Help Guide Disclaimer Contact us Login
  Advanced SearchBrowse




Journal Article

A Lambda CDM bounce scenario


Wilson-Ewing,  Edward
Quantum Gravity & Unified Theories, AEI-Golm, MPI for Gravitational Physics, Max Planck Society;

There are no locators available
Fulltext (public)

(Preprint), 538KB

(Any fulltext), 706KB

Supplementary Material (public)
There is no public supplementary material available

Cai, Y.-F., & Wilson-Ewing, E. (2015). A Lambda CDM bounce scenario. Journal of Cosmology and Astroparticle Physics, (03): 006. doi:10.1088/1475-7516/2015/03/006.

Cite as:
We study a contracting universe composed of cold dark matter and radiation, and with a positive cosmological constant. As is well known from standard cosmological perturbation theory, under the assumption of initial quantum vacuum fluctuations the Fourier modes of the comoving curvature perturbation that exit the (sound) Hubble radius in such a contracting universe at a time of matter-domination will be nearly scale-invariant. Furthermore, the modes that exit the (sound) Hubble radius when the effective equation of state is slightly negative due to the cosmological constant will have a slight red tilt, in agreement with observations. We assume that loop quantum cosmology captures the correct high-curvature dynamics of the space-time, and this ensures that the big-bang singularity is resolved and is replaced by a bounce. We calculate the evolution of the perturbations through the bounce and find that they remain nearly scale-invariant. We also show that the amplitude of the scalar perturbations in this cosmology depends on a combination of the sound speed of cold dark matter, the Hubble rate in the contracting branch at the time of equality of the energy densities of cold dark matter and radiation, and the curvature scale that the loop quantum cosmology bounce occurs at. Finally, for a small sound speed of cold dark matter, this scenario predicts a small tensor-to-scalar ratio.