Cosmology between QUaD and the CMB

Turner, Abigail 2009. Cosmology between QUaD and the CMB. PhD Thesis, Cardiff University.

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Abstract

QUaD is a ground based bolometric polarimeter which observed the cosmic microwave background (CMB) at 100 and 150 GHz for three austral winters. Two different techniques field differencing and ground template subtraction, were used to analyze the data providing highly accurate maps and power spectra of both temperature and polarization. These measurements were then used to constrain cosmological parameters and in conjunction with the results of several other experiments further our knowledge and understanding of cosmology in the early universe. This thesis presents an investigation into the astrophysical phenomena in the fore ground of QUaD's observation region. Although an area with minimal foreground was selected for the experiment, nevertheless between QUaD and the CMB there are various sources of millimeter radiation that could potentially contaminate the measurements. Template temperature maps of the dust and synchrotron radiation in the region are extrapolated to CMB frequencies and correlated with QUaD's maps to quantify the extent of any structure similarity detected. These are compared with the correlation expected by chance in a single universe to confirm the cleanliness of the field and highlight the robustness of the published CMB results. The residual signal persistently observed in the difference spectrum between QUaD's 100 GHz and 150 GHz frequency data is fitted against template spectra for the far infrared background (FIRB) and the Sunyaev-Zel'dovich (SZ) effect. The fitting analysis serves to constrain the parameters, b (the galaxy clustering bias), and a8 (the rms mass fluctuations in a Sh l Mpc sphere) upon which the amplitudes of the template spectra are dependent. The contribution to the power from the predicted background of radio point sources is subtracted before a simultaneous fit to the two parameters is carried out. It is found that cr8 = l.lllo!o6 = 3-2T to 23. Whilst these values are shown to be consistent with other recent astronomical results, the amplitudes of the FIRB and SZ effect they imply are, once extrapolated to high-, incompatible with the QUaD data on these angular scales. This suggests that some other factors perhaps instrumental systematics, features in the analysis pipeline, or indeed other astrophysical phenomena could also be responsible for the signal seen in the frequency difference spectrum.

Item Type:	Thesis (PhD)
Status:	Unpublished
Schools:	Physics and Astronomy
Subjects:	Q Science > QB Astronomy
ISBN:	9781303215308
Date of First Compliant Deposit:	30 March 2016
Last Modified:	25 Oct 2017 14:37
URI:	https://orca.cardiff.ac.uk/id/eprint/54902

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