arXiv subjects

Sunil Singh Bohra

Publications and source records attributed to Sunil Singh Bohra.

3 recordsLinked to original sources

arXiv2026

Blackhole perturbations in the Modified Generalized Chaplygin Gas model

We study blackhole in the Modified Generalized Chaplygin Gas (MGCG) model, a modified gravity framework proposed to unify dark matter and dark energy. The resulting spacetime is asymptotically non-flat and feature two distinct horizons, determined by the Chaplygin parameter $α$. Observational constraints favor negative values of $α$, which restrict the allowed parameter space. Through linear perturbation analysis, we show that this blackhole remain stable under both scalar and electromagnetic perturbation. The corresponding quasinormal mode spectra depend sensitively on the MGCG parameters, indicating that this cosmological model leaves characteristic imprints on blackhole oscillations. These results suggest that gravitational-wave observations of blackhole ringdowns may provide a means of constraining MGCG and testing unified dark sector scenarios in the strong-field regime.

gr-qc↗

arXiv2024

Gravitational atoms in the braneworld scenario

In the Randall-Sundrum (RS) II braneworld scenario, general relativity (GR) is modified by adding an extra dimension such that it is indistinguishable from GR in the weak gravity limit. However, such modifications may leave a mark in the strong field regime. We therefore analyze massive scalar perturbations around rotating black holes in the RS II model. Unlike black holes in GR, these braneworld black holes carry a tidal charge that contains information about the extra spatial dimension, and the rotation parameter for such black holes can exceed unity. Through the method of continued fractions, we investigate the quasinormal mode spectra, and the superradiant instabilities associated with the existence of quasibound states, that is, gravitational atoms. In comparison to the four-dimensional Kerr black hole, we report distinctive signatures of the tidal charge and the rotation parameter, which manifest as signals of the extra dimension, on both the fundamental quasinormal mode and the formation of gravitational atoms. These findings offer insights into testing modifications to GR and detecting ultralight bosonic particles around black holes.

gr-qc↗

arXiv2023

Traversable wormholes in bi-metric gravity

The ghost-free bi-metric gravity theory is a viable theory of gravity that explores the interaction between a massless and a massive graviton and can be described in terms of two dynamical metrics. In this paper, we present an exact static, spherically symmetric vacuum solution within this theory. The solution is spatially Schwarzschild-de Sitter, with the value of the cosmological constant determined by the graviton mass and the interaction parameters of the theory. Notably, for specific parameter ranges, the solution represents a traversable Lorentzian wormhole that violates the weak energy condition near its throat. Furthermore, we have investigated the evolution of scalar and electromagnetic fields in this wormhole spacetime and observed the presence of arbitrarily long-lived quasi-resonant modes in the quasinormal spectrum.

gr-qc↗