Integrated Sachs-Wolfe tomography with orthogonal polynomials

TL;DR

This paper introduces a novel tomographic method using orthogonal polynomials to enhance the detection of the integrated Sachs-Wolfe effect, improving parameter constraints in cosmology.

Contribution

It develops a new orthogonal polynomial-based tomography technique for iSW measurements and demonstrates its effectiveness in increasing signal-to-noise ratio and parameter estimation accuracy.

Findings

16% increase in signal-to-noise ratio for cross-spectra

Up to 30% improvement in parameter errors

Errors decrease with higher polynomial order

Abstract

Topic of this article are tomographic measurements of the integrated Sachs-Wolfe effect with specifically designed, orthogonal polynomials which project out statistically independent modes of the galaxy distribution. The polynomials are contructed using the Gram-Schmidt orthogonalisation method. To quantify the power of the iSW-effect in contraining cosmological parameters we perfom a combined Fisher matrix analysis for the iSW-, galaxy- and cross-spectra for wCDM cosmologies using the survey characteristics of PLANCK and EUCLID. The signal to noise ratio has also been studied for other contemporary galaxy surveys, such as SDSS, NVSS and 2MASS. For the cross-spectra our tomographic method provides a 16% increase in the signal to noise ratio and an improvement of up to 30% in conditional errors on parameters. Including all spectra, the marginalised errors approach an inverse square-root dependence with increasing cumulative polynomial order which underlines the statistical independence of the weighted signal spectra.