TY - JOUR
T1 - Creating statistically anisotropic and inhomogeneous perturbations
AU - Armendariz-Picon, C.
PY - 2007/9/1
Y1 - 2007/9/1
N2 - In almost all structure formation models, primordial perturbations are created within a homogeneous and isotropic universe, like the one we observe. Because their ensemble averages inherit the symmetries of the spacetime in which they are seeded, cosmological perturbations then happen to be statistically isotropic and homogeneous. Certain anomalies in the cosmic microwave background on the other hand suggest that perturbations do not satisfy these statistical properties, thereby challenging perhaps our understanding of structure formation. In this paper we relax this tension. We show that if the universe contains an appropriate triad of scalar fields with spatially constant but non-zero gradients, it is possible to generate statistically anisotropic and inhomogeneous primordial perturbations, even though the energy-momentum tensor of the triad itself is invariant under translations and rotations.
AB - In almost all structure formation models, primordial perturbations are created within a homogeneous and isotropic universe, like the one we observe. Because their ensemble averages inherit the symmetries of the spacetime in which they are seeded, cosmological perturbations then happen to be statistically isotropic and homogeneous. Certain anomalies in the cosmic microwave background on the other hand suggest that perturbations do not satisfy these statistical properties, thereby challenging perhaps our understanding of structure formation. In this paper we relax this tension. We show that if the universe contains an appropriate triad of scalar fields with spatially constant but non-zero gradients, it is possible to generate statistically anisotropic and inhomogeneous primordial perturbations, even though the energy-momentum tensor of the triad itself is invariant under translations and rotations.
KW - Cosmological perturbation theory
KW - Inflation
KW - Physics of the early universe
UR - http://www.scopus.com/inward/record.url?scp=36048971120&partnerID=8YFLogxK
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U2 - 10.1088/1475-7516/2007/09/014
DO - 10.1088/1475-7516/2007/09/014
M3 - Article
AN - SCOPUS:36048971120
SN - 1475-7516
JO - Journal of Cosmology and Astroparticle Physics
JF - Journal of Cosmology and Astroparticle Physics
IS - 9
M1 - 014
ER -