A tensorial description of particle perception in black-hole physics

Barbado, Luis C.; Barceló, Carlos; Garay, Luis J.; Jannes, Gil

doi:10.1103/physrevd.94.064004

Cited by 15 publications

(21 citation statements)

References 37 publications

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“…We also found that, after including the term capturing the effects of non-exact adiabaticity of the temperature functional, the discrepancy with the energy density obtained from the RSET increased in magnitude. One might think that this is contradictory as the energy density considered in (29) closely resembles the energy density computed from the RSET in [21], but this is not the case. This can be accounted for by the fact that the quantity computed in [21] is not the same energy density for the freely-falling observer as we computed in (13).…”

Section: Discussionmentioning

confidence: 94%

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Black hole quantum atmosphere for freely falling observers

et al. 2019

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We analyze Hawking radiation as perceived by a freely-falling observer and try to draw an inference about the region of origin of the Hawking quanta. To do so, first we calculate the energy density from the stress energy tensor, as perceived by a freely-falling observer. Then we compare this with the energy density computed from an effective temperature functional which depends on the state of the observer. The two ways of computing these quantities show a mismatch at the light ring outside the black hole horizon. To better understand this ambiguity, we show that even taking into account the (minor) breakdown of the adiabatic evolution of the temperature functional which has a peak in the same region of the mismatch, is not enough to remove it. We argue that the appearance of this discrepancy can be traced back to the process of particle creation by showing how the Wentzel-Kramers-Brillouin approximation for the field modes breaks down between the light ring at 3M and 4M , with a peak at r = 3.3M exactly where the energy density mismatch is maximized. We hence conclude that these facts strongly support a scenario where the Hawking flux does originate from a "quantum atmosphere" located well outside the black hole horizon. *

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Section: Discussionmentioning

confidence: 94%

“…Throughout the paper we considered the case of black hole collapse and worked with Unruh vacuum state. For this case, unlike[21], we do not need to consider the contribution of the effective temperature with respect to the ingoing null coordinate to the energy density.…”

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confidence: 99%

Black hole quantum atmosphere for freely falling observers

et al. 2019

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“…As already mentioned in the introduction, in this work we shall propose a clean separation between the Hawking and Unruh effects (under the simplifying assumptions of the analysis). This separation amounts to distinguishing between radiation action as the Hawking effect, and radiation back-reaction as the Unruh effect (an interpretation which we already advanced in [22]-see also [23]). In the first case, it is the radiation emitted by the black hole and already present in the field which acts upon the detector; while in the second, it is the detector that perturbs the field and, by back-reaction, modifies its trajectory at the same time that it becomes excited.…”

Section: Hawking Versus Unruh Effectsmentioning

confidence: 92%

Hawking versus Unruh effects, or the difficulty of slowly crossing a black hole horizon

Barbado

Barceló

Garay

et al. 2016

J. High Energ. Phys.

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When analyzing the perception of Hawking radiation by different observers, the Hawking effect becomes mixed with the Unruh effect. The separation of both effects is not always clear in the literature. Here we propose an inconsistency-free interpretation of what constitutes a Hawking effect and what an Unruh effect. An appropriate interpretation is important in order to elucidate what sort of effects a detector might experience depending on its trajectory and the state of the quantum field. Under simplifying assumptions we introduce an analytic formula that separates these two effects. Armed with the previous interpretation we argue that for a free-falling detector to cross the horizon without experiencing high-energy effects, it is necessary that the horizon crossing is not attempted at low velocities.

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“…This is a generalisation of the Hawking temperature which characterises the flux of outgoing radiation at future infinity. As was shown in [23], this function is directly related to the term in the RSET evaluated in dynamical vacua which regularises the divergence at the horizon of the static Boulware vacuum.…”

Section: Introductionmentioning

confidence: 75%

“…In more general terms, if κ ũ u or κ ṽ v remain constant for a sufficiently long period of time (defined by an adiabaticity condition), the vacuum state defined by the {ũ,ṽ} coordinates (through the modes in (2)) will be seen by an observer with proper coordinates {u, v} as a thermal state of outgoing or ingoing radiation respectively [22]. This function is also directly related to the outgoing and ingoing radiation fluxes which appear in the RSET after a change of vacuum state [23]. Specifically, equations (5) can be written as…”

Section: Renormalised Stress-energy Tensor In 1+1 Dimensionsmentioning

confidence: 99%

Semiclassical gravity effects near horizon formation

Barceló¹,

Boyanov²,

Carballo-Rubio³

et al. 2019

Class. Quantum Grav.

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We study the magnitude of semiclassical gravity effects near the formation of a black-hole horizon in spherically-symmetric spacetimes. As a probe for these effects we use a quantised massless scalar field. Specifically, we calculate two quantities derived from it: the renormalised stress-energy tensor (a measure of how the field vacuum state affects the spacetime) and the effective temperature function (a generalisation of Hawking temperature related to the energy flux of the field vacuum). The subject of our study are spacetimes which contain a spherical distribution of matter and an empty exterior Schwarzschild region, separated by a surface which is moving in proximity to the Schwarzschild radius r s = 2M , with M the total mass. In particular, we analyse the consequences of three types of surface movement: an oscillation just above r s , a monotonous approach towards r s in infinite time and a crossing of r s at different velocities. For a collapsing matter distribution which follows the expected dynamical evolution in general relativity, we recover the standard picture of black-hole formation and its tenuous semiclassical effects. In more general dynamical regimes, allowing deviations from the standard classical evolution, we obtain a variety of different effects: from the emission of Hawking-like radiation without the formation of a horizon, to large values of the renormalised stress-energy tensor, related to the Boulware vacuum divergence in static spacetimes.

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A tensorial description of particle perception in black-hole physics

Cited by 15 publications

References 37 publications

Black hole quantum atmosphere for freely falling observers

Black hole quantum atmosphere for freely falling observers

Hawking versus Unruh effects, or the difficulty of slowly crossing a black hole horizon

Semiclassical gravity effects near horizon formation

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