Optimising Boltzmann codes for the Planck era Export

@article{Hamann:2009yy, abstract = {High precision measurements of the Cosmic Microwave Background (CMB) anisotropies, as can be expected from the Planck satellite, will require high-accuracy theoretical predictions as well. One possible source of theoretical uncertainty is the numerical error in the output of the Boltzmann codes used to calculate angular power spectra. In this work, we carry out an extensive study of the numerical accuracy of the public Boltzmann code CAMB, and identify a set of parameters which determine the error of its output. We show that at the current default settings, the cosmological parameters extracted from data of future experiments like Planck can be biased by several tenths of a standard deviation for the six parameters of the standard Lambda-CDM model, and potentially more seriously for extended models. We perform an optimisation procedure that leads the code to achieve sufficient precision while at the same time keeping the computation time within reasonable limits. Our conclusion is that the contribution of numerical errors to the theoretical uncertainty of model predictions is well under control -- the main challenges for more accurate calculations of CMB spectra will be of an astrophysical nature instead.}, archivePrefix = {arXiv}, author = {Hamann, Jan and Balbi, Amedeo and Lesgourgues, Julien and Quercellini, Claudia}, citeulike-article-id = {4450062}, citeulike-linkout-0 = {http://arxiv.org/abs/0903.0382}, citeulike-linkout-1 = {http://arxiv.org/pdf/0903.0382}, day = {2}, eprint = {0903.0382}, keywords = {boltzmann-code, camb, cmb}, month = {Mar}, posted-at = {2009-05-01 17:02:00}, priority = {2}, title = {Optimising Boltzmann codes for the Planck era}, url = {http://arxiv.org/abs/0903.0382}, year = {2009} }

TY - JOUR ID - Hamann:2009yy L3 - citeulike-article-id:4450062 N2 - High precision measurements of the Cosmic Microwave Background (CMB) anisotropies, as can be expected from the Planck satellite, will require high-accuracy theoretical predictions as well. One possible source of theoretical uncertainty is the numerical error in the output of the Boltzmann codes used to calculate angular power spectra. In this work, we carry out an extensive study of the numerical accuracy of the public Boltzmann code CAMB, and identify a set of parameters which determine the error of its output. We show that at the current default settings, the cosmological parameters extracted from data of future experiments like Planck can be biased by several tenths of a standard deviation for the six parameters of the standard Lambda-CDM model, and potentially more seriously for extended models. We perform an optimisation procedure that leads the code to achieve sufficient precision while at the same time keeping the computation time within reasonable limits. Our conclusion is that the contribution of numerical errors to the theoretical uncertainty of model predictions is well under control -- the main challenges for more accurate calculations of CMB spectra will be of an astrophysical nature instead. TI - Optimising Boltzmann codes for the Planck era KW - boltzmann-code KW - camb KW - cmb AU - Hamann, Jan AU - Balbi, Amedeo AU - Lesgourgues, Julien AU - Quercellini, Claudia PY - 2009/Mar/02/ UR - http://arxiv.org/abs/0903.0382 ER -