Prof.
Luciano Rezzolla
(ITP, Goethe University Frankfurt)
20/07/2015, 10:00
Gravitational collapse to a rotating black hole is a common and recurrent feature of the dynamics of compact stars. I will discuss several examples of this process and the implications they have in potentially explaining some of the most dramatic and puzzling processes in astrophysics.
Prof.
Horst Stöcker
(FIAS & GSI)
20/07/2015, 11:30
Seniors
Talk
Pure SU_c Lattice Gauge Theory, LGT, predicts a strong first order phase transition from a deconfined glue plasma to a confined GlueBall fluid, at a critical temperature of T_c=270 MeV.
QCD-transport calculations show that such pure gauge matter can be created for a fleeting moment in high multiplicity pp, pA and AA collisions at the LHC at CERN and at RHiC at BNL. Pure gauge matter is...
Ali Seraj
(IPM, Tehran, Iran)
20/07/2015, 14:00
Students
We construct the classical phase space of Near-Horizon Extremal Geometries with fixed angular momenta and entropy. Each element in the phase space is a geometry with SL(2,R)×U(1)d−3 Killing isometries which has vanishing SL(2,R) and constant U(1) charges.
In four spacetime dimensions, the symmetry algebra consists of the familiar Virasoro algebra, while in d>4 dimensions the symmetry algebra,...
Mr
Mattia Colombo
(University of Nottingham)
20/07/2015, 14:20
Students
When Lorentz symmetry is broken, defining the concept of Black Hole becomes highly non-trivial. In this talk I wish to discuss the problems related to such definition and introduce a way to define the causal structure and horizons for a manifold with a preferred foliation.
Ms
Marcela Cárdenas
(Universidad de Concepción, Centro de Estudios Científicos)
20/07/2015, 14:40
Students
We present a Chern-Simons-like description of three-dimensional gravity with negative cosmological constant, where the matter source is a conformally coupled real scalar field. This description is based on a first-order action that provides a set of field equations equivalent to that derived from the usual second-order action. The system admits a rotating hairy black hole solution, which is...
Andrea Giugno
(University of Bologna)
20/07/2015, 15:00
Students
We study a corpuscular model of evaporating black holes consisting of a large number $N$
of self-confined bosons. The single-particle spectrum contains a discrete ground state of energy $m$ (corresponding to toy gravitons forming a black hole), and a gapless continuous spectrum (to accommodate for Hawking radiation with energy $\omega>m$).
In particular, we consider each constituent in a...
Dr
Hui-Yiing Chang
(University of South Carolina Sumter)
20/07/2015, 16:00
We examine a quintessence model with a modified exponential potential given by $V(\phi) = V_0(1 + e^{-\lambda \phi})$. We determine the evolution of the equation of state parameter, $w_\phi$, and the density parameter, $\Omega_\phi$, as a function of the scale factor. Our model, unlike quintessence with a standard exponential potential, can produce an acceptable accelerated expansion at late...
Cristi Stoica
(Horia Hulubei National Institute for Physics and Nuclear Engineering)
20/07/2015, 16:20
Juniors
Schwarzschild's solution is the soul of General Relativity (GR). It was found immediately after Einstein found his equation, and plays an essential role in the approximations that allow us to test GR in our solar system. Moreover, the most notable problems of GR, such as the occurrence of singularities and the information paradox, were found on the background provided by Schwarzschild's...
Tigran Kalaydzhyan
(Stony Brook University)
20/07/2015, 16:40
Juniors
Within the general theory of relativity, the curvature of space-time is related to the energy and momentum of the present matter and radiation. One of the more specific predictions of general relativity is the deflection of light and particle trajectories in the gravitational field of massive objects. Bending angles for electromagnetic waves and light in particular were measured with a high...
Dr
Tatsuo Azeyanagi
(Ecole Normale Superieure)
20/07/2015, 17:00
In this presentation, I will revisit the Noether charge formulation of black hole entropy in the presence of gravitational Chern-Simons terms in higher dimensions. I will provide a manifestly covariant formulation of the differential Noether charge and prove the (generalized version of) black hole entropy formula for gravitational Chern-Simons terms proposed by Tachikawa. In the context of...
