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Title: Data analysis and modelling for observations of polarisation of the microwave sky
Author: Clark, Caroline Natasha
Awarding Body: Imperial College London
Current Institution: Imperial College London
Date of Award: 2013
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The cosmic microwave background (CMB) temperature and polarisation anisotropies contain a wealth of cosmological information concerning the formation and evolution of the universe. Upcoming CMB experiments targeting measurements of the B-mode polarisation pattern of the CMB face a major challenge both in terms of experimental design and data analysis due to the small amplitude of the signal and the presence of experimental systematic effects and polarised foregrounds. This thesis focuses on aspects of preparation for the Spider experiment. Spider is a balloon-borne polarimeter targeting CMB polarisation, it will launch in the Austral summer of 2013 for a long duration flight from Antarctica. It consists of large arrays of 512 detectors in each receiver, creating a large volume of data that is a challenge to analyse, especially when taking into account noise correlations between detectors. We develop SPIMPI, a mapmaking algorithm for estimating temperature and polarisation maps from Time Ordered Data (TOD). To test the mapmaker, realistic TOD containing signal and noise components are generated from the simulated Spider scan strategy. We use an iterative scheme for solving linear systems (the Preconditioned Conjugate Gradient method) to produce optimal estimates of temperature and polarisation. We present templates of the intensity and polarisation of emission from two of the main polarised Galactic foregrounds, interstellar dust and synchrotron radiation. We present estimates of the level of polarised foregrounds expected, focusing on high galactic latitudes and patches that will be targeted by upcoming experiments. We describe details of a model for the 3D Galactic magnetic field, examining both large and small scales. We include details of the dust and cosmic ray electron density distributions, grain alignment, the intrinsic polarisation of the emission from an individual grain and details of synchrotron emission mechanisms. We compare the templates with WMAP MCMC best-fit templates for these foreground components.
Supervisor: Contaldi, Carlo Sponsor: Science and Technology Facilities Council
Qualification Name: Thesis (Ph.D.) Qualification Level: Doctoral