منابع مشابه
The Doppler Peaks from Cosmic Texture
We compute the angular power spectrum of temperature anisotropies on the microwave sky in the cosmic texture theory, with standard recombination assumed. The spectrum shows`Doppler' peaks analogous to those in scenarios based on primordial adiabatic uctuations such as`standard CDM', but at quite diierent angular scales. There appear to be excellent prospects for using this as a discriminant bet...
متن کاملDoppler peaks from active perturbations.
We examine how the qualitative structure of the Doppler peaks in the angular power spectrum of the cosmic microwave anisotropy depends on the fundamental nature of the perturbations which produced them. The formalism of Hu and Sugiyama is extended to treat models with cosmic defects. We discuss how perturbations can be \active" or \passive" and \incoherent" or \coherent", and show how causality...
متن کاملThe Doppler peaks from a generic defect
We investigate which of the exotic Doppler peak features found for textures and cosmic strings are generic novelties pertaining to defects. We find that the “out of phase” texture signature is an accident. Generic defects, when they generate a secondary peak structure similar to inflation, apply to it an additive shift. It is not necessary for this shift to be “out of phase”. We also show which...
متن کاملCausality and the Doppler peaks.
A considerable experimental effort is underway to detect the ‘Doppler peaks’ in the angular power spectrum of the cosmic microwave anisotropy. These peaks offer unique information about structure formation in the universe. One key issue is whether structure could have formed by the action of causal physics within the standard hot big bang, or whether a prior period of inflation was required. Re...
متن کاملCosmic Microwave Background Anisotropies from Global Texture
We investigate the global texture model of structure formation in cosmogonies with non-zero cosmological constant for different values of the Hubble parameter. We find that the absence of significant acoustic peaks and little power on large scales are robust predictions of these models. However, from a careful comparison with experiments we conclude that at present we cannot safely reject the m...
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ژورنال
عنوان ژورنال: Physical Review Letters
سال: 1995
ISSN: 0031-9007,1079-7114
DOI: 10.1103/physrevlett.75.2642