The cluster abundance in cosmic string models for structure formation |
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| Authors: | P P Avelino J H P Wu E P S Shellard |
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| Institution: | Centro de Astrofísica, Universidade do Porto, Rua das Estrelas s/n, 4150-762 Porto, Portugal;Dep. de Física da Faculdade de Ciências da Universidade do Porto, Rua do Campo Alegre 687, 4169-007 Porto, Portugal;Astronomy Department, University of California, Berkeley, CA 94720-3411, USA;Department of Applied Mathematics and Theoretical Physics, University of Cambridge, Silver Street, Cambridge CB3 9EW |
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| Abstract: | We use the present observed number density of large X-ray clusters to constrain the amplitude of matter density perturbations induced by cosmic strings on the scale of 8 h −1 Mpc ( σ 8), in both open cosmologies and flat models with a non-zero cosmological constant. We find a slightly lower value of σ 8 than that obtained in the context of primordial Gaussian fluctuations generated during inflation. This lower normalization of σ 8 results from the mild non-Gaussianity on cluster scales, where the one-point probability distribution function is well approximated by a χ 2 distribution and thus has a longer tail than a Gaussian distribution. We also show that σ 8 normalized using cluster abundance is consistent with the COBE normalization. |
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| Keywords: | cosmic strings galaxies: clusters: general cosmology: theory large-scale structure of Universe |
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