Non-Adiabaticity from Adiabatic Perturbations
Brown, Iain (Institute for Theoretical Astrophysics, University of Oslo)

Observations of the CMB suggest that the initial perturbations generated during inflation were predominantly adiabatic in nature. However, in a multifluid system adiabaticity is not conserved and the differing evolutions of density perturbations gives rise to a non-adiabatic pressure perturbation which could have consequences at higher orders in perturbation theory. We present the non-adiabatic pressure perturbation generated in the concordance cosmology and examine the main contributors and the scaling behaviours in redshift and wavenumber.