The initial conditions of the universe: how much isocurvature is allowed?
arXiv:astro-ph/0401417 · doi:10.1103/PhysRevLett.93.081301
Abstract
We investigate the constraints imposed by the current data on correlated mixtures of adiabatic and non-adiabatic primordial perturbations. We discover subtle flat directions in parameter space that tolerate large (~60%) contributions of non-adiabatic fluctuations. In particular, larger values of the baryon density and a spectral tilt are allowed. The cancellations in the degenerate directions are explored and the role of priors elucidated.
4 pages, 4 figures. Submitted to PRL