Modified general relativity as a model for quantum gravitational collapse

Kreienbuehl, Andreas; Husain, Viqar; Seahra, Sanjeev S.

doi:10.1088/0264-9381/29/9/095008

Cited by 37 publications

(37 citation statements)

References 62 publications

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“…Within Palatini gravity the collapse of charged fluids may lead to the formation of a wormhole in place of the central singularity (see [108] and [107]). Finally, in [109] it was shown how modified GR affects Choptuik's mass scaling law (see [110]) observed in the final stages of collapse of a scalar field.…”

Section: A a Brief History Of Collapse Models With Quantum Correctedmentioning

confidence: 99%

Classical Collapse to Black Holes and Quantum Bounces: A Review

Malafarina

2017

Universe

112

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Abstract:In the last four decades, different programs have been carried out aiming at understanding the final fate of gravitational collapse of massive bodies once some prescriptions for the behaviour of gravity in the strong field regime are provided. The general picture arising from most of these scenarios is that the classical singularity at the end of collapse is replaced by a bounce. The most striking consequence of the bounce is that the black hole horizon may live for only a finite time. The possible implications for astrophysics are important since, if these models capture the essence of the collapse of a massive star, an observable signature of quantum gravity may be hiding in astrophysical phenomena. One intriguing idea that is implied by these models is the possible existence of exotic compact objects, of high density and finite size, that may not be covered by an horizon. The present article outlines the main features of these collapse models and some of the most relevant open problems. The aim is to provide a comprehensive (as much as possible) overview of the current status of the field from the point of view of astrophysics. As a little extra, a new toy model for collapse leading to the formation of a quasi static compact object is presented.

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Section: A a Brief History Of Collapse Models With Quantum Correctedmentioning

confidence: 99%

Classical Collapse to Black Holes and Quantum Bounces: A Review

Malafarina

2017

Universe

112

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“…Fortunately, there are some models of canonical quantum gravity in which closed modified constraint brackets can be derived in their off-shell form. These include some versions of cosmological perturbations [4,5,6], and spherically symmetric models with nonperturbative inhomogeneity [7,8,9,10]. Here, we will use the latter models because their equations are less lengthy and show the relevant features more clearly.…”

Section: Introductionmentioning

confidence: 99%

Effective line elements and black-hole models in canonical loop quantum gravity

2018

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Canonical quantization is often used to suggest new effects in quantum gravity, in the dynamics as well as the structure of space-time. Usually, possible phenomena are first seen in a modified version of the classical dynamics, for instance in an effective Friedmann equation, but there should also be implications for a modified space-time structure. Quantum space-time effects, however, are often ignored in this setting because they are not obvious: they require a careful analysis of gauge transformations and the anomaly problem. It is shown here how modified space-time structures and effective line elements can be derived unambiguously, provided an offshell anomaly-free system of modified constraints exists. The resulting effective line elements reveal signature change as an inescapable consequence of non-classical gauge transformations in the presence of holonomy modifications. The general framework is then specialized to black-hole models in loop quantum gravity. In contrast to previous studies, a self-consistent space-time structure is taken into account, leading to a new picture of black-hole interiors.

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“…Several independent examples of modified gauge transformations have been found in different models of canonical quantum gravity, using effective [1,2,3,4,5,6,7] and operator calculations [8,9,10,11,12]. In classical canonical formulations, space-time structure is encoded not in the usual form of general covariance of tensors, but by the equivalent version of gauge covariance under hypersurface deformations in space-time [13,14].…”

Section: Introductionmentioning

confidence: 99%

“…Other such examples are given by fractional space-time models, in which the modification functions can, however, be absorbed [19]. A discrete version of the brackets has been defined in [20], which differs from (2) and (3). In the present paper, we focus on continuum effective theories in which space (but not necessarily space-time) has the classical structure.…”

Section: Introductionmentioning

confidence: 99%

Hypersurface-deformation algebroids and effective spacetime models

et al. 2016

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In canonical gravity, covariance is implemented by brackets of hypersurface-deformation generators forming a Lie algebroid. Lie algebroid morphisms therefore allow one to relate different versions of the brackets that correspond to the same space-time structure. An application to examples of modified brackets found mainly in models of loop quantum gravity can in some cases map the space-time structure back to the classical Riemannian form after a field redefinition. For one type of quantum corrections (holonomies), signature change appears to be a generic feature of effective space-time, and is shown here to be a new quantum space-time phenomenon which cannot be mapped to an equivalent classical structure. In low-curvature regimes, our constructions prove the existence of classical space-time structures assumed elsewhere in models of loop quantum cosmology, but also shows the existence of additional quantum corrections that have not always been included.

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Modified general relativity as a model for quantum gravitational collapse

Cited by 37 publications

References 62 publications

Classical Collapse to Black Holes and Quantum Bounces: A Review

Classical Collapse to Black Holes and Quantum Bounces: A Review

Effective line elements and black-hole models in canonical loop quantum gravity

Hypersurface-deformation algebroids and effective spacetime models

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