The power spectrum of systematics in cosmic shear tomography and the bias on cosmological parameters
arXiv:1307.4857 · doi:10.1093/mnras/stt2357
Abstract
Cosmic shear tomography has emerged as one of the most promising tools to both investigate the nature of dark energy and discriminate between General Relativity and modified gravity theories. In order to successfully achieve these goals, systematics in shear measurements have to be taken into account; their impact on the weak lensing power spectrum has to be carefully investigated in order to estimate the bias induced on the inferred cosmological parameters. To this end, we develop here an efficient tool to compute the power spectrum of systematics by propagating, in a realistic way, shear measurement, source properties and survey setup uncertainties. Starting from analytical results for unweighted moments and general assumptions on the relation between measured and actual shear, we derive analytical expressions for the multiplicative and additive bias, showing how these terms depend not only on the shape measurement errors, but also on the properties of the source galaxies (namely, size, magnitude and spectral energy distribution). We are then able to compute the amplitude of the systematics power spectrum and its scaling with redshift, while we propose a multigaussian expansion to model in a non-parametric way its angular scale dependence. Our method allows to self-consistently propagate the systematics uncertainties to the finally observed shear power spectrum, thus allowing us to quantify the departures from the actual spectrum. We show that even a modest level of systematics can induce non-negligible deviations, thus leading to a significant bias on the recovered cosmological parameters.
19 pages, 5 tables, 4 figures
References in corpus (14)
- The Shear TEsting Programme 2: Factors affecting high precision weak lensing analyses
- Cosmology with Weak Lensing Surveys
- Bayesian Galaxy Shape Measurement for Weak Lensing Surveys -I. Methodology and a Fast Fitting Algorithm
- Systematic Bias in Cosmic Shear: Beyond the Fisher Matrix
- Image Analysis for Cosmology: Results from the GREAT10 Galaxy Challenge
- Means of confusion: how pixel noise affects shear estimates for weak gravitational lensing
- PSF calibration requirements for dark energy from cosmic shear
- Bayesian Galaxy Shape Measurement for Weak Lensing Surveys -II. Application to Simulations
- Probing dark energy with the shear-ratio geometric test
- Morphological evolution of galaxies from ultradeep HST WFC3 imaging: the Hubble sequence at z~2
- A combined analysis of 3D Weak Lensing, Lyman-alpha forest and WMAP year three data
- Cosmological Systematics Beyond Nuisance Parameters : Form Filling Functions
- Constraining Modified Gravity with Euclid
- Future weak lensing constraints in a dark coupled universe
Cited by in corpus (9)
- Cosmology with cosmic shear observations: a review
- SKA Weak Lensing III: Added Value of Multi-Wavelength Synergies for the Mitigation of Systematics
- Increasing the Lensing Figure of Merit through Higher Order Convergence Moments
- Angular ellipticity correlations in a composite alignment model for elliptical and spiral galaxies and inference from weak lensing
- Towards a Bias-Free Selection Function in Shear Measurement
- Quantifying systematics from the shear inversion on weak-lensing peak counts
- Statistical separation of weak gravitational lensing and intrinsic ellipticities based on galaxy colour information
- Optimising tomography for weak gravitational lensing surveys
- Dark energy model selection with current and future data