Some properties and implications of the creation pressure and the generalized equilibrium: modification of the adiabatic index, cosmological perturbations (Q776799)

The author describes the energy-momentum tensor of a linear barotropic fluid with constant specific entropy particle production within the framework of relativistic thermodynamics theories. Further, the generalized equilibrium condition is written as the effective energy-momentum tensor of a perfect linear barotropic fluid where the adiabatic index is a homographic function of the initial adiabatic index. She considers the energy density contrast and velocity perturbations within the framework of the gauge-invariant formalism. The modes of the energy density contrast and velocity perturbations are decaying faster than the corresponding modes for the perfect fluid perturbations in the particle number conservation case.