arXiv subjects

Suresh C. Jaryal

Publications and source records attributed to Suresh C. Jaryal.

7 recordsLinked to original sources

arXiv2026

Quasinormal modes of the generalized JMN naked singularity using exact WKB analysis

In this paper, we study the quasinormal modes of the generalized Joshi-Malafarina-Narayan (JMN) naked singularity spacetime using the exact Wentzel-Kramers-Brillouin (WKB) method. Working in the complex radial plane, we construct the exact WKB momentum function, determine its turning points, and compute the associated Stokes geometry for representative quasinormal mode (QNM) frequencies. We obtained a bow-shaped deformation of Stokes curves on the side of the complex plane containing the central singularity in JMN spacetime. We show analytically that this structure originates from the logarithmic branch-point singularity of the WKB phase at $(r = 0)$, which is absent in Schwarzschild spacetime. This establishes the bow-shaped Stokes topology as a direct signature of the naked singularity in the global analytic structure of the perturbation equation. Our results demonstrate that exact WKB analysis provides a powerful framework for probing the analytic structure of compact objects, and suggest that topological features of Stokes geometry may offer a new avenue for distinguishing black holes from horizonless alternatives.

gr-qc↗

arXiv2025

Spherical trapped surfaces in n-dimensional general relativity

In this paper, we examine gravitational collapse of matter fields in $n$-dimensional general relativity. The matter energy-momentum tensor under consideration includes dust, perfect fluids with equations of state and matter admitting bulk and shear viscosity. By adjusting various parameters of the matter energy-momentum tensor, we determine the trapped region and spherical marginally trapped surfaces in homogeneous and inhomogeneous models of collapse. We show that, as expected, the time development of marginally trapped tube is intricately related to the initial velocity and density profiles of the collapsing matter configuration. This study clarifies the role of initial data in the formation of spacetime singularity during gravitational collapse and implies that, under generic conditions on the matter profiles, the central spacetime singularity is always covered by a horizon.

gr-qc↗

arXiv2025

Gravitational collapse in pure Gauss- Bonnet theory

In this paper, we study the gravitational collapse of matter fields, which include dust, perfect fluids as well as fluids admitting bulk and shear viscosity. The initial conditions on these matter fields have been kept to be quite general: the initial velocity profile of the matter is taken to include both the bound and the marginally bound models, while the density profile of the initial matter configuration is assumed to have physically admissible portrayal, and smooth falloffs. We determine, under these general conditions, the time of formation of the central singularity and the formation and evolution of black hole horizons, depicted here in terms of quasilocal marginally trapped surfaces. Our study shows that under these general conditions, the central singularity remains hidden from the asymptotic observer.

gr-qc↗

arXiv2023

Effects of electromagnetic field on a radiating star

In this paper we study the shear free spherical symmetric gravitational collapse of charged radiating star. All the physical quantities including pressure, density are regular. Energy conditions are satisfied throughout the interior of the matter configuration. The luminosity is time independent and mass is radiated linearly. The causal and non causal temperature remains greater than that of the uncharged collapsing scenario.

gr-qc↗

arXiv2022

Spherical Gravitational Collapse in 4D Einstein-Gauss-Bonnet theory

In this paper, we study spherical gravitational collapse of inhomogeneous pressureless matter in a well-defined $n \rightarrow4$d limit of the Einstein-Gauss-Bonnet gravity. The collapse leads to either a black hole or a massive naked singularity depending on time of formation of trapped surfaces. More precisely, horizon formation and its time development is controlled by relative strengths of the Gauss-Bonnet coupling $(λ)$ and the Misner-Sharp mass function $F(r,t)$ of collapsing sphere. We find that, if there is no trapped surfaces on the initial Cauchy hypersurface and $F(r,t)< 2\sqrtλ$, the central singularity is massive and naked. When this inequality is equalised or reversed, the central singularity is always censored by spacelike/timelike spherical marginally trapped surface of topology $S^{2}\times \mathbb{R}$, which eventually becomes null and coincides with the event horizon at equilibrium. These conclusions are verified for a wide class of mass profiles admitting different initial velocity conditions. Hence, our result implies that the $4$d Einstein-Gauss-Bonnet generically violates the cosmic censorship conjuncture. Further implications of this violation from the perspective of visibility of causal signals from the spacetime singularity are also discussed.

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arXiv2021

Gravitationally collapsing stars in $f(R)$ gravity

The gravitational dynamics of a collapsing matter configuration which is simultaneously radiating heat flux is studied in $f(R)$ gravity. Three particular functional forms in $f(R)$ gravity are considered to show that it is possible to envisage boundary conditions such that the end state of the collapse has a weak singularity and that the matter configuration radiates away all of its mass before collapsing to reach the central singularity.

gr-qc↗

arXiv2021

Radiating-collapsing models satisfying Karmarkar condition

This paper presents a class of exact spherical symmetric solutions of the Einstein equations admitting heat-conducting anisotropic fluid as a collapsing matter. The exterior spacetime is assumed to be the Vaidya metric. This class of solutions is shown to satisfy all the energy conditions throughout the interior of the star, and the luminosity is time independent, radiating uniformly throughout the collapse.

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