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Inflationary universe with anisotropic hair
Masa-Aki Watanabe1, Sugumi Kanno, Jiro Soda
1Department of Physics, Kyoto University, Kyoto, 606-8501, Japan.
Physical Review Letters
|June 13, 2009
Summary
This study shows that an anisotropic universe arises from coupling a vector field with an inflaton field during cosmic inflation. This anisotropic inflation is a tracking solution with observational implications for cosmology.
Area of Science:
- Cosmology
- Theoretical Physics
- Astrophysics
Background:
- Cosmic inflation is a leading theory explaining the early universe's rapid expansion.
- The cosmic no-hair conjecture posits that the universe should be isotropic after inflation.
- Previous models primarily focused on scalar fields, neglecting vector field dynamics.
Purpose of the Study:
- To investigate the cosmological implications of introducing a vector field coupled to the inflaton.
- To determine if such a coupling can lead to an anisotropic inflationary universe.
- To explore the observational consequences of anisotropic inflation.
Main Methods:
- Studying an inflationary scenario involving a vector field and an inflaton field.
- Analyzing the coupling functions between these fields.
- Deriving the behavior of the energy density of the vector field.
- Investigating the relationship between anisotropy and slow-roll parameters.
Main Results:
- Anisotropic inflation is shown to occur for a wide range of coupling functions.
- The vector field's energy density tracks the inflaton's energy density, forming a tracking solution.
- A universal relation is found between the degree of anisotropy and a key slow-roll parameter.
Conclusions:
- The coupling of vector and inflaton fields naturally leads to an anisotropic inflationary universe.
- This finding challenges the cosmic no-hair conjecture, providing a counterexample.
- The results have significant observational implications for understanding the early universe's properties.
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