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We present the study of exact inhomogeneous cosmological solutions to a four-dimensional low energy limit of string theory containing non-minimal interacting electromagnetic, dilaton and axion fields. We analyze Einstein-Rosen solutions of Einstein-Maxwell-dilaton-axion equations and show, by explicitly taken the asymptotic limits, that they have asymptotically velocity-term dominated (AVTD) singularities.
We study the nonlinear evolution of the spherical symmetric black holes under a small neutral scalar field perturbation in Einstein-Maxwell-dilaton theory with coupling function $f(phi)=e^{-bphi}$ in asymptotic anti-de Sitter spacetime. The non-minim
We study the fall-off behaviour of test electromagnetic fields in higher dimensions as one approaches infinity along a congruence of expanding null geodesics. The considered backgrounds are Einstein spacetimes including, in particular, (asymptoticall
We construct a specific example of a class of traversable wormholes in Einstein-Dirac-Maxwell theory in four spacetime dimensions, without needing any form of exotic matter. Restricting to a model with two massive fermions in a singlet spinor state,
Exact black hole solutions in the Einstein-Maxwell-scalar theory are constructed. They are the extensions of dilaton black holes in de Sitter or anti de Sitter universe. As a result, except for a scalar potential, a coupling function between the scal
Some exact solutions for the Einstein field equations corresponding to inhomogeneous $G_2$ cosmologies with an exponential-potential scalar field which generalize solutions obtained previously are considered. Several particular cases are studied and