Axion-dilaton cosmology and dark energy

Journal Article · Sat Mar 15 04:00:00 EDT 2008 · Journal of Cosmology and Astroparticle Physics

DOI:https://doi.org/10.1088/1475-7516/2008/03/012· OSTI ID:22137809

Catena, Riccardo; Moeller, Jan ^[1]

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1. Deutsches Elektronen-Synchrotron DESY, Theory Group, Notkestrasse 85, D-22603 Hamburg (Germany)

We discuss a class of flat FRW cosmological models based on D = 4 axion-dilaton gravity universally coupled to cosmological background fluids. In particular, we investigate the possibility of recurrent acceleration, which was recently shown to be generically realized in a wide class of axion-dilaton models, but in the absence of cosmological background fluids. We observe that, once we impose the existence of radiation- and matter-dominated earlier stages of cosmic evolution, the axion-dilaton dynamics is altered significantly with respect to the case of pure axion-dilaton gravity. Explicit computations are done considering a universal metric coupling between the dilaton and the matter fields. As a result we find that during the matter-dominated epoch the scalar fields remain either frozen, due to the large expansion rate, or enter a cosmological scaling regime. In both cases, oscillations of the effective equation of state around the acceleration boundary value are impossible. Models which enter an oscillatory stage in the low redshift regime, on the other hand, are disfavored by observations. We also comment on the viability of the axion-dilaton system as a candidate for dynamical dark energy. In a certain subclass of models, an intermediate scaling regime is succeeded by eternal acceleration. We also briefly discuss the issue of dependence on initial conditions.

• OSTI ID: 22137809
• Journal Information: Journal of Cosmology and Astroparticle Physics, Journal Name: Journal of Cosmology and Astroparticle Physics Journal Issue: 03 Vol. 2008; ISSN 1475-7516
• Country of Publication: United States
• Language: English

Related Subjects

79 ASTRONOMY AND ASTROPHYSICS
AXIONS
CALCULATION METHODS
COSMOLOGICAL MODELS
COSMOLOGY
EQUATIONS OF STATE
GRAVITATION
METRICS
NONLUMINOUS MATTER
OSCILLATIONS
RED SHIFT
SCALAR FIELDS