Conformally coupled tachyonic dark energy
Abstract
We present and study a conformally coupled dark energy model, characterized by an interaction between a tachyon field ϕ , with an inverse square potential V (ϕ ), and the matter sector. A detailed analysis of the cosmological outcome reveals different possibilities, in contrast with the previously studied uncoupled model, for which there exists only one stable critical point that gives latetime acceleration of the Universe. The introduction of the coupling translates into an energy exchange between the fluids. We find the interesting possibility of the emergence of a new fixed point, which is a scaling solution and an attractor of the system. In this case, it is possible to describe an everlasting Universe with Ω_{ϕ}≃0.7 , therefore alleviating the cosmic coincidence problem. However, we find that, in order for the evolution to be cosmologically viable, there is the need to introduce one uncoupled matter species, dominant at early times.
 Publication:

Physical Review D
 Pub Date:
 August 2019
 DOI:
 10.1103/PhysRevD.100.043539
 arXiv:
 arXiv:1903.06028
 Bibcode:
 2019PhRvD.100d3539T
 Keywords:

 General Relativity and Quantum Cosmology
 EPrint:
 18 pages, 7 figures. V3: Matches published version