Search arXiv⌕ Search
Home/Archive/arXiv

arXiv · gr-qc/0512148

Classical Solutions in Einstein's Gravity and Study of some Collapsing Models

Ujjal Debnath
View original source ↗Read source document ↗Export metadata ↓

Abstract

My research work can be classified into two parts namely, (i) Cosmological phenomena with varying speed of light and (ii) Gravitational collapse and black holes. We have investigated several cosmological phenomena when velocity of light varies with time. We have considered the variation of light as power-law in time and have studied the Brans-Dicke cosmology, Quintessence problem and others. We have also examined whether some cosmological problems can be solved using it for anisotropic space-time model. In brane scenario we have studied some cosmological implications namely, the Cosmic No-Hair Conjecture (CNHC) and variable gravity theory. In CNHC we have shown that in realistic situation no more extra conditions are needed in brane scenario. In gravitational collapse, we have mainly concentrated to spherical collapse for dust distribution. We have considered both four and higher dimensional space-time and have examined the possibility for formation of black hole or naked singularity. In marginally bound case we have found naked singularity is possible only for four and five dimension, while for non-marginally bound case the possibility of black hole increases with the increase in the dimension of the space-time. In quasi-spherical gravitational collapse for dust distribution, we have (n+2) dimensional Szekeres space-time and have examined the possibility for formation of black hole or naked singularity. In marginally bound case, we have found that possibility of naked singularity depends on dimension of the space-time.

Explore related subjects

gr-qcastro-ph

Keep this discovery

Explore connections, maps & timelines

BibTeXRIS

Ujjal Debnath. 2005-12-24. Classical Solutions in Einstein's Gravity and Study of some Collapsing Models. https://arxiv.org/abs/gr-qc/0512148

Cite the original work for its findings. Save a collection to share your selection of sources.

KEEP EXPLORING

Related papers

arXiv2026

An upper bound on the minimum orbital period of black holes

Previous research has focused on establishing lower bounds on the minimum orbital period of black holes. In this work, we explore the complementary question of whether an upper bound exists for the minimum orbital period of black holes. We investigate the minimum orbital periods of three types of black holes: Schwarzschild, Reissner-Nordström and Kerr-Newman black holes. We find that the minimum orbital period of these black holes is bounded by an upper limit $T_{min} \leqslant 6\sqrt{3}πM$, where $M$ is the black hole mass. Our results suggest that this upper bound on the minimum orbital period may be a general property in black hole spacetimes.

gr-qc↗
arXiv2026

Bounds on the minimum orbital period in the background of 5-dimensional charged black holes

In this paper, we study the upper and lower bounds on the minimum orbital period of 5-dimensional charged black holes. Our results indicate that the upper bound of the minimum orbital period corresponds to non-charged black holes, while the lower bound is achieved in the case of maximally charged black holes. We further establish precise analytical expressions for the upper and lower bounds of the minimum orbital period. Our findings provide valuable insights into 5-dimensional charged black holes and help constrain theoretical gravity models.

gr-qc↗
arXiv2026

Analysis of minimum orbital periods around d-dimensional charged black holes

This paper investigates the bounds on the minimum orbital period for test objects around d-dimensional charged black holes in asymptotically flat spacetimes. We derive the exact critical radius and the minimum orbital period. We then prove analytically that the minimum orbital period decreases strictly as the charge of the black hole increases. Thus, the upper limit is reached for an uncharged black hole, while the lower limit is attained for a maximally charged one, and the two bounds take the closed form $\frac{2π(d-2)}{d-3}[(d-2)M]^{\frac{1}{d-3}}\leqslant T_{min} \leqslant 2π\sqrt{\frac{d-1}{d-3}}\,[(d-1)M]^{\frac{1}{d-3}}$. Since the minimum period equals $2π$ times the shadow radius, the upper bound is equivalently a universal upper bound on the shadow radius. These results improve our understanding of dynamics around d-dimensional black holes and impose constraints on candidate gravity theories.

gr-qc↗