Mirah Gary
(Institute for Theoretical Physics, TU Wien)
20/07/2015, 17:20
Juniors
Working in three dimensions, we introduce flat space spin-3 gravity in the presence of chemical potentials and discuss some applications to flat space cosmology solutions, their entropy, free energy and flat space orbifold singularity resolution. Our results include flat space Einstein gravity with chemical potentials as special case. We discover novel types of phase transitions between flat...
Valeria Ferrari
(Sapienza Rome)
21/07/2015, 10:00
It is known that black holes have no hair, which means that they are fully described by only three parameters: mass, spin and charge. Conversely, a neutron star may have a very rich multipole structure, and all information about this structure is supposed to be radiated away during the gravitational collapse. However, the transition from a fully hairy star to a bald black hole may not be so...
Georgi Dvali
(LMU, Arnold Sommerfeld Center)
21/07/2015, 11:30
We discuss physics of black hole information storage and processing in a quantum portrait according to which black hole is a loose bound-state of many soft gravitons at the quantum critical point, with characteristic Liapunov exponent responsible for the quantum instability and information scrambling. This picture sheds light at the microscopic origin of black hole entropy and also shows that...
Supakchai Ponglertsakul
21/07/2015, 14:00
Students
A charged scalar field can be used to extract energy from a charged black hole via superradiant scattering. A mirror-like or AdS boundary could lead the system to an instability. This is because the scalar fields are trapped outside the black hole and repeatedly amplified, there-fore ultimately the back-reaction on the black hole background will become non-negligible.
A charged scalar field...
Antonia Micol Frassino
21/07/2015, 14:20
Students
I will talk about the effects of higher curvature corrections from Lovelock gravity on the phase structure of asymptotically AdS black holes, treating the cosmological constant as a thermodynamic pressure.
Eugene Kur
(University of California, Berkeley)
21/07/2015, 15:00
Students
I will discuss multisymplectic geometry and its application to finite spacetime regions. This allows one to perform a 3+1 decomposition where the spatial slice need not be a Cauchy surface. I show how this can lead to a modification of the symplectic structure, Hamilton's principle function, and momentum maps (conserved charges). Such modifications are in the form of boundary terms which can...
Sven Köppel
(Frankfurt Institute for Advanced Sciences)
21/07/2015, 15:20
Students
I will talk about the extension of general uncertainty principle (GUP) inspired black holes to the scenario of large spatial extradimensions (ADD).
Roberto Casadio
(Alma Mater Bologna University)
21/07/2015, 16:00
Seniors
We propose to investigate the Cosmic Censorship Conjecture in the quantum domain by means of the horizon wave-function (HWF) formalism applied to a spherically symmetric Gaussian state. When the charge-to-mass ratio q<1, the formalism allows for a straightforward quantum mechanical description of both inner and outer horizons. For q>1, where the classical theory predicts a naked singularity,...
Sabine Hossenfelder
(Nordita)
21/07/2015, 16:00
Seniors
I will discuss a new duality between strongly coupled and weakly coupled condensed matter systems. It can be obtained by combining the gauge-gravity duality with analog gravity. In my talk I will explain how one arrives at the new duality, what it can be good for, and what questions this finding raises.
Prof.
Eduardo Guendelman
(Ben Gurion University)
21/07/2015, 16:30
Seniors
A new class of gravity-matter models defined in terms of two independent non-Riemannian volume forms (alternative generally covariant integration measure densities) on the space-time manifold are studied in some detail. These models involve an additional R2 (square of the scalar curvature) term as well as scalar matter field potentials of appropriate form so that the pertinent action is...
Mariano Cadoni
(University of cagliari)
21/07/2015, 17:00
Seniors
We construct asymptotically flat black hole solutions of Einstein-scalar gravity sourced by a nontrivial scalar field with $1/r$ asymptotic behavior. Near the singularity the black hole behaves as the Janis-Newmann-Winicour-Wyman solution. The hairy black hole
solutions allow for consistent thermodynamical description. At large mass they have the same thermodynamical behavior of the...
