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Spanish-Portuguese Relativity Meeting
EREP 2017September 12th - 15th, 2017
Malaga, Spain
Conference Program
Spanish-Portuguese Relativity Meeting, 2017 Malaga, Spain
EREP 2017
Schedule at a glance (1)
The conference will be structured as follows:
• 12 Invited lectures (60 minutes including discussion). Room A.
• 72 Short talks (25 minutes including discussion). In the afternoon, three simultaneoussessions are held in rooms A, B and C.
• Poster presentations.
• A general interest talk (in Spanish) about General Relativity by the scientific bloggerFrancisco R. Villatoro. It will be held in the Rectorate building of the University ofMalaga (Paseo del Parque).
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Malaga, Spain Spanish-Portuguese Relativity Meeting, 2017
EREP 2017
Schedule at a glance (2)
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Spanish-Portuguese Relativity Meeting, 2017 Malaga, Spain
Contents
Welcome 6
Instructions for Participants 7
Invited speakers 8Krzysztof Bolejko. Gravitational entropy and the cosmological “no-hair” conjecture . 9Mihalis Dafermos. Boundedness and polynomial decay for the Teukolsky equation on
Kerr spacetimes . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 11Claudia de Rham. Beyond Einstein Gravity . . . . . . . . . . . . . . . . . . . . . . . 12Alberto Enciso. Waves in asymptotically AdS backgrounds and Einstein metrics with
prescribed conformal infinity . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 13Luis Lehner. Facing the challenge of testing GR, and extensions, with gravitational
waves . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 14Marc Mars. Slowly rotating stars: deriving the Hartle model from first principles . . 15Paolo Pani. Testing the nature of black holes with gravitational waves . . . . . . . . 16Istvan Racz. On the use of evolutionary methods in spaces of Euclidean signature . . 17Robert Wald. You Can’t Over-Charge or Over-Spin a Black Hole . . . . . . . . . . . . 18
General interest talk 19Francisco R. Villatoro. Agujeros negros. ¿Como ver lo invisible? . . . . . . . . . . . . 20
Contributed talks 21Luis Alberto Ake Hau. Causality and c-completion of multiwarped spacetimes . . . . 22Ana Alonso-Serrano. Entropy, entanglement and information in black hole evaporation 23Pablo Anglada. Size, angular momentum and mass for objects . . . . . . . . . . . . . 24Hans Bantilan. Non-Spherically Symmetric Collapse in Asymptotically AdS Spacetimes 25Carlos Barcelo. Probing extreme gravity in stellar collapse . . . . . . . . . . . . . . . 26Laura Bernard. Dynamics of compact binary systems in scalar-tensor theories at the
third post-Newtonian order . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 27Irene Brito. Conformal transformations in relativistic elasticity: applications to spher-
ical symmetry . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 28Pablo Bueno. Entanglement equilibrium for higher order gravity . . . . . . . . . . . . 29Juan Calderon Bustillo. Searching for the full symphony of binary black holes . . . . 30Armando J. Cabrera Pacheco. Constructing higher dimensional black hole initial data
sets with prescribed boundary metric . . . . . . . . . . . . . . . . . . . . . . . . 31Pablo A. Cano. Universal black hole stability in four dimensions . . . . . . . . . . . . 32Raul Carballo-Rubio. Exact solutions for static and spherically symmetric ultra-
compact relativistic stars in semiclassical gravity . . . . . . . . . . . . . . . . . . 33Nastassja Cipriani and Jose M.M. Senovilla. Geodesic completeness in Lorentzian
warped products . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 34Bartolome Coll, Joan J. Ferrando, and Juan A. Morales-Lladosa. Working in Rela-
tivistic Positioning Systems: the precision of location . . . . . . . . . . . . . . . 35
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Malaga, Spain Spanish-Portuguese Relativity Meeting, 2017
I. Cordero-Carrion. On the convexity of relativistic ideal magnetohydrodynamics andthe associated gravitational wave emission . . . . . . . . . . . . . . . . . . . . . 36
Ivan P. Costa e Silva. A Hausdorff topology on the future causal boundary: yetanother rapprochement with conformal boundaries . . . . . . . . . . . . . . . . . 37
L. Filipe Costa. The gravitational “Magnus” effect . . . . . . . . . . . . . . . . . . . 38Karoly Zoltan Csukas. Notes on geometric inequalities in spherically symmetric space-
times . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 39Roberto Dale and Diego Saez. On the CMB anisotropy deviations between AR-VTG
and GR . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 40Roberto Emparan. The Singularity is Near . . . . . . . . . . . . . . . . . . . . . . . . 41Miguel C. Ferreira. On the motion of stars driven by scalar fields . . . . . . . . . . . 42Arthur E. Fischer. The Space of Gravitational Degrees of Freedom . . . . . . . . . . 43Ales Flandera and Martin Scholtz. Kerr-Newman Black Hole in the Formalism of
Isolated Horizons . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 45Guillermo A. Gonzalez. The Einstein-Maxwell equations with thin layers of polarized
or magnetized matter . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 46Jonatan Herrera Fernandez. The causal boundary under the action of isometric group
actions . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 47Ondrej Hruska, Michal Karamazov, and Robert Svarc. Specific solutions to Quadratic
Gravity . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 48Gil Jannes. Perception tensor and Hawking versus Unruh effect near a black hole . . 49Jose Luis Jaramillo. An Ocean Drum: energetics and dynamics in a Physical Oceanography-
Gravitation dialogue . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 50Miguel Angel Javaloyes Victoria. Definitions and examples of Finsler spacetimes . . . 51Ivan Kolar. Higher-dimensional NUT-like and near-horizon geometries from the Kerr-
NUT-(A)dS metrics . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 52Wojciech Kulczycki and Edward Malec. Gravitational waves in cosmological space-
times and memory effect . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 53Michele Levi. EFT of PNG with a spin & From YM theory to GR: The classical
double copy . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 54Jorge Lopes. Chaos of the bound-states in anti-de Sitter spacetime . . . . . . . . . . . 55Hideki Maeda. Throat quantization of the Schwarzschild-Tangherlini(-AdS) black hole 56Kengo Maeda. A holographic stress-energy tensor near the Cauchy horizon inside a
rotating black hole . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 57V.S. Manko and E. Ruiz. Energy problem in the regular black hole spacetimes . . . . 58Julija Markeviciute and Jorge E. Santos. Stirring a black hole . . . . . . . . . . . . . 59Cristian Martınez. Black hole formation with a conformally coupled scalar field in
three spacetime dimensions . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 60Masato Minamitsuji. Black Holes in the Generalized Proca Theory . . . . . . . . . . 61Sindy Mojica. Innermost stable circular orbits in dilatonic Einstein-Gauss-Bonnet
theory . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 62Filipe Moura. Absorption of scalars by black holes in string theory . . . . . . . . . . . 63Anna Nakonieczna. Initializing gravitational evolutions within the parabolic-hyperbolic
formulation - black holes binary . . . . . . . . . . . . . . . . . . . . . . . . . . . 64Andrea Nerozzi. Advanced wave extraction algorithms in numerical relativity . . . . . 65Kota Ogasawara. Particle collision with an arbitrarily high center-of-mass energy near
a Banados-Teitelboim-Zanelli black hole . . . . . . . . . . . . . . . . . . . . . . 66Marcelo Ortaggio. Universal electromagnetic fields . . . . . . . . . . . . . . . . . . . . 67Tomas Ortın. Self-consistency of higher-order gravities . . . . . . . . . . . . . . . . . 68Michal Pirog. Relativistic low angular momentum accretion . . . . . . . . . . . . . . 69Alena Pravdova. On exact solutions to quadratic gravity . . . . . . . . . . . . . . . . 70
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Spanish-Portuguese Relativity Meeting, 2017 Malaga, Spain
Borja Reina. Four of a kind: I − Love−Q− δM . . . . . . . . . . . . . . . . . . . . 71Angel Rincon. Rotating BTZ black hole assuming running couplings . . . . . . . . . 72Jorge Rocha. Dynamical spacetimes in low-energy string theory and cosmic censorship 73Marcelo E. Rubio. A hyperbolic theory of relativistic conformal dissipative fluids . . . 74Diego Rubiera-Garcıa. Singular and nonsingular black holes in f(R) theories and beyond 75Nihat Sadik Deger. Homogeneous Solutions of Minimal Massive 3D Gravity . . . . . . 76Miguel Sanchez. Ehlers-Kundt conjecture about Gravitational Waves . . . . . . . . . 77Supratik Sarkar and A. Bhattacharyay. Analogue Gravity from Quantum potential in-
duced Bose-Einstein Condensates (BEC): UV-IR Coupling in analogue Hawkingradiation . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 78
Jose M M Senovilla. Area deficit of geodesic balls and gravitational energy . . . . . . 79C. A. S. Silva. Quantum corrected Friedmann equations from loop quantum black
holes entropy-area relation . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 80Philipp Stanzer. Quantum Null Energy Condition from Numerical Holography . . . . 81Otakar Svıtek. Wormhole models without symmetries . . . . . . . . . . . . . . . . . . 82Tayebeh Tahamtan. Spacetimes with Nonlinear Electrodynamics . . . . . . . . . . . . 83Kunihito Uzawa. Supersymmetric solution in dynamical M-brane background . . . . 84Bruno Vergara. Fractional wave operators and the wave equation in anti-de Sitter
spaces . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 85Vincenzo Vitagliano. Covariantly Quantum Field Theory . . . . . . . . . . . . . . . . 86Steven Willison. Gravitational degrees of freedom and isometric embedding . . . . . . 87Helvi Witek. Black holes as probes for fundamental physics . . . . . . . . . . . . . . . 88Vojtech Witzany. New conservation laws for matter near spinning black holes . . . . . 89
Posters 90Irene Brito and Filipe Mena. Initial boundary value problem for the Einstein field
equations for a class of spherically symmetric imperfect fluids . . . . . . . . . . 91Antonino Flachi. Chiral vortical effect in curved space and the Chern-Simons current 92Apratim Ganguly. Binary boson stars and numerical relativity . . . . . . . . . . . . . 93Akio Hosoya and Shunsuke Fujii. Informational Theory of Relativity . . . . . . . . . 94F. D. Lora-Clavijo and A. Cruz-Osorio. Relativistic BHL Accretion in the Presence
of Stellar Winds and Dense Clumps Around a Black Hole . . . . . . . . . . . . . 95F. Martin-Vergara, F. Rus, and F. R. Villatoro. Pseudospherical surfaces based on
the Graphene Superlattice Equation . . . . . . . . . . . . . . . . . . . . . . . . . 96Vojtech Pravda. Universal spacetimes . . . . . . . . . . . . . . . . . . . . . . . . . . . 97Ignacio Sanchez-Rodrıguez. Conformal scalar invariants of weight zero . . . . . . . . . 98C.A.S.Silva and R.G.L.Aragao. Entropic corrected Newton’s law of gravitation . . . . 99
Notes 100
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Malaga, Spain Spanish-Portuguese Relativity Meeting, 2017
EREP 2017Welcome
It is our great pleasure to welcome you to this edition of the Spanish-Portuguese RelativityMeeting, held in Malaga (Spain). These meetings are annual conferences on General Relativityand Gravitation, that date back to 1977, and are organized each year by one of the differentgroups doing research on Relativity and Gravitation in Portugal and Spain.
Scientific CommitteeNathalie Deruelle Laboratoire Astroparticule et Cosmologie
CNRS-Universite Paris7, FranceRuth Durrer Universite de Geneve, SwitzerlandValeria Ferrari Sapienza Universita di Roma, ItalyJorge Pullin Louisiana State University, USAJose M.M. Senovilla Universidad del Paıs Vasco, Spain
Organizing Committee
Miguel Atencia Departamento de Matematica Aplicada
Jose Luis Flores Departamento de Algebra, Geometrıa y Topologıa
Manuel Gutierrez Departamento de Algebra, Geometrıa y TopologıaBenjamın Olea Departamento de Matematica AplicadaFrancisco Palomo Departamento de Matematica Aplicada
Universidad de Malaga, Spain
Technical Secretariat
Viajes El Corte [email protected]
Sponsors
Universidad de Malaga http://www.uma.es
Vicerrectorado de Investigacion y TransferenciaDepartamento de Algebra, Geometrıa y TopologıaDepartamento de Matematica Aplicada
National Research Projects of the Ministerio de Economıa y Competitividad(Gobierno de Espana) and the European Union
MTM2013-47828-C2-1-PMTM2013-47828-C2-2-PMTM2016-78647-P
Academia Malaguena de Ciencias http://amciencias.com
Sociedad Malaguena de Astronomıa http://www.astromalaga.es
Metro de Malaga http://metromalaga.es
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Spanish-Portuguese Relativity Meeting, 2017 Malaga, Spain
Instructions for Participants
Internet access
• Wireless network: Congresos
– Open any web site in a browser– In the identification page that will appear, enter:
∗ Username: erep2017∗ Password: Gravitation
• Alternatively, you can use your eduroam account on the wireless network eduroam.• There are some available terminals in the computer rooms. You will have to register in
the Virtual Campus on these computers, providing your personal data.• Contact the Registration Desk or ask someone of the Organization Committee for help.
Instructions for Contributors
• Room A: Sala de grados A (2nd floor)• Room B: Sala de grados B (2nd floor)• Room C: Classroom 0.26 (ground floor)• Each room will have a digital projector and a Windows computer, but you are advised
to bring your own laptop to avoid configuration issues.• Both speakers and chairs should arrive 10 minutes before the session starts, to check the
equipment works.• Please stick to the schedule.• Posters will be displayed on A0 portrait (vertical) boards that will be installed in the hall
of the ground floor.• Contact the Registration Desk or ask someone of the Organization Committee for help.• Please, wear your badge visibly, specially at lunches.
Social program
• Date: Thursday 14th.• Meeting point for both activities: AC Hotel Malaga Palacio, Street Cortina del Muelle, 1• Walking visit to Malaga: 17:00 h.• Dinner: 20:00 h. (from the hotel we walk to the nearby restaurant).• Restaurant Los Patios de Beatas, Street Beatas, 43.• Be aware of any updates by checking the signboard next to the Registration Desk.• Please, wear your badge visibly at all social activities and lunches.
Transport
• The conference bag includes a couple of Metro tickets, each charged with two trips. Donot dispose of the cards, they can be recharged with additional trips without paying againfor the physical support (see http://metromalaga.es/en/tickets-and-fares/).
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Malaga, Spain Spanish-Portuguese Relativity Meeting, 2017
Invited speakers
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Spanish-Portuguese Relativity Meeting, 2017 Malaga, Spain
Gravitational entropy and the cosmological “no-hair”conjecture
Krzysztof Bolejko
The University of Sydney, School of Physics, NSW 2006, [email protected]
ABSTRACT
Gravitational entropy [1] and the “no-hair” conjunctures [2, 3] are seemingly
contradictory: the growth of the first one is associated with the growth of inho-
mogeneity [4, 5, 6], while the second one argues that the dark energy dominated
Universe will asymptotically approach a homogeneous and isotropic de Sitter
state[7, 8].
In my talk I will present the analysis of both of these conjectures within the
silent universes [9, 10]. Irrotational silent universes belong to a class of systems
where each worldline evolves independently of other worldlines — there is no
communication between the worldlines, i.e. no pressure gradients, no energy
flux, no gravitational radiation. In my talk I will discuss properties and evolu-
tion of the irrotational silent universe. I will focus on the gravitational entropy
and future asymptotic state of the silent universe dominated by dark energy
[11]. Finally, I will comment on the gravitational entropy of gravitational waves.
