Weak lensing tomography with orthogonal polynomials


  • Björn Malte Schäfer,

    Corresponding author
    1. Astronomisches Recheninstitut, Zentrum für Astronomie, Universität Heidelberg, Mönchhofstraße 12, 69120 Heidelberg, Germany
      E-mail: bjoern.malte.schaefer@uni-heidelberg.de
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  • Lavinia Heisenberg

    1. Centre for Astroparticle Physics, Département de Physique Théorique, Université de Genève, 24 quai Ernest Ansermet, 1211 Genève, Switzerland
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E-mail: bjoern.malte.schaefer@uni-heidelberg.de


The topic of this paper is weak cosmic shear tomography where the line-of-sight weighting is carried out with a set of specifically constructed orthogonal polynomials, dubbed Tomography with Orthogonal Radial Distance Polynomial Systems (TaRDiS). We investigate the properties of these polynomials and employ weak convergence spectra, which have been obtained by weighting with these polynomials, for the estimation of cosmological parameters. We quantify their power in constraining parameters in a Fisher matrix technique and demonstrate how each polynomial projects out statistically independent information, and how the combination of multiple polynomials lifts degeneracies. The assumption of a reference cosmology is needed for the construction of the polynomials, and as a last point we investigate how errors in the construction with a wrong cosmological model propagate to misestimates in cosmological parameters. TaRDiS performs on a similar level as traditional tomographic methods and some key features of tomography are made easier to understand.