Loop quantum cosmology and the Wheeler-De Witt equation

We present some results concerning the large volume limit of loop quantum cosmology in the flat homogeneous and isotropic case. We derive the Wheeler-De Witt equation in this limit. Looking for the action from which this equation can also be obtained, we then address the problem of the modifications to be brought to the Friedman's equation of motion and to the equation of motion of the scalar field, in the classical limit.Comment: 17 pages; 5 figure

The role of active galactic nuclei in galaxy formation

We use Monte-Carlo Markov chain techniques to constrain acceptable parameter regions for the Munich L-Galaxies semi-analytic galaxy formation model. Feedback from active galactic nuclei (AGN) is required to limit star-formation in the most massive galaxies. However, we show that the introduction of tidal stripping of dwarf galaxies as they fall into and merge with their host systems can lead to a reduction in the required degree of AGN feedback. In addition, the new model correctly reproduces both the metallicity of large galaxies and the fraction of intracluster light.Comment: Monster's Fiery Breath Conference Proceedings, 4 page

Inflaton Particles in Reheating

In many theories of reheating starting from the classical spatially homogeneous inflaton field, its accompanying inhomogeneous part (which arises from primordial quantum fluctuations) is treated as a first order perturbation. We examine some consequences of treating it non-perturbatively in a model where a first order treatment is invalid. In particular we consider effects on the long-wavelength curvature parameter relevant to the cosmic microwave background fluctuations.Comment: 14 pages, 4 figures;code corrected,figures and some conclusions change