References
[1] T. Clifton, G. F. R. Ellis, and R. Tavakol, “A gravitational entropy proposal,”Classical and Quantum Gravity, vol. 30, p. 125009, 2013.
[2] G. Gotz, “On the cosmological ’no-hair’ conjecture,” Physics Letters A,vol. 128, no. 3, pp. 129 – 132, 1988.
[3] L. G. Jensen and J. A. Stein-Schabes, “Is inflation natural?,” Phys. Rev. D,vol. 35, pp. 1146–1150, 1987.
[4] K. Bolejko and W. R. Stoeger, “Intermediate homogenization of the Uni-verse and the problem of gravitational entropy,” Phys. Rev. D, vol. 88, no. 6,p. 063529, 2013.
[5] R. A. Sussman and J. Larena, “Gravitational entropies in LTB dust models,”Classical and Quantum Gravity, vol. 31, p. 075021, 2014.
[6] R. A. Sussman , “Gravitational entropy of cosmic expansion,” AstronomischeNachrichten, vol. 335, p. 587, 2014.
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Malaga, Spain Spanish-Portuguese Relativity Meeting, 2017
[7] R. M. Wald, “Asymptotic behavior of homogeneous cosmological models inthe presence of a positive cosmological constant,” Phys. Rev. D, vol. 28,pp. 2118–2120, 1983.
[8] T. Pacher and J. A. Stein-Schabes, “On the Locality of the No Hair Con-jecture and the Measure of the Universe,” Annalen der Physik, vol. 503,pp. 518–526, 1991.
[9] M. Bruni, S. Matarrese, and O. Pantano, “Dynamics of silent universes,”Astroph. J., vol. 445, pp. 958–977, 1995.
[10] H. van Elst, C. Uggla, W. M. Lesame, G. F. R. Ellis, and R. Maartens, “Inte-grability of irrotational silent cosmological models,” Classical and QuantumGravity, vol. 14, pp. 1151–1162, 1997.
[11] K. Bolejko, In preparation, 2017.
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Spanish-Portuguese Relativity Meeting, 2017 Malaga, Spain
Boundedness and polynomial decay for the Teukolskyequation on Kerr spacetimes
Mihalis Dafermos
University of Cambridge, Department of Pure Mathematics and MathematicalStatistics, Wilberforce Road, Cambridge CB3 0WA, United Kingdom
ABSTRACT
This is joint work with Igor Rodnianski and Gustav Holzegel. As part of our
previous proof of linear stability of Schwarzschild, we showed both boundedness
and polynomial decay estimates for solutions of the spin ±2 Teukolsky equation
by exploiting a physical space transformation to solutions of the Regge-Wheeler
equation. We show how this procedure generalises to yield similar results for
the Teukolsky equation on Kerr.
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Malaga, Spain Spanish-Portuguese Relativity Meeting, 2017
Beyond Einstein Gravity
Claudia de Rham
Theoretical Physics, Blackett Laboratory, Imperial College, London, [email protected]
ABSTRACT
One hundred years after ”Die Feldgleichungen der Gravitation” by Albert
Einstein and at the beginning of a new era of direct gravitational detections,
the time is right to pause and ponder about the nature of the particle carrier
of the gravitational force: the graviton. To unify the theory of gravity with the
other forces of nature we expect the theory of General Relativity to be modified
at small distances. Could it be that General Relativity is also modified at large
distances as large as our current observable Universe? This may depend on the
very nature of the graviton.
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Spanish-Portuguese Relativity Meeting, 2017 Malaga, Spain
Waves in asymptotically AdS backgrounds and Einsteinmetrics with prescribed conformal infinity
Alberto Enciso
Instituto de Ciencias Matematicas, Consejo Superior de InvestigacionesCientıficas, 28049 Madrid, SPAIN
ABSTRACT
In this talk we will consider a couple of mathematical problems about wave
propagation in asymptotically AdS spaces. In particular, we will discuss a suit-
able local wellposedness theorem for the Einstein equations that ensures the
existence of Einstein metrics with prescribed conformal geometry. The talk is
based on joint work with Niky Kamran and Bruno Vergara.
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Malaga, Spain Spanish-Portuguese Relativity Meeting, 2017
Facing the challenge of testing GR, and extensions, withgravitational waves
Luis Lehner
Perimeter Institute for Theoretical Physics, Waterloo, Ontario N2L 2Y5, CanadaCIFAR, Cosmology and Gravity Program, Toronto, ON M5G 1Z8, Canada
ABSTRACT
Exploiting gravitational waves to probe the underlying gravitational theory
requires a thorough understanding of possible surprises in GR, as well as possible
departures from it. In this talk i will discuss a few interrelated challenges in
this task and ways to address them.
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Spanish-Portuguese Relativity Meeting, 2017 Malaga, Spain
Slowly rotating stars: deriving the Hartle model from firstprinciples.
Marc Mars
Instituto de Fısica Fundamental y Matematicas, Universidad de Salamanca,Plaza de la Merced s/n, 37008 Salamanca, Spain
ABSTRACT
The Hartle model describes slowly rigidly rotating stars in the strong field
regime by using perturbation theory up to second order. The model involves
a number of hypotheses, particularly regarding the structure of the fields when
expanded in spherical harmonics that need justification. In this talk I present
work in collaboration with Reina and Vera where the Hartle model is derived
from first principles. Our results prove in particular that, at this level of approx-
imation, the spacetime must be equatorially symmetric and is fully determined
by two parameters, namely the central pressure and the rotation parameter of
the fluid.
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Malaga, Spain Spanish-Portuguese Relativity Meeting, 2017
Testing the nature of black holes with gravitational waves
Paolo Pani
CENTRA, Departamento de Fısica, Instituto Superior Tecnico, Universidade deLisboa, Avenida Rovisco Pais 1, 1049 Lisboa, Portugal
Dipartimento di Fisica, “Sapienza” Universita di Roma and Sezione INFNRoma1, Piazzale Aldo Moro 5, 00185, Roma, Italy
ABSTRACT
Gravitational wave (GW) astronomy allows us for unprecedented tests of the
nature of dark compact objects. In this context, I will discuss two signatures
of new physics at the horizon scale: GW “echoes” in the postmerger ringdown
phase of a binary coalescence, and finite-size effects of exotic compact objects
that affect the inspiral premerger phase. In the first case, the ringdown wave-
form of exotic ultracompact objects is initially identical to that of a black hole,
and putative corrections at the horizon scale appear only at later times as a mod-
ulated and distorted train of echoes of the modes of vibration associated with the
photon sphere. As for the second case, I will discuss the tidal heating and tidal
Love numbers of different families of boson stars, gravastars, wormholes, and
other toy models for quantum corrections at the horizon scale. These corrections
display a universal logarithmic dependence on the location of the surface in the
black-hole limit. I will discuss the ability of present and future GW detectors to
measure these effects. Both LIGO, ET and LISA can impose interesting con-
straints on boson stars, while LISA is able to probe even Planckian corrections.
We argue that these effects provide a smoking gun of new physics at the horizon
scale, and that future GW measurements of a binary coalescence provide a novel
way to test black holes and general relativity in the strong-field regime.
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Spanish-Portuguese Relativity Meeting, 2017 Malaga, Spain
On the use of evolutionary methods in spaces of Euclideansignature
Istvan Racz
Wigner RCP, Konkoly Thege Miklos ut 29-33, H-1121 Budapest, [email protected]
ABSTRACT
Two examples of physical interest will be presented. Both, contrary to the
folklore, demonstrate that evolutionary methods may play a significant role in
spaces of Euclidean signature. First, the propagation of the constraints is con-
sidered. It is shown that once a clear separation of the evolutionary and con-
straint equations is done, the subsidiary equations satisfied by the constraint
expressions form a first order symmetric hyperbolic system regardless whether
the ambient Einsteinian space is of Lorentzian or Euclidean signature. Second,
the constrains of Einstein’s theory of gravity are considered. Since the seminal
observations of Lichnerowicz and York these equations are usually referred to
as a semilinear elliptic system. It will be shown that-according to the choice of
the dependent variables-the constraints may have different characters. In par-
ticular, they may take the form of either a parabolic-hyperbolic or a strongly
hyperbolic system. Some of the recent developments related to these alternative
forms will also be discussed..
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Malaga, Spain Spanish-Portuguese Relativity Meeting, 2017
You Can’t Over-Charge or Over-Spin a Black Hole
Robert Wald
Enrico Fermi Institute and Department of Physics, The University of Chicago,5640 South Ellis Avenue, Chicago, Illinois 60637, USA
ABSTRACT
The Kerr-Newman solutions are the only stationary black hole solutions of the
Einstein-Maxwell equations in 4-dimensions. However, these solutions describe
black holes only when the inequality M2 ≥ (J/M)2 + Q2 is satisfied, where
M , J , and Q are the mass, angular momentum, and charge of the black hole.
Therefore, if an extremal or nearly extremal black hole can be made to absorb
matter with sufficiently large angular momentum or charge as compared with
its energy, one would obtain an apparent contradiction with cosmic censorship.
Hubeny and others have made proposals as to how this might be done, but a
proper analysis of this proposal requires a calculation of all second order effects
on energy, including, in particular, effects arising from self-force. We show in
this work that when all of the second order effects are taken into account, no
over-charging or over-spinning of a black hole can occur, provided only that the
non-electromagnetic matter satisfies the null energy condition.
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Spanish-Portuguese Relativity Meeting, 2017 Malaga, Spain
General interest talk
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Malaga, Spain Spanish-Portuguese Relativity Meeting, 2017
Agujeros negros. ¿Como ver lo imposible?
Francisco R. Villatoro
Universidad de [email protected]
ABSTRACT
Se espera que este verano (quizas antes de septiembre) se publique la primera
observacion del agujero negro supermasivo de nuestra galaxia con una resolucion
comparable al tamano de su horizonte de sucesos (algo ası como la orbita de
Mercurio). Hasta ahora solo se ha observado con una distancia del orden de la
orbita de Neptuno.
Las observaciones se estan realizando ahora mismo y ya son noticia en algunos
medios: se esta usando una red de telescopios a escala mundial que equivalen a
un telescopio con un espejo del tamano de toda la Tierra. Tanto si para el dıa de
la charla ya se han publicado estos resultados, como si aun no se han publicado,
creo que en septiembre esta noticia aparecera en varios medios. Por ello sobre
esa fecha el publico estara muy interesado en los agujeros negros supermasivos
y como se ven usando redes de telescopios.
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Spanish-Portuguese Relativity Meeting, 2017 Malaga, Spain
Contributed talks
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Malaga, Spain Spanish-Portuguese Relativity Meeting, 2017
Causality and c-completion of multiwarped spacetimes
Luis Alberto Ake Hau.
Universidad de Malaga, Departamento de Algebra, Geometrıa y Topologı[email protected]
ABSTRACT
We discuss the causal properties of doubly warped spacetimes and the causal
boundary of these spacetimes. Some applications of our results in examples of
physical interest are considered: Schwarzschild spacetimes, Reissner Nordstrom
and in the context of Maldacena’s conjecture. This talk is based on the joint
work with J.L. Flores and J. Herrera in [1].
References
[1] L. Ake, J.L. Flores and J. Herrera, Causality and c-completion of doublywarped spacetimes, arXiv:1709.00234.
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Spanish-Portuguese Relativity Meeting, 2017 Malaga, Spain
Entropy, entanglement and information in black holeevaporation
Ana Alonso-Serrano
Institute of Theoretical Physics, Faculty of Mathematics and Physics, CharlesUniversity, 18000 Prague, Czech Republic
ABSTRACT
It can be found that blackbody radiation contains (on average) an entropy
of 3.9± 2.5 bits per photon. The flip side of this observation is the information
budget: If the emission process is unitary, as it certainly is for normal physical
burning, then this entropy is exactly compensated by the “hidden information”
in the correlations that we choose not to consider within the specific coarse-
graining. We can also extend this argument to the Hawking radiation from
black holes, demonstrating that the assumption of unitarity leads to a perfectly
reasonable entropy/information budget.
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Malaga, Spain Spanish-Portuguese Relativity Meeting, 2017
Size, angular momentum and mass for objects
Pablo Anglada
Facultad de Matematica, Astronomıa y Fısica, Universidad Nacional de Cordoba,Instituto de Fısica Enrique Gaviola, IFEG, CONICET, Ciudad Universitaria,
Cordoba, [email protected]
ABSTRACT
We present a new geometrical inequality involving the ADM mass, the angu-
lar momentum and the size of an ordinary axially symmetric object. The main
tool we use to use to prove it is the monotonicity of the Geroch quasi- local
energy along the inverse mean curvature flow. We also compute numerical
examples to test the robustness of our hypotheses and results. [1].
References
[1] Anglada, Pablo and Gabach-Clement, M. E. and Ortiz, Omar E. Size, angularmomentum and mass for objects. arXiv [gr-qc], 1612.08658, 2016.
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Spanish-Portuguese Relativity Meeting, 2017 Malaga, Spain
Non-Spherically Symmetric Collapse in Asymptotically AdSSpacetimes
Hans Bantilan
School of Mathematical Sciences, Queen Mary University of London, Mile EndRoad, London E1 4NS, United Kingdom
Centre for Research in String Theory, School of Physics and Astronomy, QueenMary University of London, E1 4NS, UK
Department of Applied Mathematics and Theoretical Physics (DAMTP), Centrefor Mathematical Sciences, University of Cambridge, Wilberforce Road,
Cambridge CB3 0WA, United [email protected]
ABSTRACT
We numerically simulate gravitational collapse in asymptotically anti-de Sit-
ter spacetimes away from spherical symmetry. Starting from initial data sourced
by a massless real scalar field, we solve the Einstein equations with a negative
cosmological constant in five spacetime dimensions and obtain a family of non-
spherically symmetric solutions, including those that form two distinct black
holes on the axis. We find that these configurations collapse faster than spheri-
cally symmetric ones of the same mass and radial compactness. Similarly, they
require less mass to collapse within a fixed time.
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Malaga, Spain Spanish-Portuguese Relativity Meeting, 2017
Probing extreme gravity in stellar collapse
Carlos Barcelo
Instituto de Astrofısica de Andalucıa IAA-CSIC, Glorieta de la Astronomıa s/n,18008 Granada, Spain
ABSTRACT
The standard way to understand quantum corrected black holes leads to the
information loss paradox and the lifetime dilemma. A radical way out of this
situation is to give up a hypothesis which is tacitly assumed in the vast majority
of works on the subject: that the classical singularity is substituted by something
effectively acting as a sink for a long period of time, as seen by asymptotic ob-
servers. Eliminating this characteristic changes drastically much of the physics
now associated to black holes. A nice feature of the new hypothesis it that it of-
fers a clear possibility of experimental falsifiability with upcoming gravitational
waves observations. In this talk I will discuss these possibilities.
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Spanish-Portuguese Relativity Meeting, 2017 Malaga, Spain
Dynamics of compact binary systems in scalar-tensortheories at the third post-Newtonian order
Laura BERNARD
Instituto Superior Tecnico - [email protected]
ABSTRACT
In the upcoming years, the observation of gravitational waves from inspiraling
compact binary systems will allow us to test General Relativity in its strong
field regime. Both the detection and precise determination of the physical
parameters of gravitational waves require a bank of very accurate template
gravitational waveforms. In order to constrain the deviations from General
Relativity, one also has to build template waveforms in alternative theories of
gravity. In this talk, I will focus on massless scalar-tensor theories and address
the question of the dynamics of non-spinning compact binary systems at 3PN
order in harmonic coordinates. This is needed in order to compute the scalar
and gravitational waveforms at 2PN order. In particular, I will present our
method which is based on a Fokker action adapted to the specificities of both
the post-Newtonian formalism and ST theories. I will then derive the conserved
energy and momentum at 3PN order.
