Regular black holes and noncommutative geometry inspired fuzzy sources

Kobayashi, Shinpei

doi:10.1142/s0217751x16500809

Cited by 5 publications

(9 citation statements)

References 29 publications

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“…In fact, it is claimed that the curvature singularity vanishes in non-commutative spacetime and black hole emits radiation till it becomes a zero temperature extremal black hole [17]. Noncommutativity is viewed as smearing of spacetime points and non-commutative geometry near black holes is studied using smeared sources rather than point like sources [18,19]. A detailed analysis of non-commutative black hole in Moyal space has been given in [20].…”

Section: Introductionmentioning

confidence: 99%

Hawking radiation in κ-spacetime

Harikumar

Zuhair

2017

Int. J. Mod. Phys. A

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In this paper, we analyze the Hawking radiation of a κ-deformed-Schwarzschild black hole and obtain the deformed Hawking temperature. For this, we first derive deformed metric for the κ-spacetime, which in the generic case, is not a symmetric tensor and also has a momentum dependence. We show that the Schwarzschild metric obtained in the κ-deformed spacetime has a dependence on energy. We use the fact that the deformed metric is conformally flat in the 1 + 1 dimensions to solve the κ-deformed Klein-Gordon equation in the background of the Schwarzschild metric. The method of Bogoliubov coefficients is then used to calculate the thermal spectrum of κ-deformed-Schwarzschild black hole and show that the Hawking temperature is modified by the noncommutativity of the κ-spacetime.

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Section: Introductionmentioning

confidence: 99%

Hawking radiation in κ-spacetime

Harikumar

Zuhair

2017

Int. J. Mod. Phys. A

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“…where m(r, θ) is given by (4). In the following we discuss the generic properties of (10) for a matter distribution obeying the minimum set of constraints (7), (8), and (9).…”

Section: Generic Properties Of the Metricmentioning

confidence: 99%

“…is called the standard Cauchy 4 distribution [17]. It has been used to model dark haloes in spiral galaxies in the 4 Its generalization [18], know as the generalized Cauchy distribution f (z), is proportional to σ (σ p + |z − θ| p ) 2/p , where θ is the location parameter, σ is the scale parameter, and p is the tail constant. center and in the outer spatial regions [19]; the model is widely accepted.…”

Section: A Definitionmentioning

confidence: 99%

“…This is the case with fourdimensional charge distributions [3], which may be noncentral (of Weibull character in some instances) and vanish at the origin. Three-dimensional non-central mass distributions with a central void have been shown to exist too [4]. The presence of the central void is to ensure existence of a two-horizon structure.…”

mentioning

confidence: 99%

“…The presence of the central void is to ensure existence of a two-horizon structure. Let m(r, θ) denote the mass inside a sphere of radius r. This is given by (4) where M is the total mass of the solution. To simplify the notation we have set…”

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confidence: 99%

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Smoothed one-core and core–multi-shell regular black holes

Azreg‐Aïnou¹

2018

Eur. Phys. J. C

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We discuss the generic properties of a general, smoothly varying, spherically symmetric mass distribution D(r, θ), with no cosmological term (θ is a length scale parameter). Observing these constraints, we show that (a) the de Sitter behavior of spacetime at the origin is generic and depends only on D(0, θ), (b) the geometry may posses up to 2(k + 1) horizons depending solely on the total mass M if the cumulative distribution of D(r, θ) has 2k + 1 inflection points, and (c) no scalar invariant nor a thermodynamic entity diverges. We define new two-parameter mathematical distributions mimicking Gaussian and step-like functions and reduce to the Dirac distribution in the limit of vanishing parameter θ. We use these distributions to derive in closed forms asymptotically flat, spherically symmetric, solutions that describe and model a variety of physical and geometric entities ranging from noncommutative black holes, quantum-corrected black holes to stars and dark matter halos for various scaling values of θ. We show that the mass-to-radius ratio πc 2 /G is an upper limit for regular-black-hole formation. Core-multi-shell and multi-shell regular black holes are also derived.

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Non-singular Brans–Dicke collapse in deformed phase space

et al. 2016

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We study the collapse process of a homogeneous perfect fluid (in FLRW background) with a barotropic equation of state in Brans-Dicke (BD) theory in the presence of phase space deformation effects. Such a deformation is introduced as a particular type of non-commutativity between phase space coordinates. For the commutative case, it has been shown in the literature [M A Scheel, S L Shapiro & S A Teukolsky, Phys Rev D 51 4236 (1995)], that the dust collapse in BD theory leads to the formation of a spacetime singularity which is covered by an event horizon. In comparison to general relativity (GR), the authors concluded that the final state of black holes in BD theory is identical to the GR case but differs from GR during the dynamical evolution of the collapse process. However, the presence of non-commutative effects influences the dynamics of the collapse scenario and consequently a non-singular evolution is developed in the sense that a bounce emerges at a minimum radius, after which an expanding phase begins. Such a behavior is observed for positive values of the BD coupling parameter. For large positive values of the BD coupling parameter, when non-commutative effects are present, the dynamics of collapse process differs from the GR case. Finally, we show that for negative values of the BD coupling parameter, the singularity is replaced by an oscillatory bounce occurring at a finite time, with the frequency of oscillation and amplitude being damped at late times.

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Regular black holes and noncommutative geometry inspired fuzzy sources

Cited by 5 publications

References 29 publications

Hawking radiation in κ-spacetime

Hawking radiation in κ-spacetime

Smoothed one-core and core–multi-shell regular black holes

Non-singular Brans–Dicke collapse in deformed phase space

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