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Simulations and Observations of the Microwave Universe
Michael Peel
[Thesis].The University of Manchester;2009.
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Abstract
Simulations and observations of the microwave sky are of great importance for under- standing the Universe that we reside in. Specifically, knowledge of the Cosmic Mi- crowave Background (CMB) and its foregrounds – including the Sunyaev-Zel’dovich (SZ) effect from clusters of galaxies and radio point sources – tell us about the Universe on its very largest scales, and also what the Universe is made of.We describe the creation of software to carry out large numbers of virtual sky sim- ulations. The simulations include the CMB, SZ effect and point sources, and are de- signed to examine the effects of point sources and the SZ effect on present and recent observations of the CMB. Utilizing sets of 1,000 simulations, we find that the power spectrum resulting from the SZ effect is expected to have a larger standard deviation by a factor of 3 than would be expected from purely Gaussian realizations. It also has a distribution that is significantly skewed towards increased values for the power spectrum, especially when small map sizes are used. The effects of the clustering of galaxy clusters, residual point sources and uncertainties in the gas physics are also in- vestigated, as are the implications for the excess power measured in the CMB power spectrum by the CBI and BIMA experiments. We also investigate the possibility of using the One Centimetre Receiver Array (OCRA) receivers to observe the CMB and measure this high-multipole excess.An automated data reduction package has been created for the OCRA receivers, which has been used in end-to-end simulations for OCRA-p observations of point sources. We find that these simulations are able to realistically simulate the noise present in real observations, and that the introduction of 1/ f noise into the simulations significantly reduces the predicted ability of the instruments to observe weak sources by measuring the sources for long periods of time.The OCRA-p receiver has been used to observe point sources in the Very Small Array fields so that they can be subtracted from observations of the CMB power spectrumWe find that these point sources are split between steep and flat spectrum sources. We have also observed 550 CRATES flat spectrum radio sources, which will be useful for comparison to Planck satellite observations.Finally, the assembly and commissioning of the OCRA-F receiver is outlined. This receiver is now installed on the Torun ́ 32-m telescope, and is currently being calibrated prior to starting observations in the next few months.This thesis was submitted by Michael Peel to The University of Manchester for the degree of Doctor of Philosophy in the Faculty of Engineering and Physical Sciences on the 18th December 2009.