Conformally rescaled spacetimes and Hawking radiation

Nielsen, A. B.; Firouzjaee, Javad T.

doi:10.1007/s10714-013-1560-7

Cited by 28 publications

(24 citation statements)

References 56 publications

(137 reference statements)

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“…It is claimed that it is the trapping horizon area, and not the area of the event horizon, which should be associated with entropy in black hole thermodynamics [63,71,32,96]. This claim is somewhat controversial [121,34,98]. The Parikh-Wilczek [108] "tunneling" approach, originally applied to study Hawking radiation from stationary black holes, is in principle applicable also to apparent and trapping horizons.…”

Section: Apparent and Trapping Horizonsmentioning

confidence: 99%

Embedding Black Holes and Other Inhomogeneities in the Universe in Various Theories of Gravity: A Short Review

Faraoni

2018

Universe

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The classic black hole mechanics and thermodynamics are formulated for stationary black holes with event horizons. Alternative theories of gravity of interest for cosmology contain a built-in time-dependent cosmological "constant" and black holes are not stationary. Realistic black holes are anyway dynamical because they interact with astrophysical environments or, at a more fundamental level, because of backreaction by Hawking radiation. In these situations the teleological concept of event horizon fails and apparent or trapping horizons are used instead. Even as toy models, black holes embedded in cosmological "backgrounds" and other inhomogeneous universes constitute an interesting class of solutions of various theories of gravity. We discuss the known phenomenology of apparent and trapping horizons in these geometries, focusing on spherically symmetric inhomogeneous universes.

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Section: Apparent and Trapping Horizonsmentioning

confidence: 99%

Embedding Black Holes and Other Inhomogeneities in the Universe in Various Theories of Gravity: A Short Review

Faraoni

2018

Universe

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“…Their calculation is based in the WKB approximation assumed for the light coming from the apparent horizon to the observer. As discussed in [25,28], the WKB approximation cannot hold for light passing the FLRW apparent horizon, except in the case of de Sitter spacetime. As a result, there is no particle creation in the FLRW metric in the matter and radiation dominated eras.…”

Section: A Particle Creation In Flrw Spacetimementioning

confidence: 99%

Particle creation from the quantum stress tensor

Firouzjaee

Ellis

2015

Phys. Rev. D

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Among the different methods to derive particle creation, finding the quantum stress tensor expectation value gives a covariant quantity which can be used for examining the back-reaction issue. However this tensor also includes vacuum polarization in a way that depends on the vacuum chosen. Here we review different aspects of particle creation by looking at energy conservation and at the quantum stress tensor. It will be shown that in the case of general spherically symmetric black holes that have a \emph{dynamical horizon}, as occurs in a cosmological context, one cannot have pair creation on the horizon because this violates energy conservation. This confirms the results obtained in other ways in a previous paper [25]. Looking at the expectation value of the quantum stress tensor with three different definitions of the vacuum state, we study the nature of particle creation and vacuum polarization in black hole and cosmological models, and the associated stress energy tensors. We show that the thermal temperature that is calculated from the particle flux given by the quantum stress tensor is compatible with the temperature determined by the affine null parameter approach. Finally, it will be shown that in the spherically symmetric dynamic case, we can neglect the backscattering term and only consider the s-waves term near the future apparent horizon.Comment: 26 pages,4 figures, 2 tables. arXiv admin note: substantial text overlap with arXiv:0705.4012 by other author

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“…Various authors have investigated the conformal behavior of Hawking temperature and Bekenstein-Hawking entropy, either (i ) based on the classical definitions of surface gravity and black hole horizons [10][11][12][13][14][15], or (ii ) [10,11,13,[15][16][17] based on the various methods devised in the literature for recovering those famous formulas [18][19][20][21] (see also the nice review in Ref. [22]).…”

Section: Introductionmentioning

confidence: 99%

Black hole mechanics and thermodynamics in the light of Weyl transformations

2018

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The fate of black hole thermodynamics under Weyl transformations is investigated by going back to the laws of black hole mechanics. It is shown that the transformed surface gravity, that one would identify with the black hole temperature in the conformal frame, as well as the black hole entropy, that one would identify with the horizon area, cannot be invariant. It is also shown that the conformally invariant surface gravity, attributed to the so-called "conformal Killing horizon", cannot represent the black hole temperature in the conformal frame. Finally, using familiar thought experiments, we find that the effect a Weyl transformation should have on black hole thermodynamics becomes even subtler than what is suggested by the laws of black hole mechanics.

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Conformally rescaled spacetimes and Hawking radiation

Cited by 28 publications

References 56 publications

Embedding Black Holes and Other Inhomogeneities in the Universe in Various Theories of Gravity: A Short Review

Embedding Black Holes and Other Inhomogeneities in the Universe in Various Theories of Gravity: A Short Review

Particle creation from the quantum stress tensor

Black hole mechanics and thermodynamics in the light of Weyl transformations

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