String cosmology in higher dimensional spherically symmetric space-time

Some cosmological solutions for string model are derived in higher dimensional spherically symmetric space-time, following the techniques used by Letelier. The equations of state for strings have been used for different solutions. Also polynomial relation between the metric coefficients has been assumed in some cases.     

String cloud and domain walls with quark matter in 5-D Kaluza–Klein cosmological model

In this study Kaluza–Klein Cosmological solutions are obtained for quark matter coupled to the string cloud and domain wall in the context of general relativity. For this purpose Einstein field equations are solved by using anisotropy feature of the universe in the five-dimensional Kaluza–Klein Cosmological model. Also, the features of obtained solutions are discussed.     

Magnetized strange quark matter solutions in f(R,T) gravity with cosmological constant

In this research, we have studied magnetized strange quark matter (SQM) solutions for Friedmann-Robertson-Walker (FRW) universe in f(R, T) gravity. To obtain exact solutions of modified field equations we have used $f(R,T)=R+2f\left(T\right)$ and $f(R,T)=f_1\left(R\right)+f_2\left(T\right)$ models given by Harko et al. (Harko et al. in Phys. Rev. D 84:024020, 2011) and $f(R,T)=R+f_3\left(T\right)$ model (here f₃ is an arbitrary function) with cosmological constant Λ. For t → ∞ we obtain $p=?\rho$ dark energy situation with small constant values of cosmological constant in three different f(R, T) gravitation models. In our solutions magnetic field does not observe also we have transformed our solutions from FRW universe to Static Einstein Universe (SEU) and we get f(R, T) gravity results for SEU universe. Finally we discussed our physical solutions.