A Search for Cosmic Microwave Background Anisotropies on Arcminute Scales

Citation

Sayers, Jack (2008) A Search for Cosmic Microwave Background Anisotropies on Arcminute Scales. Dissertation (Ph.D.), California Institute of Technology. doi:10.7907/2Q9Q-JA33. https://resolver.caltech.edu/CaltechETD:etd-12232007-013248

Abstract

This thesis describes the results of two sets of observations made in 2003 and 2004 using Bolocam from the Caltech Submillimeter Observatory (CSO), along with a description of the design and performance of the instrument. Bolocam is a large format camera consisting of 144 bolometers with an eight arcminute field of view at the CSO, and can be operated non-simultaneously at 1.1, 1.4, or 2.1 mm. All of the data described in this thesis was collected at 2.1 mm, where the individual beams are approximately one arcminute in size. The observations were made over a total of seventy-nine nights, and consisted of surveys of two science fields, Lynx and the Subaru/XMM Deep Field (SDS1), covering a total area of approximately 1 square degree. The noise properties of the maps are extremely uniform, with RMS variations in coverage of approximately 1.5% for twenty arcsecond map pixels. The point source sensitivity of the maps is approximately 100 μK_CMB per beam. Fluctuations in emission from the atmosphere limited the sensitivity of our measurements, and several algorithms designed to remove these fluctuations are described. These algorithms also removed astronomical flux, and simulations were used to determine the effect of this attenuation on a CMB power spectrum. Assuming a flat CMB band power in C_ℓ, our data corresponds to an effective angular multipole of ℓ_eff = 5700, with a FWHM_ℓ = 2800. At these scales the CMB power spectrum is expected to be dominated by anisotropies induced by the Sunyaev-Zel'dovich effect (SZE), and have a reasonably flat spectrum. Our data is consistent with a band power of C_ℓ = 0 μK²_CMB1, and an upper limit of C_ℓ < 755 μK²_CMB at a confidence level of 90%. From this result we find that σ₈ < 1.55 at a confidence level of 90%.

Thesis Files