The Einstein static universe in Scalar-Fluid theories
  A new Lagrangian framework has recently been proposed to describe
interactions between relativistic perfect fluids and scalar fields. In this
paper we investigate the Einstein static universe in this new class of
theories, which have been named Scalar-Fluid theories. The stability of the
static solutions to both homogeneous and inhomogeneous perturbations is
analysed deriving the relevant cosmological perturbation equations at the
linear order. We can find several configurations corresponding to an Einstein
static universes which are stable against inhomogeneous perturbations, but
unstable against homogeneous perturbations. This shows the possible
applications of Scalar-Fluid theories to the inflationary emergent universe
scenario.
