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Scalar-field-dominated cosmology with a transient acceleration phase.
F C Carvalho1, J S Alcaniz, J A S Lima
1Observatório Nacional, Rua Gal. José Cristino 77, 20921-400 Rio de Janeiro, RJ, Brasil. fabiocc@on.br
Physical Review Letters
|October 10, 2006
Summary
This study introduces a new cosmological model with a scalar field that predicts a transient cosmic acceleration. This scenario offers an alternative to standard models and may resolve conflicts with string theory.
Area of Science:
- Cosmology
- Theoretical Physics
- Astroparticle Physics
Background:
- The standard cosmological model (Lambda-CDM) faces challenges reconciling dark energy with string/M-theory.
- Scalar fields are proposed candidates for dark energy, but their potentials require careful consideration.
Purpose of the Study:
- To investigate a new cosmological scenario driven by a scalar field with a specific exponential potential.
- To explore the implications of this model for cosmic evolution, including acceleration and deceleration phases.
Main Methods:
- Derivation of the equation of state for a homogeneous scalar field with a V(Phi) potential (exponential with quadratic and linear terms).
- Analysis of the predicted cosmic evolution, including past deceleration, current acceleration, and future deceleration.
- Confrontation of theoretical predictions for the scalar field + dark matter dominated era with cosmological observations.
Main Results:
- The model predicts a transient phase of cosmic acceleration, beginning around redshift z=1.
- The universe decelerated in the past, is currently accelerating, and is predicted to decelerate in the future.
- This dynamic behavior differs significantly from the standard Lambda-CDM model.
Conclusions:
- The proposed scalar field model offers a viable alternative to standard cosmology and may alleviate tensions with string/M-theory.
- The transient acceleration scenario warrants further investigation and observational testing.
- The model's predictions for the present epoch are consistent with current cosmological data.
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