Voce esta aquiSimulating large scale structure observables with lognormal fields: a new approach
Simulating large scale structure observables with lognormal fields: a new approach
It is common practice in cosmology to use lognormal random fields to model large-scale structure observables such as matter density and weak lensing convergence. However, I will show that lognormal fields have fundamental limitations which prevent its use for jointly modelling these two observables and will propose two ways of overcoming these limitations. The first approach slightly distorts the power spectra of the fields while the second one generates a different weak lensing convergence marginal distribution by intergrating the lognormal density along the line of sight. The latter approach also provides a way to determine directly from theory the skewness of the convergence distribution and, therefore, the parameters for a lognormal fit. We present the public code Full-sky Lognormal Astro-fields Simulation Kit (FLASK) which can make tomographic realisations on the sphere of an arbitrary number of correlated lognormal or Gaussian random fields by applying either of the two proposed solutions, and show that it can create joint simulations of clustering and lensing with sub-per-cent accuracy over relevant angular scales and redshift ranges.