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Jonas Neuser (FAU - Erlangen)06/05/2024, 16:30Cosmology, Black Holes, and other applications/phenomenology
Black hole perturbations are mostly considered up to second order. In this talk we investigate the problem of incorporating perturbations of higher than second order and the new technical challenges that arise.
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Asier Alonso-Bardaji06/05/2024, 16:45Cosmology, Black Holes, and other applications/phenomenology
We explore spherically symmetric black-hole models with corrections motivated by loop quantum gravity. We derive a general family of Hamiltonians satisfying specific covariance conditions so that the dynamics generated by such families define a spacetime geometry independently of gauge or coordinate choices. By construction, there are no propagating degrees of freedom, but we show that the...
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Geeth Chandra Ongole (Baylor)06/05/2024, 17:00Cosmology, Black Holes, and other applications/phenomenology
Abstract: This work examines a family of loop quantizations for the classical Kruskal spacetimes using the effective description motivated from loop quantum gravity for four generic parameters, $c_o, m, \delta_b$, and $\delta_c$, where the latter two denote the polymerization parameters capturing the underlying quantum geometry. The focus lies on the family where polymerization parameters...
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Andrés Mínguez-Sánchez (CSIC)06/05/2024, 17:15Cosmology, Black Holes, and other applications/phenomenology
Considerable attention has been paid to the study of the quantum geometry of nonrotating black holes within the framework of Loop Quantum Cosmology. This interest has been reinvigorated since the introduction of a novel effective model by Ashtekar, Olmedo, and Singh. Despite recent advances in its foundation, there are certain questions about its quantization that still remain open. Here we...
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Idrus Belfaqih (The University of Edinburgh)06/05/2024, 17:30Cosmology, Black Holes, and other applications/phenomenology
We use emergent modified gravity as a covariant, effective framework for obtaining black hole solutions in loop quantum gravity with an arbitrary, scale-dependent holonomy parameter λ in vacuum spherical symmetry. The construction is robust and can be applied in general for any type of triangulation. We obtained vacuum solutions not only for asymptotically flat spacetime but also for dS and...
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Jorden Roberts (University of Alberta)06/05/2024, 17:45Canonical QG: Fundamental theory
Following the techniques of canonical loop quantum gravity, a full Thiemann regularization is performed on the scalar constraint of classical general relativity. The regularized Hamiltonian is then considered for a general spherically-symmetric spacetime, without recourse to additional gauge-fixing conditions commonly imposed to aid in computing the radial holonomies. By investigating the form...
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Francesca Vidotto (Western University, Canada)07/05/2024, 14:00Cosmology, Black Holes, and other applications/phenomenology
Primordial black holes have grown in popularity as a dark matter candidate. Different mass spectrum for them are currently under consideration. In this talk I discuss how Loop Quantum Cosmology can integrate the presence of primordial black holes, either in an inflationary scenario or in a ekpyrotic scenario. I review some recent results and discuss the current work in progress. I focus in...
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Madhavan Varadarajan07/05/2024, 14:15Cosmology, Black Holes, and other applications/phenomenology
We consider 4d spherical collapse of a massless scalar field with a novel Areal Radius dependent coupling and obtain the following results:
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(i) classical collapse is described by the Vaidya solution (ii) quantum back reaction can be explicitly computed (iii) the semiclassical solution
describes black hole formation, subsequent evaporation along a timelike `dynamical horizon' and a back... -
GUILLERMO ANTONIO MENA MARUGAN (Instituto de Estructura de la Materia, CSIC)07/05/2024, 14:30Cosmology, Black Holes, and other applications/phenomenology
We present a description of axial perturbations in Kantowski-Sachs spacetimes, corresponding to nonrotating, uncharged black hole interiors. Perturbations are expressed in terms of perturbative gauge invariants, linear perturbative constraints, and their momenta. Moreover, the entire system formed by these perturbations and the background degrees of freedom is described by a canonical set of...
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Alvaro Torres-Caballeros (CSIC)07/05/2024, 14:45Cosmology, Black Holes, and other applications/phenomenology
Author: Álvaro Torres-Caballeros Instituto de Estructura de la Materia, IEM-CSIC Serrano 121, 28006 Madrid, Spain alvaro.torres@iem.cfmac.csic.es Co-authors: Jerónimo Cortez Departamento de Física, Facultad de Ciencias, Universidad Nacional Autónoma de México. Ciudad de México 04510, Mexico jacq@ciencias.unam.mx Beatriz Elizaga Navascués Department of Physics and Astronomy, Louisiana State...
