ar X iv : a st ro - p h / 96 02 01 8 v 1 3 F eb 1 99 6 Global textures and the Doppler peaks
نویسندگان
چکیده
We review recent work aimed at showing how global topolog-ical defects influence the shape of the angular power spectrum of the cosmic microwave background radiation on small scales. While Sachs–Wolfe fluctuations give the dominant contribution on angular scales larger than about a few degrees, on intermediate scales, 0.1 • < ∼ θ < ∼ 2 • , the main rôle is played by coherent oscillations in the baryon radiation plasma before recombination. In standard cosmological models these oscillations lead to the 'Doppler peaks' in the angular power spectrum. Inflation–based cold dark matter models predict the location of the first peak to be at ℓ ∼ 220/ √ Ω 0 , with a height which is a few times the level of anisotropies at large scales. Here we focus on perturbations induced by global textures. We find that the height of the first peak is reduced and is shifted to ℓ ∼ 350.
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