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Malaga, Spain Spanish-Portuguese Relativity Meeting, 2017
Conformal transformations in relativistic elasticity:applications to spherical symmetry
Irene Brito
Centro de Matematica, Universidade do Minho, 4710-057 Braga, [email protected]
ABSTRACT
Conformal space-time configurations are considered in the context of gen-
eral relativistic elasticity. Expressions relating densities, pressures and energy-
momentum tensors are obtained for the conformal configurations. The results
are applied to spherically symmetric space-times with elastic matter [1],[2],
showing how a new non-static shear-free solution of the Einstein field equations
can be generated [3].
References
[1] Brito, I., Carot, J., Vaz, E.G.L.R., Gen. Rel. Grav. 42, 2357 (2010) and Gen.Rel. Grav. 44, 287 (2012).
[2] Magli, G., Gen. Rel. Grav. 24, 139 (1992).
[3] Brito, I., J. Math. Phys 56, 092502 (2015).
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Spanish-Portuguese Relativity Meeting, 2017 Malaga, Spain
Entanglement equilibrium for higher order gravity
Pablo Bueno
Instituut voor Theoretische Fysica, KU Leuven, Celestijnenlaan 200D, B-3001Leuven, Belgium
ABSTRACT
I will start with a quick review of the main approaches to the problem of
deriving gravitational dynamics from entanglement/thermodynamic-based prin-
ciples. My focus will be then on Jacobson’s recent “entanglement equilibrium”
proposal [1], which connects Einstein’s equations to an equilibrium condition
on the entanglement entropy of small spherical regions in vacuum. I will ex-
plain that this principle can be extended to the linearized equations of general
higher-derivative corrections [2]. These corrections are naturally associated with
the subleading divergences in the entanglement entropy, which take the form of
a Wald entropy evaluated on the entangling surface. Variations of this Wald
entropy are related to the field equations through a new identity for causal dia-
monds in maximally symmetric spacetimes. If the variations are taken holding
fixed a geometric functional that we called the “generalized volume”, the identity
becomes an equivalence between the linearized constraints and the entanglement
equilibrium condition. I will explain that the fully nonlinear higher curvature
equations cannot be derived from the linearized equations applied to small balls,
in contrast to the situation encountered in Einstein gravity. I will also discuss
possible applications of our generalized volume (which generalizes the notion of
volume to higher-derivative gravities in a similar way as Wald’s entropy func-
tional generalizes that of area), e.g., in the context of holographic complexity.
References
[1] T. Jacobson, Phys. Rev. Lett. 116 (2016) no.20, 201101 [arXiv:1505.04753[gr-qc]].
[2] P. Bueno, V. S. Min, A. J. Speranza and M. R. Visser, Phys. Rev. D 95(2017) no.4, 046003 [arXiv:1612.04374 [hep-th]].
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Malaga, Spain Spanish-Portuguese Relativity Meeting, 2017
Searching for the full symphony of binary black holes
Juan Calderon Bustillo
Center for Relativistic Astrophysics and School of Physics, Georgia Institute ofTechnology, Atlanta, GA 30332
ABSTRACT
The discovery of the gravitational wave signals GW150914 and GW151226
has open the era of gravitational wave astronomy [1, 2]. The source of both sig-
nals were identified as binary black holes with mass ratio q < 3 and a total mass
below 100M�. Furthermore, a search for heavier systems recently reported no
detections [3]. Current searches for binary black holes omit the so called higher
order modes, focusing only on the identification of the dominant mode of the
emitted gravitational waves. In this talk I will present a search for binary black
holes that considers all the modes of the emitted radiation. This is crucial in
order to detect more exotic sources than the ones LIGO has currently detected:
large mass ratio and intermediate mass binary black holes [4].
References
[1] B. P. Abbott et al. (Virgo, LIGO Scientific), Phys. Rev. Lett. 116, 061102(2016), arXiv:1602.03837 [gr-qc].
[2] B. Abbott et al. (Virgo, LIGO Scientific), Phys. Rev. Lett. 116, 241103 (2016),arXiv:1606.04855 [gr-qc].
[3] B. P. Abbott et al. (Virgo, LIGO Scientific), (2017), arXiv:1704.04628 [gr-qc].
[4] Juan Calderon Bustillo, Pablo Laguna, and Deirdre Shoemaker Phys. Rev. D95, 104038
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Spanish-Portuguese Relativity Meeting, 2017 Malaga, Spain
Constructing higher dimensional black hole initial data setswith prescribed boundary metric
Armando J. Cabrera Pacheco
Mathematics Department, University of [email protected]
ABSTRACT
Recently Mantoulidis and Schoen [1] constructed smooth asymptotically flat
initial data sets with prescribed horizon boundary, whose mass can be made ar-
bitrarily close to the optimal value in the Riemannian Penrose inequality, while
the geometry of the horizon is far from being rotationally symmetric. In this
talk, combining their construction with some geometric flows, we will discuss
how to obtain higher dimensional initial data sets with analogous properties.
This talk is based on a joint work with Pengzi Miao [2].
References
[1] Mantoulidis, C.; Schoen, R., On the Bartnik mass of apparent horizons, Class.Quantum Grav., 32 (2015), no. 20, 205002, 16pp.
[2] Cabrera Pacheco, A. J.; Miao, P., Higher dimensional black hole initial datawith prescribed boundary metric, arXiv:1505.01800.
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Malaga, Spain Spanish-Portuguese Relativity Meeting, 2017
Universal black hole stability in four dimensions
Pablo A. Cano
Instituto de Fısica Teorica UAM/CSIC, C/ Nicolas Cabrera, 13-15,C.U. Cantoblanco, 28049 Madrid, Spain
ABSTRACT
We show that four-dimensional black holes become stable below certain mass
when the Einstein- Hilbert action is supplemented with higher-curvature terms.
We prove this to be the case for an infinite family of ghost-free theories involv-
ing terms of arbitrarily high order in curvature. The new black holes, which
are non-hairy generalizations of Schwarzschild’s solution, present a universal
thermodynamic behavior for general values of the higher-order couplings. In
particular, small black holes have infinite lifetimes. When the evaporation pro-
cess makes the semiclassical approximation break down (something that occurs
after a time which is usually infinite for all practical purposes), the resulting
object retains a huge entropy, in stark contrast with Schwarzschild’s case.
References
[1] P. Bueno and P. A. Cano, “Universal black hole stability in four dimensions”,arXiv:1704.02967 [hep-th].
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Spanish-Portuguese Relativity Meeting, 2017 Malaga, Spain
Exact solutions for static and spherically symmetricultra-compact relativistic stars in semiclassical gravity
Raul Carballo-Rubio
SISSA, Via Bonomea 265, 34136 Trieste, Italy and INFN, Sezione di [email protected]
ABSTRACT
Astrophysical black holes may be ultra-compact relativistic stars instead of
proper general-relativistic black holes. The detection of gravitational waves has
revived interest in this possibility, that has been under development by a few
different groups during the last decade. The theoretical status of these hypo-
thetical objects is however uncertain. In this talk I will present some recent
developments aimed at changing this situation. In particular, I will discuss:
(i) how to construct an extension of the equations of stellar equilibrium in gen-
eral relativity to include the semiclassical effect of quantum vacuum polarization,
and (ii) that there exist exact solutions to these equations, describing static and
spherically symmetric ultra-compact relativistic stars. This talk will be based on
[1].
References
[1] Raul Carballo-Rubio, “Stellar equilibrium in semiclassical gravity”arXiv:1706.05379 (2017).
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Malaga, Spain Spanish-Portuguese Relativity Meeting, 2017
Geodesic completeness in Lorentzian warped products
Nastassja Cipriani and Jose M. M. Senovilla
KU Leuven, Department of Mathematics, Celestijnenlaan 200B – Box 2400,BE-3001 Leuven, Belgium
Fısica Teorica, Universidad del Paıs Vasco, Apartado 644, 48080 Bilbao, [email protected]
ABSTRACT
Most singularity theorems in general relativity are based on the existence of
trapped submanifolds with co-dimension two. In [1] the authors show that this
can be generalized: they prove singularity theorems by using trapped submani-
folds with arbitrary co-dimension. In particular, they provide a key, sufficient,
trapping condition (*) for the existence of focal points.
Let M be a Lorentzian manifold of dimension 4, Y a compact Riemannian man-
ifold of dimension 6, and consider the warped product M = M ×f Y. We make
a systematic study of the spacelike submanifolds ofM and, using condition (*),
find those admitting focal points. When possible, we show that M is geodesi-
cally incomplete, thus singular. Our results have applications to the instability
of extra space dimensions in string theory [2].
References
[1] G.J.Galloway and J.M.M.Senovilla, “Singularity theorems based on trappedsubmanifolds of arbitrary co-dimension”, Classical Quant. Grav. 27 (2010),no. 15, 152002, 10 pp
[2] R. Penrose, “On the instability of extra space dimensions” in The futureof the theoretical physics and cosmology, G. W. Gibbons, E. P. S. Shellard,and S. J. Rankin, eds. (Cambridge, 2002), 185–201, Cambridge Univ. Press,Cambridge, 2003
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Spanish-Portuguese Relativity Meeting, 2017 Malaga, Spain
Working in Relativistic Positioning Systems: the precisionof location
Bartolome Coll, Joan J. Ferrando and Juan A. Morales–Lladosa
Universitat de Valencia, Departament d’Astronomia i Astrofı[email protected], [email protected], [email protected]
ABSTRACT
Relativistic Positioning Systems (RPSs) are the sole known locating systems
allowing to construct, in any space-time, primary physical coordinate systems.
The fundamental concepts of the theory of RPSs are already known, but its
implementation needs further development ([1-5]). The basic ingredient of the
theory is a set of four emitters broadcasting their proper times (emission coor-
dinates). In this talk, the main RPSs topics are presented. In particular, for a
basic RPS in a flat space-time, we are interested in the precision with which it
is able to locate space-time events. It appears that this precision is related to
the Jacobian, J , of the transformation from emission to inertial coordinates.
We stress in detail how the value of J is related to the uncertainties in the de-
termination of the position at every event. This result is interesting in current
navigation satellite systems. For instance, among the visible satellite tetrads
for a user, that which provides the more precise user position is the one having
the maximum value of J .
References
[1] B. Coll, Relativistic positioning systems: perspectives and prospects, ActaFutura, 7, 35-47 (2013).
[2] B. Coll, J. J. Ferrando and J. A. Morales-Lladosa, Positioning systems inMinkowski spacetime: from emission to inertial coordinates, Class. QuantumGrav. 27, 065013 (2010).
[3] B. Coll and J. M. Pozo, Relativistic positioning systems: the emission coor-dinates, Class. Quantum Grav. 23, 7395-7416 (2006).
[4] P. Delva, U. Kostic, and A. Cadez, Numerical modeling of a Global Naviga-tion Satellite System in a general relativistic framework, Advances in SpacesResearch, 47, 370-379 (2011).
[5] N. Puchades and D. Saez, Approaches to relativistic positioning around Earthand error estimations, Advances in Spaces Research, 57, 499-508 (2016).
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Malaga, Spain Spanish-Portuguese Relativity Meeting, 2017
On the convexity of relativistic idealmagnetohydrodynamics and the associated gravitational
wave emission
I. Cordero-Carrion
University of Valencia, C/ Dr. Moliner 50, 46100 Burjassot, Valencia (Spain)[email protected]
ABSTRACT
This work has been done in collaboration with J. M. Ibanez, N. Sanchis-
Gual, J.A. Font, M.A. Aloy, J.M. Martı, J.A. Miralles and A. Marquina. We
analyze the influence of the relativistic effects and magnetic field in the con-
vexity properties of the relativistic magnetohydrodynamics system of equations.
To this purpose we use the approach of Lax, based on the analysis of the lin-
early degenerate / genuinely nonlinear nature of the characteristic fields. The
non-relativistic, unmagnetized limits are properly recovered. The characteristic
fields corresponding to the material and Alfven waves are linearly degenerate
and, then, not affected by the convexity issue. The analysis of the characteris-
tic fields associated with the magnetosonic waves reveals, however, a dependence
of the convexity condition on the magnetic field. The result is expressed in the
form of a generalized fundamental derivative written as the sum of two terms
[1]. The first one is the generalized fundamental derivative in the case of purely
hydrodynamical (relativistic) flow [2]. The second one contains the effects of
the magnetic field, and generalizes the non-relativistic magnetic case [3]. To
illustrate the influence of the relativistic effects encoded in the first term, we
present some numerical simulations using an EoS for which the sound speed is
non-monotonous, which implies that the fundamental derivative can be negative
and the EoS non-convex. Non-convex fluid dynamics can yield to the devel-
opment of unusual wave structures such as rarefaction-shocks and compound
waves. We use a non-convex phenomenological EoS to evolve a rotating star as
a toy model and compute the gravitational wave emission.
References
[1] J.M. Ibanez, I. Cordero-Carrion, M.A. Aloy, J.M. Martı and J.A. Miralles.Class. Quantum Grav. 32, 095007 (2015).
[2] J.M. Ibanez, I. Cordero-Carrion, J.M. Martı and J.A. Miralles. Class. Quan-tum Grav. 30, 057002 (2013).
[3] S. Serna and A. Marquina. Phys. Fluids 26, 016101 (2014).
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Spanish-Portuguese Relativity Meeting, 2017 Malaga, Spain
A Hausdorff topology on the future causal boundary: yetanother rapprochement with conformal boundaries
Ivan P. Costa e Silva
Department of Mathematics, Federal University of Santa [email protected]
ABSTRACT
A natural Hausdorff topology τc is defined on the future causal completion M
of a spacetime M with the following desirable features: the chronological future
and pasts of points in M are open, future-directed sequences converge, M is a
open dense set in M and the inclusion i : M → M is open and continuous. In
particular, the induced topology in M coincides with the manifold topology. The
topology τc is shown to be strictly finer than the future chronological topology
introduced in [1] and extensively discussed and championed in [2]. Inspired by
recent work of O. Muller [3], this topology is compared to the future conformal
boundary of M induced by a conformal extension M ↪→ M such that (i) M is a
globally hyperbolic spacetime, (ii) M ⊂ I−(K, M) for some compact set K ⊂ Mand (iii) M is causally convex in M . Of course, the standard conformal exten-
sions of Minkowski, Schwarzschild and Robertson-Walker spacetimes are of this
sort. Although τc is a priori distinct from the (also Hausdorff) topology defined
on the future causal completion in [3], it reproduces results obtained therein for
the future conformal boundary ∂+M := I+(M, M)∩∂M , namely (a) that ∂+M
is a C0 achronal hypersurface in M homeomorphic to a Cauchy hypersurface
in M , and (b) M ∪ ∂+M endowed with the topology induced by its inclusion in
M is homeomorphic to M with the topology τc. The homeomorphism maps the
conformal boundary onto the future causal boundary, so that both boundaries
coincide and are homeomorphic to Cauchy hypersurfaces in M .
References
[1] J.L. Flores, The Causal Boundary of spacetimes revisited, Commun. Math.Phys. 276 (2007), 611-643.
[2] J.L. Flores, J. Herrera and M. Sanchez, On the final definition of the causalboundary and its relation with the conformal boundary, Adv. Theor. Math.Phys. Volume 15 (2011), 991-1058. arXiv:1001.3270
[3] O. Muller, Which spacetimes admit conformal compactifications?, to appearin Adv. Theor. Math. Physics (2017), arXiv:1409.8136.