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Farshid Soltani (Western University)07/05/2024, 15:00Cosmology, Black Holes, and other applications/phenomenology
The Oppenheimer-Snyder model is the prototypical example of black hole formation by gravitational collapse. It predicts that a black hole horizon is formed once a star collapses to within its own Schwarzschild radius. After that, the collapsing matter reaches Planckian densities in a short proper time. What happens next is outside the reach of general relativity, as it involves the quantum...
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Sami VIOLLET07/05/2024, 15:15Cosmology, Black Holes, and other applications/phenomenology
The black hole information puzzle can be solved if two conditions are met: information about what falls inside a black hole must remain encoded in d.o.f that persist after the black hole has completely evaporated. Moreover, these d.o.f must not contribute significantly to the energy of the system, given that the macroscopic mass of the initial black hole has been radiated to infinity in the...
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Francesco Sartini (OIST)07/05/2024, 15:30Boundaries, Symmetries, and Classical aspects
Homogenous cosmological models and black holes belong to classes of space-time metrics defined in terms of a finite number of degrees of freedom. For these, the dynamics reduces to a one-dimensional mechanical model. It is then easy to investigate their classical symmetries and the corresponding Noether charges.
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These dynamical symmetries have a geometric interpretation, not in terms of... -
Carlo Rovelli07/05/2024, 15:45Cosmology, Black Holes, and other applications/phenomenology
Covariant LQG predicts that the end of the black hole evaporation leaves a long-living remnant described by a white hole geometry, and stabilized by the LQG area gap. This result provides an intriguing candidate for dark matter, which does not require any new physics besides General Relativity and quantum theory,
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Francesco Fazzini (University of New Brunswick)07/05/2024, 16:30Cosmology, Black Holes, and other applications/phenomenology
Effective models of gravitational collapse in loop quantum gravity for the Lemaître-Tolman-Bondi spacetime predict that collapsing matter reaches a maximum finite density, bounces, and then expands outwards. I explain how in the marginally bound case, shell-crossing singularities commonly occur for inhomogeneous initial profiles of the dust energy density; this is the case in particular for...
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Luca Cafaro (University of Warsaw)07/05/2024, 16:45Cosmology, Black Holes, and other applications/phenomenology
The collapse of a spherically symmetric ball of dust has been intensively studied in Loop Quantum Gravity (LQG). From a quantum theory, it is possible to recover a semiclassical regime through a polymerization procedure. In this setting, general solutions to the Polymerized Einstein Field Equations (PEFE) will be discussed both for the interior and the exterior of the dust cloud. Exterior...
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Mateo Pascual Gomez-Cuetara07/05/2024, 17:00Cosmology, Black Holes, and other applications/phenomenology
At the end of its evaporation, a black hole may leave a remnant where a large amount of information is stored. We argue that the existence of an area gap as predicted by Loop Quantum Gravity removes a main objection to this scenario. Remnants should radiate in the low-frequency spectrum. We model this emission and derive properties of the diffuse radiation emitted by a population of such...
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Rafael Guolo Dias (Florida Atlantic University)07/05/2024, 17:15Cosmology, Black Holes, and other applications/phenomenology
A notion of residual diffeomorphism covariance in quantum Kantowski-Sachs (KS), describing the interior of a Schwarzschild black hole will be introduced, and the solution for the family of Hamiltonian constraint operators satisfying the condition will be briefly presented.
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The result will then be compared to Hamiltonian constraints proposed for Loop Quantum KS in the literature, especially... -
Samantha hergott (York University / Perimeter Institute for Theoretical Physics)07/05/2024, 17:30Cosmology, Black Holes, and other applications/phenomenology
I will discuss a class of time-dependent, asymptotically flat and spherically symmetric metrics which model gravitational collapse in quantum gravity developed by myself and the other listed authors. Motivating the work was the intuition that quantum gravity should not exhibit curvature singularities and indeed, the metrics lead to singularity resolution with horizon formation and evaporation...
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Evan Vienneau (University of Alberta)07/05/2024, 17:45Cosmology, Black Holes, and other applications/phenomenology
We construct the full spacetime of a minimal uncertainty inspired black hole, borrowing the improved prescription from loop quantum gravity. In the minimal uncertainty approach, minimalization of the uncertainty relations leads to the deformation of the algebra leading to an effective theory. We show that the asymptotic and classical limits of our model match the Schwrazschild solution, and...
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Erick Muino Garcia (Penn State University)07/05/2024, 18:00Cosmology, Black Holes, and other applications/phenomenology
In asymptotically flat quantum gravity, the dimension of the Hilbert space is given by the exponential of the Bekenstein-Hawking entropy. Can we understand this thermodynamic entropy as a consequence of entanglement in a typical state at a definite ADM energy? We approach this question by exploring the behavior of the typical entanglement entropy in large quantum systems under constraints....
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