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キーワード:
General Relativity and Quantum Cosmology, gr-qc,Astrophysics, Cosmology and Extragalactic Astrophysics, astro-ph.CO
要旨:
For a certain type of modified dispersion relations, the vacuum quantum state
for very short wavelength cosmological perturbations is scale-invariant and it
has been suggested that this may be the source of the scale-invariance observed
in the temperature anisotropies in the cosmic microwave background. We point
out that for this scenario to be possible, it is necessary to red-shift these
short wavelength modes to cosmological scales in such a way that the
scale-invariance is not lost. This can be done by inflation with a sufficiently
large Hubble rate, without any requirement for slow roll. We also show that in
the case of slow-roll inflation, modes that start in their vacuum quantum state
will become nearly scale-invariant when they exit the Hubble radius for any
power law modified dispersion relation.