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Malaga, Spain Spanish-Portuguese Relativity Meeting, 2017
The gravitational “Magnus” effect
L. Filipe Costa
Center for Mathematical Analysis, Geometry and Dynamical Systems(CAMGSD), Instituto Superior Tecnico, Universidade de Lisboa, Portugal
ABSTRACT
It is well known that a spinning body moving in a fluid suffers a force orthog-
onal to its velocity and rotation axis — it is called the Magnus effect. Recent
(indirect) theoretical predictions [1] and numerical simulations [2], inferred from
the effect of a spinning back hole on the surrounding matter, have suggested that
a somewhat analogous effect may take place in gravity, although its magnitude
and precise direction were still unclear. Starting from the rigorous equations of
motion for spinning bodies in General Relativity (Mathisson-Papapetrou-Dixon
equations), we show that indeed such an effect takes place, it is a fundamental
part of the spin-curvature force, and arises whenever, relative to the body, a
current of mass/energy, non-parallel to its spin, exists. We compute it in some
astrophysical systems of interest: a galactic dark matter halo, a black hole ac-
cretion disk, and FLWR spacetime. We consider also the reciprocal problem:
the “force” exerted by the body on the surrounding matter, showing that (from
this perspective) the effect is due to the body’s gravitomagnetic field. In the
process we clarify some common misconceptions regarding the action-reaction
law in post-Newtonian gravity.
References
[1] H. Okawa, V. Cardoso, Phys. Rev. D 90, 104040 (2014).
[2] J. A. Font, J. M. Ibanez, P. Papadopoulos, MNRAS 305, 920 (1999).
[3] L. F. O. Costa, R. Franco, V. Cardoso, to appear.
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Spanish-Portuguese Relativity Meeting, 2017 Malaga, Spain
Notes on geometric inequalities in spherically symmetricspacetimes
Karoly Zoltan Csukas
Wigner Research Center for Physics, [email protected]
ABSTRACT
ADM mass is usually preferred against quasi-local notions of mass in de-
riving geometric inequalities. In spherical symmetry there is a highly accepted
quasi-local notion of mass: the Misner-Sharp mass. It is closely related to the
energy contained within a 2-surface and its null-expansions, which are used to
determine if a surface is trapped. My talk is to present some cases where the
use of the Misner-Sharp mass is rewarding.
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Malaga, Spain Spanish-Portuguese Relativity Meeting, 2017
On the CMB anisotropy deviations between AR-VTG andGR.
Roberto Dale1 and Diego Saez2,3
1Departament d’Estadıstica, Matematiques i Informatica, Universitat MiguelHernandez, 03202-Elx, Alacant, Spain.
[email protected] de Astronomıa y Astrofısica, Universidad de Valencia,
46100-Burjassot, Valencia, Spain.3Observatorio Astronomico, Universidad de Valencia, E-46980 Paterna,
Valencia, [email protected]
ABSTRACT
As is well known, Cosmic Microwave Background (CMB) anisotropies are
divided into two types: those produced at decoupling and before (primary
anisotropies), and the anisotropies generated between the last scattering surface
and the observer (secondary). There is a viable vector-tensor gravity (VTG)
theory, whose vector field produces repulsive forces, and those corresponding
to the cosmological background are identical to the forces produced by vacuum
energy (cosmological constant) [1, 2, 3]. VTG has been also studied in static
spherically symmetric case, in which the existence and number of event horizons
have been proved to be dependent on the value of a certain VTG parameter [4].
There exists opposite gravitational forces in this theory, so it will be hereafter
called AR-VTG (attractive-repulsive vector-tensor gravity). In this paper we
study some differences between the cosmological predictions of AR-VTG and
those of the standard model of general relativity (GR) with cold dark matter
and cosmological constant. In particular, we show that the differences between
the CMB anisotropies of both models are secondary, since they are due to the
so-called late integrated Sachs Wolfe effect.
References
[1] R. Dale, J.A. Morales and D. Saez, arXiv:0906.2085[astro-ph.CO]
[2] R. Dale and D. Saez, Phys. Rev. D, 89, 044035 (2014)
[3] R. Dale and D. Saez, J. Cosmol. Astropart. Phys, 01 (2017) 004
[4] R. Dale, M.J. Fullana and D. Saez, Astrophys. Space Sci. 357, 116 (2015)
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Spanish-Portuguese Relativity Meeting, 2017 Malaga, Spain
The Singularity is Near
Roberto Emparan
ICREA and Universitat de [email protected]
ABSTRACT
I discuss work with Umpei Miyamoto and Jorge Rocha to understand the
violation of cosmic censorship in the evolution and break up of black strings,
using ideas borrowed from the theory of drop formation in fluid jets.
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Malaga, Spain Spanish-Portuguese Relativity Meeting, 2017
On the motion of stars driven by scalar fields
Miguel C. Ferreira
CENTRA, Departamento de Fısica, Instituto Superior Tecnico, Universidade deLisboa,
Avenida Rovisco Pais, 1, 1049 Lisboa, [email protected]
ABSTRACT
Ultra light scalar fields have been predicted in a variety of scenarios and advo-
cated as a possible component of dark matter [1]. Its phenomenology includes the
formation of compact regular structures - boson stars [2] - and, in the presence
of a black hole, of scalar hair [3, 4]. In the latter case, the scalar field modifies
the geometry of the spacetime surrounding the black hole, which gives rise to
non-trivial effects on the motion of bodies orbiting it. We address this question
by analysing an Extreme Mass Ratio Inspiral composed of a super massive black
hole supporting an ultra light scalar field, which is orbited by a compact object
(a stellar mass black hole, a neutron star or a white dwarf). Given the fact
that the mass of the scalar field is very small, we use a perturbative approach
to investigate its contribution to the motion of the compact object. We find
that the presence of the scalar field leaves imprints on the orbital motion of the
compact object, particularly it is responsible for the appearance of resonant or-
bits whose location depend on its mass. The existence of these resonances may
enable angular momentum exchange between the scalar field and the orbiting
object, giving rise to mechanisms similar to planet migration in proto-planetary
discs. These effects have a direct consequence on the orbital evolution of binary
systems and may be used as probes for the existence of scalar fields.
References
[1] L. Hui, J. P. Ostriker, S. Tremaine, and E. Witten, Phys. Rev. D95, 043541(2017), arXiv:1610.08297 [astro-ph.CO]
[2] S. L. Liebling and C. Palenzuela, Living Rev. Rel. 15, 6 (2012),arXiv:1202.5809 [gr-qc]
[3] H. Okawa, H. Witek, and V. Cardoso, Phys. Rev. D89, 104032 (2014),arXiv:1401.1548 [gr-qc]
[4] C. A. R. Herdeiro and E. Radu, Phys. Rev. Lett. 112, 221101 (2014),arXiv:1403.2757 [gr-qc]
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Spanish-Portuguese Relativity Meeting, 2017 Malaga, Spain
The Space of Gravitational Degrees of Freedom
Arthur E. Fischer
Department of Mathematics, University of California, Santa Cruz, CA [email protected]
ABSTRACT
In general relativity, physical states are represented by isometry classesof solutions of Einstein’s field equations. The resulting space Grav(V ) ofthe totality of such states on a 4-dimensional manifold V is known as thespace of gravitational degrees of freedom. We investigate the mathematicalstructure of this space when V is di↵eomorphic to R ⇥ M , where M is aclosed 3-dimensional manifold which represents the spatial cosmic topologyof the universe. One of our main results is how the topology of M getsencoded into the structure of Grav(V ). We give a simple generic topologi-cal condition on M such that for spacetimes with constant mean curvaturehypersurfaces, Grav(V ) has the natural structure of an infinite-dimensionalsymplectic manifold on an open dense subset and that on the complementof this set, a nowhere dense subset, Grav(V ) has singularities which are oforbifold type, that is, of a manifold modulo a finite group action.
Let ⌧ be a real number < 0 and let E⌧ (V ) denote the space of globally-hyperbolic maximally-developed vacuum spacetimes that admit a Cauchy hy-persurface ⌃⌧ with (CMC) constant mean curvature = ⌧. Let D(V ) denotethe group of di↵eomorphisms of V . The space of gravitational degrees offreedom of E⌧ (V ) is then defined to be Grav⌧ (V ) = E⌧ (V )/D(V ). LetCH(M)\C�(M)\C⌧ (M) denote the intersection of the spaces of ADM Cauchydata (g, ⇡) on M that satisfy the Hamiltonian and divergence constraints andthat have constant mean curvature ⌧ . Then we construct a natural bijection
Grav⌧ (V ) ⌘ E⌧ (V )
D(V )
bijection! CH(M) \ C�(M) \ C⌧ (M)
D(M), [g
V] ! [(g⌧ , ⇡⌧ )]
that maps orbits to orbits and which provides a natural parameterization forGrav⌧ (V ).
We give a simple generic topological condition on M , deg M = 0, wheredeg M = max{dim Ig(M) | g 2 Riem(M)} is the maximum dimension of allisometry groups Ig(M) of all Riemannian metrics g on M . This conditionguarantees that the constraint space CMC(⌧) ⌘ CH(M) \ C�(M) \ C⌧ (M) isa smooth global infinite dimensional manifold of Wheeler dimension 713 =(12�1�3�1)13. The orbit space of isometry classes of CMC(⌧) Cauchy data
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Malaga, Spain Spanish-Portuguese Relativity Meeting, 2017
(CH(M) \ C�(M) \ C⌧ (M))/D(M) is then an infinite dimensional manifold ofWheeler dimension 413 = (7�3)13 away from the orbifold type singularitieswhich occur on a nowhere dense set.
We discuss potential applications of our work to 3-manifold geometriza-tion and cosmology, which if successful, would give a dynamical reason, pro-vided by Einstein’s equations, to explain the observed fact that the universeis spatially locally homogeneous and isotropic and in such a state so as tocontinue expanding forever. In such a case, these physical aspects of our uni-verse would be a temporal asymptotic consequence of Einstein’s evolutionequations, rather than having to be imposed externally as part of a cosmo-logical principle, and thus would be a spectacular and dramatic cosmologicalconfirmation of Einstein’s equations.
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Spanish-Portuguese Relativity Meeting, 2017 Malaga, Spain
Kerr–Newman Black Hole in the Formalism of IsolatedHorizons
Ales Flandera and Martin Scholtz
Institute of Theoretical Physics, Faculty of Mathematics and Physics, CharlesUniversity, Czech Republic
ABSTRACT
We study the Kerr-Newman black hole in the formalism of weakly isolated
horizons using a near horizon solution of Einstein’s equations. General form of
such solution has been found by Krishnan in 2012 [1]. His solution establishes
the existence of a null tetrad which is tangent to the horizon and parallelly prop-
agated off the horizon along a non-twisting null geodesic congruence. However,
the explicit construction of such tetrad for the Kerr-Newman metric is not given
in [1]. We formulate apropriate initial data and firstly construct the tetrad in
a perturbative way in the neighborhood of the horizon. Finally, we find also its
exact form everywhere in the Kerr-Newman spacetime.
References
[1] B. Krishnan, Class. Quantum Grav. 29, 205006 (2012).
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Malaga, Spain Spanish-Portuguese Relativity Meeting, 2017
The Einstein-Maxwell equations with thin layers ofpolarized or magnetized matter
Guillermo A. Gonzalez
Grupo de Investigacion en Relatividad y Gravitacion, Escuela de Fısica,Universidad Industrial de Santander, A. A. 678, Bucaramanga 680002, Colombia
ABSTRACT
The Einstein-Maxwell equations for material media when there is a thin layer
of polarized or magnetized matter are presented. By taking for the energy-
momentum tensor of polarized or magnetized matter the expression presented
in [1–3], and using the formalism of tensorial distributions [4–6], discontinuity
conditions through the thin layer of matter are obtained. These conditions are
expressed as relations between the jumps of the electromagnetic potential and
field with the surface polarization-magnetization tensor. By requiring also that
the electromagnetic energy-momentum tensor will be free of quadratic singular
distributions, additional compatibility conditions electromagnetic potential and
the surface polarization-magnetization tensor. Finally, the physical implications
of the obtained conditions are analyzed.
References
[1] R. A. Grot and A. C. Eringen, Int. J. Engng. Sci. 4, 639 (1966).
[2] G. A. Maugin, Ann. Inst. Henri Poincare 15, 275 (1971).
[3] G. A. Maugin, J. Math. Phys. 19, 1198 (1978).
[4] A. Papapetrou and A. Hamouni, Ann. Inst. Henri Poincare 9, 179 (1968).
[5] A. Lichnerowicz, C.R. Acad. Sci. 273, 528 (1971).
[6] A. H. Taub, J. Math. Phys. 21, 1423 (1980).
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Spanish-Portuguese Relativity Meeting, 2017 Malaga, Spain
The causal boundary under the action of isometric groupactions
Jonatan Herrera Fernandez
Departamento de Matematicas, Universidad de Cordoba, [email protected]
ABSTRACT
We discuss how an isometry group G acting freely and properly discontinu-
ously on a spacetime V affects its causal completion. Concretely, we study the
principal covering projection π : V → M , where M = V/G is again a Lorentz
manifold with the induced metric. We show, by means of an example, that such
a map cannot be extended in general to the corresponding causal completions.
However, under certain mild hypotheses we can ensure both the existence of
such an extension and its continuity. Moreover, the extended map allows us to
define a homeomorphism which is also a chronological isomorphism between the
causal completion of M and a suitable quotient of the causal completion of V .
Finally, we present some applications of this result by considering certain iso-
metric group actions over Robertson-Walker spacetimes, including the Anti-de
Sitter model.
This presentation is based on joint work with L. Ake (U. Malaga) [1].
References
[1] L. Ake, J. Herrera, Spacetime coverings and the causal boundary. Journalof High Energy Physics (2017) 2017:51.
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Malaga, Spain Spanish-Portuguese Relativity Meeting, 2017
Specific solutions to Quadratic Gravity
Ondrej Hruska, Michal Karamazov, Robert Svarc
Institute of Theoretical Physics, Faculty of Mathematics and Physics,Charles University
[email protected], [email protected], [email protected]
ABSTRACT
One of the extensions of Einstein’s theory is the Quadratic Gravity, where the
action contains additional terms that are quadratic combinations of Riemann
tensor and its contractions [1], [2]. A metric that admits a non-expanding,
non-twisting and shear-free null geodesic congruence is called the Kundt met-
ric [3]. Its definition is purely geometrical and it does not depend on the field
equations; inserting the Kundt metric into Quadratic Gravity field equations
then gives us restrictions on the metric [4]. We focus on the vacuum solutions
with a cosmological constant. We study specific subcases of the Kundt metric
in Quadratic Gravity, such as the pp-waves and VSI spacetimes, and look for
their geometrical and physical interpretation.
References
[1] Deser, S. and B. Tekin, Energy in Generic Higher Curvature Gravity Theories,Phys. Rev. D 67, 084009 (2003).
[2] Malek, T. and V. Pravda, Types III and N solutions to quadratic gravity,Phys. Rev. D 84, 024047 (2011).
[3] Podolsky, J. and R. Svarc, Algebraic structure of Robinson–Trautman andKundt geometries in arbitrary dimension, Class. Quant. Grav. 32, 015001(2015).
[4] Podolsky, J. and R. Svarc, Kundt and Robinson–Trautman spacetimes inquadratic gravity, Preprint (2016).
