In this work we illustrate how form-invariance transformations (FIT) can be used to construct phantom and complementary tachyon cosmologies from standard tachyon field universes. First we show how these transformations act ...

We investigate a flat Friedmann-Robertson-Walker spacetime filled with k essence and find the set of functions F that generate three different families of extended tachyon fields and Chaplygin gases. They lead to accelerated ...

In the present work the power spectrum of a particular class of tachyon fields is compared with the one corresponding to a cosmological constant model. This is done for different barotropic indexes (Formula presented.) and ...

We investigate a k-essence field localized on the brane evolving linearly with the cosmological time for some kinetic functions and consider the atypical k-essence model for linear and nonlinear k-fields in FriedmannRobe ...

We devise a method to obtain a phantom version of FRW k-essence cosmologies with homogeneous k fields by applying form-invariance transformations. It can be seen that the transformation performs the maps [Formula Presented] ...

We investigate a Bianchi type-I cosmology with k-essence and find the set of models which dissipate the initial anisotropy. There are cosmological models with extended tachyon fields and k-essence having a constant barotropic ...