General conditions for scale-invariant perturbations in an expanding universe
Journal Article
·
· Journal of Cosmology and Astroparticle Physics
We investigate the general properties of expanding cosmological models which generate scale-invariant curvature perturbations in the presence of a variable speed of sound. We show that in an expanding universe, generation of a super-Hubble, nearly scale-invariant spectrum of perturbations over a range of wavelengths consistent with observation requires at least one of three conditions: (1) accelerating expansion, (2) a speed of sound faster than the speed of light, or (3) super-Planckian energy density.
- OSTI ID:
- 22280144
- Journal Information:
- Journal of Cosmology and Astroparticle Physics, Vol. 2011, Issue 11; Other Information: Country of input: International Atomic Energy Agency (IAEA); ISSN 1475-7516
- Country of Publication:
- United States
- Language:
- English
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