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Spanish-Portuguese Relativity Meeting, 2017 Malaga, Spain
Perception tensor and Hawking versus Unruh effect near ablack hole
Gil Jannes
Departamento de Ciencias y Tecnologıa, Universidad Europea de Madrid
ABSTRACT
We show that it is possible to define an objective, tensorial quantity cor-
responding to a seemingly subjective quantity, namely the particle perception
by different observers in a black-hole spacetime [1]. The definition of such a
PeRSET (Perception Renormalized Stress-Energy Tensor) allows for a clean
separation between the Hawking and Unruh effects near a black hole. As a re-
sult, a detector with a generic horizon-crossing trajectory will suffer a buoyancy
force. Surprisingly, when the horizon crossing is attempted at sufficiently low
velocity, this buoyant effect could even be strong enough to prevent the horizon
crossing altogether. [2].
References
[1] L. C. Barbado, C. Barcelo, L. J. Garay and G. Jannes, “A tensorial descrip-tion of particle perception in black-hole physics,” Phys. Rev. D 94, 064004(2016)
[2] L. C. Barbado, C. Barcelo, L. J. Garay and G. Jannes, “Hawking versusUnruh effects, or the difficulty of slowly crossing a black hole horizon,” JHEP1610, 161 (2016)
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Malaga, Spain Spanish-Portuguese Relativity Meeting, 2017
An Ocean Drum: energetics and dynamics in aPhysical Oceanography-Gravitation dialogue
Jose Luis Jaramillo
Institut de Mathematiques de Bourgogne (IMB)[email protected]
ABSTRACT
The main goal of this talk is to discuss a physical setting where mutual
transfer of concepts and tools between Physical Oceanography and Gravita-
tional Physics seems appropriate. Specifically, we revisit the description of the
(mesoscale) slow motions in the ocean, in the setting of the so-called quasi-
geostrophic equations, by adopting a geometric perspective akin to the relativistic
treatments of Gravity [1]. In a first stage, we introduce an effective Rieman-
nian metric in the ocean basin allowing for a rewriting of quasi-geostrophic
energetics in terms of the spectral problem of the associated Laplace-Beltrami
operator. This leads to a toy model naturally admitting an equilibrium statistical
mechanics treatment, aiming at a thermodynamical approach for the study of
stratification and topographic features in the deep ocean. In a second stage, we
briefly discuss the possible insights that this problem might offer into two dis-
tinct gravitational settings: i) stability of apparent black hole horizons, and ii)
propagation of fields on a slowly evolving spacetime background in “wave-mean
flow” theory approach.
References
[1] J.L. Jaramillo, An Ocean Drum: quasi-geostrophic energetics from a geomet-ric perspective, J. Phys. A: Math. Theor. 49, 194005 (2016).doi: 10.1088/1751-8113/49/19/194005
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Spanish-Portuguese Relativity Meeting, 2017 Malaga, Spain
Definitions and examples of Finsler spacetimes
Miguel Angel Javaloyes Victoria
Department of Mathematics, University of [email protected]
ABSTRACT
We will analyze the different definitions of Finsler spacetimes provided by
Beem [3], Asanov [2], Pfeifer-Wohlfarth [7], Kostelecky [6], Javaloyes-Sanchez
[4], Amir-Aazami [1], describing their advantages and disadvantages in every
case, and what type of results can be obtained. Finally we will describe how to
generate a big quantity of examples in order to test the theory [5].
References
[1] A. B. Aazami and M. A. Javaloyes, Penrose’s singularity theorem in aFinsler spacetime, Classical Quantum Gravity, 33 (2016), pp. 025003, 22.
[2] G. S. Asanov, Finsler geometry, relativity and gauge theories, FundamentalTheories of Physics, D. Reidel Publishing Co., Dordrecht, 1985.
[3] J. K. Beem, Indefinite Finsler spaces and timelike spaces, Canad. J. Math.,22 (1970), pp. 1035–1039.
[4] M. A. Javaloyes and M. Sanchez, Finsler metrics and relativistic space-times, Int. J. Geom. Methods Mod. Phys., 11 (2014), p. 1460032 (15 pages).
[5] M. A. Javaloyes and M. Sanchez, Definition and examples of Finslerspacetimes. Preprint, 2017.
[6] V. A. Kostelecky, Riemann-Finsler geometry and Lorentz-violating kine-matics, Phys. Lett. B, 701 (2011), pp. 137–143.
[7] C. Pfeifer and M. Wohlfarth, Causal structure and electrodynamics onfinsler space- times, Phys. Rev. D, 84 (2011).
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Malaga, Spain Spanish-Portuguese Relativity Meeting, 2017
Higher-dimensional NUT-like and near-horizon geometriesfrom the Kerr–NUT–(A)dS metrics
Ivan Kolar
Institute of Theoretical Physics, Faculty of Mathematics and Physics, CharlesUniversity, V Holesovickach 2, 180 00 Prague, Czech Republic
ABSTRACT
The Kerr–NUT–(A)dS metrics describe the gravitational fields of higher-
dimensional black holes rotating in several independent planes of rotation in the
presence of a cosmological constant and NUT parameters. In this talk, I would
like to present several limits of these metrics which we have studied recently [1].
In particular, I will focus on a class of geometries, where some roots of the met-
ric functions degenerate. I will describe our limiting procedure that leads, for
example, to the Taub–NUT–(A)dS spacetime and extreme near-horizon geome-
tries. Also, I will discuss the enhanced symmetries of the resulting spacetimes
which are manifested by the presence of supplementary Killing vectors and the
decomposition of Killing tensors into Killing vectors.
References
[1] I. Kolar and P. Krtous, NUT-like and near-horizon limits of Kerr–NUT–(A)dS, 2017, arXiv:1701.03950 [gr-qc]
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Spanish-Portuguese Relativity Meeting, 2017 Malaga, Spain
Gravitational waves in cosmological spacetimes andmemory effect
Wojciech Kulczycki and Edward Malec
Instytut Fizyki Mariana Smoluchowskiego, Uniwersytet Jagiellonski, Lojasiewicza 11, 30-348 Krakow, Poland
ABSTRACT
We show initial data for gravitational axial waves, that are twice differentiable
but which are not C2. They generate wave pulses that interact with matter in
the radiation cosmological era. This forces the radiation matter to rotate. This
rotation is permanent — it persists after the passage of the gravitational pulse.
The observed inhomogeneities of the cosmic microwave background radiation
put a bound onto discontinuities of superhorizon metric perturbations. Smooth
initial perturbations that are at least C2 give rise to gravitational wave pulses
that do not interact with the background during the radiation epoch. [1].
References
[1] Wojciech Kulczycki and Edward Malec, Axial gravitational waves in FLRWcosmology and memory effect, arXiv:1706.09620
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Malaga, Spain Spanish-Portuguese Relativity Meeting, 2017
EFT of PNG with a spin&
From YM theory to GR: The classical double copy
Michele Levi
Institut de Physique Theorique, CEA Saclay, Universite Paris-Saclay,91191 Gif-sur-Yvette, France
ABSTRACT
1. EFT of PNG with a spin The recent observations of GW signals
emitted by coalescing black hole binaries reinforced the need to get hold of
the analytical description of binary systems made of spinning objects at the
inspiral phase by the post-Newtonian (PN) approximation of Gravity (PNG).
We have entered a new era of high precision GW observations, for which PN
corrections and their related gauge invariant observables are required to high
orders. To this end, we present the main ideas of the Effective Field Theory
(EFT) approach to the PN formalism of the binary inspiral problem, where we
formulated an EFT for gravitating spinning objects. In particular, we present
the complete framework, which we dub “EFT of PNG”, also in terms of its
useful automatization from the fundamental theory stages to the extraction
of Hamiltonians, EOMs, and other gauge invariant observables, such as the
binding energy, and the conserved integrals of motion.
2. From Yang-Mills theory to GR: The classical double copy In
recent years powerful and intriguing duality and correspondence relations have
been discovered in the context of scattering amplitudes in supergravity theories.
The so called color-kinematics duality, and the related double copy correspon-
dence, state that once written in a specific dual form, Yang-Mills amplitudes
can be mapped onto their gravity theory counterparts by applying a prescribed
set of color to kinematics replacement rules. Beyond the opportunity to reveal
more on the underlying origin of these relations at the fundamental level of
the theories, and thus improve our current understanding of gravity, this corre-
spondence offers a compelling novel approach to handle perturbative (and exact)
computations in classical gravity, and in particular also for BHs and GWs. We
will present our first implementations of the classical double copy in gravity.
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Spanish-Portuguese Relativity Meeting, 2017 Malaga, Spain
Chaos of the bound-states in anti-de Sitter spacetime
Jorge Lopes
CENTRA, Instituto Superior [email protected]
ABSTRACT
Chaos is an emergent phenomenon in a wide variety of nonlinear scenarios,
and we will demonstrate that the scalar field in AdS is no exception. We will
give numerical evidences for the presence and properties of chaos in AdS. The
presence of chaos in AdS is critical to understand the thermalization process
because the chaotic behaviour may prevent the field to collapse to a black hole.
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Malaga, Spain Spanish-Portuguese Relativity Meeting, 2017
Throat quantization of theSchwarzschild-Tangherlini(-AdS) black hole
Hideki Maeda
Department of Electronics and Information Engineering, Hokkai-GakuenUniversity, Sapporo 062-8605, Japan
ABSTRACT
Adopting the throat quantization pioneered by Louko and Makela [1], we de-
rive the mass and area spectra for the arbitrary-dimensional Schwarzschild-
Tangherlini black hole and its AdS and topological generalizations in the sta-
tionary state [2]. While area/entropy is equally spaced for asymptotically flat
black holes, mass is equally spaced in the asymptotically AdS case. We also in-
vestigate physical properties of the toroidal AdS black hole in the non-stationary
state described by exact wave functions [3].
References
[1] J. Louko and J. Makela, Phys. Rev. D 54, 4982 (1996).
[2] G. Kunstatter and H. Maeda, Class. Quant. Grav. 31, 115009 (2014).
[3] H. Maeda and G. Kunstatter, in preparation.
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Spanish-Portuguese Relativity Meeting, 2017 Malaga, Spain
A holographic stress-energy tensor near the Cauchyhorizon inside a rotating black hole
Kengo Maeda
Faculty of Engineering, Shibaura Institute of Technology, Saitama, 330-8570,[email protected]
ABSTRACT
We investigate a stress-energy tensor for a 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 per-
turbatively construct a black droplet solution by applying the “derivative expan-
sion” method, generalizing the work of Haddad [4], 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 quan-
tum 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.
References
[1] N. Haddad, “Black Strings Ending on Horizons,” Class. Quantum Grav. 29(2012) 245001.
[2] W. A. Hiscock, “Stress-energy tensor near a charged, rotating, evaporatingblack hole,” Phys. Rev. D 15 (1977) 3054.
[3] J. Maldacena, “The Large N limit of superconformal field theories and super-gravity” Adv. Theor. Math. Phys. 2 (1998) 231, O. Aharony, S. Gubser, J.Maldacena, H. Ooguri, and Y. Oz, “Large N field theories, string theory andgravity” Phys. Rep. 323 (2000) 183.
[4] N. Haddad, “Hawking Radiation from Small Black Holes at Strong Couplingand Large N,” Class. Quantum Grav. 30 (2013) 195002.
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Malaga, Spain Spanish-Portuguese Relativity Meeting, 2017
Energy problem in the regular black hole spacetimes
V.S. Manko
Departamento de Fısica, Centro de Investigacion y de Estudios Avanzados delIPN, A.P. 14-740, 07000 Ciudad de Mexico, Mexico
E. Ruiz
Instituto Universitario de Fısica Fundamental y Matematicas, Universidad deSalamanca, 37008 Salamanca, Spain
ABSTRACT
We discuss an important property of various known singularity-free models of
black holes obtained in the framework of Einstein’s gravity coupled to nonlinear
electromagnetism — the equality of the total electromagnetic energy to the total
mass [1]. We show that this property is characteristic of a large family of
solutions of this type.
References
[1] V.S. Manko and E. Ruiz, Phys. Lett. B 760 (2016) 759.
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Spanish-Portuguese Relativity Meeting, 2017 Malaga, Spain
Stirring a black hole
Julija Markeviciute†, and Jorge E. Santos
DAMTP, University of [email protected]
ABSTRACT
I will present novel asymptotically AdS4 solutions, constructed by turning on
a dipolar differential rotation at the conformal boundary. At fixed energy and
boundary profile, we find two different geometries: a horizonless AdS soliton,
and a deformed black hole with zero net angular momentum, both of which exist
up to some maximum amplitudes of the boundary profile. For sufficiently high
temperatures, the large black holes are elastic and have an extended hourglass
shape. At the maximum amplitude, these hot, large black holes develop an
ergoregion attached to the boundary, which signals a superradiant instability.
I will discuss the full phase diagram, including the possibility of phases with
disconnected horizons, by considering the Mathisson-Papapetrou equations for
a spinning test particle. Finally, I will comment on the possible implications of
this work for weak cosmic censorship.
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Malaga, Spain Spanish-Portuguese Relativity Meeting, 2017
Black hole formation with a conformally coupled scalarfield in three spacetime dimensions
Cristian Martınez
Centro de Estudios Cientıficos (CECs), Av. Arturo Prat 514, Valdivia, [email protected]
ABSTRACT
We study the black hole formation in three spacetime dimensions by consid-
ering a self-interacting scalar field conformally coupled to gravity in presence
of a negative cosmological constant. We find two classes of time-dependent
exact solutions. The first class contains configurations that evolve to a known
static hairy black hole [1, 2], and also includes the particular solution recently
obtained in [3]. The second type is characterized by solutions with a vanish-
ing energy-momentum tensor, which represent a stealth scalar field overflying
a BTZ black hole [4].
References
[1] C. Martınez and J. Zanelli, “Conformally dressed black hole in (2+1)-dimensions,” Phys. Rev. D 54, 3830 (1996).
[2] M. Henneaux, C. Martınez, R. Troncoso and J. Zanelli, “Black holes andasymptotics of 2+1 gravity coupled to a scalar field,” Phys. Rev. D 65, 104007(2002).
[3] W. Xu, “Exact black hole formation in three dimensions,” Phys. Lett. B 738,472 (2014).
[4] E. Ayon-Beato, C. Martınez and J. Zanelli, “Stealth scalar field overflying a(2+1) black hole,” Gen. Rel. Grav. 38, 145 (2006).
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Spanish-Portuguese Relativity Meeting, 2017 Malaga, Spain
Black Holes in the Generalized Proca Theory
Masato Minamitsuji
Centro Multidisciplinar de Astrofisica - CENTRA, Instituto Superior Tecnico -IST, Universidade de Lisboa - UL, Avenida Rovisco Pais 1, 1049-001, Portugal
ABSTRACT
We investigate static and spherically symmetric black hole solutions in the
generalized Proca theory which corresponds to the generalization of the shift-
symmetric scalar-tensor Horndeski theory to the vector-tensor theory [1]. Any
solution obtained in this paper possesses a constant spacetime norm of the vec-
tor field, X := −12gµνAµAν = X0 = constant. The solutions in the theory
with generalized quartic coupling G4(X) generalize the stealth Schwarzschild
[2] and the Schwarzschild- (anti-) de Sitter [3] solutions obtained in the the-
ory with the nonminimal coupling to the Einstein tensor GµνAµAν . While in
the vector-tensor theory with the coupling GµνAµAν the electric charge does
not explicitly affect the spacetime geometry, in more general cases with nonzero
G4XX(X0) 6= 0 this property does not hold in general. The solutions in the
theory with generalized cubic coupling G3(X) are given by the Schwarzschild-
(anti-) de Sitter spacetime, where the dependence on G3(X) does not appear in
the metric function.
