Towards Precision Cosmology on the Largest Observable Scales

cosmology;Cosmic Microwave Background;large scale structure;Dark Energy Survey;systematic errors;simulations;Physics;Science;Physics

Muir, JessicaPierce, Aaron Thomas ;

University of Michigan

关键词: cosmology;    Cosmic Microwave Background;    large scale structure;    Dark Energy Survey;    systematic errors;    simulations;    Physics;    Science;    Physics;   

Others  :  https://deepblue.lib.umich.edu/bitstream/handle/2027.42/146041/jlmuir_1.pdf?sequence=1&isAllowed=y

瑞士|英语

来源: The Illinois Digital Environment for Access to Learning and Scholarship

【 摘 要 】

One of the primary goals of cosmology is to extract information about fundamental physics from observations of the universe on large scales.With the advent of increasingly large cosmological datasets (and correspondingly small statistical uncertainties), future progress in the field will fundamentally be determined by our ability to account for systematic errors, understand model predictions, and protect analyses from sources of bias. This thesis presents three projects in this theme. We first examine the interpretation of large-angle features of the Cosmic Microwave Background (CMB) which are statistically unlikely in Lambda-CDM. Particularly, we study some of these features might be due to the imprint of large scale structure (LSS) through the integrated Sachs-Wolfe (ISW) effect, testing the reliability of a method forISW signal reconstruction based on LSS data. Using simulated ISW and LSS maps, we show thatdirection-dependent calibration errors are by far the most limiting survey systematic and that for current levels of calibration control, reconstructed ISW maps from existing data are almost entirely noise. Thus, current data cannot be reliably used to separate primordial and late-time contributions to CMB features. We additionally use ensembles of simulated CMB maps toperform a comprehensive study of the covariance between eight features associated with commonly studied large-angle anomalies. The latter part of this thesis shifts its focus to LSS data, introducing a new method for blinding theDark Energy Survey;;s (DES) combined analysis of correlations between galaxy positions and weak lensing shear.This technique, which works by modifying LSS tracers;; two-point correlation functions, will be used to prevent experimenter bias from influencing DES;; precision measurements of dark energy. We demonstrate using simulated DES Year 3 datathat this method successfully shifts the analysis pipeline;;s output cosmological parameters while preserving the ability to check for systematic errors. Given this, the technique will be used to blind the DES Year 3 multi-probe cosmology analyses, and as implemented, will be the most sophisticated blinding strategy for a cosmology analysis to date. Together, these three projects represent varied ways characterizing and developing tools for ensuring future tests of Lambda-CDM are both precise and accurate.