Tachyon Field in Cosmology

Abstract

We study cosmological effects of homogeneous tachyon field as dark energy. We concentrate on two different scalar field potentials, the inverse square potential and the exponential potential. These models have a unique feature that the matter density parameter and the density parameter for tachyons remain comparable for a large range in redshift. It is shown that there exists a range of parameters for which the universe undergoes an accelerated expansion and the evolution is consistent with structure formation requirements. For a viable model we require fine tuning of parameters comparable to that in LCDM or in quintessence models. For the exponential potential, the accelerated phase is followed by a phase with a(t)~ t^{2/3} thus eliminating a future horizon.

arXiv comment3 pages, based on talk at PASCOS'03. To appear in special issue of Pramana

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• Constraining non-minimally coupled tachyon fields by Noether symmetry
• Cosmological model with fermion and tachyon fields interacting via Yukawa-type potential
• Understanding the origin of CMB constraints on Dark Energy
• Evolution of perturbations in distinct classes of canonical scalar field models of dark energy
• Dark Sector from Interacting Canonical and Non-Canonical Scalar Fields
• Evolution of Dark Energy Perturbations for Slotheon Field and Power Spectrum
• Chaplygin Gas of Tachyon Nature Imposed by Symmetry and Constrained via H(z) Data
• Interacting tachyon with varying mass dark matter
• Perturbations In Some Dark Energy Models
• Phase space analysis and cosmography of a two-fluid cosmological model