Prof.
Bernard Carr
(QMU, London)
22/07/2015, 09:00
Keynotes
Black holes span 60 decades of mass - from the Planck scale ($10^{-5}$g) to the cosmological scale ($10^{22} M_\text{Sun}$) - and probe many domains of physics (quantum gravity, high-energy physics, gravitational physics, astrophysics and cosmology). Quantum black holes, here regarded as the ones for which quantum evaporation is important (i.e. those hotter than the CMB temperature), span the...
Prof.
George Ellis
(Cape Town)
22/07/2015, 10:00
Black hole evaporation calculations are usually carried out in a static asymptotically flat context. However real black holes are imbedded in an expanding universe filled with Cosmic Background radiation. This talk will discuss the relevant horizons and causal limits in this context, and make the case that black hole evaporation cannot take place until very late stages in the expansion of the...
Prof.
Carlo Rovelli
(Marseille University)
22/07/2015, 11:30
I describe an extension of the Schwarzschild metric that describes matter collapsing into a black hole and then bouncing out of a white hole. The metric is locally, but not globally, isomorphic to the Kruskal extension, and has a compact internal region where a violation of the Einstein equations mimics quantum effects. The metric may describe an actual black hole explosion.
Prof.
Daniel Grumiller
(TU Vienna)
22/07/2015, 14:00
Keynotes
If the holographic principle is a true aspect of Nature it must work beyond AdS/CFT. In this talk I address a particular aspect of the question how general holography is by considering flat space holography. I report recent progress, in particular the calculation of stress tensor correlators in three-dimensional gravity, microstate counting and holographic entanglement entropy, all of which...
Prof.
Herman Verlinde
(Princeton)
23/07/2015, 09:30
Keynotes
Prof.
Steven Giddings
(UC Santa Barbara)
23/07/2015, 11:00
Keynotes
If nature respects quantum-mechanical principles, this implies significant modification to our semiclassical picture of black holes. The ongoing project to image the black hole at the center of our galaxy offers a possible opportunity to probe such departures from this picture initiated by Schwarzschild.
Robert Mann
(University of Waterloo)
23/07/2015, 12:00
Black Hole Chemistry is a new perspective on black hole thermodynamics, one that indicates that once vacuum energy is taken into account, black holes behave more like chemical systems. As a consequence mass becomes chemical enthalpy, the notion of a thermodynamic volume appears, and black holes exhibit a broad range of chemical phenomena, including liquid/gas phase transitions similar to a...
Prof.
Claus Lämmerzahl
(ZARM/Bremen)
23/07/2015, 14:00
Keynotes
Francesca Vidotto
(Radboud University Nijmegen)
23/07/2015, 15:00
Juniors
Quantum gravity may allow black holes to tunnel into white holes. If so, the lifetime of a black hole would be shorter than the one given by Hawking evaporation, solving the information paradox. More interestingly, this could open to a new window for quantum-gravity phenomenology, in connection with the existence of primordial black holes. I discuss in particular the power of the associated...
Dr
Dennis D. Dietrich
(Goethe-Universität)
23/07/2015, 15:30
Seniors
Recently, I have shown how an AdS$_{d+1}$ description of $d$ dimensional gauge field theories arises readily in the worldline formalism of quantum field theory. In this talk I will dicuss the role the AdS black hole plays in this worldline based approach to holography.
Silke Britzen
(MPIfR)
23/07/2015, 15:30
Seniors
Highest resolution Event Horizon Telescope (EHT) observations will probably soon
tell us more about the supermassive black hole at the Galactic Centre (Sgr A*) and the cores of active galactic nuclei (AGN).
It might also help to clarify the long-standing question whether the central massive
objects in AGN are instead close pairs of black holes. Mergers of supermassive black hole pairs...
Prof.
REMO GARATTINI
(University of Bergamo)
23/07/2015, 16:00
Seniors
We consider the effects of Distorted Gravity on the traversability of the wormholes. In particular, we consider configurations which are sustained by their own gravitational quantum fluctuations. The Ultra-Violet divergences appearing to one loop are taken under control with the help of a Noncommutative geometry representation and Gravity's Rainbow. In this context, it will be shown that for...
