A model of an emergent universe is obtained in brane world. Here the bulk energy is in the form of cosmological constant, while the brane consists of a fluid satisfying an equation of state of the form p b = 1 3 ρ b , which is effectively a radiation equation of state at high energies. It is shown that with the positive bulk cosmological constant, one of our models represents an emergent universe.The search for singularity free inflationary models in the context of Classical General Relativity has recently led to the development of emergent universes.Harrison [1] obtained a model of the closed universe containing radiation, which approaches the state of an Einstein static model asymptotically, i.e. as t → −∞. This kind of model has so far been discovered subsequently by several workers in the recent past such as that of Ellis and Maartens [2], Ellis et al. [3]. They obtained closed universes with a minimally coupled scalar field φ with a special form for self interacting potential and possibly some ordinary matter with equation of state p = ωρ where − 1 3 ≤ ω ≤ 1. However, exact analytic solutions were not presented in these models, although their behaviour alike that of an emergent universe was highlighted. An emergent universe is a model universe in which there is no timelike singularity, is ever existing and having almost static behaviour in the infinite past (t → −∞) as is mentioned earlier. The model eventually evolves into an inflationary stage. In fact, the emergent universe scenario can be said to be a modern version and extension of the original Lemaitre-Eddington universe. Mukherjee et al. [4] obtained solutions for Starobinsky model for flat FRW space time and studied the features of

Communicated by J. PullinModified Chaplygin gas (MCG) is a strong candidate for the unified model of dark matter and dark energy. The equation of state of this modified model is valid from the radiation era to the ΛCDM model. In the early epoch (when ρ was large), dark matter had the dominant role, while at later stages (when ρ is small), the MCG model behaves as dark energy. In this work, we have found an exact solution to static, spherically symmetric Einstein equations describing a wormhole for an inhomogeneous distribution of MCG. For the existence of a wormhole solution, there are some restrictions concerning the parameters in the equation of state for MCG and the throat radius of the wormhole. Physical properties and characteristics of such modified Chaplygin wormholes are analyzed in detail.

In this work, the five-dimensional black hole solutions are presented in Einstein–Maxwell–Gauss–Bonnet theory. The geometry of the black hole thermodynamics has also been studied briefly.

In this work, we study some parameterizations of the deceleration parameter and investigate the accretion of the fluid in these parameterized models upon the higher-dimensional black hole (BH) and wormholes. For the undergoing analysis, [Formula: see text]-dimensional wormhole (proposed by Morris and Thorne) and Schwarzschild BH were chosen in the backdrop of higher-dimensional Friedmann–Robertson–Walker (FRW) space-time. For these parameterized models, we analyze the change of masses of BH and wormhole in different dimensions.

A thin-shell Lorentzian wormhole with spherical symmetry has been constructed in Einstein-Yang-Mills-Gauss-Bonnet theory. The generalized Darmois-Israel matching conditions are applied to the bounding shell and energy localized on the shell has been calculated. The amount of exotic matter for the existence of the wormhole has been evaluated and it has been shown graphically for certain choices of the parameters involved that ordinary matter is sufficient for the formation of thin-shell wormholes.

In this work, we have considered the magnetic universe in non-linear electrodynamics. The Einstein's field equations for non-flat FRW model have been considered when the universe is filled with the matter and magnetic field only. We have discussed the validity of the generalized second law of thermodynamics of the magntic universe bounded by Hubble, apparent, particle and event horizons using Gibb's law and the first law of thermodynamics for interacting and non-interacting scenarios. It has been shown that the GSL is always satisfied for Hubble, apparent and particle horizons but for event horizon, the GSL is violated initially and satisfied at late stage of the universe. *

In Einstein gravity, for an inhomogeneous phantom energy distribution having linear equation of state (but anisotropic), there exists simple exact solution for spherically symmetric space time describing a wormhole. At infinity, the space time is not asymptotically flat and possesses a regular cosmological Killing horizon with an infinite area. In this work, we have shown that, this wormhole solution is also possible in brane world for various matter distribution, which are not necessarily phantom in nature.Keywords Wormhole · Brane world PACS 98.80.Cq · 04.20.Gz · 04.50.+h Wormholes are usually defined as smooth bridges between different universes or topological handles (i.e, throats, having no horizons) between remote parts of a single universe. Earlier, wormholes are purely of theoretical curiosity (Moris and Thorne 1988;Visser 1995;Visser and Hochberg 2007), but recently this theoretical aspect has gained significant importance due to the present accelerating phase of our universe (Reiss et al. 1998;Perlmutter et al. 1999). There is a nice similarity between this theoretical phenomenon and the recent observational aspects. A traversable wormhole is supported by so called exotic matter with a negative pressure (p < 0) and violation of the null energy condition (i.e., ρ + p < 0) at least in a neighbourhood of the wormhole throat (Hochberg and Visser 1998). On the other hand, the

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