Combined cosmological tests of a bivalent tachyonic dark energy scalar field model

Abstract

A recently investigated tachyonic scalar field dark energy dominated universe exhibits a bivalent future: depending on initial parameters can run either into a de Sitter exponential expansion or into a traversable future soft singularity followed by a contraction phase. We also include in the model (i) a tiny amount of radiation, (ii) baryonic matter (${\Omega }_b{h}^2=0.022161$, where the Hubble constant is fixed as $h=0.706$) and (iii) cold dark matter (CDM). Out of a variety of six types of evolutions arising in a more subtle classification, we identify two in which in the past the scalar field effectively degenerates into a dust (its pressure drops to an insignificantly low negative value). These are the evolutions of type IIb converging to de Sitter and type III hitting the future soft singularity. We confront these background evolutions with various cosmological tests, including the supernova type Ia Union 2.1 data, baryon acoustic oscillation distance ratios, Hubble parameter-redshift relation and the cosmic microwave background (CMB) acoustic scale. We determine a subset of the evolutions of both types which at 1$\sigma$ confidence level are consistent with all of these cosmological tests. At perturbative level we derive the CMB temperature power spectrum to find the best agreement with the Planck data for ${\Omega }_{CDM}=0.22$. The fit is as good as for the $\Lambda$CDM model at high multipoles, but the power remains slightly overestimated at low multipoles, for both types of evolutions. The rest of the CDM is effectively generated by the tachyonic field, which in this sense acts as a combined dark energy and dark matter model.

25 pages, 15 figures

References in corpus (16)

• Cosmology and the Fate of Dilatation Symmetry
• Baryon Acoustic Oscillations in the Lyα forest of BOSS DR11 quasars
• Model independent evidence for dark energy evolution from Baryon Acoustic Oscillations
• CMB anisotropies from primordial inhomogeneous magnetic fields
• Kinetic k-essence and Quintessence
• How well do we understand cosmological recombination?
• DBI-essence
• Quantum cosmology with big-brake singularity
• Effective field theory of modified gravity with two scalar fields: dark energy and dark matter
• Singular fate of the universe in modified theories of gravity
• Affine equation of state from quintessence and k-essence fields
• How far is it to a sudden future singularity of pressure?
• Viscous dissipative Chaplygin gas dominated homogenous and isotropic cosmological models
• Tachyon cosmology, supernovae data and the Big Brake singularity
• Will the tachyonic Universe survive the Big Brake?
• Constraints on the generalized tachyon field models from latest observational data

Cited by in corpus (3)

• Gravitational Waves in Locally Rotationally Symmetric (LRS) Class II Cosmologies
• Dark energy and dark matter perturbations in singular universes
• Criticality and Big Brake singularities in the tachyonic evolutions of closed Friedmann universes with cold dark matter