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Published on: August 12, 2013
Tensor modes from a primordial Hagedorn phase of string cosmology
Robert H Brandenberger1, Ali Nayeri, Subodh P Patil
1Department of Physics, McGill University, Montréal QC, H3A 2T8, Canada. rhb@hep.physics.mcgill.ca
Physical Review Letters
|August 7, 2007
Summary
String gas cosmology
Area of Science:
- Cosmology
- String Theory
- Theoretical Physics
Background:
- String gas cosmology offers a new mechanism for generating primordial fluctuations.
- Traditional models often rely on cosmic inflation, which requires a period of accelerated expansion (de Sitter expansion).
Purpose of the Study:
- To compute the spectrum of tensor metric fluctuations (gravitational waves) within the Hagedorn phase of string gas cosmology.
- To compare the predicted spectra of scalar and tensor fluctuations with those from slow-roll inflation.
Main Methods:
- Calculation of the primordial gravitational wave spectrum.
- Analysis of the spectral tilt for both scalar and tensor modes.
Main Results:
- The spectrum of tensor metric fluctuations is found to be nearly scale-invariant.
- Unlike scalar modes, tensor modes exhibit a small blue tilt, contrasting with slow-roll inflation predictions.
Conclusions:
- The Hagedorn phase of string gas cosmology provides a causal mechanism for generating nearly scale-invariant scalar and tensor fluctuations.
- The distinct spectral tilts of scalar and tensor modes offer a potential observational signature to differentiate this model from conventional slow-roll inflation.
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