2026-07-072026-07-07http://salesiana.dossiersoluciones.com/handle/123456789/8663Mainly used to set constraints on cosmological parameters, CMB anisotropies can give information on primordial universe. Unfortunately, initial conditions and late time cosmology are degenerated. I focus on the effect of the shape of the initial power spectrum of fluctuations on the cosmological parameter estimation from CMB temperature anisotropies. Strong constraints obtained using a priori knowledge of the initial spectrum disappear when the latter is let free.4 pages, Proceedings SF2A 2004 conference, Paris, eds.: F. Combes, D. Barret, T. Contini, F. Meynadier and L. PaganiAstrophysicstext