Constraining isocurvature initial conditions with WMAP 3-year data

Abstract

We present constraints on the presence of isocurvature modes from the temperature and polarization cosmic microwave background (CMB) spectrum data from the WMAP satellite alone, and in combination with other data sets including SDSS galaxy survey and SNLS supernovae. We find that the inclusion of polarization data allows the WMAP data alone, as well as in combination with complementary observations, to place improved limits on the contribution of CDM and neutrino density isocurvature components individually. With general correlations, the upper limits on these subdominant isocurvature components are reduced to $\ensuremath{\sim}60%$ of the first year WMAP results, with specific limits depending on the type of fluctuations. If multiple isocurvature components are allowed, however, we find that the data still allow a majority of the initial power to come from isocurvature modes. As well as providing general constraints we also consider their interpretation in light of specific theoretical models like the curvaton and double inflation.