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A. T. N. Silva

Publications and source records attributed to A. T. N. Silva.

4 recordsLinked to original sources

Shadow of a Noncommutative Thin-Shell Gravastar

One of the main challenges in astronomy is the direct observation of black holes. However, distinguishing black holes from ultra-compact horizonless objects through photon observations can be difficult, since the latter may also possess unstable circular photon orbits. An example of an Ultra-Compact Object is a Gravastar (gravitational vacuum star), initially proposed by Mazur and Mottola. For definition purposes, we construct a spherically symmetric thin-shell gravastar model within a noncommutative model, in which these effects are integrated by a Lorentzian distribution of the energy density with a minimum width $\sqrtθ$. The model is constructed using the cut-and-paste technique to connect a nonsingular de Sitter interior to a noncommutative Schwarzschild exterior, satisfying the Israel junction conditions on the interface hypersurface $Σ$. We examine the stability of the model through its energy conditions, highlighting the influence of the noncommutative parameter on its behavior. {Model stability was also investigated using the parameter $η$, derived from the linearized stability analysis.} We also show that, owing to noncommutativity, the photon trajectories and deflection angles change as the noncommutative parameter increases. Our proposed gravastar model, with noncommutative geometry on its exterior, can be considered a stable and viable alternative to the charged black hole in the context of this type of gravity.

gr-qc↗

Thin-shell gravastar model in a BTZ geometry with minimum length

In this paper, we construct two spherically symmetric thin-shell gravastar models within a BTZ geometry with minimum length. Therefore, in the inner region of the gravastar, we consider an anti- de Sitter metric with minimum length. Thus, for the first model, we introduce the minimum length effect using the probability density of the ground state of the hydrogen atom in two dimensions. For the second gravastar model, we adopt a Lorentzian-type distribution. Also in the outer region, we consider the BTZ black hole metric. So, by examining the inner spacetime, the thin shell, and the outer spacetime, we find that there are different physical characteristics regarding their energy densities and pressures that make the gravastar stable. This effect persists even when the cosmological constant is zero. In addition, we determined the entropy of the gravastar thin shell. Besides, we explore the thermodynamic properties of the BTZ black hole with minimum length in Schwarzschild-type form and also check its stability.

gr-qc↗

Thin-shell gravastar in a noncommutative BTZ geometry

In this paper, we build a thin-shell gravastar model within a noncommutative BTZ geometry. For this, we consider a noncommutative BTZ metric in the inner region and a geometry associated with a BTZ solution in the outer region, joined by the generalized join technique. After investigating the inner spacetime, surface and outer spacetime, we observe that there is a surface energy density and surface pressure, such as to make gravastar stable. This effect persists even when the cosmological constant is zero. Besides, we found a bound for the noncommutativity parameter. In addition, we examine the thermodynamics of the noncommutative BTZ black hole in Schwarzschildtype form in three-dimensional spacetime. We also check the stability condition by calculating the specific heat capacity.

gr-qc↗

Hawking radiation and entropy of a BTZ black hole with minimum length

In this paper we consider a BTZ black hole with minimum length which has been introduced through the probability density of the ground state of the hydrogen atom. We analyzed the effect of the minimum length by calculating the thermodynamic quantities such as temperature and entropy and verified the stability of the black hole by computing the specific heat capacity.

hep-th↗