Abstract:We have analyzed the transformation from initial coordinates (v, r) of the Vaidya metric with light coordinate v to the most physical diagonal coordinates (t, r). An exact solution has been obtained for the corresponding metric tensor in the case of a linear dependence of the mass function of the Vaidya metric on light coordinate v. In the diagonal coordinates, a narrow region (with a width proportional to the mass growth rate of a black hole) has been detected near the visibility horizon of the Vaidya accreti… Show more
“…where a in < a is the scale factor at which the object becomes cosmologically coupled and p 0. This mechanism explains the local mass scaling, such as the one present in the McVittie metric (63), but does not capture the local dynamics. We begin the procedure of embedding a PBH into a spatially flat FRLW background by writing its metric in the form of Eq.…”
Section: Models Of Compact Objects With Cosmological Boundary Conditi...mentioning
confidence: 96%
“…Different aspects of the black hole geometry are best captured by different coordinate systems. However, transformations between them are difficult [50], and where exact coordinate transformations do exist, multiple coordinate patches are required to cover the entire spacetime [63]. In what follows we assume a linear evaporation law, such that…”
Section: Linear Mass Loss: Exact Coordinate Transformationsmentioning
Working in the semi-classical setting, we present an exactly solvable candidate model for astrophysical black holes, which can be embedded in a cosmological background and possess regular apparent horizons that form in finite observational time. We construct near-horizon quantities from the assumption of regularity of the renormalized expectation value of the energy-momentum tensor, and derive explicit coordinate transformations in the near-horizon region. We discuss the appropriate boundary conditions for the embedding of the model into an FRWL background, describe their evaporation in the linear regime, and highlight consequences for the laws of black hole mechanics when back-reaction is present.
“…where a in < a is the scale factor at which the object becomes cosmologically coupled and p 0. This mechanism explains the local mass scaling, such as the one present in the McVittie metric (63), but does not capture the local dynamics. We begin the procedure of embedding a PBH into a spatially flat FRLW background by writing its metric in the form of Eq.…”
Section: Models Of Compact Objects With Cosmological Boundary Conditi...mentioning
confidence: 96%
“…Different aspects of the black hole geometry are best captured by different coordinate systems. However, transformations between them are difficult [50], and where exact coordinate transformations do exist, multiple coordinate patches are required to cover the entire spacetime [63]. In what follows we assume a linear evaporation law, such that…”
Section: Linear Mass Loss: Exact Coordinate Transformationsmentioning
Working in the semi-classical setting, we present an exactly solvable candidate model for astrophysical black holes, which can be embedded in a cosmological background and possess regular apparent horizons that form in finite observational time. We construct near-horizon quantities from the assumption of regularity of the renormalized expectation value of the energy-momentum tensor, and derive explicit coordinate transformations in the near-horizon region. We discuss the appropriate boundary conditions for the embedding of the model into an FRWL background, describe their evaporation in the linear regime, and highlight consequences for the laws of black hole mechanics when back-reaction is present.
“…As mentioned above, such an exterior stationary metric is needed to support the interior scalar field dynamics. For the case of stable configurations, the perpetual bounded oscillating interior spacetime could in principle be matched with some sort of Vaidya spacetime [26]. For the case of unstable configurations on the other hand, the same procedure could be performed considering a Vaidya layer before its extension to the Reissner-Nordstöm-de Sitter exterior solution [27].…”
In this paper we examine the stability of stellar configurations in which the interior solution is described by a closed FLRW geometry sourced with a charged pressureless fluid and radiation. An interacting vacuum component and a conformally coupled massive scalar field are also included. Given a simple factor for the energy transfer between the nonrelativistic fluid and the vacuum component we obtain bounded interior oscillatory solutions. We show that in proper domains of the parameter space the interior dynamics is highly unstable so that the break of the KAM tori leads to a disruptive ejection of mass. For such configurations the interior solution asymptotically matches an exterior Reissner-Nordström-de Sitter spacetime.
“…the formation of a transient trapped region when used as an exterior metric for particular models of collapsing stars, or a singularity (naked or hidden behind the event horizon). 142,146 The EMT has only one non-zero component…”
Section: Spherical Symmetry: Relations With Popular Modelsmentioning
confidence: 99%
“…On the one hand, it is conceivable that the horizon crossing time according to Bob becomes finite. 146 On the other hand, if r g recedes faster the particle approaches it, there will be no crossing at all. We investigate both of these non-classical possibilities: (i) that Alice's and Bob's times are finite, and (ii) that horizon crossing does not happen.…”
Section: Finite Blueshift and Finite Infall Timementioning
For distant observers black holes are trapped spacetime domains bounded by apparent horizons. We review properties of the near-horizon geometry emphasizing the consequences of two common implicit assumptions of semiclassical physics. The first is a consequence of the cosmic censorship conjecture, namely that curvature scalars are finite at apparent horizons. The second is that horizons form in finite asymptotic time (i.e. according to distant observers), a property implicitly assumed in conventional descriptions of black hole formation and evaporation. Taking these as the only requirements within the semiclassical framework, we find that in spherical symmetry only two classes of dynamic solutions are admissible, both describing evaporating black holes and expanding white holes. We review their properties and present the implications. The null energy condition is violated in the vicinity of the outer and satisfied in the vicinity of the inner apparent/anti-trapping horizon. Apparent and anti-trapping horizons are timelike surfaces of intermediately singular behavior, which is demonstrated in negative energy density firewalls. These and other properties are also present in axially symmetric solutions. Different generalizations of surface gravity to dynamic spacetimes are discordant and do not match the semiclassical results. We conclude by discussing signatures of these models and implications for the identification of observed ultra-compact objects.
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