References
[1] L. Heisenberg, JCAP 1405, 015 (2014) doi:10.1088/1475-7516/2014/05/015[arXiv:1402.7026 [hep-th]].
[2] J. Chagoya, G. Niz and G. Tasinato, Class. Quant. Grav. 33, no. 17, 175007(2016) doi:10.1088/0264-9381/33/17/175007 [arXiv:1602.08697 [hep-th]].
[3] M. Minamitsuji, Phys. Rev. D 94, no. 8, 084039 (2016)doi:10.1103/PhysRevD.94.084039 [arXiv:1607.06278 [gr-qc]].
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Malaga, Spain Spanish-Portuguese Relativity Meeting, 2017
Innermost stable circular orbits in dilatonicEinstein-Gauss-Bonnet theory
Sindy Mojica1
in collaboration with Burkhard Kleihaus2, Jutta Kunz2 andGuillermo A. Gonzalez1
1Grupo de Investigacion en Relatividad y Gravitacion, Escuela de Fısica,Universidad Industrial de Santander, A.A. 678, Bucaramanga 680002, Colombia.
2Institut fur Physik, Universitat Oldenburg, D-26111 Oldenburg, [email protected]
ABSTRACT
Rapidly rotating compact objects are considered laboratories to test General
Relativity and theories beyond. Motivated by string theory astrophysical com-
pact objects in dilatonic Einstein-Gauss-Bonnet theory (dEGB) were studied in
[1],[2],[3],[4] showing the effects of the dilaton on the astrophysical signatures
of black holes and neutron stars. Solutions in General Relativity are compared
with the results obtained in dEGB, especially the innermost stable circular orbit
(ISCO) which is affected by the presence of the scalar field. It is expected that
such effects might be observable in astrophysical systems.
References
[1] Kleihaus, Burkhard and Kunz, Jutta and Mojica, Sindy, Quadrupole mo-ments of rapidly rotating compact objects in dilatonic Einstein-Gauss-Bonnettheory, PhysRevD.90.061501, 2014.
[2] Kleihaus, B. and Kunz, J. and Mojica, S. and Zagermann, M., Rapidly Ro-tating Neutron Stars in Dilatonic Einstein-Gauss-Bonnet Theory, Phys. Rev.D 93, 064077, 2016.
[3] Kleihaus, Burkhard and Kunz, Jutta and Radu, Eugen, Rotating Black Holesin Dilatonic Einstein-Gauss-Bonnet Theory, PhysRevLett.106.151104, 2011.
[4] Kleihaus, Burkhard and Kunz, Jutta and Moica, Sindy and Radu, Eu-gen, Spinning black holes in Einstein-Gauss-Bonnet-dilaton theory: non-perturbative solutions, Phys. Rev. D 93, 044047, 2016.
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Spanish-Portuguese Relativity Meeting, 2017 Malaga, Spain
Absorption of scalars by black holes in string theory
Filipe Moura
Centro de Matematica da Universidade do Minho,Escola de Ciencias, Campus de Gualtar,
4710-057 Braga, [email protected]
ABSTRACT
We show that the low frequency absorption cross section of minimally coupled
test massless scalar fields by extremal spherically symmetric black holes in d di-
mensions is equal to the horizon area, even in the presence of string–theoretical
α′ corrections. Classically one has the relation σ = 4GS between that absorp-
tion cross section and the black hole entropy. By comparing in each case the
values of the horizon area and Wald’s entropy, we discuss the validity of such
relation in the presence of higher derivative corrections for extremal black holes
in many different contexts: in the presence of electric and magnetic charges;
for nonsupersymmetric and supersymmetric black holes; in d = 4 and d = 5
dimensions. The examples we consider seem to indicate that this relation is
not verified in the presence of α′ corrections in general, although being valid in
some specific cases (electrically charged maximally supersymmetric black holes
in d = 5). We argue that the relation should be valid for the absorption cross
section of scalar fields which are part of the model (and not “test”), at least in
string theory.
References
[1] F. Moura, Absorption of scalars by extremal black holes in string theory,submitted to Gen. Rel. Grav. [arXiv:1406.3555 [hep-th]].
[2] F. Moura, Absorption of scalars by nonextremal charged black holes in stringtheory, Gen. Rel. Grav. 47 (2015) 12, 148 [arXiv:1406.2012 [hep-th]].
[3] F. Moura, Scattering of spherically symmetric d-dimensional α′−correctedblack holes in string theory, JHEP 1309 (2013) 038 [arXiv:1105.5074
[hep-th]].
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Malaga, Spain Spanish-Portuguese Relativity Meeting, 2017
Initializing gravitational evolutions withinthe parabolic-hyperbolic formulation – black holes binary
Anna Nakonieczna
Faculty of Physics, University of Warsaw, Pasteura 5, 02-093 Warsaw, [email protected]
ABSTRACT
The parabolic-hyperbolic formulation of the initial data of the Einstein equa-
tions for multiple black holes systems has been proposed recently [1–3]. It pro-
vides an alternative to the traditional conformal method [4]. During the talk,
a numerical implementation of the above-mentioned evolutionary approach to
the initial data problem of general relativity will be presented. It will involve
a binary system composed of superposed Kerr-Schild black holes.
References
[1] I.Racz, Constraints as evolutionary systems, Class. Quant. Grav. 33, 015014(2016).
[2] I.Racz, A simple method of constructing binary black hole initial data,arXiv:1605.01669 (2017).
[3] I.Racz, On the ADM charges of multiple black holes, arXiv:1608.02283 (2017).
[4] G.B.Cook, Initial data for numerical relativity, Living Rev. Rel. 3, 5 (2000).
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Spanish-Portuguese Relativity Meeting, 2017 Malaga, Spain
Advanced wave extraction algorithmsin numerical relativity
Andrea Nerozzi
Centro Multidisciplinar de Astrofısica - CENTRA, Departamento de Fısica,Instituto Superior Tecnico - IST, Universidade de Lisboa - UL, Avenida Rovisco
Pais 1, 1049-001 Lisboa, [email protected]
ABSTRACT
With the recent detection of gravitational waves and the expected improve-
ments in accuracy of current and future experiments, it is of primary impor-
tance that numerical simulations achieve higher degrees of accuracy as well.
In particular, the process of extracting gravitational waveforms from numeri-
cal simulations can be still subject by possible systematic errors, mostly because
of the gauge freedom that is encountered along the way. I will present recent
results in the field of wave extraction using the Newman-Penrose (NP) formal-
ism, specifically aiming to remove all gauge ambiguities in the calculation of
the NP quantities at finite radius. I will also discuss possible extensions of this
methodology to obtain a gauge fixed signal at null infinity.
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Malaga, Spain Spanish-Portuguese Relativity Meeting, 2017
Particle collision with an arbitrarily high center-of-massenergy near a Banados-Teitelboim-Zanelli black hole
Kota Ogasawara
Department of Physics, Rikkyo University, Toshima, Tokyo 171-8501, [email protected]
ABSTRACT
We consider a particle collision with a high center-of-mass energy near a
Banados-Teitelboim-Zanelli (BTZ) black hole. We obtain the center-of-mass
energy of two general colliding geodesic particles in the BTZ black hole space-
time. We show that the center-of-mass energy of two ingoing particles can be
arbitrarily large on an event horizon if either of the two particles has a critical
angular momentum and the other has a noncritical angular momentum. We
also show that the motion of a particle with a subcritical angular momentum
is allowed near an extremal rotating BTZ black hole and that a center-of-mass
energy for a tail-on collision at a point can be arbitrarily large in a critical
angular momentum limit. [1].
References
[1] N. Tsukamoto, K. Ogasawara, and Y. Gong, Phys. Rev. D 96, 024042 (2017).
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Spanish-Portuguese Relativity Meeting, 2017 Malaga, Spain
Universal electromagnetic fields
Marcello Ortaggio
Institute of Mathematics of the Czech Academy of Sciences,Zitna 25, 115 67 Prague 1, Czech Republic
ortaggio(at)math(dot)cas(dot)cz
ABSTRACT
Already in the 30s, Schroedinger observed that all null Maxwell fields solve
the equations for the electromagnetic field in any non-linear electrodynamics.
More generally, we study properties of “universal” p-forms, i.e., electromagnetic
fields that solve simultaneously any generalized electrodynamics (for which the
field equations contain arbitrary powers and derivatives of the field strenght).
Some results including the coupling to Einstein’s gravity are also discussed, and
analogies with “universal spacetimes” (which solve simultaneously virtually any
theory of gravity) mentioned.
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Malaga, Spain Spanish-Portuguese Relativity Meeting, 2017
Self-consistency of higher-order gravities
Tomas Ortın
Instituto de Fısica Teorica UAM/CSICC/ Nicolas Cabrera, 13–15, C.U. Cantoblanco, E-28049 Madrid, Spain
ABSTRACT
We show that, in all metric theories of gravity with a general covariant action,
gravity couples to the gravitational energy-momentum tensor in the same way it
couples to the matter energy-momentum tensor order by order in the weak field
approximation around flat spacetime. We discuss the relation of this property
to the Strong Equivalence Principle, the self-consistency problem and bootstrap.
This talk is based on ref. [1]
References
[1] T. Ortın, “Higher order gravities and the Strong Equivalence Principle,”arXiv:1705.03495 [gr-qc].
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Spanish-Portuguese Relativity Meeting, 2017 Malaga, Spain
Relativistic low angular momentum accretion.
Michal Pirog
Jagiellonian [email protected]
ABSTRACT
I will report on the results of the joint numerical project with J.A. Font and
P. Mach. We investigated low angular momentum accretion of inviscid fluids
on black holes. The Newtonian calculation in this topic have been already done
by D. Proga and M. Begelman [1]. Our work promotes their models to fully
relativistic setting. The staring point of those simulations is the Bondi-type
accretion solution, perturbed by adding a small amount of angular momentum.
The results of simulations will be discussed, emphasizing the similarities and
differences with Newtonian models.
References
[1] D. Proga, M. Begelman, Accretion of Low Angular Momentum Material ontoBlack Holes: Two-dimensional Hydrodynamical Inviscid Case, Astrophys. J.582, 69 (2003).
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Malaga, Spain Spanish-Portuguese Relativity Meeting, 2017
On exact solutions to quadratic gravity
Alena Pravdova
Institute of Mathematics of the Czech Academy of Sciences,Zitna 25, 115 67 Prague 1, Czech Republic
ABSTRACT
Quadratic gravity arises by adding corrections quadratic in the curvature
to the Einstein-Hilbert action. Corresponding field equations are considerably
more involved than the Einstein equations and as a result very few exact solu-
tions are known, mostly various generalizations of pp-waves with traceless Ricci
tensor of type N. We prove that in quadratic gravity under quite general as-
sumptions, the traceless Ricci tensor of type N or III implies that the spacetime
is Kundt, explaining thus in retrospect why virtually all known exact solutions
in quadratic gravity are Kundt. We also present examples of new Kundt and
non-Kundt vacuum solutions. We also show that static spherically symmetric
non-Schwarzschild vacuum black hole in quadratic gravity, recently discovered
by Lu, Perkins, Pope, and Stelle using numerical methods, is conformal to
Kundt and show how this simplifies mathematical description of the problem.
This talk is based on joint works with J. Podolsky, V. Pravda and R. Svarc
[1, 2].
References
[1] V. Pravda, A. Pravdova, J. Podolsky, and R. Svarc, Exact solutions toquadratic gravity, Phys. Rev. D95 (2017) 084025.
[2] J. Podolsky, V. Pravda, A. Pravdova, and R. Svarc, in preparation (2017)
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Spanish-Portuguese Relativity Meeting, 2017 Malaga, Spain
Four of a kind: I-Love-Q-δM
Borja Reina
Dublin City University, Universidad del Paıs [email protected]
ABSTRACT
In a recent work [1] we applied a rigorous perturbed matching framework [2]
to show the amendment of the mass of rotating stars in Hartle’s model [3].
Here, we apply this framework to the tidal problem in binary systems [4]. Our
approach fully accounts for the correction to the Love numbers needed to obtain
the universal I-Love-Q relations [5]. This correction arises from the jump in
the first derivative of one of the functions in the perturbations at the surface of
the star, proportional to the energy density there. Hence it is relevant for linear
equations of state, used to model quark stars. The combination of this correction
for tidal numbers and the correction for the mass of rotating stars allows us to
find a universal relation involving the second-order contribution to the mass
δM . We thus complete the set of universal relations for the tidal problem in
binary systems, involving four perturbation parameters, namely I, Love, Q, and
δM . These relations can be used to obtain the perturbation parameters directly
from observational data.
References
[1] B. Reina and R. Vera (2015) Revisiting Hartle’s model using perturbedmatching theory to second order: amending the change in mass. Class. Quan-tum Grav. 32 155008.
[2] M. Mars (2005) First and second order perturbations of hypersurfaces. Class.Quantum Grav. 22 3325–3348.
[3] J. B. Hartle (1967) Slowly Rotating Relativistic Stars. I. Equations of Struc-ture. Astrophys. J. 150 1005–1029.
[4] B. Reina, N. Sanchis-Gual, R. Vera and J. A. Font (2017) Completionof the universal I-Love-Q relations in compact stars including the mass.arXiv :1702.04568
[5] K. Yagi and N. Yunes (2013) I-Love-Q: Unexpected Universal Relations forNeutron Stars and Quark Stars. Science 341 365-368
K. Yagi and N. Yunes (2014) Erratum for the Report: ”I-Love-Q: UnexpectedUniversal Relations for Neutron Stars and Quark Stars” by K. Yagi and N.Yunes Science 344 1250349
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Malaga, Spain Spanish-Portuguese Relativity Meeting, 2017
Rotating BTZ black hole assuming running couplings
Angel Rincon
Instituto de Fısica, Pontifıcia Universidad Catolica de Chile,Av. Vicuna Mackenna 4860, Santiago, Chile
ABSTRACT
In the present work a generalization of the rotating BTZ black hole for the case
of scale dependent couplings is studied. One starts by using the effective action
for scale dependence couplings to derive a generalization of the corresponding
Einstein field equations. Moreover, one obtains new solutions for lapse func-
tion, cosmological coupling and Newtons coupling. In addition, we show the
effect of scale dependent couplings on the classical solution. Besides, asymp-
totic behaviour as well as thermodynamic properties were computed in detail.
References
[1] B. Koch, I. A. Reyes and A. Rincon, Class. Quant. Grav. 33, no. 22, 225010(2016) doi:10.1088/0264-9381/33/22/225010 [arXiv:1606.04123 [hep-th]].
[2] A. Rincon, B. Koch and I. Reyes, J. Phys. Conf. Ser. 831, no. 1, 012007(2017) doi:10.1088/1742-6596/831/1/012007 [arXiv:1701.04531 [hep-th]].
[3] A. Rincon, E. Contreras, P. Bargueno, B. Koch, G. Panotopoulos andA. Hernandez-Arboleda, arXiv:1704.04845 [hep-th].
