|Speaker||Talk Date||Talk Series|
|Oliver Piattella (Portsmouth)||8 July, 2009||Institute of Astronomy Seminars|
We investigate a new class of Unified Dark Matter (UDM) models described by adiabatic equations of state which are able to avoid the no-go theorem by Sandvik-Tegmark-Zaldarriaga-Waga (2004). In particular, we investigate those UDM models which allow a fast transition of the pressure during the dark matter epoch. These models avoid the strong time evolution of the gravitational potential and, consequently, they lead to structure formation. In more detail, we analyse their properties from the point of view of the background and perturbative evolution and compare the predicted CMB anisotropies and matter power spectrum with observation.