by owlice » Wed Jun 29, 2011 2:19 am CLASS: Cosmic Linear Anisotropy Solving System
Abstract: Boltzmann codes are used extensively by several groups for constraining cosmological parameters with Cosmic Microwave Background and Large Scale Structure data. This activity is computationally expensive, since a typical project requires from 10'000 to 100'000 Boltzmann code executions. The newly released code CLASS (Cosmic Linear Anisotropy Solving System) incorporates improved approximation schemes leading to a simultaneous gain in speed and precision. We describe here the three approximations used by CLASS for basic LambdaCDM models, namely: a baryon-photon tight-coupling approximation which can be set to first order, second order or to a compromise between the two; an ultra-relativistic fluid approximation which had not been implemented in public distributions before; and finally a radiation streaming approximation taking reionisation into account.
Credit: Diego Blas, Julien Lesgourgues, Thomas Tram
Site: http://lesgourg.web.cern.ch/lesgourg/class.html
http://arxiv.org/abs/1104.2933
http://arxiv.org/abs/1106.2607
ID: ascl:1106.020