Dr
Ilia Musco
(CNRS, Observatorire de Paris, LUTH (Meudon))
23/07/2015, 16:00
Seniors
In the context of gravitational collapse to form a black hole, one sees the appearance of inner and outer trapping horizons (foliated by marginally trapped surfaces), as was already noted in numerical calculations in the 1960s. This phenomenology has acquired new interest in connection with discussions of the Hayward unified first law of black hole dynamics. We have investigated the nature of...
Prof.
Mariafelicia De Laurentis
(Tomsk State Pedagogical University)
23/07/2015, 16:30
Seniors
Axially symmetric solutions for f(R)-gravity can be derived starting from exact spherically symmetric solutions achieved by Noether symmetries. The method takes advantage of a complex coordinate transformation previously developed by Newman and Janis in general relativity. An example is worked out to show the general validity of the approach. The physical properties of the solution are also considered.
Dr
Fabio Scardigli
(American University of the Middle East)
23/07/2015, 16:30
Seniors
We compute the corrections to the Schwarzschild metric necessary to reproduce the Hawking temperature derived from a Generalized Uncertainty Principle (GUP), so that the GUP deformation parameter is directly linked to the deformation of the metric. Using this modified Schwarzschild metric, we compute corrections to the standard General Relativistic predictions for
the light deflection and...
Jürgen Struckmeier
(GSI)
23/07/2015, 17:00
Seniors
Any physical theory that follows from an *action principle* should be *invariant in its form* under mappings of the reference frame in order to comply with the *general principle of relativity*. The required form-invariance of the action principle implies that the mapping must constitute a particular *extended canonical transformation*.
In the realm of the covariant Hamiltonian formulation...
Shoichi Kawamoto
(Chung Yuan Christian University)
23/07/2015, 17:00
Seniors
We study a statistical ensemble of a single polymer with self gravitational interaction. This is a model of a gravitating string --- the precursor of a black hole. We analyze averaged sizes by mean field approximations with an effective Hamiltonian a la Edwards with Newtonian potential as well as a contact repulsive interaction. We find that there exists a certain scaling region where the...
Gerardus 't Hooft
(Utrecht University)
23/07/2015, 19:30
We rephrase the einstein-Hilbert theory of gravity by focusing on local conformal symmetry as an exact, but spontaneously broken symmetry of nature. We then put a constraint on the theory by imposing regularity of the action as the dilaton field variable tends to 0, which is a constraint on the small distance behaviour. This appears to turn a black hole into a regular, topologically trivial...
Prof.
Ralf Schützhold
(Uni Duisburg-Essen)
24/07/2015, 09:00
Many quantum radiation phenomena such as black hole evaporation (Hawking effect) are far removed from experimental access.
Therefore, analogies between these fundamental phenomena and laboratory physics can help to understand both sides better -- from a theoretical as well as from an experimental point of view.
This talk will start with a brief introduction into black hole evaporation with...
Prof.
Achim Kempf
(PI/Waterloo)
24/07/2015, 10:00
Keynotes
Elizabeth Winstanley
(The University of Sheffield)
24/07/2015, 11:30
According to the no-hair conjecture, equilibrium black holes are simple objects, completely determined by global charges which can be measured at infinity. This is the case in Einstein-Maxwell theory due to beautiful uniqueness theorems. However, the no-hair conjecture is not true in general, and there is now a plethora of matter models possessing hairy black hole solutions. In this talk we...
Mr
ALI OVGUN
(Eastern Mediterranean University-FAMAGUSTA , NORTHERN CYPRUS)
Students
Poster
The unbounded center-of-mass (CM) energy of colliding particles near horizon of a black hole emerges even in 1+1- dimensional Horava-Lifshitz gravity. The latter has imprints of renormalizable quantum gravity characteristics in accordance with simple power counting. The result obtained is valid also for a 1- dimensional Compton process between a massive/massless Hawking photon emaneting from...
