arXiv subjects

Sara Saghafi

Publications and source records attributed to Sara Saghafi.

24 records · Page 2Linked to original sources

arXiv2023

Shadow Behavior of the Quantum-Corrected Schwarzschild Black Hole Immersed in Holographic Quintessence

In this paper, we aim to explore the impact of the Planck scale corrections and the Holographic quintessence on the shadow behavior of non-rotating black holes. To do this, we consider the quantum-corrected Schwarzschild black hole surrounded by the quintessence field inspired by the Kazakov-Solodukhin and the Kiselev ideas, and we call this combination the Kazakov-Solodukhin-Kiselev (KSK) black hole. We conclude that the quintessence field as the candidate of dark energy in the black hole can be interpreted as Holographic quintessence. To find the geodesic equations of the black hole, we employ the Hamilton-Jacobi approach and also, the Carter procedure. We discover that the size of the shadow of this black hole, which depends on its central mass, is also determined by the Planck scale effects and Holographic quintessence.

hep-th↗

arXiv2022

Hawking-Like Radiation as Tunneling from a Cosmological Black Hole in Modified Gravity: Semiclassical Approximation and Beyond

Hawking radiation as a quantum phenomenon is generally attributed to the existence of the event horizon of a black hole. However, we demonstrate in this paper that there is indeed ingoing Hawking-like radiation associated with apparent horizons of the first cosmological black hole solution in the framework of Scalar-Tensor-Vector Gravity (STVG) theory living in the Friedmann-Lema\^ıtre-Robertson-Walker (FLRW) background. Such radiation can be attributed also to the cosmological apparent horizon of the FLRW universe and even to the cosmological event horizon of de Sitter spacetime. We see how STVG theory as a good theory for explaining black holes both on local and global scales affect the Hawking effect. Based on semiclassical approximation, we follow Hamilton-Jacobi and Parikh-Wilczek tunneling methods, respectively with and without back-reaction effects. We find out that back-reaction effects make a correlation between the emission modes in Parikh-Wilczek tunneling formalism, which can address the information paradox. We obtain the corresponding Hawking-like temperature as a function of inverse powers of apparent horizons radiuses of the cosmological black hole in STVG theory. We analyze the influence of the STVG parameter associated with a deviation of the STVG theory from General Theory of Relativity (GR) on both apparent horizons and the Hawking-like temperature of the cosmological black hole. We show that increasing the STVG parameter results in appearing the Hawking-like temperature in later cosmic times with some smaller values. Also, we follow the Hamilton-Jacobi approach beyond semiclassical approximation to involve all quantum correction terms in the deduced semiclassical outcomes for the cosmological black hole in the STVG theory.

gr-qc↗

arXiv2020

Quantum Corrections to the Accretion onto a Schwarzschild Black Hole in the Background of Quintessence

It is well known that quantum effects may lead to remove the intrinsic singularity point of back holes. Also, the quintessence scalar field is a candidate model for describing late-time acceleration expansion. Accordingly, Kazakov and Solodukhin considered the existence of back-reaction of the spacetime due to the quantum fluctuations of the background metric to deform Schwarzschild black hole, which led to change the intrinsic singularity of the black hole to a 2-sphere with a radius of the order of the Planck length. Also, Kiselev rewrote the Schwarzschild metric by taking into account the quintessence field in the background. In this study, we consider the quantum-corrected Schwarzschild black hole inspired by Kazakov-Solodukhin's work, and Schwarzschild black hole surrounded by quintessence deduced by Kiselev to study the mutual effects of quantum fluctuations and quintessence on the accretion onto the black hole. Consequently, the radial component of 4-velocity and the proper energy density of the accreting fluid have a finite value on the surface of its central 2-sphere due to the presence of quantum corrections. Also, by comparing the accretion parameters in different kinds of black holes, we infer that the presence of a point-like electric charge in the spacetime is somewhat similar to some quantum fluctuations in the background metric.

gr-qc↗

arXiv2020

Thermodynamics of Non-Commutative Scalar-Tensor-Vector Gravity Black holes

In this paper, we analyze the thermodynamic stability of Schwarzschild Modified Gravity (MOG) black holes in a non-commutative framework. We show that, unlike a commutative MOG black hole, in the coherent state picture of non-commutativity MOG black holes are thermodynamically stable. At the final stage of evaporation, a stable remnant with zero temperature and finite entropy is left in this noncommutative framework. Also, we consider Parikh-Wilczek tunneling mechanism of massive particles from non-commutative MOG black holes and demonstrate that information leaks out of non-commutative MOG black holes in the form of some non-thermal correlations.

gr-qc↗

arXiv2019

Black Hole Production in the Presence of a Maximal Momentum in Horizon Wave Function Formalism

We study the Horizon Wave Function (HWF) description of a generalized uncertainty principle (GUP) black hole in the presence of two natural cutoffs as a minimal length and a maximal momentum. This is motivated by a metric which allows the existence of sub-Planckian black holes, where the black hole mass $m$ is replaced by $M=m\Big(1+\frac{β^{2}}{2}\frac{M_{pl}^{2}}{m^{2}}-β\frac{M_{pl}}{m}\Big)$. Considering a wave-packet with a Gaussian profile, we evaluate the HWF and the probability that the source might be a (quantum) black hole. By decreasing the free parameter the general form of probability distribution, ${\mathcal{P}}_{BH}$, is preserved , but this resulted in reducing the probability for the particle to be a black hole accordingly. The probability for the particle to be a black hole grows when the mass is increasing slowly for larger positive $β$, and for a minimum mass value it reaches to $0$. In effect, for larger $β$ the magnitude of $M$ and $r_{H}$ increases, matching with our intuition that either the particle ought to be more localized or more massive to be a black hole. The scenario undergoes a change for some values of $β$ significantly, where there is a minimum in ${\mathcal{P}}_{BH}$ , so this expresses that every particle can have some probability of decaying to a black hole. In addition, for sufficiently large $β$ we find that every particle could be fundamentally a quantum black hole.

physics.gen-ph↗

arXiv2018

Black hole thermodynamics in Snyder phase space

By defining a noncommutative symplectic structure, we study thermodynamics of Schwarzschild black hole in a Snyder noncommutative phase space for the first time. Since natural cutoffs are the results of compactness of symplectic manifolds in phase space, the physics of black holes in such a space would be affected mainly by these cutoffs. In this respect, this study provides a basis for more deeper understanding of the black hole thermodynamics in a pure mathematical viewpoint.

gr-qc↗