Exhaustive study of cosmic microwave background anisotropies in quintessential scenarios - art. no. 103505

Recent high-precision measurements of the CMB anisotropies performed by the BOOMERanG and MAXIMA-1 experiments provide an unmatched set of data allowi ng us to probe different cosmological models. Among these scenarios, motiva ted by the recent measurements of the luminosity distance versus redshift r elation for type Ia supernovas, is the quintessence hypothesis. It consists of assuming that the acceleration of the Universe is due to a scalar field whose final evolution is insensitive to the initial conditions. Within thi s framework we investigate the cosmological perturbations for two well-moti vated potentials: the Ratra-Peebles and the SUGRA tracking potentials. We s how that the solutions of the perturbed equations possess an attractor and that, as a consequence, the insensitivity to the initial conditions is pres erved at the perturbed level. Then. we study the predictions of these two m odels for structure formation and CMB anisotropies and investigate the gene ral features of the multipole moments in the presence of quintessence. We a lso compare the CMB multipoles calculated with the help of a full Boltzmann code with the BOOMERanG and MAXIMA-I data. We pay special attention to the location of the second peak and demonstrate that it significantly differs from the location obtained in the cosmological constant case. Finally, we a rgue that the SUGRA potential is compatible with all the recent data with s tandard values of the cosmological parameters. In particular, it fits the M AXIMA-1 data better than a cosmological constant or the Ratra-Peebles poten tial.