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Spanish-Portuguese Relativity Meeting, 2017 Malaga, Spain
Dynamical spacetimes in low-energy string theory andcosmic censorship
Jorge Rocha
Departament de Fısica Quantica i Astrofısica, Institut de Ciencies del Cosmos,Universitat de Barcelona, Martı i Franques 1, E-08028 Barcelona, Spain
ABSTRACT
Stationary black holes in low-energy string theory have been investigated for
decades but little is known about their non-stationary counterparts. I will dis-
cuss spherically symmetric — but time-dependent — solutions of the Einstein-
Maxwell-axion-dilaton system, which arises as its low-energy effective descrip-
tion. Two new classes of exact radiating spacetimes with constant electric and
magnetic charges will be presented, and their intricate causal structure is clari-
fied. An even larger class of dynamical spacetimes describing the accretion (or
radiation) of null dust is also obtained. It is shown that, within this family
of solutions, a black hole cannot turn into a naked singularity if the null dust
satisfies standard energy conditions. This result supports the cosmic censorship
conjecture in the context of effective string theory.
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Malaga, Spain Spanish-Portuguese Relativity Meeting, 2017
A hyperbolic theory of relativistic conformal dissipativefluids
Marcelo E. Rubio∗
FaMAF – UNC, IFEG – CONICET, (5000) Cordoba, [email protected]
ABSTRACT
We develop a complete description of the class of conformal relativistic dissi-
pative fluids of divergence form, following the formalism carried out by Geroch
and Lindblom in the early 90’s. These theories are described in terms of evolu-
tion variables whose dynamics is governed by total divergence-type equations.
More specifically, we give a characterization of the whole family of conformal
fluids in terms of a single master scalar function up to second order in dissi-
pative variables. We identify the equilibrium states of the theory, and derive
the corresponding constitutive relations, as well as a Fourier-like law for heat
conduction. Finally, we prove that these type of theories is symmetric hyper-
bolic, implying that, under certain algebraic conditions, there exists a well posed
initial value problem for the evolution equations.
∗Work in collaboration with Luis Lehner and Oscar Reula.
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Spanish-Portuguese Relativity Meeting, 2017 Malaga, Spain
Singular and nonsingular black holes in f(R) theories andbeyond
Diego Rubiera-Garcia
Institute of Astrophysics and Space Sciences, Lisbon University (Portugal)[email protected]
ABSTRACT
The search for regular black holes in the literature usually focus on obtain-
ing bounded curvature scalars, despite the fact that the singularity theorems are
based instead of the (in)completeness of geodesics. In this talk I consider a fam-
ily of quadratic f(R) extensions of General Relativity coupled to an anisotropic
fluid satisfying standard energy conditions to show that, in black hole space-
times obtained in these extensions, divergences in the curvature scalars are not
necessarily correlated to geodesic incompleteness. Further, using generalizations
under the form of Ricci-squared terms and Born-Infeld-type actions I show that
spacetimes containing curvature divergences are not unavoidably pathological.
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Malaga, Spain Spanish-Portuguese Relativity Meeting, 2017
Homogeneous Solutions of Minimal Massive 3D Gravity
Nihat Sadik Deger
Department of Mathematics, Bogazici University, [email protected]
ABSTRACT
In this talk we construct simply transitive homogeneous solutions of the three-
dimensional Minimal Massive Gravity (MMG) model [1]. In addition to those
that have analogs in Topologically Massive Gravity [2], such as warped AdS and
pp-waves, there are several solutions genuine to MMG. Among them, there is a
stationary Lifshitz metric with the dynamical exponent z=-1 and an anisotropic
Lifshitz spacetime where all coordinates scale differently. Moreover, we identify
a homogeneous Kundt solution at the chiral point of the theory. We also show
that in a particular limit of the physical parameters in which the Cotton tensor
drops out from the MMG field equation, homogeneous solutions exist only at the
merger point in the parameter space if they are not conformally flat.
References
[1] E. Bergshoeff, O. Hohm, W. Merbis, A.J. Routh and P.K. Townsend, MinimalMassive 3D Gravity, Class.Quant.Grav. 31 (2014) 145008, arXiv:1404.2867.
[2] S. Deser, R. Jackiw and S. Templeton, Topologically Massive Gauge Theories,Ann.Phys. 140 (1982) 372.
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Spanish-Portuguese Relativity Meeting, 2017 Malaga, Spain
Ehlers-Kundt conjecture about Gravitational Waves
Miguel Sanchez
Departamento de Geometrıa y Topologıa, Univ. Granada.Facultad de Ciencias, Campus Fuentenueva s/n. E-18071 Granada (Spain)
ABSTRACT
Ehlers-Kundt conjecture asserts that all geodesically complete gravitational
pp-waves must be plane waves. Mathematically, it becomes equivalent to a prob-
lem on the Euclidean plane R2 with a very simple formulation in Classical Me-
chanics: given a non-necessarily autonomous potential V (z, u), (z, u) ∈ R2×R,
harmonic in z (i.e. source-free), the trajectories of its associated dynamical sys-
tem z(s) = −∇zV (z(s), s) are complete (living eternally) if and only if V (z, u)
is a polynomial in z of degree at most 2 (that is, V is a standard mathemat-
ical idealization of vacuum). Along the talk, the conjecture will be discussed
and solved in the significative case that V is bounded polynomially in z at any
u ∈ R. Based in joint work with J.L. Flores, [1].
References
[1] J.L. Flores, M. Sanchez, Ehlers-Kundt Conjecture about Gravitational Wavesand Dynamical Systems, arxiv: 1706.03855.
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Malaga, Spain Spanish-Portuguese Relativity Meeting, 2017
Analogue Gravity from Quantum potential inducedBose-Einstein Condensates (BEC): UV-IR Coupling in
Analogue Hawking radiation
Supratik Sarkar1, A. Bhattacharyay1
1 Indian Institute of Science Education and Research (IISER) - Pune, [email protected]
ABSTRACT
The presence of the Lorentz-breaking quantum potential term in the non-
local BEC model apparently gives rise to the massive scalar excitations for large
wavelength phonon modes (of O(1/ξ)) characterized by a ‘massive’ minimally
coupled free Klein-Gordon equation in the context of experimental observations
of analogue Hawking radiation where at least one spatial dimension is kept free
to allow for the source/sink of the background fluid flow [1]. Thus arising out
of a non-relativistic non-local BEC, an Analogue gravity model is formulated
upto O(ξ2) accuracy in the presence of the quantum potential term for a canon-
ical acoustic black hole in (3+1)-d spacetime. A UV-IR coupling between short
wavelength ‘primary’ modes (which are supposedly Hawking radiated through the
sonic event horizon) and the large wavelength ‘secondary’ modes is the strik-
ing upshot which is inevitable in the quantum gravity experiments of analogue
Hawking radiation in the laboratory. These ‘secondary’ modes would grow over
space by gaining energy from the Hawking radiated quanta (‘primary’ modes)
that are distinguished by their characteristic features of the respective growth
rates [2]. .
References
[1] Supratik Sarkar and A. Bhattacharyay, Phys. Rev. D 93, 024050 (2016).
[2] Supratik Sarkar and A. Bhattacharyay, arXiv 1703.08027 [gr-qc] (2017).
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Spanish-Portuguese Relativity Meeting, 2017 Malaga, Spain
Area deficit of geodesic balls and gravitational energy
Jose M M Senovilla
Fısica teorica, Universidad de Paıs Vasco, Apartado 644, 48080 Bilbao, [email protected]
ABSTRACT
Gravity manifests itself as curvature of spacetime, and its strength can be
measured by considering the deficit of the volume of small geodesic balls with
respect to their counterparts in flat spacetime. The area deficit of the enclosing
boundaries can actually be put in relation, via the Einstein field equations, with
the energy density of matter at the ball’s centre, and this led Jacobson to pro-
pose a novel “maximal entanglement hypothesis”, establishing a thermodynamic
principle for quantum gravitational theories [1].
In this contribution we consider what happens when the matter energy density
vanishes. The area still feels the effect of pure gravity, and this change should
be related to the gravitational strength, or in simple words, to the gravitational
energy density with respect to the mentioned observer. The area deficit now
involves terms quadratic in the curvature related to classical quantities [2], but
there arise some subtleties and ambiguities to be resolved.
Work based on a collaboration with Ted Jacobson and Antony Speranza.
References
[1] T. Jacobson, Entanglement equilibrium and the Einstein equation, Phys. Rev.Lett. 116 (2016) 201101
[2] J.M.M. Senovilla, Super-energy tensors, Classical and Quantum Gravity 17(2000) 2799.
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Malaga, Spain Spanish-Portuguese Relativity Meeting, 2017
Quantum corrected Friedmann equations from loopquantum black holes entropy-area relation
C. A. S. Silva
Instituto Federal de Educacao, Ciencia e Tecnologia da Paraıba - CampusCampina Grande
ABSTRACT
Based upon the holographic principle, Jacobson demonstrated that the space-
time can be viewed as a gas of atoms with a related entropy given by the
Bekenstein-Hawking formula [1]. Following this argument, Friedmann equa-
tions can be derived by using Clausius relation to the apparent horizon of
Friedmann-Robertson-Walker (FRW) universe [2]. Loop Quantum Gravity is a
propose to description of the spacetime behavior in situations where its atomic
characteristic arises. Among these situations, the behavior of our universe near
the Big Bang singularity is described by Loop Quantum Cosmology (LQC). How-
ever, a derivation of the LQC equations based on the Bekenstein bound is lack-
ing. In this work, we obtain the quantum corrected Friedmann equations from
the entropy-area relation given by loop quantum black holes (LQBH), setting a
still absent connection between holographic and LQC descriptions of the cosmos.
Connections with braneworld cosmology have been also addressed.
References
[1] T. Jacobson, Phys. Rev. Lett. 75 (1995) 1260.
[2] R. G. Cai and S. P. Kim, JHEP 0502 (2005) 050.
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Spanish-Portuguese Relativity Meeting, 2017 Malaga, Spain
Quantum Null Energy Conditionfrom Numerical Holography
Philipp Stanzer
Institute for Theoretical Physics, TU Wien, Vienna, [email protected]
ABSTRACT
Since all the classical energy conditions fail at some point, it is necessary to
improve them. The quantum null energy condition is a novel approach for a
local energy condition valid also in relativistic quantum field theories. In the
past two years several proofs for this conjecture were provided, with increasing
generality. In this talk I am going to present the first examples where the QNEC
is calculated explicitly and its (non-)saturation is studied.
In addition to the analytic result for vacuum, we were able to calculate the
entanglement entropy of a thermal state using numerical holography. Further
we investigate a system of colliding lumps of energy in which the classical null
energy condition is violated.
References
[1] “Exploring nonlocal observables in shock wave collisions,”C. Ecker, D. Grumiller, P. Stanzer, S. A. Stricker and W. van der Schee,J. High Energ. Phys. (2016) 2016: 054.doi:10.1007/JHEP11(2016)054
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Malaga, Spain Spanish-Portuguese Relativity Meeting, 2017
Wormhole models without symmetries
Otakar Svıtek
Institute of Theoretical Physics, Faculty of Mathematics and Physics, CharlesUniversity, V Holesovickach 2, 180 00 Prague 8, Czech Republic
ABSTRACT
We present two types of wormholes based on the Robinson–Trautman class of
spacetimes generally containing geometries without symmetries. The first one
is a global model sourced by a ghost scalar field where we study asymptotics, sta-
bility and other issues. The second one is a thin-shell model which approaches
a simple spherically symmetric wormhole in the distant future. The generaliza-
tion of the second model to higher dimensions provides a possibility of avoiding
the energy condition violation.
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Spanish-Portuguese Relativity Meeting, 2017 Malaga, Spain
Spacetimes with Nonlinear Electrodynamics
Tayebeh Tahamtan
Institute of Theoretical Physics, Faculty of Mathematics and Physics, CharlesUniversity, V Holesovickach 2, 180 00 Prague 8, Czech Republic
ABSTRACT
Recently, substantial attention was devoted to study the role of different mod-
els of Nonlinear Electrodynamics in curing the spacetime singularities thus ob-
taining regular black holes. These models usually considered highly symmetric
situations. We would like to address the genericity of this and other features in
a more general setup. We will also study the interplay between the resolution
of curvature and electromagnetic field singularities.
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Malaga, Spain Spanish-Portuguese Relativity Meeting, 2017
Supersymmetric solution in dynamical M-brane background
Kunihito Uzawa
Department of Physics, School of Science and Technology, Kwansei GakuinUniversity, Sanda, Hyogo 669-1337, Japan
ABSTRACT
The supersymmetry arises in certain theories of fermions coupled to gauge
fields and gravity in a spacetime of eleven dimensions [1]. The dynamical brane
backgrounds have mainly been studied for the class of purely bosonic solutions
only [2, 3, 4], but developments involving time-dependent supersymmetric so-
lution have made it clear that one can get more information by asking what
happens on dynamical brane systems [5]. In this presentation, we show an
exact supersymmetric solution of dynamical M-brane background in the eleven-
dimensional supergravity and consider applications to dynamics of geodesic mo-
tion and black hole physics.
References
[1] E. Cremmer, B. Julia and J. Scherk, “Supergravity Theory in Eleven-Dimensions,” Phys. Lett. 76B (1978) 409.
[2] G. W. Gibbons, H. Lu and C. N. Pope, “Brane worlds in collision,” Phys.Rev. Lett. 94 (2005) 131602 [arXiv:hep-th/0501117].
[3] P. Binetruy, M. Sasaki and K. Uzawa, “Dynamical D4-D8 and D3-D7 branesin supergravity,” Phys. Rev. D 80 (2009) 026001 [arXiv:0712.3615 [hep-th]].
[4] K. i. Maeda, N. Ohta and K. Uzawa, “Dynamics of intersecting brane sys-tems – Classification and their applications –,” JHEP 0906 (2009) 051[arXiv:0903.5483 [hep-th]].
[5] H. Kodama and K. Uzawa, “Moduli instability in warped compactifications ofthe type IIB supergravity,” JHEP 0507 (2005) 061 [arXiv:hep-th/0504193].
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Spanish-Portuguese Relativity Meeting, 2017 Malaga, Spain
Fractional wave operators and the wave equation inanti-de Sitter spaces
Bruno Vergara
ICMAT – Institute of Mathematical Sciences, Universidad Autonoma de [email protected]
ABSTRACT
In this talk I will discuss the connection between the fractional powers of the
standard wave operator with the problem of the massive wave equation on anti-
de Sitter spaces with boundary data at infinity. This relation can be seen as
the Lorentzian analog of well known results derived in the context of non-local
elliptic equations and conformal geometry for the fractional Laplacian. The talk
is based on a joint work with A. Enciso and M.d.M. Gonzalez [1] .
References
[1] A. Enciso, M.d.M. Gonzalez, B. Vergara. Fractional powers of the waveoperator via Dirichlet-to-Neumann maps in anti-de Sitter spaces. PreprintarXiv:1607.04390.
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Malaga, Spain Spanish-Portuguese Relativity Meeting, 2017
Covariantly Quantum Field Theory
Vincenzo Vitagliano
CENTRA - Instituto Superior Tecnico, University of Lisbon, [email protected]
ABSTRACT
The usual calculation of effective actions relies on some assumption about
the split between background and fluctuating field variables, in principle lead-
ing to a further dependence of the results on the choice of background and
gauge. Arguing that such dependence of the effective action is a by-product
of the quantum fields’ dependence on the parametrization, Vilkovisky and De-
Witt developed a geometrical, field-space covariant procedure to modify the
usual background-field method which renders the effective action gauge- and
background-independent. In this talk, I will present some modern cosmological
applications of the Vilkovisky-DeWitt method, and further suggestions about the
role of quantum corrections in astrophysical systems.
