  The Special Relativity allows the possibility of a class of particles, known
tachyons, that have spacelike 4-velocities, i.e., which move with velocity
greater than speed of light in vacuum. In this existence frame, the tachyons
have energy and momentum and they must contribute to the gravitational field
through by the means of the energy-momentum tensor. The superluminal perfect
fluid tensor is obtained assuming the framework Lagrangian formalism and
spacelike 4-velocities flowlines of tachyons with energy density. The perfect
fluid of tachyons gives rise a positive energy density and a form of negative
pressure, which according to various cosmological theoretical results, it is
associated with dark energy.

General Physics