Constraining accelerating models of the universe with SNe type IA, galaxy clusters, small-scale structure and complementary observations

Abstract

Current observations based on Type Ia Supernovae are indicating that the present Universe is accelerating (see Amanulah et al. 2010 and Refs. there in). Such observations are suggesting that the bulk of energy density in the Universe is repulsive and may appear like a dark energy component [in addition to the ordinary dark matter] which is probably of primordial origin.This is the interpretation currently adopted by the main stream of Cosmology. All available data are in good agreement with the cosmic concordance model, i.e., a vacuum energy plus cold dark matter (CDM) scenario (Spergel 2007, Komatsu et al. 2008). However, ›CDM models are plagued with some basic conceptual dificulties: (i) the coincidence problem, (ii) the cosmological constant problem, and (iii) the so-called small-scale problems (Del Popolo & Gamberra 1998; Del Popolo 2001; Perivoloropoulos 2008) which includes: the origin of the angular momentum of galaxies, the central density problem (Zentner & Bullock 2002), and the statistics of satellites (Primack 2009). In this context, the basic aim of this one year research project is described with some detail in the 8 topics presented in the main text (see research proposal). In general lines, the main objective of the project is to confront the ›CDM model with some alternative cosmologies, with emphasis on models with creation of cold dark matter (CCDM) recently proposed by our group (see main text). In this kind of model there is a reduction of the dark sector since the Universe accelerates due to the existence of a negative creation pressure, that is, there is no dark energy. The interest in our approach is that we will apply a joint analysis envolving data from large scale (see subproject 3-4) and small scales (subprojects 5-8). (AU)