carbon black or precipitated silica aggregates show similar behavior. The relation to strain-induced crystallization is discussed.
The Maximum Mass of Rotating Strange Stars
NASA Astrophysics Data System (ADS)
Szkudlarek, M.; Gondek-Rosiń; ska, D.; Villain, L.; Ansorg, M.
2012-12-01
Strange quark stars are considered as a possible alternative to neutron stars as compact objects (e.g. Weber 2003). A hot compact star (a proto-neutron star or a strange star) born in a supernova explosion or a remnant of neutron stars binary merger are expected to rotate differentially and be important sources of gravitational waves. We present results of the first relativistic calculations of differentially rotating strange quark stars for broad ranges of degree of differential rotation and maximum densities. Using a highly accurate, relativistic code we show that rotation may cause a significant increase of maximum allowed mass of strange stars, much larger than in the case of neutron stars with the same degree of differential rotation. Depending on the maximum allowed mass a massive neutron star (strange star) can be temporarily stabilized by differential rotation or collapse to a black hole.
Charged black rings at large D
NASA Astrophysics Data System (ADS)
Chen, Bin; Li, Peng-Cheng; Wang, Zi-zhi
2017-04-01
We study the charged slowly rotating black holes in the Einstein-Maxwell theory in the large dimensions ( D). By using the 1 /D expansion in the near regions of the black holes we obtain the effective equations for the charged slowly rotating black holes. The effective equations capture the dynamics of various stationary solutions, including the charged black ring, the charged slowly rotating Myers-Perry black hole and the charged slowly boosted black string. Via different embeddings we construct these stationary solutions explicitly. For the charged black ring at large D, we find that the charge lowers the angular momentum due to the regularity condition on the solution. By performing the perturbation analysis of the effective equations, we obtain the quasinormal modes of the charge perturbation and the gravitational perturbation analytically. Like the neutral case the charged thin black ring suffers from the Gregory-Laflamme-like instability under the non-axisymmetric perturbations, but the charge weakens the instability. Besides, we find that the large D analysis always respects the cosmic censorship.
Magnetically-charged black branes and viscosity/entropy ratios
NASA Astrophysics Data System (ADS)
Liu, Hai-Shan; Lü, H.; Pope, C. N.
2016-12-01
We consider asymptotically-AdS n-dimensional black brane solutions in a theory of gravity coupled to a set of N p-form field strengths, in which the field strengths carry magnetic charges. For appropriately chosen charges, the metrics are isotropic in the ( n - 2) transverse directions. However, in general the field strength configurations break the full Euclidean symmetry of the ( n - 2)-dimensional transverse space, and the shear viscosity tensor in the dual theory is no longer isotropic. We study the linearised equations for transverse traceless metric perturbations in these backgrounds, and by employing the Kubo formula we obtain expressions for the ratios η/S of the shear viscosity components divided by the entropy density. We find that the KSS bound on the ratios η/S is generally violated in these solutions. We also extend the discussion by including a dilatonic scalar field in the theory, leading to solutions that are asymptotically Lifshitz with hyperscaling violation.