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Spanish-Portuguese Relativity Meeting, 2017 Malaga, Spain
Gravitational degrees of freedom and isometric
embedding
Steven Willison
CENTRA, IST, UTL, Av. Rovisco Pais 1, 1049-001 Lisboa, Portugal
Abstract
When physical space-time is treated as a submanifold embeded in ahypothetical 14 dimensional Minkowski space-time, the Einstein Equa-tions can be reformulated as a system of nonlinear wave equations in theembedding coordinate functions. We will focus on possible applications ingravitational physics and give a discussion of the initial value/constraintsproblem .
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Malaga, Spain Spanish-Portuguese Relativity Meeting, 2017
Black holes as probes for fundamental physics
Helvi Witek
Departament de Fısica Quantica i Astrofısica & Institut de Ciencies del Cosmos(ICCUB), Universitat de Barcelona, Martı i Franques 1, E-08028 Barcelona,
ABSTRACT
Confronting general relativity (GR) with observations, thus supporting its
role as our standard model of gravity is almost as old as the theory itself. Al-
though GR has passed all experimental tests so far, most of which were limited
to solar system or weak gravity scales, both cosmological observations and the
quest for a unified theory of quantum gravity strongly motivate extensions to
it in the strong gravity regime.
After entering the gravitational wave era in 2016 we are now in the unique
position to test gravity in its most challenging, highly dynamical regime using
black holes. To do so, however, we need to understand the black hole binary
problem in extensions of GR. In this talk I will give an update on the latest
progress concerning this problem.
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Spanish-Portuguese Relativity Meeting, 2017 Malaga, Spain
New conservation laws for matter near spinning black holes
Vojtech Witzany
ZARM, Universitat Bremen, Am Falturm 2, 28359 Bremen, [email protected]
ABSTRACT
The axisymmetric and stationary Kerr space-time, which represents the
gravitational field of a spinning black hole, possesses an additional “hidden”
symmetry expressed in the existence of a Killing-(Yano) tensor. In this talk, we
show that this symmetry is connected to non-trivial conservation laws for the
evolution of test matter in Kerr space-time and use them to test the validity of
numerical simulations of relativistic hydrodynamics on the Kerr background.
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Malaga, Spain Spanish-Portuguese Relativity Meeting, 2017
Posters
90
Spanish-Portuguese Relativity Meeting, 2017 Malaga, Spain
Initial boundary value problem for the Einstein fieldequations for a class of spherically symmetric imperfect
fluids
Irene Brito, Filipe Mena
Centro de Matematica, Universidade do Minho, 4710-057 Braga, [email protected], [email protected]
ABSTRACT
We consider the initial boundary value problem for a class of spherically
symmetric imperfect fluids and prove existence and uniqueness of solutions of
the Einstein field equations [1]. This work generalizes the results obtained in
[2] for perfect fluids.
References
[1] Brito, I., Mena, F., Initial boundary value problem for the spherically sym-metric Einstein equations with fluids with tangential pressure, submitted(2017).
[2] Kind, S., Ehlers, J., Initial boundary value problem for the spherically sym-metric Einstein equations for a perfect fluid, Class. Quantum Grav. 10, 2123(1993).
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Malaga, Spain Spanish-Portuguese Relativity Meeting, 2017
Chiral vortical effect in curved space and theChern-Simons current
Antonino Flachi
Department of Physics & Research and Education Center for Natural Sciences,Keio University, Yokohama, Japan
ABSTRACT
In the presence of rotation, gravity induces, even at zero temperature, a chiral
vortical current. This current is interpreted as emerging from the gravitational
Chern-Simons current. We argue that this gravitational Chern-Simons chiral
vortical current may provide a novel universal microscopic mechanism behind
the generation of collimated jets from rotating astrophysical compact sources.
References
[1] A. Flachi, K. Fukushima, Chiral vortical effect in curved space and the Chern-Simons current, arXiv:1702.04753 [hep-th]
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Spanish-Portuguese Relativity Meeting, 2017 Malaga, Spain
Binary boson stars and numerical relativity
Apratim Ganguly
Department of Mathematics, Rhodes University, 6140 Grahamstown, SouthAfrica
ABSTRACT
Recent discoveries of gravitational waves from black hole binaries were a
strong validation of general relativity in the strong-field limit. To fully con-
strain the theory, however, it is necessary to establish whether sources other
than classical black holes might potentially generate analogous signals. For ex-
ample, boson stars are an exotic matter source that arise in certain scalar-tensor
gravity theories. The advantage of studying boson stars is that they are useful
probes of strong-field gravity without facing problems associated with regular
matter such as shocks and discontinuities in fluid variables. This talk reports
on numerical studies of binary boson stars using a computational model to un-
derstand aspects of the gravitational wave signature of boson star interactions
and discusses some results from explorations of the orbital dynamics of boson
star binaries.
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Malaga, Spain Spanish-Portuguese Relativity Meeting, 2017
Informational Theory of Relativity
Akio Hosoya
Department of Physics, Tokyo Institute of Technology, Tokyo 152-8551, [email protected]
Shunsuke Fujii
Department of General Education, National Institute of Technology, TokyoCollege, Tokyo 193-0097, Japan
ABSTRACT
Assuming the minimal time to send a bit of information in the Einstein
synchronization of the two clocks located at different positions, we introduce
the extended metric to the information space [1] with the coordinate σ,
ds2 = gµν(x)(dxµ − uµτdσ)(dxν − uντdσ) + (a + 1)τ2(dσ)2 .
This modification of relativity changes the red shift formula keeping the geodesic
equation intact. Extending the gauge symmetry hidden in the metric to the 5-
dimensional general invariance, we start with the Einstein-Hilbert action in the
5-dimensional space-time. After the 4+1 decomposition, we obtain the effective
action which includes the Einstein-Hilbert action for gravity, the Maxwell-like
action for the velocity field uµ and the Lagrange multiplier term which ensures
the normalization of the time-like velocity field,
S = c4
16πG
∫ √−(a − gξηuξuη) det(gαβ)d4xτdσ
[gαβRαβ − gαβgρσ
4(a+1) AαρAβσ + 16πGc4
λ(gαβuαuβ + 1)],
where gαβ = gαβ + uαuβ
a+1 , Rαβ is the Ricci tensor and the field strength of the
velocity field is Aαρ := Dαuρ − Dρuα. G and C are Newton’s constant and
the light velocity. The resultant action turns out to be a particular case of the
so-called Einstein-Aether theories [2]. As an application we found a spherically
symmetric solution of the field equation, which exhibits a Schwarzschild-like
space-time but with the minimal radius. I will discuss the informational mean-
ing of the coordinate σ going back to the Einstein synchronization.
References
[1] A. Hosoya and S. Fujii, arXiv:1703.03971
[2] C. Eling, T. Jacobson, Class.Quant.Grav. 23 (2006) 5625-5642, Erratum:Class.Quant.Grav. 27 (2010) 049801 [gr-qc/0603058]
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Relativistic BHL Accretion in the Presence of Stellar Winds andDense Clumps Around a Black Hole
F. D. Lora-Clavijo and A. Cruz-Osorio
Grupo de Investigacion en Relatividad y Gravitacion, Escuela de Fısica,Universidad Industrial de Santander, A. A. 678, Bucaramanga 680002, Colombia.
ABSTRACT
In the astrophysical context, relativistic Bondi-Hoyle-Lyttleton (BHL) accretion has
been used to study different processes, from the vibrations in the shock cone, which may
potentially explain high energy phemomena like QPOs [1, 2, 3, 4], to ultra-relativistic
processes associated with the growth of primordial BHs during the radiation era [5,
6]. Given the importance of undertanding the accretion process, the relativistic BHL
problem has been also studied in the presence of magnetic fields [7], radiative terms [8],
and with density or velocity gradients [9, 10]. In this work, we study the relativistic
BHL accretion onto a Schwarzschild black hole, which is surrounded by rigid and small,
randomly distributed, bodies. These bodies are idealized representations of substructure
like bubbles created by stellar winds or cold clumps. We consider cases where the flow
moves supersonically towards the black hole. The interaction with these rigid obstacles
transforms ram pressure of the flow into thermal pressure through bow shocks, slowing
down the flow and making the accreting gas turbulent. As a consequence, although the
flow reaches a fairly steady state, the accretion rate presents some variability.
References
[1] Donmez O., Zanotti O., Rezzolla L., 2011 MNRAS, 412, 1659
[2] Cruz-Osorio A., Lora-Clavijo F. D., Guzman F. S., 2012, MNRAS, 426, 732
[3] Donmez O., 2012, MNRAS, 426, 1533
[4] Lora-Clavijo F. D., Guzman F. S., 2013, MNRAS, 429, 3144
[5] Penner A. J., 2013, MNRAS, 428, 2171
[6] Cruz-Osorio A., Lora-Clavijo F. D., Guzman F. S., 2013, AIP ConferenceSeries Vol. 1548, pp 323-327
[7] Penner A. J., 2011, MNRAS, 414, 1467
[8] Zanotti O., Roedig C., Rezzolla L., Del Zanna L., 2011, MNRAS, 417, 2899
[9] Lora-Clavijo F. D., Cruz-Osorio A., Moreno Mendez E., 2015, ApJS, 219, 30
[10] Cruz-Osorio A., Lora-Clavijo F. D., 2016, MNRAS, 460, 3193
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Pseudospherical surfaces based on the GrapheneSuperlattice Equation
Martin-Vergara, F., Rus, F., and Villatoro, F. R.
Lenguajes y Ciencias de la Computacion. Universidad de Malaga, 29071 [email protected], [email protected], [email protected]
ABSTRACT
The sine-Gordon equation (sGeq) describe a relativistic scalar field in 1+1
dimensions. Its solutions can be interpreted as pseudospherical surfaces [1].
This geometric interpretation was introduced by Lamb [2] and it is applicable
to other evolution equations with soliton solutions [3]. Electromagnetic solitary
waves can propagate in a graphene superlattice i.e., a sheet of graphene de-
posited on a superlattice, with periodically alternating layers of SiO2 and h-BN,
under THz radiation. The nonlinear d’Alembert equation for the dimensionless
z-component of the electromagnetic vector potential is the following graphene
superlattice equation (GSLeq):
∂2α
∂t2− c2
∂2α
∂x2+
ω20 b
2 sinα√1 + b2 (1− cosα)
= 0,
as derived by Kryuchkov and Kukhar’ [4]; this equation is a generalization of the
sGeq, where ω20 is the normalized frequency, b ≤ 1 is a geometrical parameter of
the superlattice, c is the speed of light, x is position and t is time. The GSLeq has
a solitary wave solution of the form α(x, t) = α(φ), where φ = x−ct. The GSLeq
is nonintegrable but can be understood as a perturbation of the sGeq for small
b. The kinks, antikinks and breathers of the sGeq correspond to solitary wave
solutions of the GSLeq. Such solutions can be interpreted as pseudospherical
surfaces, like those of the sGeq. Here, we study such surfaces and compare
them with those of the sGeq.
References
[1] R.Sasaki, ”Soliton equations and pseudospherical surfaces” Nuclear Phys.B154: 343-357 (1979).
[2] G. L. Lamb Jr., ”Solitons on moving space curves” J. Math. Phys. 18: 1654-1661 (1977).
[3] A. Sym, J. Corones, ”Lie-Group Explanation of Geometric Interpretations ofSolitons” Phys. Rev. Lett. 42: 1099-1102 (1979).
[4] S. V. Kryuchkov and E.I. Kukhar’, ”The solitary electromagnetic waves inthe graphene superlattice”, Phys. B: Condensed Matter, 408: 188-192 (2013).
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Spanish-Portuguese Relativity Meeting, 2017 Malaga, Spain
Universal spacetimes
Vojtech Pravda
Institute of Mathematics of the Czech Academy of Sciences,Zitna 25, 115 67 Prague 1, Czech Republic
ABSTRACT
Universal spacetimes simultaneously solve vacuum field equations of all the-
ories of gravity with the Lagrangian being a polynomial curvature invariant
constructed from the metric, the Riemann tensor and its covariant derivatives
of an arbitrary order. We present several results on universal spacetimes. While
for type N and III the results are dimension independent, for type II we con-
struct universal metrics only for composite number dimensions and prove the
non-existence for five dimensions. The existence of type II universal spacetimes
for prime number dimensions remains open.
We also discuss recent results on four-dimensional universal spacetimes. We
show that in this case, universal spacetimes are necessarily algebraically spe-
cial and Kundt. We find necessary and sufficient conditions for universality
for Petrov types III and D and discuss type II universal spacetimes. Explicit
examples of universal metrics of various algebraic types are also given.
These results were obtained in collaboration with S. Hervik, T. Malek and
A. Pravdova [1, 2, 3].
References
[1] S. Hervik, V. Pravda, and A. Pravdova, Type III and N universal spacetimes,Class. Quantum Grav. 31 (2014) 215005.
[2] S. Hervik, T. Malek, V. Pravda, and A. Pravdova, Type II universal space-times, Class. Quantum Grav. 32 (2015) 245012.
[3] S. Hervik, V. Pravda, and A. Pravdova, Universal spacetimes in four dimen-sions, arXiv: 1707.00264
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Conformal scalar invariants of weight zero
Ignacio Sanchez–Rodrıguez
Department of Geometry and Topology, University of Granada, [email protected]
ABSTRACT
In a lesser known paper [1] Albert Einstein announces that it is possible to add
an equation to the field equations of General Relativity. We explore this sugges-
tion from a geometrical point of view, and then we obtain a family of conformal
scalar differential invariants of weight 0 for generic (pseudo-)Riemannian me-
trics in more than three dimensions.
References
[1] A. Einstein, Berliner Ber. 1921, pp. 261-264.
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Entropic corrected Newton’s law of gravitation
C.A.S.Silva
Instituto Federal de Educacao, Ciencia e Tecnologia da Paraıba (IFPB), CampusCampina Grande - Rua Tranquilino Coelho Lemos, 671, Jardim Dinamerica I.
R.G.L.Aragao
Departamento de Fısica, Universidade Federal de Campina Grande (UFCG),Caixa Postal 10071, 58109-970 Campina Grande, Paraıba, Brazil
ABSTRACT
The entropic interpretation of gravity introduced by Verlinde has provide a
way to derive the Newton’s law of gravitation from the Bekenstein-Hawking
entropy-area formula [1]. It is well known, on the other hand, that such for-
mula can be affected by quantum gravity corrections. As a consequence, one
may hope that such corrections can influence the Newton’s gravitational law. In
this sense, the entropic approach to the Newton’s law could be a fertile frame in
order to test the validity of quantum corrections to ordinary gravity in regimes
accessible to observations. In this work, by using the nonrelativistic Verlinde’s
approach, we obtain a quantum gravity corrected Newton’s law from the entropy-
area relation given by loop quantum black holes, a semiclassical black hole so-
lution that emerges from Loop Quantum Gravity [2]. Besides, in the sense of
relate our investigations with the current experimental activity, we discuss the
quantum mechanical properties of a gravitational atom formed by a light neutral
elementary particle [3] orbiting a loop quantum black hole. The results present
in this work have been published the reference [4].
References
[1] E. P. Verlinde, ”On the Origin of Gravity and the Laws of Newton,”JHEP1104 (2011) 029 [arXiv:1001.0785 [hep-th]]
[2] MODESTO, L.; PREMONT-SCHWARZ, I. Self-dual black holes in loopquantum gravity: Theory and phenomenology. Physical Review D, APS, v.80, n. 6, p. 064041, 2009.
[3] V. V. Flambaum and J. C. Berengut, ”Atom made from charged elementaryblack hole,” Phys. Rev. D63 (2001) 084010 doi:10.1103/PhysRevD.63.084010[gr-qc/0001022].
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