Cosmological tachyon condensation

TL;DR

This paper explores the unification of dark matter and dark energy using k-essence theories, developing models that incorporate pressure effects and inhomogeneities, and demonstrating their evolution into mixed systems resembling cold dark matter.

Contribution

It introduces a framework connecting k-essence scalar fields with hydrodynamic and braneworld descriptions, extending dust models to include pressure and acoustic horizons, and applies this to tachyon models.

Findings

Inhomogeneous tachyon models evolve into dark matter-like condensates.

The methods are applicable to various dark energy and dark matter mixtures.

The variable Chaplygin gas model shows significant dark matter components.

Abstract

We consider the prospects for dark matter/energy unification in k-essence type theories. General mappings are established between the k-essence scalar field, the hydrodynamic and braneworld descriptions. We develop an extension of the general relativistic dust model that incorporates the effects of both pressure and the associated acoustic horizon. Applying this to a tachyon model, we show that this inhomogeneous "variable Chaplygin gas" does evolve into a mixed system containing cold dark matter like gravitational condensate in significant quantities. Our methods can be applied to any dark energy model as well as to mixtures of dark energy and traditional dark matter.